Total Knee Replacement

Take a look my thesis. It is a review of history of TKR

History

The awareness of the history of knee arthroplasty is necessary to appreciate not only its current status but also its future. In 1860 Verneuil used a flap of joint capsule as interpositional material to reconstruct the knee joint.

Soon after in 1861 W.Ferguson in an article “ excision of knee joint: recovery with a false joint and useful limb” described excision of the surfaces of an ankylosed tubercular knee joint. It resulted in early mobility, but later the joint used to fuse or it was unstable depending on the amount of bone that was resected.

Subsequently Ollier in 1886 used muscle as an interpositional material, Murphy in 1913 used fascia lata and Baer used pigs bladder in 1918. In 1930 Campbell utilized free fascial flaps and McAusland used fat in 1933. Cellophane was used in 1949 by Sampson. Nylon was used in 1950 by Kuhns, which gave early favourable reports.

Use of interpositional material in knee arthroplasty did not give favourable results but it opened a gateway in knee reconstruction and gave an alternative to arthrodesis.

In the meantime hip arthroplasty was developing at a much faster rate. In 1923 Smith Peterson developed “Mould arthroplasty” as an alternative to interpositional arthroplasty in the hip. W C Campbell and Boyd in 1940 attempted mould hemiarthroplasty in the knee, they interposed vitallium plates. In 1949 Speed and Trout published a follow up study of this type of arthroplasty done in Massechusets General Hospital. The results were not encouraging.

At this point several investigators began developing endoprosthesis to replace one side of the articulation. Although other materials achieved limited success, metal endoprosthesis became the implants of choice.

In 1943 Otto Rohm introduced polymethylmethacrylate (PMMA) cement commomnly known as acrylic cement. Sir John Charnley initiated the use of cement in arthroplasty in 1958 when he used cold curing acrylic cement for fixation of hip implants. He also introduced low friction torque arthroplasty in hip after he observed resistance to Judet’s acrylic femoral head on acetabulum. The concepts in the evolution of hip arthroplasty had a great impact on that of the knee. While advances in technology were incorporated in the hip, (e.g use of cement, reducing friction for longitivity of the implant, metal backed components etc.) knee arthroplasty was in a race to match with that of the hip.

The first attempt to replace both the articulating surface of the knee was when Borge Wallidus (1951) and Shiers (1953) designed the hinged prosthesis- the Wallidus hinge. The implant was made from vitallium. The two halves of the prosthesis were united by a roller bearing held in place by a locking screw. The patella was not resurfaced. Cement was not used to allow future arthrodesis if required. A femoral intramedullary nail, 8 cm long was used and it had a flange anteriorly to provide an articular surface for the patella. The tibial component had an intramedullary nail of the same length and a posterior flange, which fixed the cancellous bone. With this it was possible to correct severe varus/ valgus deformity and flexion deformity. Range of motion (ROM) was 5º hyperextension to 90º of flexion. This resulted in surprising freedom from pain and increased ROM. Most patients walked with sticks, the knee was carried stiffly, but it could be flexed to full ROM of prosthesis while climbing stairs. The stiff leg gait was due to lack of joint sensation.

McIntosh in 1958 was the first person to replace one articulation of the knee joint as an acrylic tibial plateau, which was later changed to metal, the plateau was used as a simple metallic disc made of vitallium without any cement. The intercondylar notch was untouched. Postoperatively there was no significant improvement in the gait. Later the prosthesis utilized a second component, which was fixed to the femur. The era of hemiarthroplasty had begun with McIntosh’s design.

Duncan. C McKeever in 1960 gave a design similar to that of McIntosh. He was of the opinion that arthrodesis and other destructive procedures are an admission to defeat. His implant had a metallic D contoured with the tibial plateau with a T shaped perpendicular block attached to the undersurface to be inserted inside the tibial metaphysis. Cement was not used. This design was particularly successful in rheumatoid arthritis. He was the one of the first to lay down biomechanical principles of knee prosthesis. Some of them are:

1. There should be optimal relationship between surface area and range of functional stress to be borne by the prosthesis and transmitted from it to the bone. He calculated it to be 2,550 pounds per square inch.

2. An endoprostehesis should be self-retaining. Instead of any retaining device it should be designed in such a manner so that the normal forces acting on the knee could hold it in place.

3. The direction of the stress transfer should be constant and must take place at a single level. If there is angular variation in the direction of the stress resorption will take place.

4. Complete functional restoration of the joint should be the goal; prostesis may play a small though vital role in the outcome.

The first case although had advanced villonodular synovitis, tibial plateaus were inserted, joint was debrided, cellophane was interposed and patellar prosthesis was used. This is the earliest record of patellar resurfacing in the literature.

Another hemiarthroplasty design the Townly prosthesis was given in 1964 by Charles O. Townley. First implanted in 1953, it utilized a single horseshoeshap sagittaly concave tibial component with two anterior overhanging holes for screw fixation to the tibia placed anteroposteriorly.

However none of these hemiarthroplasty designs provided long term pain relief sought by patients with arthritic joints because the unreplaced joint surface remained a source of persistant pain. The solution to this problem was given by metal on metal, hinged total joint replacement of the knee. This was a parellel development to knee hemiarthroplasty and interpositional arthroplasty.

The simple hinged implants failed to account for the complex knee motion and had a high rate of infection, loosening and mechanical failure. These concepts later developed into the second-generation hinges Sheehan’s, GUEPAR, Herbert&Trillat, spherocentric, Marmore, and further into modern kinematic rotating hinge.

Studies on the subject continued and Dr. Frank Gunston, who worked under Sir John Charnley in England carried McIntosh’s idea a step further and developed a polycentric knee. The though was conceived in 1960s but the idea was reported in 1971. Instead of using metallic disc between articulating surfaces, he embedded hemispherical femoral metallic runners of EN58J stainless steel for the two condyles. The runners articulated with two tracks of RCH 1000 high-density polyethylene troughs attached to tibial plateau. He was the first one to use acrylic cement in knee joint. The diameters of the components were so designed that it stimulated normal knee motion. Circular configuration of the runners instead of spiral was a compromise for the ease of manufacturer. The articulating groove in the plastics track allowed 20 degrees of axial rotation. The ligaments were preserved. He took many concepts from Charnleys low friction hip arthroplasty. He introduced the concept of femoral roll back. Femoral roll back is a process during flexion of the knee by which the femur is pulled back on the tibial condyle progressively as it flexes, this results in clearance of posterior femoral condyles from the posterior tibial articulating surface making flexion possible to normal 140 degrees. This process is physiologically done by the posterior cruciate ligament (PCL). He was the first to recognize that knee is not a simple hinge but the femoral condyles roll and glide on the tibia with constantly changing center of rotation. This implant was a conceptual breakthrough in the history of knee joint replacement. This prosthesis enjoyed early success but failed on account of inadequate fixation to bone.

With the Gunston polycentric knee the stage was set for the bicompartmental knee prosthesis.

Sheehan total knee hinge was introduced in 1971 after two years of biomechanical and design study. This semi constrained hinge device allowed minimal bone resection in unstable knees. It used tibial and femoral components with intramedullary stems made of cobalt chrome alloy. A screw was used to fix a high-density polyethylene tibial component to the tibia. It was believed that there was some inherent difficulty in the design that contraindicates patellar resurfacing. His early results indicated that patellofemopal discomfort after the operation was not a major problom and decreased with time. But later Miehlke in 1980 introduces patellar resurfacing.

Multiple problems were being faced with the hinge implants in early seventies. Kaufer and Mathews in1971 thus put forward the spherocentric design. (Published in 1977) An intrinsically stable, linked design capable of triaxial rotation. The femoral stem was shot as compared to other hinges.It had metal on plastic articulating surface and incorporated the CAM mechanism. In 1981 results of four years follow up of 82 knees by the originators (Kaufer and Mathews) reported 9% of reoperation rate and recommended spherocentric knee for severe deformity and unstable knees

Another very important development had taken place at the London Hospital in form of the Freeman & Swanson prosthesis. In 1971 when they invented the prosthesis there were four design concepts, viz:

1. Completely constrained hinges- Wallidus and Shiers.

2. Modified hinges- with some form of rotational and axial movement-Herbert, spherocentric.

3. Condylar replacements- the polycentric, geometric and McKeever

4. Roller-in-trough principle- the femur acts as a roller on the tibial groove

The roller-in-trough principle was incorporated in which the integrity and stability was maintained by the intact collaterals. Patella was not resurfaced as the clinical experience had shown that the incidence of postoperative patellar pain, delayed wound healing and infection could be decreased if patella was left intact. For the first time excision of the anterior and the posterior cruciate ligament was advocated. A spacer was used to maintain the tension in the collaterals. The femoral component was relatively flat distally and did not have anterior flange for the patellar articulation. The principles given by M.A.R. Freeman in 1973 were:

1) A salvage procedure should be readily available. The implantation of the prosthesis should require the removal of no more bone than for primary arthrodesis and should leave large, flat surface of cancellous bone.

2) The chances of loosening should be minimized. That is: -

a. The femoral and tibial components should be incompletely constrained relative to each other so that twisting; varus or valgus moments cannot be transmitted to the prosthesis and bone interface.

b. The friction between the components should be minimized.

c. Any hyperextension- limiting arrangement should be progressive and not sudden.

d. The prosthetic component should be fitted to the bone by means that spread the loads over the largest possible areas of the bone prosthesis interface. That implies use of cement.

3) The rate of production of wear debris should be minimized; the bearing surface should be as large as possible to keep the surface stresses low.

4) The debris should be as innocuous as possible. Till that time polyethylene was coming up as the preferred bearing material.

5) The probability of infection should be minimized by having compact prosthetic components with few dead spaces, and minimal chance of soft tissue trapping.

6) The consequences of infection should be minimized by avoiding long intramedullary stems and intramedullary cement.

7) A standard insertion procedure should be available.

8) The prosthesis should give movement from 5 degrees of hyperextension to at least 90 degree of flexion. They said that more than 120 degrees of flexion is not likely to be useful.

9) Some freedom of rotation should be resisted.

10) Excessive movements in any direction should be resisted by the soft tissues, particularly the collateral ligaments.

11) It is not prudent to depend upon cruciates for proper functioning of the implant.

12) The prostheses should allow removal of intercondylar notch as it is usually diseased or its removal is necessary for the correction of the deformity.

13) Prosthetic patella should be used in the patients who require them( probably few).

14) The cost of the implant should be minimized.

Most of these objectives remain valid today; two points cited in the report remain issues for debate. These are

1. The place of the cruciate ligament in TKA and,

2. The need to replace the patellofemoral joint.

Subsequently in London hospital two improvisations of the above-mentioned prosthesis were made. The ICLH design incorporating patellar resurfacing and cementless fixation and the Freeman –Samulson press fit design.

An important step in the development of bicompartmental replacement was the Duocondylar design in 1972. Insall and Ranawat at the Hospital for Special Surgery gave it as a replacement to the earlier polycentric design. It was the first knee of its kind. The femoral runners like that in polycentric were joined together anteriorly so that there is no need for aligning two separate femoral components. The PE tibia was also one piece. Patella was not resurfaced. Both the cruciates were preserved. The advantages were that the tibial and femoral components were small, so less bone was resected, It did not violate the femoral canal while insertion as did hinge prosthesis, stability was maintained by the ligaments and partly by the prosthesis and it provided a range of motion in the physiological limits.

The disadvantages were that the patella was not resurfaced; the cement was not contained beneath the prosthesis as the size was small, the insertion was difficult because of a curved femoral design and there were some difficult in the fixation of one-piece unit.

Anatomic total knee was developed on the basis of previous Townley prosthesis by the originator in 1972.it was a nonconstrained design. The tibial plate was thin horseshoe shaped to preserve the cruciates. Femur had a condylar component similar to the normal knee. Later in 1977 porous coating was done and the design was called porous coated anatomic (PCA) device.(16)

Leonard Marmore introduced Marmor unicompartmental design in 1972. He recommended double incision for the two compartments; advised synovectomy for the patients of rheumatoid arthritis. His concept was to allow rotation of the femoral component, by not providing the groove in polyethylene tibial component. The results were much better for the lateral condyle.(19)

The next development came as the Geometric knee, (supplied as Geomedic TM) developed by Coventry et al at Mayo clinic in 1973. It had vitallium femoral condylar unit and a high density PE tibial plateau .The femoral unit consisted of 2 spherical weight bearing surfaces of 23.8 mm radius which were joined by a cross bar to obviate the need to align each segment separately. The femoral unit in addition to medial and lateral condylar pins had depressions in the undersurface of the anterior and posterior portions of bearing units to provide additional areas of fixation. PMMA cement was used. Posterior tibial unit was concave to restrict motion in anteroposterior and lateral planes. But some rotation was permitted. The tibial cups were joined anteriorly by a bridge to allow insertion of tibial unit without significant removal of the tibial attachment of the cruciates. It was designed to be fixed with PMMA. Jig was used for femoral and tibial component. Patellectomy was done for severely damaged patella.

They laid out a few guidelines for the ideal implant.

1. Anteroposterior, rotatory and lateral stability should be inherent.

2. The designs should preserve cruciates and collaterals if they are present.

3. As little as possible bone should be resected, preferably less than one inch.

4. ROM of full extension to at least 90 degrees should be achieved.

5. The material used should be acceptable to the intraarticular environment.

6. The implant should correct varus/valgus and flexion deformity of knee.

7. intramedullary implant fixation should be avoided . (9) (3)3.1

Retaining the cruciates was a flaw in the prosthetic design. Vince called it a “kinematic conflict”. He defined it as the inability of the knee to serve two masters. Either the articular geometry of the implant (inevitably different from human knee.) must be free to determine how the components will move in respect to each other or anatomic structures such s posterior cruciate ligament (PCL) must be allowed to pull the femur across the surface of tibia.

In 1973 a group of Paris surgeons gathered to form a not so physiological prosthesis called the GUEPAR hinge. The axis of rotation as compared to initial hinges was kept more posterior. A silastic thruster was introduced and there was a valgus tilting of the stem. Chrome-cobalt-molybdenum was used as the metal. Range of motion was increased and the bulk was reduced.

In 1973 Waugh gave the UCI design (University of California Irvine) as an improvement over the geometric. It accommodated rotation about the long axis of the leg. Tibial insert was horseshoe shaped to allow cruciate retension.

Yet another breakthrough in the design concept was by Insall and Ranawat at the HSS in 1973- The Total Condylar Prosthesis (TCP). It was the first tricompartmental total knee replacement that is still used in its original form, and set a gold standard for the future total knee designs. A priliminay report of the design concept was given in an article in 1976. They said that though knee arthroplasty is coming up as a major joint replacement surgery the results are not as successful as that of the hip. The concept arose out of previously used designs the duocondylar, geometric, and Freeman-Swanson. These three design shared common problems

· Tibial component loosening and sinkage

· Problems arising from Unreplaced patella.

· Surgical technique difficulties.

These designs had many good features that were incorporated in the total condylar knee. The femoral curvature was taken from the duocondylar, the cup shaped tibial articulation was similar to geomedic, bicruciate excision was done as in the Freeman design.

The femoral component: made up of co-cr-mo alloy, contained a symmetrical groove. There was an anterior flange separating into two condyles posteriorly.it had decreasing sagittal radius of curvature posteriorly and in the coronal plane it was convex symmetrically.

Tibial component: made of HDPE in one piece, with two separate biconcave tibial plateaus that mate with femoral condyles in extension. No rotation was possible in extension. In flexion they are slightly incongruent which allows rotatory and gliding motion.the two condyles are separated by a round intercondylar eminence. Mediolateral and anteroposterior stability was given by the eminence and anterior and posterior lips of the component. The bony surface had an intramedullary stem to resist tilting of prosthesis during asymmetrical loading. The patella was made of polyethylene. It was dome shaped with a central rectangular fixation lug. This was the first design to routinely resurface patella. This prosthesis could not be positioned by “eye” and required precise instrumentation.

The components closely conform in extension to provide the stability and reduce wear. When the knee is flexed the conformity is lost as the femoral component had a decreasing sagittal radius of curvature posteriorly allowing the normal rocking and gliding movements. Its main weaknesses were that it could attain flexion upto 90 degrees only and the tibial component had the propensity to subluxate posteriorly. It was thought that sacrificing PCL caused these problems.

Hence they thought of “substituting” the PCL by building a central post on tibial component. This was the total condylar knee prosthesis II. TCP II gave poor early results due to tibial loosening, which was thought to be due to the design modification. The next step was the origin of posterior stabilized prosthesis, described later.18.3

Murray developed Variable Axis prosthesis in 1974. It gave adjustments for thickness, stability, alignment and subsequent change of worn out PE insert. Decreased constraint dramatically reduced loosening but no flexion was possible beyond ninety-five degrees.

In 1974 Unicondylar knee, a unicompartmental metal arthroplasty by Boston and Brigham was introduced. This was one of the first modern unicompartmental design used at the Hospital for special surgery and gained popularity. Other unicondylar designs, which later came, were the Bucholtz, Oxford knee, etc. Unicompartmental designs have a limited role in mild disease involving one compartment only.

Insall&Ranawat in 1976 reported a two to four year follow up of 94 consecutive knees implanted with a duocondylar design. According to HSS scale the ratings were excellent to good in 75% of the cases. The need for patellar resurfacing correct insertion technique and improvised fixation of the tibial component was emphasized. He also said that the second-generation implants- the duopatellar and total condylar offered improvement in this regard.

Insall, Ranawat and Aglietti in 1976 in a classical study compared four models of TKA. The article made the concepts of knee replacement clearer as well as made some errorneous conclusions due to short follow up. They catagorised prosthesis into two main categories:

1. Condylar type- where the surfaces are replaced and ligaments are needed to provide stability a) Prosthesis which simulated normal joint motion- the unicondylar, duocondylar, UCI, St, George, Marmor. b) Prosthesis which have constrained radius- Gunston, Polycentric, geometric.

2. Hinge type: in which the ligaments were sacrificed and the stability provided by the design.a) fixed center of rotation- Wallidus and Shiers, GUEPAR, Stanmore and b)Variable axis of rotation- Stabilocondylar, Herbert and Lyons rotational prosthesis.

The results were classified into four groups, according to HSS scale scores (compiled in the early 1970s) Excellent: 85+, Good: 70 to 84, Fair: 60 to 69, failure: less than 60.

29 unicondylar , 64 duocondylar , 50 GUEPAR and 50 geometric were studied.The unicondylar was used in less affected cases so the complications were the least, but the results were not good as compared to the other designs. The duocondylar was proved to be best for osteoarthritis with mild deformities. Geometric was rated the best for knees with moderate to severe deformity. GUEPAR was used in the most severe cases so the postoperative improvement in the score was greater and it appeared that it was the best prosthesis design. But later the GUEPAR hinges failed on the account of loosening, infection and component breakage. Patellar pain was recognized as a major problem and patellectomy was discouraged.

Insall and Walker in 1976 published their results on unicondylar knee. 24 knees were replaced, 5 lateral and 19 medial. Results were analysed using the HSS score. They found excellent to good results in 100% of lateral and 58% of medial condyle replacement.

In 1976 Goodfellow and O’Connor came up with an experimental prosthesis-the Oxford knee which incorporated analogus of natural menici. The need for a more anatomical knee was increasing. The follow up results of the fixed bearing condylar prosthesis viz total condylar, geometric, ICLH, duocondylar and hinged prosthesis were coming. the results emphasized a rotational component to be included in the design. most of the earlier designs had agreed to the fact that for a prosthesis to be successful, the kinematics of the changed knee should be as close to the natural knee as possible. Gunston had already laid the concepts of rocking and gliding and rotatory motion of the knee and incorporated them in his design.

This was the beginning of the new generation called the mobile bearing implants. The inventors in their initial design incorporated two independent plastic bearings situated in the curved tracks on a polished metal tibial plate. They preserved the cruciates. The second version featured a single plastic bearing that freely rotated in the post seated within a hole in the tibial tray.

The prosthetic design:

Femoral component was spherical with a 24 mm radius, independent for each condyle. The tibial component had a flat articular surface with a keel on the bony surface that was reduced over two years to minimize bone excavation from the tibial metaphysis. Later an anterior lip was added 4 mm high to prevent dislocation.

The meniscal bearings were made up of polyethylene, they were circular and were surrounded by a metal ring. The upper articular surface had 5.8 square centimeter of contact area. Because the surfaces were congruent throughout the range of motion, a contact area of 11.6 cm sq. was available to carry load in all position of the joint.

The intercondylar eminence was left intact. Usual medial parapatellar approach was used; no effort was made to align the bones on account of pre operative varus, valgus or flexion deformity. Gap gauges were used. No soft tissue release was performed. The ligaments were appropriately tensed by applying bearings of proper thickness. The fixed flexion deformity (FFD) of up to 45 degrees was corrected with proper ligamentous balance. There was no need to align the components as the sliding motion of the bearings adjusted the small amount of incongruity. Since the femoral component was spherical no anteroposterior adjustment was made. Posterior displacement was a major cause of failure. (30)

In the next year 1977 F.F. Buechel and M.J.Pappas inspired by the oxford design gave the concept of the New Jersey Low Contact Stress (LCS) knee. The meniscal bearing versions had dovetail groove on the tibial base plate two independent polyethylene bearings and preserved both cruciates. The rotating platform bearing featured a single plastic bearing that freely rotated about its post seated within a hole in the tibial tray. Patellar component was anatomical, instead of a dome. It also included a rotating bearing.

LCS (used mobile bearings)

Rotating platform bearings Meniscal bearings

(Non-cruciate retaining)

Unicompartmental Bicruciate retaining PCL retaining

The improvisation made over the Oxford were that a meticulous tibial and femoral alignment was done; the design had decreasing radius of curvature posteriorly; dovetail tracks given in the tibial plate prevented posterior dislocation.

Later many mobile bearing designs came into existence:

· Rotaglide in1986 by Polyzoides.

· SAL by Bourn& Rorabeck in 1987

· Total articulating cementless knee (TACK) in 1990

· Interax integrated system

· Medially biased kinematics knee by Insall and Aglietti in 1992

· Natural knee systems

In the line of development of total condylar, a constrained, non-linked prosthesis was designed called the total condylar III in 1977 in Hospital for special surgery. it had a rectangular tibial post and a deep femoral box gave mediolateral stability. The long intramedullary stem gave the required fixation. The design was meant to be used with severely affected knees.

In 1977 the ICLH design was put forward. The emphasis was on the principles of cementless fixation and second on the patellofemoral joint reconstruction. The all polyethylene insert had two serrated fins that occupy slots made in the tibia. The bone grew around the finns and gave a stable fixation. An anterior flange for the femoral component was given which was flat mediolaterally. The patella was replaced with a non-metal backed polyethylene component that was concave proximodistally and flat mediolaterally. It was designed in this manner so that the contact with the femoral flange could be maximized while minimizing the stress.

In the year 1978 another design inspired by Oxford knee introduced by Minns and J.Campbell called the Minn’s total knee. It allowed rotation as well as had conforming surfaces. The tibial insert was forced to move in the anteroposterior direction by the geometry of the design. The tibial plateau was D shaped made of stainless steel, the superior surface had a T shaped groove which located but did not attach the meniscal component.

Coventry and Finermann gave Anametric knee in 1978 as an improvement to geometric knee. Some modern concepts were laid like medial and lateral femoral condyles had multiple radii, which increased flexion. PCL was retained. Rotation was allowed in the design. Decreasing the conformity decreased bone-cement interface stresse. Anterior flange was given. The tibial tray had a central fixation lug. They suggested routine patellar resurfacing.

Shaw and Chatterji in 1978 gave a design similar to the polycentric knee- the Manchester knee. It had two femoral and two tibial components the cruciates were preserved. Instead of stainless steel Alivium was used as the metal.(13)

In 1978 Insall and Burstein introduced the “Posterior stabilized” prosthesis at the HSS as a modification to the total condylar design. They succeded in substituting the role of PCL by introducing a central tibial polyethylene spine and a transverse CAM on the femoral compartment. It was a semiconstrained device, tibial component was entirely of ultrahigh molecular weight polyethylene, it had bicondylar wells nearly conformed to the femoral condyles, there was a posterior tilt inherit in the design resembling the natural slope of the tibial plateau. The Cam mechanism engages the spine at about 70 degrees causing the femoral roll back. However it did not have any effect on the stability in extension nor did it prevent anterior subluxation. The collaterals gave Anterior and mediolateral stability.

The design subsequently underwent several modifications. Burstein and Bartel gave metal backing to the tibia after their study of performance of the tibial component in 1981. The next change was rounding of the anterior portion of the femoral component and deepening of the femoral groove to improve patellar tracking.

The total condylar knee prosthesis III was intended for difficult revision operations. The femoral component has a stem and the tibial peg was enlarged .The tibial post is not tapered and fits within the femoral recess so that both medial-lateral, and anteroposterior stability are provided.

Simultaneously in 1978 sibling prosthesis at HSS- the duopatellar prosthesis was designed by Edwald and Thomas, as a derivative of duocondylar design, as there were many complications with the patellofemoral joint. The femoral component was anatomic in sagittal plane. There was an anterior flange for patella to articulate. Medial and lateral tibial plateaus were separate but soon they were converted to one-piece polyethylene plateau. The patellar component was similar to total condylar design. This prosthesis later developed into kinematic II, press fit condylar design(PFC).

In 1979 Insall, Tria and Scott showed the results of first five years of total condylar prosthesis. They recommended Patellar resurfacing. 461 knees were reviewed in one to five year of follow up. Excellent results in 68%. Good in 23.5%, fair in 4%, poor in 4.5%. The results were comparable to total hip arthroplasty.

Ritter and Stinger in a 1979 publication reported improvement of residual fixed flexion contracture postoperatively in the knee with time. This was a similar result to Tanzer and Miller(1989). They reported average residual flexion contracture of 15 degrees tended to improve to 3 degrees at 4.5 years follow up. But other authors like Schurman et al (1985), Tew and Foster, Parker et al etc. gave contrasting results. They found that maximal correction of flexion contracture occurred in the operating room and did not improve with time.

The Insall Burstein II posterior stabilized modular prosthesis was introduced after major changes made in instrumentation and design of the original Posterior stabilized in 1982. The use of “tensor” was abandoned. Modularity was introduced for various patient needs. The tibial spine was elevated and was shifted anteriorly to increase stability to the prosthesis. The rest of the design remained as such and it is one of the most widely used designs retaining the original configuration.

The next introduction in the lineage of PS design was the NexGen Legacy™. Other modern PCL substituting designs are the Duracon PS™, PFC Sigma™, Genesis II™, Maxim™, ADVANCE PS™, and OPTETRACK™.

In year 1980 the Freeman-Samulson prosthesis was designed. It was a cementless, press fit design. The femoral flange was further increased the tibia was metal backed. More emphasis was given on patellofemoral reconstruction.

Laskin in 1981 reported the use of Total Condylar Prosthesis in rheumatoid arthritis patient after a 2-year follow-up. Results were not reported with HSS knee score but as a detailed analysis of function. 86% patients were almost completely pain free, 88% had markedly increased walking ability, 3-4% required revision surgery for painful varus-valgus instability, patellar component loosening and patellar ligament necrosis. No deep infection occurred.

Hood W.,Vanni M and Insall 1981 series of 225 knees with Insall Burstein posterior stabilized prosthesis studied the correction of knee alignment. This was the first report describing clinical results with the Posterior Stabilized prosthesis although the title was “The correction of knee alignment in 225 consecutive Total Condylar prosthesis”. At this time PS designs were refered to as a generic type of total condylar prosthesis, this confusion was later corrected. Of the 126 knees that were in varus preoperatively, only one was found to be in varus after the operation. No arthroplasty was complicated by posterior tibial dislocation, one of the problems experienced with the Total Condylar. They emphasized on the effectiveness of soft tissue release in severely deformed, unstable knees. They said that most malposition occurred because of inaccurate location of the hip joint while surgery.

Norman Scott et al 1982 reported his experience with 43 posterior Stabilized Arthroplasties in Lenox Hill Hospital New York. There were 34 patients with osteoarthritis, 4 with rheumatoid arthritis and 4 revision surgery. He observed most of the poor results in revision surgery on HSS score and best in osteoarthritis patients after posterior stabilized arthroplasty. Average range of motion for entire group was 112 degree with 120 degree in osteoarthritis patients, 104 degree in rheumatoid arthritis and 88 degree in post-traumatic arthritis. The complications included two deaths, two infections, one transient peroneal nerve palsy and two cases of myositis ossificans. This was an early preliminary report of PS designs in institutions other than that of the originators.

Insall et al (1982) reported 118 primary posteriorly stabilized Total Knee Arthroplasties with 2-4 years follow-up, (intermediate follow up using all poly tibia). They found 97% good to excellent results by HSS Knee rating score. Mean flexion achieved with this device was 105 degree (95 degree with the total condylar studies). Three times as many patients (76%) could ascend the stairs and rise from a chair than could patients with total condylar replacements. 13 patellar complications (11 %) were reported. Two (1.7%) of these were lateral subluxation and ten (8.4%) were stress fractures. But even after fracture, the range of motion remained so, which was measured when the fracture had united, one incidence of fracture was twice with 28mm patellar resurfacing dome than with 35mm prosthesis. No fracture was found with 32mm patellar component. Three complications were reported, one due to tibial component loosening, one due to femoral component loosening and one due to deep sepsis.

Andriachi and Galante (1982) showed improved stability on stairs especially during descent with cruciate retaining total knee arthroplasty.

Insall (1983) with a follow-up of 5-9 year& of 100 consecutive replacements reported 64% excellent, 27% good, 2% fair, and 7% poor results by HSS score system. Seven knees were regarded as failure; one knee suffered deep infection, which was later arthrodesed, and one had posterior tibial subluxation in flexion. One arthroplasty aligned in varus was revised to correct alignment to eliminate pain. One of the two knees had loosening of tibial component and one had been aligned in varus. One knee had progressively increasing varus instability,which was raised 8 years later.

Landon and Galante in 1984 started using non-cemented anatomic resurfacing type prosthesis that retained PCL, known as the Miller-Galante prosthesis. The tibial surface had four short pegs, which were ment for insertion of four screws. A carbon reinforced polyethylene articulating surface was used.

Aglietti and Renonapoli (1984) with 5 years follow-up with 33 Total Condylar Prosthesis knee reported 64% excellent, 21 % good, 9% fair and 6% poor results by HSS knee score. Two knees had tibial component loosening due to varus alignment. They concluded that varus alignment was not tolerated with the passage of time. Second, there were no problems caused by routine use of patellar component.1

Schurman and Colleagues (1985) from Stanford University published a short duration study of Total Condylar Knee Arthroplasties concentrating on factors that influence the range of motion. 55 patients with 71 total knee arthroplasties and two years follow-up were reviewed. Knees with pre-operative flexion more than 100 degree had lost motion where as those less than 100 degree gained motion. Mean flexion was 106 degree- 108 degrees exceeding 95 degree that has been generally associated with Total Condylar prosthesis. They found that of the patients whose pre­operative flexion contracture was 10 degree or more, virtually all improvement in contracture occurred at the time of surgery. Tibial and femoral alignment had no effect on flexion. It was also postulated that increased posterior tilt would increase flexion.

Insall et al (1985) described patellofemoral joint reconstruction as the major residual complication in an otherwise successful surgical procedure. Scott et al (1986) in his series of 56 knees reported 87% excellent, 71 % good, 2% fair and 4% poor results with posterior stabilized arthroplasties. Notable finding in this series was 3 cases of patellar fractures, with 41mm polyethylene button.

Rand et al (1985, 1986, 1987) in a non-randomized comparison of 50 cemented to 41 cementless PGA arthroplastic knees at 2 years follow-up found 97% good to excellent results with cemented knees as compared to 83% with cementless knees by HSS knee score. Radiolucent lines were significantly more frequent in the cementless knees than in the cemented. Anterior and medial subsidence of the cementless tibial components was observed more frequently. One aspect of knee arthroplasty kinematics and surgical technique that receives little attention is the effect of relative ligament tension in flexion and extension. It may, however, be a significant factor in the increased flexion reported with the Posterior Stabilized. Many patients are able to flex further with their knees less tight.

Japanese surgeons Yoshino and Shoji in 1987, in a country where it is culturally important to kneel for social functions, developed prosthesis similar to the Total Condylar design and took into consideration the kinematic aspect of full flexion. They used a surgical instrument resembling a tensor to measure accurately ligament tension in both flexion and extension. They believed that it is desirable to construct a flexion gap with slightly less tension, such that at the arthroplasty it is relatively tighter and more stable in extension. Vigorous daily postoperative rehabilitation was continued for four weeks. Results were good to excellent in all but two of 50 consecutive knee operations on 39 patients. A minimum of 90 degrees flexion was achieved in all cases, a mean flexion exceeding 125 degree, a better average range of motion than those reported in the past. Four patients (six knees) achieved full squatting. The combination of three elements, prosthetic geometry, well-controlled soft tissue balancing for flexion and extension phases, and vigorous rehabilitation, is important for the recovery of range of motion.

Ecker, Lotke and colleagues (1987) addressed the problem of radiolucencies with respect to Total Condylar Prosthesis. They reviewed 102 consecutive Total Condylar Prosthesis done between 1975-78 and reported the presence of radiolucent lines in 15% of knees. In 36% the lines were 2mm or less and located under medial or lateral tibial plateau. Bilateral lines were noted in 22% cases. In 7% knees circumferential lines either 2mm or more than 2mm were present. They did not find any correlation between thin lines and knee score but with thick lines consistently poor score was observed.

Hungerford et al in 1987 reported their early experience with 98 knees (78patients) with arthritis of 3 years follow-up using Porous Coated Anatomic uncemented prosthesis. 63 knees (57patients) with osteoarthritis had 95% good to excellent results by HSS scores whereas 25 knees (21 patients) with rheumatoid arthritis had 92% good to excellent results. There were four patellar revisions. 17% patients had radiolucent lines adjacent to the tibial component and only one patient had a femoral radiolucency.

Ritter MA, Faris PM, Keating EM. in 1987 published a study to describe and evaluate the use of a posterior cruciate ligament balancing technique. Two hundred sixty total knee arthroplasties in 156 patients were performed between January 1984 and December 1985 using the described technique of posterior cruciate ligament balancing when necessary. Seventy-eight arthroplasties (30%) required ligament balancing to obtain a smooth flexion arc. At 1-year minimum follow-up evaluation, no knee was found to be unstable in the anterior-posterior plane. Average flexion arc for the posterior cruciate ligament balanced knees was 2 degrees - 114 degrees and for the standard arthroplasty was 2 degrees - 107 degrees. They said that posterior cruciate ligament balancing is a useful adjunct in total knee arthroplasty surgery when flexion gap tightness occurs.

Rorabeck et al (1988) in a non-randomized study comparing 110 Kinematics II cemented knee arthroplasties to 50 cementless porous Coated Anatomic prosthesis of 2-3 years follow-up, found HSS Knee score to be 88 for cemented knees and 79 for cementless ones. The reoperation rate was 4% in cemented knees compared to 12% in cementless series.

Scott et al in 1988 published 2-8 years follow up 0 f 119 primary posterior stabilized arthroplasties. In this review by HSS score, 83% of the arthroplasties were rated as excellent, 15% good, none fair and 2% poor. Three arthroplasties showed subsidence of tibial component, two had deep infection, patellar fracture occurred in 6 knees, 5 of which healed subsequently. Survivorship of 93% at 8 years was reported. Scott and his associates attributed patellar fracture to avascularity as each patient had lateral patellar retinacular release with transaction of lateral genicular artery. They also concluded that the results were better in patients with osteoarthritis as compared to the patients with rheumatoid arthritis and that of patients having preoperative varus deformity was better than patiens with valgus deformity.

Goldberg et al (1988) reviewed 153 Total Condylar prosthesis implanted between 1975 and 1979 in 113 patients. 30 patients (42 knees) died and one (2 knees) was lost to follow up. Out of 109 arthroplasties in 82 patients, 6 had tibial implant loosening, 3 tibial posterior dislocation and 3 had supra-condylar femur uactures. They also found a gradual decline in knee score, which reflected a hat, out 0 gradual deterioration in function resulting from advancing age. Superior results were reported with patellar resurfacing.

Ranawat and Boachie-Adjei (1988) after 8-11 years follow up in 112 knees reported 53.3% excellent results, 39% good results, 3.8% fair results and 4.4% poor results. The endpoint of survivorship was defined as

· The need for revision due to septic or aseptic loosening.

· Roentgenographic loosening evidenced by a shift of component position; or

· Radiolucency extending under the condyle of the tibial component and partially along the peg, when associated with clinical symptoms.

94% survivorship was reported at the end of the study. There was a correlation between body weight and the presence or absence of radiolucencies.(figure.2)

Ritter; Faris; Keating in 1988 emphasized the use of a trial tibial component that lacks a stem. They said that if the tibial tray lifts off anteriorly with knee flexion, PCL tension is excessive.

Matsueda M, Gengerke TR in 1988 investigated the relationship between the individual steps in a medial (eight anatomic specimen knees) or lateral (four anatomic specimen knees) soft tissue release sequence, the resulting change in the medial and lateral tibiofemoral gaps, and the change in coronal angulation caused by 10 Nm varus and valgus moments in extension and 90 degrees flexion. In the medial release sequence, a significant increase in coronal angulation and medial gap occurred after the release of the anteromedial sleeve 8 cm from the medial joint line. In the lateral release sequence, there was a significant increase in the coronal angle and lateral gap after the lateral collateral ligament and popliteus tendon were released from the femur. Release of the posterior cruciate ligament led to a significant increase in angle and gap in medial and lateral release sequences. These results were specific for the particular release sequences studied, with release of the posterior cruciate being the final step in each sequence.

Aglietti and Buzzi (1988) published 3-8 years follow up of 85 posterior Stabilized arthroplasties. They reported 57% excellent, 33% good, 5% fair and 5% poor results. They did not experience any patellar stress fracture despite performing lateral retinacular release in 48% without preserving the genicular artery. This attributed to modest flexion of 98 pegree (70 degree to 130 degree) in this series, which might have protected the patella. However, they experienced 20% incidence of patellofemoral impingement, which they co-related to proximal soft tissue rubbing against the anterior edge of the femoral component. One case of patella Baja was identified. They highlighted the fact that smooth contoured anterior femoral flanges reduced the problem of patellofemoral impingement. They also found, consistent with several studies, viz. Ritter and Sturger (1979), Vince et al (1988) that postoperative flexion co-related better with pre-operative flexion that with the height of patella.

In his second study of 73 patients in 1988 reviewed patellofemoral complications. Joints were examined for catching and locking (“impingement”) when there was 30 to 40 degrees of flexion as the knee was extended. Revision was done in one patient only. He concluded that the new design reduced patellofemoral complications.

Andriacchi TP, Galante JO (1988); Retention of the posterior cruciate ligament in total knee arthroplasty was discussed in biomechanical and clinical terms and the implications for design, kinematics, function, and prosthesis longevity considered. The specific roles of passive range of motion, femoral rollback, stresses on the implant-bone-prosthesis cement system, and wear are examined. The author argued that the posterior cruciate ligament improves passive range of motion, the mechanical efficiency of the knee musculature and thus improved stairclimbing efficiency, reduces stress at the cement-bone-implant interfaces, and has little or no impact on the polyethylene wear problems.

Laskin et al (1988) compared the results of posterior cruciate sparing prosthesis and posterior cruciate sacrificing posteriorly Stabilized prosthesis keeping all the pertinent variables comparable. This study was done in severely deformed knees and found that posteriorly stabilized prosthesis had better ability to eliminate flexion contracture and restoration of desired valgus alignment.

Ranawat and Handsaw (1989) published the results of Total Condylar knees implanted between 1979-80 wherein satisfactory range of component sizes was available and surgical tecnique had been revised. They reported superior results- 64% excellent, 35% good, 0% fair, and only 1 % poor results. Mean flexion noted was 100 degrees, a significant improvement over 95 degree as usually reported with Total Condylar knees.

Hagena et al in 1989 carried out Total Knee Arthroplasty in 12 patients with severe rheumatoid arthritis or osteoarthritis and the cruciate ligaments were resected. The ligaments were examined histologically and biomechanically, using ten specimens from healthy adtults as a control. A significant difference was found in the tensile stiffness and viscoelastic properties of the ligaments between the arthritic and the control group. The ligaments in the rheumatoid knees had a distinctly inferior tensile strength when compared with the osteoarthritis knees. Total Knee Replacement, which also replaces ligament function, should therefore be considered in severely damaged rheumatoid knees.

Shuddery et al (1989) did a survivorship analysis of 1430 cemented knee arthroplasties performed over a 15 year period on the HSS Knee Service evaluated 224 Total Condylar prosthesis with a polyethylene tibia, 289 Posterior Stabilized prostheses with a polyethylene tibia and 917 Posterior Stabilized prostheses with a metal-backed tibial component. Over the IS-year study period, there were 12 failures amongst the Total Condylar with an annual failure rate of 0.27% and a 10-y~ar success rate of 97.34%. The metal-backed tibial components had 0.19% failures annually and a 7 year success rate of 98.75%. No metal-backed tibial components needed revision during the 7 years of study.

Andersen, Havid, Sneppen in 1989. Study done in Denmark. Observed results in TKA of 103 knees with Insall Burstein total condylar design (a modification of total condylar I) performed in center other than that of the originators. In a 4 to 6 yr. Follow up they found out that the modified total condylar I prosthesis was excellent. It has a low failure rate in gonnoarthrosis. The prosthetic survival rate (PSR) was 98%.

In 1990 Shoji H, Solomonow M, Yoshino S, studied Factors affecting postoperative flexion in total knee arthroplasty. In the review of 67 cases with total condylar (TC) prostheses, 59 with TC posterior stabilizers, 70 with TC prostheses modified with flat posterior tibial plateau, and 35 with porous-coated arthroplasty (PCA) prostheses, multiple cross-examinations of various factors for postoperative flexion were performed. Follow up was 2 to 9 years. In nearly all cases, no further improvement of flexion was noted after 1 year following surgery. The most influential factor for good postoperative flexion was intense physical therapy, leading to good suprapatellar pouch reconstitution. Residual flexion contracture was more frequent when the posterior cruciate ligament (PCL) was retained in the cases with significant preoperative flexion contracture. However, retention of PCL or preoperative ACL condition did not bear any significance to the ultimate flexion.

Insall and Stern in 1990 gave intermediate results of 257 metal backed Posterior stabilized prosthesis in a 2 to 6 years follow up. 98.5% were excellent to good, 3 were fair (1%), and one was poor (0.5%)

Wright et al (1990) studies results of hybrid fixation (cementless femur and cemented tibia) using Press fit Condylar knees in 104 knees at 2-8 years of follow-up. 94% good to excellent results were reported. Radiolucent line was identified in 30% of the uncemented femoral component and 30% of the cemented tibial component.

1990 (Bert M.B). 43 New Jersy Low contact stress TKAs were performed and dislocation/ subluxation of the meniscal bearings were studied. A 9.3% of dislocation / subluxation occurred.

(1991) Becker et al evaluated 30 cruciate retaining and cruciate-substituting Total Knee Arthroplasties with 2-5 years follow-up. In general, the more deformed knees received the cruciate substituting designs. Both types of prostheses performed well in this series of patients with no real clinical advantage on one type over the other. Major issue was, therefore, survival of implant. Authors concluded on the basis of this clinical study and long-term follow-up of the total condylar and Insall Burstein posterior stabilized prosthesis, that one should continue sacrificing the posterior cruciate ligament.

Gordon and Parker et al in 1991. Results of total knee arthroplasty using the posterior stabilized condylar prosthesis a report of 137 consecutive cases. Observed in 29.2 months follow up that 98% of the patient had no or mild pain. HSS scale was used to evaluate the results. The good results as per the author were because of improved postoperative management of TKA. Early result by Insall showed a remanipulation rate greater than 60%, most patients were managed in cylinder cast for one to two weeks. The author emphasized on early ambulation after drain removal. This has decreased the remanipulation rate dramatically. The author validated posterior stabilized total condylar design as a reliable implant for obtaining excellent result when measured by a large number of parameters.

Patel and Ferris et al (1991) studied axial alignment on short and long radiographs in 50 knees in 34 patients who had undergone posteriorly stabilized (Insall-Burstein) condylar knee arthroplasty. A mean difference of 1.6 degrees was found when the tibiofemoral angles were compared on short and long radiographs. Short radiographs are probably adequate for routine assessment of knee replacements in a busy outpatient clinic, but for accurate scientific studies the long radiographs are preferable.

Insall and Stern in1992, reviewed 289 Posterior stabilized knees in a long term follow up of 9 to 12 years, there were 180 intact prosthesis left for analysis. There were fewer excellent results (61%) as compared to the previous follow up of 2 to 4 years (88%). One possible explanation given by the authors were the advancing age, another could be the use of new Knee society rating scale which was used to assess outcomes in this study.

Goodfellow J. In 1993 defined characteristics of the Oxford knee and basic concepts of surface replacements. He emphasized that mechanical and kinematic principles are very important in knee prostheses. The use of artificial menisci is the only way to provide a kinematically free range of motion with a wide area of load transfer. This allows polyethylene wear to be minimized.

In 1993Carr A, Keyes G, Miller R, O'Connor J, Goodfellow J treated one hundred twenty-one knees with medial compartment osteoarthrosis by unicompartmental arthroplasty with the Oxford Knee. The strict selection criteria were (1) the presence of a functioning anterior cruciate ligament, (2) fully correctable deformity, and (3) full thickness of articular cartilage in the lateral compartment. The mean elapsed time from surgery was 44.4 months. One knee has required revision for a loose tibial component.  They concluded that the results at that stage were as acceptable as those of tricompartmental knee arthroplasty and better than those of high tibial osteotomy.

Swany and Scott in 1993 emphasized direct observation of femoral roll-back during flexion, they said that the tibiofemoral contact point should not move onto the posterior third of the tibial articular surface. Also that with knee in 90 degrees of flexion, firm pressure should cause the PCL to deflect 1 to 2 mm.

Japanese surgeons Nagamine R, Kondo K,in 1993 used a tensor/balancer device with 30 inch-pounds of torque (in.lbs) both in extension and flexion. The results showed that a 24 or 25-mm joint gap expanded by a Tensor/balancer device in full extension was optimal for a 10-mm bearing insert. Therefore, if the resection level of the tibia is set 24 or 25 mm from the femoral cut surface, a 10-mm bearing insert can be used. In 49 cases, the size of the femoral component was one size (4 mm) larger than that predicted based on the bony structure shown in the radiographs of the knee. With this procedure, ligament balancing and optimal joint gap both in extension and flexion can be obtained based on the predicted bearing insert in the knee.

Ranawat et al in 1993 in their study of 112 consecutive Total Condylar Arthroplasties of an average 15 years follow-up (between 1974-92) reported 94% clinical survivorship and. 90.9% survivorship when roentgenographic failures were included. There was a correlation between body weight and presence of radiolucencies. Patients who weighed more than 80 Kgs had the lowest survivorship at 15 years: 89.2% clinical survival and 70.6% clinical plus roentgeographic survival. Thus, Total Condylar knee arthroplasty has a 94.6% clinical survival at 15 years, with predictably good results.

In 1994 Hirsch and Colleagues in a study of 242 consecutive Total Knee Arthroplasties suggested that preserving the posterior cruciate ligament does not consistently lead to improved functional range of movement.

Simmons et al in 1996 measured proprioception in two groups of patients following successful total knee arthroplasty (TKA). In one group, the posterior cruciate ligament was retained and an unconstrained cruciate-retaining total knee component was used; in the other group, the posterior cruciate ligament was excised and a cruciate-substituting design was implanted. The degree of preoperative arthritis was objectively classified according to Resnick and Niwoyama. Threshold to detection of passive motion was quantified as a measure of proprioception. There was no difference in threshold to detection for passive motion in cruciate retaining versus cruciate substituting TKA.

Anouchi et al (1996) did a multicenteric prospective clinical study using a modified Knee Society scoring system which evaluated the effect of age, gender, weight, preoperative range of motion and knee score, previous surgery, and modification of the posterior femoral condyle geometry on postoperative range of motion. The primary outcome variable was change in flexion. Patients were divided into 3 groups: preoperative flexion less than 90 degrees, 90 to 105 degrees and greater than 105 degrees. When comparing the patients with preoperative motion less than 90 degrees of those with motion greater than 105 degrees, the first group improved 26 degrees more than the latter. They also improved 12 degrees more than the midrange group. The midrange group improved 14 degrees more than the upper range group. None of the other variables showed a significant correlation with the flexion outcome. The patients with preoperative knee scores below 27 improved 16 points more than those in the 27 to 40 score range and 33 points more than the above 40 group. To analyze functional evaluation, the patients were divided into 3 groups based on preoperative score: less than 40, 41 to 50 and greater than 50. Those in the less than 40 group improved 14 points more than the midrange' group and 35 points more than the greater than 50 group. Age, weight, previous open surgical procedure, and altered femoral component contour, did not seem significantly correlated with changes in postoperative clinical results and the reoperative scores.

Laskin et al (1996) studied a group of patients with preoperative varus contracture of at least 15 degrees who underwent total knee replacement with retention of the posterior cruciate ligament. Their outcomes at 10 years were compared with a group of patients with similar contracture in whom a posterior stabilized implant was used, and to a group of patients in whom there was no contracture. In the contracture group where posterior cruciate ligament was retained, there was an increased incidence of pain, an increased incidence of bone cement radiolucencies, and a decrease in the eventual flexion arc. There was likewise an increased revision rate and a decreased survivorship. In patients with such contracture, the posterior cruciate ligament is a part of the deformity: the deformity cannot be corrected by medial release procedures alone. All these results suggest that for the patients with a fixed varus contracture a posterior cruciate release should be performed and a posterior stabilized type of implant be used.

Rand et al in 1996 said that if posterior cruciate ligament is released to more than 75%, then a prosthesis with greater posterior constraint should be chosen to avoid late posterior instability.

Emmerson et al (1996) reviewed 109 primary total knee replacements in 95 patients at a mean follow-up time of 12.7 years (10 to 14) using kinematic stabilizer posterior-cruciate substituting design. They used survival analysis with failure defined as revision of the implant. They gave a cumulative survival rate of 95% at ten years and 87% at 13 years. These results from an independent center confirm the value of an established design of cemented total knee replacement and question the wisdom of the introduction of modifications and new designs without properly controlled studies.

In 1997 Yoshino et al studied flexion characteristics after total knee replacement in rheumatoid arthritis using Yoshino-Shoji total knee replacements. Twenty-three of 327 patients with rheumatoid arthritis (38 out of 509 knees) had primary between 1984 und 1990 and were able to squat fully in the Japanese style after the procedure. Seven had died of conditions unrelated to their operations. Of the remaining 16, 5 were able to squat fully at follow-up; 2 were unable to do so, but had full passive flexion; 9 were unable to squat and did not have full flexion. The cumulative survival rates of patients able to squat were 82.2%, 65.7% and 47% at 2, 5 and 8 years after operation. At follow-up, 3 were able to walk out of doors for less than 30 min, 6 for 30 min or more and in 7 walking was unlimited. These results suggest that daily exercises are important in maintaining full flexion. The absence of complications may be due low body weight and limited activity due to the disease.

Diduch et al (1997) reviewed total knee arthroplasties performed between 1977 and 1992 in patients who were fifty-five years old or less to determine the appropriate management for younger patients who have severe osteoarthritis. A posterior stabilized, posterior cruciate-substituting design was used for all. At the latest follow-up examination, the average knee score according to the system of the Hospital for Special Surgery had improved from 55 points preoperatively to 92 points. According to the system of the Knee Society, the average knee score was 94 points and the average functional score was 89 points. The result for all 103 knees was good or excellent according to the knee score of The Hospital for Special Surgery and the Knee Society. Ninety-seven knees (94%) had good or excellent function according to the functional score of the Knee Society. The average activity score of Tenger and Lysholm improved form 1.3 points (range, 0 to 4 points) preoperatively to 3.5 points (range, 1 to 6 points) at the latest follow-up examination. Nine (9 percent) of the 103 knees had non­progressive tibial radiolucent lines. Two patients had a revision because of late infection, and on~ patient had revision of a well-­fixed tibial component because of wear of the polyethylene. In addition, three patellar components were revised for loosening, and one spacer was exchanged to treat instability. With failure defined as revision of ether the femoral or the tibial component, the over all rate of survival was 94 percent at eighteen years. When the three­patellar revisions were included in the failures, the survival rate was 90 percent at eighteen years. It can be concluded that arthroplasty with cementing of a posterior stabilized total knee prosthesis is an effective operative treatment with; durable results for osteoarthritis in young patients when other, less invasive measures have failed. Within the average eight year follow-up interval of this study, polyethylene wear, osteolysis, and loosening of the conforming posterior cruciate substituting prosthesis were not major problems of these younger, active patients, although it is possible that this observation could change with a longer follow up.

Phillip J. Michael J. 1997 an in vitro comarision of kinematics of New Jersy LCS, PCL retaining meniscal bearing and PCL sacrificing rotating platform total knee arthroplasty tested antero- posterior translation at 30 degrees and 90 degrees and reported that the AP translation of PCL retaining was greater than that of the PCL sacrificing rotating platform TKA.

Laskin et al (1997) studied a series of patients with rheumatoid arthritis who underwent total knee replacement with posterior cruciate ligament retention and were observed for a minimum of 6 years and a mean duration of 8.2 years. A group of patients with osteoarthritis with an identical prosthesis and a group of patients with rheumatoid arthritis with a posterior stabilized implant served as controls. In the rheumatoid arthritis group with posterior cruciate ligament retention, there was an increased incidence in posterior instability and recurvatum deformity, resulting in an increased revision rates. Those patients undergoing revision for instability had a higher incidence of recurrent synovitis, and at revision the posterior cruciate ligament was grossly absent with a grade 1synovial reaction. In patients with rheumatoid arthritis undergoing total knee replacement, a posterior stabilized prosthesis rather than a posterior cruciate ligament sparing prosthesis should be used.

Banks et al (1997) evaluated three groups of knee arthroplasty subjects with excellent clinical outcomes and similar range of motion. Each group received different prosthetic components and surgical treatments of the posterior cruciate ligament (PCL). Group 1 had relatively flat articular surfaces with retention of the bony insertion of the PCL, group 2 had similar articular geometry but recessed the PCL without retaining the bony insertion, and group 3 had prosthesis with greater sagital conformity and post/cam substitution of the sacrificed PCL. Although none of the knees exhibited normal knee kinematics, the ranges of axial rotation and condylar translation for group 1 were similar to ranges previously reported for normal and anterior cruciiite deficient knees. Axial rotations and condylar translations decreased when the PCL was surgically resected or substituted. The smallest kinematic ranges were observed in-group 3. The result indicates that both prosthetic&component selection and surgical technique have a significant effect on prosthesis knee kinematics during functional activities. A fluoroscopic measurement technique was used to provide detailed three- dimensional kinematic assessment of knee arthroplasty function during a step up activity.

Worland et al (1997) did a study to evaluate any possible untoward effect of PCL recession. Twenty-one patients who underwent simultaneous bilateral total knee arthroplasty between 1988 and 1992 with a PCL recession performed only on one side (necessary to balance the knee) served as the study group. The average follow-up period was 4 years. The patients were evaluated subjectively, by manual physical testing, by radiography, and by KT-I000 astrometry (Medmetris, San Diego, CA). There were no significant differences between the recessed and non-recessed knees. The conclusion is that PCL recession is appropriate and safe long term for the patient in whom the PCL is found to be tight at the time of knee arthroplasty.

Kim et al (1997) did a clinical; and radiographic study of 49 posterior cruciate ligaments retaining total knee arthroplasties in 38 patients (11 bilateral and 27 unilateral), using prosthesis of same design. It was undertaken to quantify the amount of in vivo rollback (i.e., the anterior-posterior translation of the tibia with respect to the femur during flexion). No co-relations were found between the degree of translation of the tibiofemoral contact point relative to the prosthetic tibial tray and the posterior tilt of the tibial tray, the preoperative tibiofemoral angle, and the postoperative tibiofemoral angle. In conclusion, this study indicated no demonstrable rollback occurring in the posterior cruciate ligament retaining total knee arthroplasty.

Stiehl et al (1997) evaluated factors effecting range of motion at 24 months in 782 total knee arthroplasties performed between 1983 and 1987 in a nonrandomized, multi-center clinical trial by 17 independent surgeons. A mobile bearing prosthesis was used with either a posterior cruciate ligament PCL retaining or PCL sacrificing technique. Age and gender did not reveal any difference in outcome. For individual surgeons, the outcome was highly variable and did not reflect the number of cases performed. Postoperative range of motion was greater for the PCL retaining implant; however, there was also a significant difference in the preoperative motion compared with the PCL sacrificing device. Postoperative motion improved from preoperative values for the whole group. Preoperative motion group less than 90 degrees gained 28 degrees, 90 degrees to 105 degrees gained 15' degrees, and more than 105 degrees lost 1 degree.

Ishii et al (1997) did a comparison of joint position sense, determined by reproducibility of index angles and their subsequent change, was performed in 55 knees that had undergone a semi constrained total knee arthroplasty. Knees were stratified into groups that represented arthroplasties performed with or without cement for fixation. There was no significant difference in joint position sense among all arthroplasty groups. Likewise, there was no difference in joint position sense between any of the arthroplasty groups and an age matched control group of 32 knees in 32 patients who had not previously undergone a total knee arthroplasty. Knee arthroplasty does not affect joint position sense.

Duffy et al (1998) studied 74 consecutive total knee arthroplasties in 54 patients who were 55 years of age or younger (average age 43 years). All patients had a minimum follow up of 10 years with an average follow up of 13 years (range, 10-17 years). The preoperative diagnosis was rheumatoid arthritis in 47, gonarthrosis in 12, posttraumatic arthritis in 6, and osteonecrosis in 3, and hemophilia in 2, and 1 patient each with pigmented villonodular synovitis, tuberculosis, systemic lupus erythematosus, and achondroplasia. The knee score iinproved from an average of 36 points (range, 10-80 points) preoperatively to 84 points (range 37­100 points) at the latest follow up. The functional score improved from 45 points (range, 0-100 points) to 60 points (range, 0-100 points) at the latest follow up. Two patients had their implant revised: one at three years because of ligamentous laxity and one at 13 years because of aseptic loosening of the tibial component. There was no deep infection. There were no radiological loose implants at the latest follow up. The implant survival to revision at 10 years was estimated at 99 % (confidence limit, 96-100%) the implant survival to revision at 15 years was estimated at 95% (confidence limit, 88-100%). Cemented total knee arthroplasty in the young patient is a reliable procedure and has excellent results at 13 years follow up with an estimated survivorship of 99% at 10 years.

Barracks et al (1998) studied a series of 123 revision total knee replacements performed at three centers with follow up for 2-4 years. In cases in which exposure could be obtained with undue tension on the patellar tendon, the: surgical approach was modified using either quadriceps turndown (14 cases) or tibial tubercle Osteotomy (15 cases). The remaining 94 patients underwent a standard operative approach that consisted of medial Para patellar capsule incision, which in 31 cases was combined with a quadriceps snip. The results were compared using the Knee Society clinical score, a patient satisfactory survey, and a patellofemoral questionnaire. Postoperatively, the group of patients who had a quadriceps snip was equivalent to the group of patients who underwent a standard approach irl every parameter measured, and the groups therefore were combined for comparison purposes. The patients who had quadriceps turndown and the tibial tubercle Osteotomy had equivalent scores. Postoperatively both of which were significantly lower than the standard group. The group of patients who had quadriceps turndown had a significantly greater increase in arc of motion than the tibial tubercle Osteotomy group. The tibial tubercle Osteotomy group had a lower degree of extension lag but a higher percentage of patients who had difficulty with kneeling and stooping and a higher percentage of patients who thought the surgery was unsuccessful in relieving pain and unsuccessful in returning them to normal daily activities.

McCaskie et al (1998) did a randomized prospective study that compared cemented and uncemented total knee replacement and reported the results of 139 prostheses at five years. Outcome was assessed clinically by independent examination using the Nottingham knee score and radiologically using the knee society scoring system. Independent statistical analysis of the data showed no significant difference between cemented and uncemented fixation for pain, mobility or movement. There was no difference in the radiological alignment at 5 years, but there was a notable disparity in the radiolucent line score. With cemented fixation there was a significant greater number of radiolucent lines on antero posterior radiographs of the tibia and lateral radiograph of the femur. At 5 years following clinical results did not support the use of the more expensive cementless fixation whereas the radiological results are of no known significance.

Yang et al (1998) retrospectively compared the accuracy of the intramedullary and extramedullary guides for tibial cutting in patients undergoing total knee arthroplasty. Total knee arthroplasty was performed in 100 knees (68 patients) during a two-year period. The intramedullary rod was used for preparation of the femur in all cases. For the tibia, each guide system was used in 50 knees. The intramedullary rod was not used in tibia with extreme deformity where the rod could not pass at least two third of the way through the medullary canal. Standing anteroposterior radiographs of the hip to the ankle were taken before surgery and 2 to 6 months postoperatively. The angle formed by the intersection of the tibial mechanical axis and the undersurface of the tibial component (tibial component angle) was measured to check the accuracy of the tibial alignment system. They found no significant differences in the mechanical axis, tibiofemoral alignment or the tibial component angle between the two groups. If the tibia is not badly deformed, the intramedullary rod could produce tibial cuts as accurately as the extramedullary system.

Rogers et al (1998) studied the role of preoperative physical therapy in primary total knee arthroplasty. In order to evaluate the efficacy of preoperative physical therapy for patients undergoing elective primary total knee arthroplasty, 10 patients completed 6 weeks of physical therapy before surgery (Pt group). Ten patients served as control (C group). Physical therapy produced modest gains in is kinetic flexion strength in these severely arthritic knees but no difference in extension strength. The decrease in is kinetic strength after surgery was not affected by preoperative physical therapy. Muscle area did not decrease significantly for the physical therapy group, but it did decrease for the control group after surgery. While postoperative strength difference could not be demonstrated, preoperative physical therapy preserved thigh muscle area after surgery. The clinical significance of this finding is uncertain. Consequently, this study failed to support' the routine use of preoperative physical therapy in knee replacement surgery.

Bassett et al (1998) retrospectively studied a total of 893 patients with 1000 Performance total knee prostheses. The mean duration of follow up was period of 5.2. Years. In 584 cases, the femoral and tibial components were cemented. All patients received a cemented all polyethylene patellar replacement. Tibial bone density determines fixation type. The average age of patients with cementless fixation was 64.3 years versus 76.2 years for patients with cemented implant. The average subjective and functional knee society scores were 91.2 and 90.1 for patients with cementless knee and 89.6 and 83.5 for those with cemented replacements. A surprising absence of osteolysis around screw fixation was noted, and at 5 years, there was 99% implant survival.

Engh et al (1998) did a study on preoperative radiographic planning for revision total knee arthroplas,ty which begins with obtaining excellent quality anteroposterior and lateral radiographs that permit: first; evaluation of the extent of bone loss in the metaphyseal region of the femur and tibia. Second, full visualization of the patient’s intramedullary canal for determining appropriate stem size and length. The surgeon should then determine the appropriate bone defect classification, keeping in mind the provisions needed to address type 2 and 3 defects.; These provisions include any augments or allografts, stemmed components, and the degree of component constrained needed in the patients revision surgery. Through preoperative templating, the surgeon can determine whether a particular implant system provides the options necessary to achieve an optimal surgical result. Whenever templating leaves unanswered questions regarding the extent of bone damage or the degree of knee instability, the surgeon must prepare for the worst-­case scenario to ensure that the appropriate components and graft material are made available.

Murray et al (1998) did a study on pain in the assessment of total knee replacement. The results of total knee replacement are commonly assessed by survival analysis using revision as the endpoint. They used the assessment of pain by a patient based questionnaire as an alternative. In one hospital 66 surgeons between 1987 and 1993 performed 1429 TKRs. The survival at seven years, with revision as the endpoint, was 97.5%. There were no significant difference between the three different types of implant used, the AGC, the IB-ll and the Nuffield knee. When the endpoint was the development of moderate pain, the survival at 7 years for the AGC knee was 72% and that for the IB-ll was similar. Significantly more patients with the Nuffield knee, however, had developed moderator pain. In this investigation 30% of the patients reported moderate pain at some stage by 7 years from operation.

Thomason et al (1998) did a prospective study of 35 cemented press fit condylar knee and studied the prevalence of radio lucent lines Imm wide or wider using two methods of detection: conventional (pin) and fluoroscopically guided radiographs. All films were evaluated in accordance with the knee society total knee arthroplasty roentgen graphic evaluation and scoring system. A total of 12 radiolucencies were detected in nine knees (26% of all knees) using conventional radiographs versus 25 radiolucencies in 13 knees (37% of all knees) using fluoroscopically guided radiographs. This was a statistically significant difference and suggest that the true prevalence of peri-prosthetic radiolucencies will be underestimated if conventional radiographs are used to evaluate the bone-prostheses interface and questions the value of routine postoperative plain film radiographs to evaluate the result of knee arthroplasty.

Schurman et al (1998) did a study in which postoperative knee flexion in patients undergoing Insall-Burstein-11 total knee arthroplasty at 22 years was evaluated. Thirteen preoperative variables and four postoperative variables were used in an attempt to explain postoperative flexion. The significant preoperative factors identified include preoperative flexion, flexion arc, tibiofemoral angle, extensor lag, diagnosis and age. The only postoperative variable of significance was tibio femoral angle. Among the potential determinants of postoperative flexion that failed to appear predictive were the knee society scores and surgeon. Preoperative flexion is lrnown to be a critical determinant of postoperative flexion in total knee replacement. However, in the current study, preoperative flexion accounted for only half of the difference between the best and the worst group, as determined with regression tree analysis.

Itokazu Met al (1998) studied the relationship between the range of motion following total knee arthroplasty and the height of chairs, when rising from a seated position was analysed. 46 TKA subjects were evaluated; 16 had osteoarthritis, 30 had rheumatoid arthritis. It was concluded that a minimum of 100 degrees of postoperative flexion is desired and that a higher chair is more suitable for TKA patients.

Dorr LD, Boiardo RA. In 1999 recommended some steps to provide optimal result in total knee arthroplasty. They were:-1.The tibia should be cut no more than 5 mm from the medial subchondral bone, if the posterior cruciate ligament is sacrificed, and between 5 mm and 8 mm, if the posterior cruciate is saved. 2.a defect should be filled as necessary with bone graft. 3.The tibia should be cut 90 degrees to its axis in the medial-lateral plane and with 5 degrees posterior tilt. 4.the anterior-posterior height of the femur should be maintained to ensure flexion stability. 5.The distal femur should be used as the "adjustment cut" even if the joint line is elevated. 6.If the posterior cruciate ligament tension is tight, it should be lengthened or converted to a sacrificing design. 7.Deformity should be corrected with soft tissue release and not angular bone cuts. 8.The patella cut should be performed so that the result is a symmetrical patella that is not increased from its anatomic height.

They said that if these principles are followed, the instrumentation use and order of osteotomy of the distal femur or tibia do not matter.

During flexion of the normal knee, the tibia stays within a plane that is aligned anterior-to-posterior and passes near the center of the hip, knee, and ankle. To align the knee during total knee arthroplasty, the distal femoral cuts are aligned in 5 degrees to 7 degrees valgus to the long axis of the femur, and the tibial surface is cut perpendicular to the long axis of the tibia. To align the knee in the flexed position, the femoral surfaces are resected perpendicular to the anteroposterior axis of the femur. After alignment, sizing, and implant positioning are done, only tight ligaments are released. In 1999 Whiteside said that this technique results in a knee that is balanced to varus and valgus stresses in flexion and extension, but it often leaves anteroposterior and rotational instability, which requires a more highly conforming tibial component or posterior stabilized knee.

Politi J, Scott R. in 1999 reported the technique and results of a cruciform lateral release performed on 35 consecutive knees having > or =15 degrees of valgus with minimum 2-year follow-up. The posterior cruciate ligament (PCL) was preserved in all knees. Stable flexion and extension gaps were achieved in all cases, and stability was maintained at follow-up. They concluded that this lateral cruciform retinacular release provides a simple surgical technique for most valgus deformities of the knee and allows for stable ligamentous balancing.

Krackow KA, Mihalko WM. did a cadaveric study of flexion-extension joint gap changes after lateral structure release for valgus deformity correction in 1999. This study used a cadaveric model to i) study the amount of correction achieved with each release step in 2 sequences of lateral release, ii) compare the amount of release in extension versus flexion, and iii) measure any associated rotational changes of the tibia. Six fresh-frozen cadaveric knees were used to test the amount of change into varus after sectioning the iliotibial band (ITB), the popliteus tendon (Pop), the lateral collateral ligament (LCL), and the tendon of the lateral head of the gastrocnemius (LG). This sequence was then compared with a second sequence in another 6 cadavers as follows: LCL, Pop, ITB, and LG. The amount of valgus correction was tested in 90 degrees, 45 degrees flexion, and full extension. Results showed that complete lateral structure release provides limited correction into a varus direction with a balanced distracted soft tissue gap or extension space (8.9 degrees with the LG released), and the lateral aspect of the flexion gap opens more than the extension gap (8.9 degrees compared with 18.1 degrees in flexion). Early LCL release provided a more uniform release of the joint gap, and rotational changes were variable, tending toward external rotation of the tibia (6.0 degrees in full extension with release of the LCL). They suggested that when severe valgus deformities are present, the LCL should be considered first for release and the Pop and ITB be used to grade the release.

Paschal et al (1999) did a study on the kneeling ability after total knee arthroplasty. 70 patients with 100 total knee arthroplasty were asked to comment on their ability to kneel. 31 patients with 44 knees said they could kneel easily, 29 patients with 41 knees said they were able to kneel but avoided doing so, and 10 patients with 15 knees said they were unable to kneel. Regarding observed kneeling ability; all patients were able to kneel under supervision. The authors concluded that kneeling, as an important function of the knee should be given additional consideration in relation to the functional results of total knee arthroplasty. Patients should be counseled regarding factors affecting the future ability to kneel after total knee arthroplasty.

Farrington WJ, Charnley GJ,studied the position of the popliteal artery in 32 patients with primary osteoarthritis of the knee in 1999. A total of 45 knees were studied using a noninvasive technique with color-flow duplex scanning. The distance between the popliteal artery and the posterior tibial cortex was measured in various positions of flexion. The distance separating them was found to be maximal between 60 degrees and 90 degrees. The study was repeated in a smaller series of 17 patients (20 knees) after knee replacement but with less conclusive results. They believed that the safest position on which to operate in primary arthroplasty is with the knee in flexion, but the safety margins are not the same in revision surgery.

Coyle et al (1999) reviewed the hospitalization statistics for 1301 revision total knee arthroplasties. They found that rheumatoid arthritis was associated with the lowest rate of revision and that the young age (55 or younger) was associated with the shortest implant survival time.

White RE. Jr.; Allman JK, 1999 Clinically compared the Midvastus and Medial Parapatellar Surgical Approaches, the two most commonly used surgical approaches in total knee replacement. This study compared surgical and clinical parameters associated with both surgical approaches in primary total knee replacement. One hundred nine patients who underwent bilateral primary total knee replacements had a medial parapatellar approach to one knee and a midvastus approach to the opposite knee. The prosthetic design and physical therapy were identical in all 109 patients. The patients and physical therapists were blinded to the type of approach used on each knee. The comparison included the surgical parameters of difficulty of exposure, surgical time, incidence of lateral retinacular release, and total blood loss. The clinical parameters of pain, range of motion, ability to perform a straight leg raise, and complications were compared at 8 days, 6 weeks and 6 months. The comparison between the two surgical approaches showed a statistically significant difference in four parameters, all of which favored the midvastus approach. The patients who had the midvastus approach required fewer lateral retinacular releases, had less pain at 8 days, had less pain at 6 weeks, and had a higher incidence of ability to straight leg raise at 8 days. There was no statistical difference between the two surgical approaches in all other surgical and clinical parameters. There was no increased difficulty of exposure using the midvastus approach when compared with the medial parapatellar approach even in patients with severe varus or valgus deformities.. However, the clinical results at 6 months were identical between the two surgical approaches.

Gill Gurdev S; Joshi Atul B, DM. Mills, (1999) analyzed 16- to 21-Year Results of Total Condylar Knee Arthroplasty. This study presented long term results of arthroplasty with posterior cruciate retention using the Total Condylar Knee implant. From 1976 to 1982, 139 patients had 159 knee arthroplasties using Total Condylar Knee prostheseswere used. Prosthesis survivorship at 20 years was 98.6% for patients who had revision surgery. No femoral components were revised for aseptic loosening. Retention of the posterior cruciate in Total Condylar Knee prosthesis produces results comparable with the results of the original Total Condylar Knee prosthesis with cruciate sacrifice.

The benefits of closing the surgical wound of a primary and revision total knee prosthesis with the knee in full flexion were examined by Emerson Jr and C.Ayers;(1999). Of 108 selected sequential primary knee arthroplasties, the first 52 knees were closed surgically with the leg in full knee extension, and the second 56 knees were closed in 90° to 110° flexion, depending on the available motion of the joint. The patients in each group were matched closely in age, weight, height, gender, and surgical technique. At all followup intervals, the flexion measurements were significantly better in the flexion closure group. At 1 year, the flexion group had 117.9° and the extension group had 112.9° flexion. The revision series also was a selected sequential series with 13 knees in each closure group. In the revision case, the 1-year findings were similar, with significantly more knee flexion in the flexion closure group (118.7° compared with 112.7°). In matched groups, flexion closure in primary and revision knee replacements significantly increased total range of motion, as seen at the 1-year followup.

Mihalko WM, Whiteside LA.in 2000 did a retrospective study of 103 knees who had primary total knee arthroplasty with a flexion contracture ranging from 20 degrees to 60 degrees, tabulation of the primary soft tissue structures released during surgery and identification of any residual deformity was done. The average flexion contracture preoperatively was 27.1 degrees +/- 8 degrees and postoperatively was 2.7 degrees +/- 3.4 degrees. The average followup was 70.4 months Only medial or lateral soft tissue balancing procedures were necessary to correct the flexion contracture in 37 knees (35.9%) and no medial or lateral release was necessary in 25 knees (24.3%), of which 16 had a balanced posterior cruciate ligament. The posterior capsule was released on the deformity side of the knee in 15 knees (14.6%) and on the opposite side of the deformity in seven knees (6.8%). The posterior cruciate ligament was balanced in 21 knees (20.4%) and was released in four knees (3.9%). For all knees in which the posterior cruciate ligament was released or balanced, it was done for excessive rollback and tightness in flexion and not for flexion contracture management. In two patients (2%) an additional 4 mm of distal femur was resected for a 45 degrees and a 25 degrees flexion contracture. The data suggest that a contracted collateral ligament is the most likely primary structure whose effective release allows correction of the flexion contracture in most cases.

Thadani P J; Vince KG in 2000 compiled Ten-to 12-Year Followup of the Insall-Burstein I. The purpose of this study was to evaluate long-term wear with this design. The first 100 total knee arthroplasties were followed prospectively. The average age of the patients at the time of surgery was 69.7 years. All patients were evaluated at 10 to 12 years followup. Knee Society scores and radiographs were obtained. No patients were lost to followup. The average Knee Society clinical score at latest followup was 91.6 points. The average function score was 69 points. One knee arthroplasty failed because of tibial loosening, one failed because of patella wear and fracture, two failed because of sepsis, and two failed because of nonspecific pain. There were seven patella fractures (7%) in the 100 knees. At long-term radiographic analysis, valgus alignment averaged 6° (range, 0°–11°). Polyethylene wear averaged 0.40 mm. There was no catastrophic wear of tibial polyethylene. Thirty-two knees in 32 patients (65%) had radiolucencies in at least one zone; no lucency filled a zone, and none was wider than 2 mm. The absence of clinically significant tibial polyethylene wear at long-term followup was of particular interest. The author concluded that the performance of the molded, nonmodular polyethylene articulation is encouraging and needs to be analyzed critically against the more widely used machined, modular components used today.

MacDonald S J; Rorabeck C;Robert B. Bourne (2000) The authors reported the results of a prospective randomized clinical trial using continuous passive motion after total knee arthroplasty. One hundred twenty patients were assigned randomly to one treatment group: No continuous passive motion (Group I), continuous passive motion from 0° to 50° and increased as tolerated (Group II), and continuous passive motion from 70° to 110° (Group III). The continuous passive motion was initiated in the recovery room and was maintained for a maximum of 24 hours at which point all patients began identical postoperative physiotherapy regimens. Patients were assessed preoperatively, during their hospital stay, at 6 weeks, 12 weeks, 26 weeks, and 52 weeks after their surgery. There were no statistical differences between any of the treatment groups regarding cumulative analgesic requirements, range of motion at any measured interval, length of stay (Group I, 5.1 days; Group II, 5.2 days; Group III, 5 days) or Knee Society scores. This study did not support the use of short-term continuous passive motion after total knee replacement. A standard and a high flexion continuous passive motion protocol failed to show any advantage over physiotherapy alone in the parameters evaluated.

Dorr et al (2000) did a study in which 38 matched pairs of osteoarthritis knees from patients who underwent primary total knee arthroplasty with minimum two year of follow up to compare the functional outcome between a cruciate retention and posterior stabilized design with essentially identical articulation surfaces. The patients were evaluated functionally by three methods; a self-administered questionnaire, the knee society score system and an activity rating based on distance walked. In addition, in vivo fluoroscopic examination was performed in 10 cruciate retention and 10 cruciate stabilized knees to determine the functional knee kinematics. There was no difference between the preoperative and 2-year postoperative knee society patient functional scores and knee functional scores for the cruciate retention and posterior stabilized knees. There was significant improvement in the 2-year patient function and knee function scores of both groups when compared with the preoperative scores. Postoperative ROM was equal to or slightly less than before surgery in 8 knees (5 cruciate retention and 3 posterior stabilized. Fluoroscopic kinematics showed that the posterior stabilized knee had a more normal [pattern of femoral tibial translation than did the posterior cruciate ligament retained knee.

John Callaghan, Insall, Greenwald et al (2000) studied mobile bearing TKR concepts and results. The mean flexion reported was of 102 degrees. They conceptualized that dual surface articulation design offered the advantage of conformational geometry with diminished surface and subsurface stress distribution, while the mobility of the bearing served to minimize the development of interfacial bone stresses. One of the principal features of the MBK is the promotion of load sharing through the relative displacement between the tibial and femoral components. Load sharing reduces the loosening stresses that are transferred to the implant bone interface and it also promotes soft tissue strengthening.

Mihalko WM, Whiteside LA.in 2000 did a retrospective study of 103 knees who had primary total knee arthroplasty with a flexion contracture ranging from 20 degrees to 60 degrees, tabulation of the primary soft tissue structures released during surgery and identification of any residual deformity was done. The average flexion contracture preoperatively was 27.1 degrees and postoperatively was 2.7 degrees. The average followup was 70.4 months. Only medial or lateral soft tissue balancing procedures were necessary to correct the flexion contracture in 37 knees (35.9%) and no medial or lateral release was necessary in 25 knees (24.3%), of which 16 had a balanced posterior cruciate ligament. The posterior capsule was released on the deformity side of the knee in 15 knees (14.6%) and on the opposite side of the deformity in seven knees (6.8%). The posterior cruciate ligament was balanced in 21 knees (20.4%) and was released in four knees (3.9%). For all knees in which the posterior cruciate ligament was released or balanced, it was done for excessive rollback and tightness in flexion and not for flexion contracture management. The data suggested that a contracted collateral ligament is the most likely primary structure whose effective release allows correction of the flexion contracture in most cases.

In 2000 Whiteside LA, Mihalko WM. Evaluated surgical procedure for flexion contracture and recurvatum in TKA. 530 patients (552 knees) who had flexion contracture (542 knees) or recurvatum (10 knees) before surgery were analyzed. Ligament release and correction of varus or valgus contracture corrected flexion contracture to less than 3 degrees in 515 knees (95%). Sixteen knees (3%) had release of the posterior capsule to correct residual flexion contracture, and 11 knees (2%) required overresection of the distal femoral surface to achieve correction of flexion contracture. In all cases, bone resection was done first, osteophytes were resected next, and ligaments were balanced after the trials were in place. Extra bone was resected from the distal femur to correct residual flexion contracture only if ligament balancing failed to correct the deformity. In cases of flexion contracture, the protocol included choosing the larger femoral size when the femur was between sizes to make the flexion space smaller and to allow overresection of the tibial surface to correct the flexion contracture. In cases of recurvatum, the smaller femoral size was chosen to enlarge the flexion space, allowing underresection of the tibia to stabilize the knee in extension. The cutting guides were positioned so that 3 to 5 mm less than the distal thickness of the femoral component was removed to stabilize the knee in extension. By 1 year the flexion contracture was 2 degrees +/- 1 degree. In the knees with preoperative recurvatum, none had residual recurvatum at the conclusion of surgery, and none had recurrent deformity. None of the knees required a hinge or a stabilized component with a highly conforming central post.

Jess H.Lonner et al (2000) did a study on knee arthroplasty in patients 40 years of age or younger. The results of 32 total knee arthroplasties performed for osteoarthritis in 32 patients who were 40 years of age or younger was reviewed. At a mean follow up of 7.9 years the knee society knee scores increased from an average of 47 to 88 points, and the function scores from 45 to 70 points. Flexion contracture decreased to an average of 1.5 degrees, flexion arc increased 0 to 110 degrees. The results were reported favourable in the above-mentioned follow up period.

Darryl D. D lima Michael Trice Clifford W. C et al (2000) did a study on the comparison between the kinematics of fixed and rotating bearing knee prostheses. In this study, the effect of rotating platform knee replacement with or without posterior cruciate ligament substitution on knee kinematics was investigated. 5 knees were implanted sequentially with standard (fixed) bearing and then with rotating platform prosthesis, each in posterior cruciate retaining and substituting designs. 3dimensional kinematic for all knees were measured in an Oxford knee rig. Rotating bearing did not significantly change knee kinematics when compared with fixed bearings.

Venous thrombosis is a major risk after total knee arthroplasty. Without prophylaxis, the prevalence of deep vein thrombosis is as high as 84%, with proximal occurrence as high as 20%. Of more concern is the occurrence of pulmonary embolism as high as 7%, with fatal pulmonary embolism as high as 0.7%. Low molecular weight heparin has been studied extensively and is safe and effective prophylaxis after total knee arthroplasty. Low molecular weight heparins have a predictable dose response, offer high bioavailability at low doses, and produce linear pharmacokinetics. CW Colwell, Jr evaluated effect of Low Molecular Weight Heparin Prophylaxis in Total Knee Arthroplasty in 2001. He stated that this high prevalence mandates the prophylaxis for thromboembolic disease for patients undergoing total knee arthroplasty. Routine pharmacologic prophylaxis with low molecular weight heparin seems to be effective in decreasing the occurrence of venous thromboembolism. However, venographic prevalence of deep vein thrombosis among patients undergoing total knee arthroplasty and receiving prophylaxis remains substantial at 30.6%. Prophylaxis with low molecular weight heparin beyond hospitalization may be indicated with decreased hospital stays, although studies have not been convincing that extended outpatient prophylaxis for more then 7 to 10 days is necessary.

Brandt K D., Block JA. Michalski et al 2001 evaluated efficacy and safety of Intraarticular Sodium Hyaluronate in Knee Osteoarthritis A prospective, multicenter, randomized, double-blind, controlled trial was conducted in 226 patients with knee osteoarthritis. Patients were randomized to three weekly injections of 30 mg sodium hyaluronate or physiologic saline (control) and were observed for an additional 25 weeks. In comparison with the control group, among patients who completed at least 15 weeks of the study and whose Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score for the contralateral knee was less than 12 at baseline, sodium hyaluronate injection resulted in improvement in WOMAC scores. Few side effects were attributed to treatment, and no differences between treatment groups were seen in this respect (sodium hyaluronate, nine [8%]; saline, 11 [10%]). The incidence of injection site reactions was low (sodium hyaluronate, 1.2%; saline, 1.5%). The results indicate that sodium hyaluronate treatment is well tolerated and produces statistically and clinically significant improvement of symptoms in patients with mild to moderate knee osteoarthritis in which pain in the contralateral knee is relatively modest.

Rodriguez; Harish Bhende; Chitranjan S. Ranawat et al (2001) did a study on total condylar knee replacement 20-year follow up data were presented. Between 1976 and 1979, 220 total knee replacements were done on 164 patients. The average 20-year followup data were presented for 45 knees in 30 patients using Knee Society evaluations. The average knee society clinical scores for the surviving patients were 88 points, and the average functional score was 58 points. The average overall alignment was 3 degree valgus. Femoral radiolucencies were present in 17 of 40 lateral views. Two femoral components were loose. 22 tibial components had radiolucencies. The remaining 41 knees retained a well-fixed cemented central peg. The author concluded The Total Condylar Knee replacement maintains excellent durability at 20-years followup.

Christian Michael Bach et al (2001) did a study on radiographic assessment in total knee arthroplasty. 65 total knee arthroplasties were evaluated by the knee society radiological evaluation system. For measurement of radiolucent lines, interobserver correlation was low for all components. The results of inter­observer variability of the patellar evaluation revealed high inter ­observer correlation for the patellar angle and for patellar subluxation and dislocation evaluation. For assessment of patellar medio lateral and super-inferior displacement a low inter-observer correlation was found. For radiographic assessment of total knee arthroplasty, the measurement of angles, including alpha, beta, femorotibial shaft angle, sagital femoral and tibial components angles, patellar angle, and patellar subluxation and dislocation evaluation were recommended. The author recommended reconsideration of the method of assessing radiolucent lines.

Rowley DI, McGurty DW. 2001 published their seven-year experience of data collection on the Insall-Burstein II total knee arthroplasty. This was a prospective record of 1439 patients who had an Insall-Burstein II (IBII) prosthesis implanted between 1990 and 1994. The data were collected using the American Knee Society scoring system. The results emphasized the need for the long-term collection of data on commonly used devices implanted by a cross-section of surgeons. They concluded that for most patients the IBII cemented, posteriorly stabilised, cruciate-substituting prosthesis will relieve pain and give excellent functional results throughout the patients' remaining years with a very small incidence of revision, except in cases of infection.

John J. Callaghan et al, in 2001 gave Clinical Results of Mobile-Bearing Knee replacement. They studied Oxford unicompartmental replacement and the LCS (low contact stress) total knee systems. 95 to 97% 10-year survivorship rates of the Oxford unicompartmental replacement were reported. Low contact stress meniscal-bearing survivorship rates of 98% at 6 years and 94.6% at 8 years were reported. Ninety-five to 100% survivorship rates at the 11-and 12-year followup have been reported for low contact stress rotating platform knee replacements. Complications with the Oxford unicompartmental replacement included an increase in bearing dislocation and an increase in loosening rate when the components were placed in knees that had anterior cruciate ligament deficiency. Complications with the low contact stress total knee system include bearing dislocation (meniscal, rotating platform, and patellar), bearing breakage, and polyethylene wear. If mobile-bearing knee replacements were inserted with the same precision as fixedbearing knee replacements, the results would at least be comparable. They concluded that there may be some potential for an increase in durability, compared with fixed-bearing knee replacements, especially those of a modular design.

Rorabeck et al (2001) did a comparative study on posterior stabilized and cruciate retaining total knee replacement. A randomized controlled study was done to compare the clinical, radiographic and quality of life outcomes between posterior stabilized and cruciatate retaining primary total knee implants. 143 patients were enrolled in the study. Patients ranged in age trom 57-89 years had a primary diagnosis of osteoarthritis, and an intact functioning posterior cruciate ligament. The overall total knee society clinical rating at 3 years: the scores averaged 156.8 points in the posterior stabilized group and 163.5 points in the cruciate retaining group. The range of motion component of the knee society score averaged 113.6 degrees for the posteriorly stabilized group and 108.5 degrees for the cruciate retaining group at 2 years. Based on the numbers available, there were no detectable differences among any of these outcome measures in patients with posterior cruciate retaining and posterior cruciate sacrificing knee replacements.

Benjamin J; Tucker T (2001) raised a question whether Obesity is a Contraindication to bilateral TKA in single sitting? Three hundred sixteen patients who underwent 405 primary knee replacements between 1994 and 1999 were reviewed for the incidence of local wound and systemic complications after unilateral and simultaneous bilateral total knee arthroplasties. A body mass index of 30 or greater was used to define obesity, and patients were divided into four groups based on obesity and whether they were undergoing unilateral or bilateral total knee arthroplasties. Local wound complication rates did not differ between any of the study groups. Patients who were not obese who underwent unilateral total knee arthroplasty had lower systemic complication rates (3%) than the other groups; however, there was no significant difference in complication rates between patients with obesity who underwent unilateral or simultaneous bilateral total knee arthroplasties. Based on these findings,they said that obesity does not seem to be a contraindication to bilateral total knee arthroplasties under one anesthetic.

Kim YH; Kook; Kim JS, South Korean surgeons compared Fixed-Bearing and Mobile-Bearing Total Knee Arthroplasties in 2001. The purpose of this study was to directly compare the results of fixed-bearing and mobile-bearing total knee arthroplasties in the same patient who had bilateral simultaneous total knee replacements. A fixed-bearing total knee prosthesis (AMK) was implanted in one knee and a mobile-bearing total knee prosthesis (LCS) was implanted in the other knee in 116 patients. The average age of the patients was 65 years (range, 33–70 years). The average followup was 7.4 years (range, 6–8 years). Clinical and radiographic followup was done using Knee Society and Hospital for Special Surgery knee rating systems at 6 weeks, 3 months, 6 months, 1 year after surgery, and yearly thereafter. Total knee score, pain score, mean functional score, and range of motion were comparable in both groups. Two knee replacements (2%) in one patient with AMK prostheses were revised because of complete wear of tibial bearing polyethylene. One knee replacement (1%) in one patient with an LCS prosthesis was revised because of dislocation of the medial tibial bearing polyethylene and one knee replacement (1%) in one patient with an LCS prosthesis was revised because of complete wear of the medial tibial bearing polyethylene. No knee had aseptic loosening or osteolysis in either group. After a minimum followup of 6 years, the results of fixed-and mobile-bearing total knee prostheses in the current series are favorable. However, there is no evidence to prove the superiority of the mobile-bearing total knee design.

Laskin Richard S. (2001) stated that proper patellar tracking in the trochlear groove is critical for a total knee replacement to be well functioning. A lateral release may be required to ensure such central tracking. During surgery, an evaluation was made of patellar tracking in 178 patients. The Genesis II prosthesis was used for all the patients. The evaluation was made using the nontouch technique and the axial traction (modified no-touch) technique before and after release of the tourniquet. With the tourniquet still inflated, there were 29 knees in which the patella tilted laterally and 11 additional knees in which the patella subluxed laterally. Using the modified no-touch technique, there were only 12 knees in which the patella tilted laterally and five in which it subluxed laterally. With the tourniquet deflated, only nine of the patellas tilted laterally and three subluxed laterally, indicating that patellar tracking tests should be done after tourniquet release for true results. It was only in this final group that a lateral release was done for an overall lateral release rate of 6%(12 knees). Eleven of these 12 knees had a preoperative fixed valgus deformity greater than 10°. Only one lateral release was required for a patient with a preoperative varus deformity. Four patients with a preoperative fixed valgus deformity and a laterally subluxed patella did not require a lateral release. Axial realignment and reconstitution of an anterior trochlear surface by the implant were sufficient to centralize the patella. Had only the no-touch test been used, there would have been 18 unnecessary lateral releases done.

When the knees were evaluated radiographically, there was no statistical difference in patellar position between the knees that required a lateral release than with the group that didn’t.

Stiehl J B.; Komistek R D., (2001) Analyzed frontal plane kinematics after mobile bearing total knee arthroplasty. Frontal plane kinematics including condylar lift-off and medial to lateral translation were investigated in 10 patients who had total knee arthroplasty with a mobile-bearing rotating platform or a similar implant that had been modified with a posterior stabilizer. The rotating platform had condylar lift-off (average, 2 mm) and medial tibial translation (average, 4.3 mm) in all implants tested. The posterior-stabilized prosthesis had significantly less condylar lift-off (average, 1.2 mm) and medial translation (average, 1.7 mm). The difference is attributed to constraint of the posterior stabilizer mechanism in the frontal plane. The author stated that the important kinematic functions of frontal plane condylar lift-off and medial to lateral translation must be accounted for by contemporary total knee prosthetic designs because abnormalities may lead to abnormal wear and loss of prosthetic fixation.

Vertullo Easley, Scott 2001 in mobile bearings in primary total knee arthroplasty emphasized that adequate soft tissue balancing and balanced flexion and extension gaps have a greater role in mobile bearing than in fixed bearing total knee arthroplasties.

Otto J K.; Callaghan J J et al (2001) published a paper on Mobility and Contact Mechanics of a Rotating Platform Total Knee Replacement. They said that despite their increasing clinical use, mobile-bearing total knee replacements have not been well characterized biomechanically. An experimental and finite element analysis was done to assess the mobility and contact mechanics of a widely used rotating platform total knee replacement. Parameters that varied were axial load, condylar load allocation, flexion angle, and static versus dynamic loading. Similar results from the physical model and finite element model lend credence to the validity of the findings. The torque enquired to initiate rotation (static torque) was greater than that to sustain rotation (dynamic torque). For all practical purposes, the polyethylene insert rotated simultaneously with the femoral component, leading to maintenance of high contact area, desirable behavior clinically. Walking cycle simulations produced a total axial rotation range of motion of 6°. The high frictional torques observed at the mobile interface may explain why a percentage of these mobile-bearings fail to rotate under routine functional load.

Hofmann Evanich, Ferguson (2001) did a 10- to 14-Year Clinical Followup of the Cementless Natural Knee System and compared with cemented TKA.Of 300 consecutive knees (238 patients) that had undergone arthroplasty with the cementless Natural Knee prosthesis from 1985 to 1989, 176 knees (141 patients) were available for followup at an average of 12 ± 1 years after the operation. Knee function was improved significantly. Modified Hospital for Special Surgery knee scores improved from 59.1 ± 13.2 points preoperatively to 97.8 ± 4.7 points at last followup. At last followup, knee range of motion averaged 0° ± 2° to 120° ± 10°. Implant survival was 93.4% including infection and simple polyethylene exchanges) and 95.1% (excluding infection and simple polyethylene exchanges) at 10 years when applying the Kaplan-Meier survival analysis, using loose components, revision, or both as failure criteria. Besides the three revisions for infection, only two femoral and one tibial component required revision. The patellar component survivorship at 10 years was 95.1%. All patellar revisions were attributed to edge wear. Subsequent operative and design changes, including patellar component medialization and countersinking, have decreased the incidence of patellar revision. The long-term results of this cementless knee system compare favorably with those of cemented systems. The Natural Knee design has provided excellent and predictable long-term clinical results in this series of active patients.

Ritter M A.; Berend ME, in (2001) did Long-Term Followup of Anatomic Graduated Components Posterior Cruciate-retaining Total Knee Replacement. the purpose of this study was to evaluate the author’s 15-year experience with the Anatomic Graduated Components total knee replacement. This is a report of the survivorship of 4583 Anatomic Graduated Component total knee arthroplasties. Kaplan-Meier survival analyses were performed with the end point defined as radiographic loosening, revision, or both. There were six (0.18%) femoral, 21 (0.46%) tibial, and 180 (4.2%) all-polyethylene patellar component failures secondary to aseptic loosening. All femoral components and 90% of the tibial components were revised; however, only 15 patellar components were revised. The clinical survival rate with revision of one or more of the components was 98.86% at 15 years. Despite having nearly flat-on-flat geometry and retaining the posterior cruciate ligament, which should increase the stresses in the polyethylene and at the bone-cement interface, this total knee replacement has proved to have minimal wear and excellent longevity with time. The authors thought this is a result of the direct compression molded polyethylene articulation and the nonmodular configuration that incorporates metal backing on the tibial component and eliminates back-sided tibial component polyethylene wear.

Schroeder-Boersch H (2001) in a German publication summarised new knowledge about knee kinematics and induces a new discussion about the design of total knee arthroplasty (TKA) components. According to these new observations, knee flexion is not linked to femoral rollback but to a rotational movement between tibia and femur. The axis of this rotation is situated in the medial compartment of the knee when an intact anterior craciate ligament is present and not centrally through the tibial spines. In case of ACL insufficiency, such as that following TKA, the center of rotation shifts into the lateral compartment. Furthermore, the form of the posterior femoral condyle is not elliptical but round. He concluded that rotational movements between femoral component and tibial baseplate with the polyethylene-inlay have to be possible. One needs an asymmetric surface of the polyethylene-inlay, because different movements occur in the medial compartment than in the lateral compartment. The option to construct the posterior femoral condyle with a single radius allows a high congruency with the articulating inlay. The surgeon should let the new findings influence his choice of a TKA system. A closer analysis of modern prosthetic designs with either fixed or mobile bearings reveals that a few systems have already incorporated some of the new kinematic aspects of the knee.

Buechel SrFF., Buechel FF Jr., M J. Pappas, (2001) Twenty-Year evaluation of Meniscal Bearing and Rotating Platform Knee Replacements

In this study clinical result of the initial cemented and cementless series of 373 New Jersey Low Contact Stress total knee replacements in 282 patients surviving at least 10 years was analyzed using a strict knee scoring scale. The study showed excellent, good, fair, or poor results in 68.1%, 29.8%, 2.1%, or 0% of primary posterior cruciate retaining meniscal bearing knee replacements, 46.7%, 53.3%, 0%, or 0% results in primary cemented rotating platform knee replacements, and 68.1%, 29.8%, 2.1%, or 0% results in primary cementless rotating platform knee replacements, respectively. Radiographic evaluation at minimum 10-year followup showed stable fixation of all components, no gross migration but significant osteolysis requiring bearing exchange and bone grafting in three cementless rotating platform knee replacements (1.8%) in three patients who underwent previous surgeries at an average of 10.2 years from the index surgery. Survivorship of the patients who underwent primary cementless posterior cruciate-retaining meniscal bearing knee replacements was 97.4% at 10 years and 83% at 16 years. With primary cemented rotating platform knee replacements it was 97.7%, and with cementless rotating platform it was 98.3%.

T.Ashraf et al (2002) did a study on the lateral unicompartmental knee replacement. They described 88 knees (79 patients) with lateral unicompartmental osteoarthritis, which had been treated by the St Georg Sled prosthesis. At a mean follow up of 9 years, 15 knees had revision surgery, 9 for progression of arthritis, 6 for loosening, 4 for breakage of a component and 4 for more than one reason .6 patients complained of moderate to severe pain at the final follow up in the 21 year period. At 15 years the cumulative survival rate was 74%.

2002 Sofka CM; HG. Potter; R Laskin studied Magnetic Resonance Imaging of Total Knee Arthroplasty. They said that evaluation of painful total knee arthroplasty can be clinically difficult, and traditional imaging techniques such as conventional radiographs, arthrography, and bone scintigraphy are limited by poor contrast resolution and specificity. Metal artifact makes traditional magnetic resonance imaging techniques nondiagnostic. Forty-one patients (46 knees) had magnetic resonance imaging, tailored to reduce metallic susceptibility artifact, after total knee arthroplasty, and the findings and clinical and surgical followup were reviewed. All studies consistently showed the integrity of the periprosthetic soft tissues. Magnetic resonance imaging findings led to surgical or other therapeutic interventional procedures in 20 patients, and influenced clinical treatment in all patients. They concluded that optimized magnetic resonance imaging, in which the metallic artifact is diminished, is a clinically useful adjunct to traditional imaging techniques in evaluation of patients with painful total knee arthroplasty.

Buecel MJ; and Pappas JJ, in (2002) presented with 10 year follow up with LCS knees. There were 72 Bicruciate retaining meniscal bearing implants, 49 PCL retaining meniscal bearing implants,and 137 PCL sacrificing rotating platform implants, with 80 revision arthroplasties. Eighty-nine percent of the patients had either excellent results (231 patients) or good results (87 patients). The remaining patients had either fair or poor results. There were 7 (3.2%) rotating platform dislocations and 1 (0.7%) traumatic meniscal bearing dislocation.

Chun-Hsiung Huang et al (2002) did a study on osteolysis comparing mobile-bearing with a fixed bearing implant. 80­ revision total knee arthroplasties performed between 1995 and 1998 were included in this study. All had radiographic evidence of advanced polyethylene wear. The group consisted of 34 knees with a low contact stress mobile bearing implant, and the fixed bearing group included 46 knees. The average time from the primary operation to the revision was 102.8+-26.5 months in the mobile bearing group and 96.0+-30.1 months in the fixed bearing group. The prevalence of osteolysis was significantly higher in the mobile­ bearing group (47%) than in the fixed bearing group (13%). In the present study osteolysis was found both in knees with cemented prostheses and in cementless prostheses of different designs.

Douglas (2002) did a study on the polyethylene wear in mobile bearing prostheses. Contact stresses within polyethylene components were much higher when polyethylene thickness was thin «10mm in thickness). They recommend that the contact stresses be kept <5-10 Mpa to minimize fatigue failure.

David C. Pollock et al (2002) did a study on the synovial entrapment, which is a complication of posterior stabilized total knee arthroplasty involving hypertrophy of tissue proximal to the patella associated with pain during active knee extension from 90 degrees of flexion. 26 patients in whom arthroscopic debridement of the knee or open arthrotomy with debridement of the knee had been subsequently performed because of a diagnosis of synovial entrapment were studied. Symptoms (grating, crepitation, and pain with active knee extension from 90 degree) necessitating subsequent debridement occurred in 13.5% of 141 knees treated with the AMK-Congruency implant, 3.8% of 212 treated with the AMK ­posterior stabilized implant and none of the 106 treated with the PFC sigma-posterior stabilized implant. Authors concluded that synovial entrapment is characterized by hypertrophied synovial tissue at the superior pole of the patella. Use of a posterior stabilized femoral component with a proximally positioned or wide femoral box is more likely of result in this complication.

In (2002) JP.McAuley; MF.Harrer; in a study of outcome of TKA in patients with poor preoperative range of motion Involving 27 consecutive total knee arthroplasties in 21 patients said that patients with stiff knees who are debilitated severely can have an improved quality of life after total knee arthroplasty, reflected by an increased walking tolerance, increased functional abilities, and decrease in pain, but in association with a high risk of complications and subsequent revisions. All patients had a preoperative range of motion of less than 50°, severe debilitation, and a minimum clinical and radiographic follow-up of 2 years (mean, 6 years; range, 2.3-11.8 years). The mean preoperative arc of motion was 30° (range, 0°-50°) and improved to a mean 74° (range, 15°-110°) postoperatively. Preoperative flexion contracture was corrected from a mean 28° (range, 0°-60°) to a mean postoperative flexion contracture of 4.4° (range, -5°-30°). In this series, the overall complication rate was 41% and the revision rate was 18.5%.

Lawrence D. Dorr (2002) said that PE Wear was not an issue with total knee replacements that had a round-on-round design such as the Total Condylar and the Insall-Burstein prostheses. As long as designs do not try to reproduce normality in kinematics, wear will not be an issue. He stated that presently, there is no data that mobile-bearing knee replacements will decrease wear complications as compared with round-on-round fixed designs. Wear is not an issue if the total knee replacement is done with a round-on-round design with a cobalt chrome femoral component, monoblock tibial component, and an all-polyethylene patella, all with cemented fixation.

John J. Callaghan; Michael R. O'Rourke (2002) stated that tibial post-femoral cam impingement seen in modular component retrievals of the Posterior-stabilized total knee replacements can be corrected by Femoral cam-tibial post designs that allow hyperextension and limit rotational. Technical considerations including the avoidance of femoral component flexion and posterior tibial slope could also minimize anterior tibial post impingement.

RH. Emerson, Jr; T Hansborough(2002), Compared a mobile with a fixed-bearing unicompartmental knee implant. The results were comparable in both the groups. The first group of 51 knees was treated with a fixed-bearing knee implant and the second 50 knees were treated with a mobile meniscal-bearing implant. Follow-up was 7.7 years for the patients with fixed-bearing implants and 6.8 years for patients with mobile-bearing implants. Both groups functioned well clinically. Radiographic analysis with 3-foot standing views taken preoperatively showed both groups had an average varus alignment of -2°. Postoperatively patients with fixed-bearing implants had an average +2.6° alignment and the patients with mobile-bearing implants had +5.5° alignment, which was significantly different. Survivorship showed a 99% survival for the meniscal-bearing implant and 93% survival for the fixed-bearing implant at 11 years. However, the fixed-bearing knee implants failed significantly more often because of tibial component failure, in six of eight knees, at an average of 6.3 years. The mobile-bearing implants showed a trend to fail because of arthritic degeneration in the lateral compartment, at an average of 10 years, although not statistically significant. The mobile-bearing implants had no tibial component failures. These differences may be attributable to implant design or surgical technique.

W J. Hozack; P F. Sharkey tried to find out the cause of failure of TKRs as the rate of revision knee surgeries was quite high. In 2002 they published a report stating that the reasons for failure listed in order of prevalence among the patients in this study were polyethylene wear, aseptic loosening, instability, infection, arthrofibrosis, malalignment or malposition, deficient extensor mechanism, avascular necrosis in the patella, periprosthetic fracture, and isolated patellar resurfacing. Two hundred twelve surgeries were done on 203 patients (nine patients had bilateral surgeries). More than half of the revisions in this group of patients were done less than 2 years after the index operation.

CM Bach; M Nogler (2002), reviewed the effectiveness of Scoring Systems in Total Knee Arthroplasty. Hungerford score, the Hospital for Special Surgery score, the Knee Society score, and the Bristol score were compared by two independent observers. One hundred eighteen total knee arthroplasties were investigated.The highest interobserver correlation was computed for the Bristol score (interobserver correlation coefficient, 0.88). They emphasized that for clinical assessment of total knee arthroplasty, pain should be measured on a four-step system, the knee should be assessed by measurement of range of motion, extension lag, and flexion contracture, and function should be measured on a separate score assessing walking distance and walking aids.

Otto J K.; Callaghan J J.; Brown T D. in 2003 compared functional load transmission and kinematic performance for standard versus posterior-stabilized versions of a rotating-platform total knee implant, over a standardized loading cycle, using three-dimensional contact finite element analysis. These two design variants differ primarily in terms of the latter's polyethylene insert having a cam that engages with the femoral component during appreciable flexion. The finite element model, previously validated experimentally, afforded direct comparisons of anterior lift-off of the insert from the tibial tray, of bearing mobility, of femoral rollback, and of metal-on-polyethylene contact stresses at the bearing and backside surfaces of the insert. Both design variants generally performed comparably. However, the posterior-stabilized design had slightly more rollback, and slightly less anterior lift-off and rotation, than did the standard rotating-platform design. Peak polyethylene stresses occurred on the backside of the insert near the posterior edge of the medial compartment, the magnitude being approximately 18% higher for the posterior-stabilized design (21 MPa) than for the standard design.

In 2003 Bourne; Masonis et al, Analyzed Rotating-Platform TKRs. Parameters like knee kinematics, lower contact stresses on the polyethylene tibial component, minimized constraint, and self-alignment characteristics of the implant were studied. Gait studies during normal gait showed that the stance phase was associated with knee flexion between 8° and 15°. Contact area studies have shown two types of rotating-platform total knee replacements, namely gait congruous (congruous only during the stance phase of gait) and totally congruous (congruous up to 90° knee flexion) implants. Knee simulator studies showed increased gravimetric wear with rotating-platform total knee replacements compared with their fixed-bearing counterparts. Rotate-only implants had less gravimetric wear than rotate and translate rotating-platform total knee replacements. They said that clinical studies show similar outcomes when rotating-platform and fixed-bearing total knee replacements are compared. Although attractive, the benefits of rotating-platform total knee replacements still need to be proven.

Price, Rees et al (2003) did a study on mobile bearing and fixed bearing prosthesis.40 patients and 80 knees were studied. Preoperatively, there was no obvious systematic difference in the Oxford Knee Score (OKS), AKSS or the range of flexion between the patients’ two knees. At 1 year follow up, the mean scores for the mobile bearing device were better than those of the AGC, using the AKSS (P=0.015), The OKS (p=0.013) and both measurements of pain (AKSS, P=0.015;oksP=O.009). The difference was small but statistically significant.

In 2003 Whiteside LA. did selective lateral release in two hundred thirty-one knees that had a valgus deformity (range, 12 degrees-45 degrees). They were corrected with valgus alignment to 5 degrees by resecting the intact joint surfaces to match implant thickness. Femoral joint surfaces were aligned in 5 degrees valgus to the long axis of the femur and parallel to the epicondylar axis of the femur in flexion and extension. The tibial surfaces were aligned perpendicular to the long axis of the tibia. For knees that were tight in flexion and extension, the lateral collateral ligament and popliteus tendon were released. Those knees that remained tight only in extension had release of the iliotibial band. Posterior capsular release was done only when necessary for persistent lateral ligament tightness. Neither ligament advancement procedures nor varus or valgus stabilized implant systems were needed to achieve stability with this procedure. The knees with ligament releases all fell within a range of 4 degrees to 7 degrees mean varus and valgus laxity, and were not significantly different from one another. No cases of clinical instability occurred, and joint stability did not deteriorate with time.

2003 Scott Banks et al studied knee motions during maximum flexion in fixed and mobile-bearing arthroplasties. Full flexion is a critical performance requirement for patients in Asia and the Middle East. There has been considerable work characterizing maximum flexion in terms of clinical, surgical, and preoperative factors, but less in vivo experimental work after rehabilitation. The purpose of this investigation was to determine whether anteroposterior tibiofemoral translation influenced maximum weightbearing knee flexion in patients with good or excellent clinical and functional outcomes. 121 knees including 16 different articular surface designs were studied using fluoroscopy and shape matching to determine knee kinematics in a weight bearing deep flexion activity. A relatively posterior position of the femur on the tibia was significantly correlated with greater maximum knee flexion. Posterior-stabilized arthroplasties had significantly more posterior femoral position and maximum flexion than posterior cruciate-retaining fixed-bearing arthroplasties, which had more posterior femoral position and greater maximum flexion than mobile-bearing arthroplasties.

In 2004 February, Matsuda Y. Ishii. In a stress arthrometric study done in 60 knees. Compared in vivo laxity of Low contact stress mobile bearing knees in two groups. First was PCL retaining meniscal bearing and second was PCL sacrificing rotating platform mobile bearing total knee arthroplasty. Laxity in various planes is desirable in mobile bearing knees. This is the first report to evaluate the degree of laxity that is desirable to obtain a good clinical result in LCS design in vivo. Telos arthrometer was used to measure antero-posterior and adduction abduction laxity. The results of this series disagree with that of Phillip et al.

There has been an increasing interest in mobile bearing total knee replacement designs in the present time. The concept of self-alignment and the suggestion that it can accommodate small rotational mismatches while implanting the tibial and femoral components this leads to better patellar tracking, lower incidence of lateral release, and improved patello femoral function like stair climbing.

Pagnano M., Trousdale R.T. in 2004 november reported a study of 240 primary TKRs. They reported no significant improvement of patellar tracking as compared to the other groups. There was no decrease in prevalence of lateral retinacular release or patellar tilt or subluxation or improved stair climbing ability at 1 yr post operatively as compared with a posterior stabilized, fixed bearing implant. They used no thumb technique for per operative assess meant of patellar tracking the prevalence of lateral release was similar to that reported by Laskin in 2001 and lower than reported by Rasquinha et al. The later study had 100 knees, but interestingly it reported a decrease from 10% in fixed bearing to 0% in mobile bearing implant.4

In 2004 Mihalko WM, Miller C, Krackow KA studied ligament balancing and gap kinematics with posterior cruciate ligament retention and sacrifice designs. This cadaver study was undertaken to gain insight into the effects that posterior cruciate ligament retention and sacrifice would have on the amount of deformity correction obtained with medial and lateral structure release during total knee arthroplasty. Twenty-seven cadaveric specimens were used to sequentially release medial and lateral structures with and without posterior cruciate support. Each release sequence was tested in full extension and 90 degrees flexion.

In varus model, in full extension, the resulting change into valgus after release of the PCL, and posteromedial structures was 6.9 degrees, and it increased to 13.4 degrees in 90 degrees flexion. With preservation of the PCL this decreased to 5.2 degrees in extension and 8.7 degrees in flexion.

For the valgus knee model with release of the PCL and posterolateral structures, 8.9 degrees of change into varus was seen in extension and 18.1 degrees in 90 degrees flexion. With PCL retention 5.4 degrees and 4.9 degrees of change into varus was seen in extension and flexion, respectively. Significantly less change with retention of the posterior cruciate ligament was seen with both medial and lateral release and more opening of the flexion gap was seen on the release side of the joint for all groups except those with lateral release with sacrifice of the posterior cruciate ligament.

Mihalko WM, Krackow KA. evaluated Posterior cruciate ligament effects on the flexion space in total knee arthroplasty in 2004. The authors concluded that a major result of posterior cruciate ligament sacrifice is the creation of a larger flexion gap. This result provides insight into relative joint line changes that can occur after posterior cruciate ligament sacrifice. It also suggested the need for greater attention to flexion stability when sacrificing the posterior cruciate ligament and rethinking the role of posterior cruciate ligament release in the management of pure, primary flexion contracture.

In 2004 ; Komistek RD, Dennis DA, Mohamed RM studied in vivo kinematics of fixed and mobile bearing implants.the earlier kinematic studies documented the presence of axial rotation in TKR both in fixed and mobile bearing. The knees were analyzed using 3D computer model fitting technique. This rotation occurred at femoral comp and superior surface of PE or at the tibial tray and inferior surface of the PE insert or both, was in doubt. This study confirmed the presence of mobility in the rotating platform design. All nine patients had mobility at 3 and 15 months follow up leading to assumption that soft tissue ingrowth does not prevent bearing mobility. Also the mobility occurred mainly at the PE insert and the tibial tray rather than at PE and femoral component as in fixed bearing. They stated that this might have a role in reducing the PE wear after mobile bearing TKAs.

In 2005 March Dixon; Brown; Scott et al published fifteen-year follow up of Modular fixed-bearing total knee arthroplasty with retention of the posterior cruciate ligament. Only a limited number of studies of total knee arthroplasties with durations of follow-up of fifteen years have taken place, and no study according to the author has taken place involving this kind of prosthesis. A consecutive series of 139 total knee arthroplasties in 109 patients (average age, sixty-seven years) were taken, In this single-surgeon series, modular fixed-bearing posterior cruciate-retaining TKAs had good clinical and radiographic results with excellent survivorship for up to fifteen years. These results are comparable with those in long-term studies of posterior stabilized implants and of prostheses with mobile-bearing and nonmodular tibial inserts

PATELLAR RESURFACING

To date we have three options regarding patellar resurfacing. To resurface it routinely- done in 80s after the success of duopatellar designs; not to resurface- a concept in 90s after seeing the complications like patellar fracture, maltracking, dislocation, patella baja, patellar clunk syndrome, avascular necrosis, tendon rupture and persistence of anterior knee pain etc; or to resurface it as and when required- that is in severe patelofemoral disease, or inflammatory arthritis,cystic changes in patella,maltracking following femoral and tibial resurfacing or incongruence between the patella and the trochlear design of the implant. Many randomized trials have provided inconclusive evidence regarding the fact that patellar should be resurfaced or not.

The first knee arthroplasties did not include patellofemoral replacement. In 1973 in the article by Freeman stated that in theory, patellofemoral joint should be resurfaced, but practically there is difficulty and complications in doing so, hence it must be left alone.

Guepar hinges were a successful design since their introduction in 1969, but in a review of 292 patients in1976 they reported patellofemoral pain to be one of the major concerns. They opined of finding other solutions to this problem (Deburg).

Clayton, Insall, Ranawat in different studies in late 70s and early 80s reported the prevalence of patellofemoral pain to be up to 58%. An attempt to solve this problem was there in some implant design where they incorporated a mediolateral bar extending across the patellofemoral joint. This probably increased the pain. The total condylar knee developed at the hospital of special surgery was the first one to incorporate patella resurfacing as a routine. But these early designs were using dome shaped patella, which is not ideal. Also the fact that it had one central fixation lug led to increased stress. This fallacy was recognized and led to the development of anatomic designs(e.g. porous coated anatomical and low contact stress had this design. LCS design had a metal backed patellar component, which is successful).

Ranawat and Rand in 1986 reported that surgical techniques used in TKR could devascularize the patella resulting in fractures, fragmentation and loosening.

Brick and Scott in 1988 gave the oval or sombrero shaped. An oval patella provides greater coverage of the surface area, and a sombrero shape had better wear characteristics theoretically. The sombrero shaped patella had three fixation pegs that reduced the stress on the bone.

Campbell et al(1980) and Ritter et al (1989) reported no difference in patellar complication in the group undergoing lateral release as compared with the group in which no release was done.

Kayler et al in 1988 reported disruption of anastomotic ring when arthrotomies are placed within one centimeter of patellar margin. Also the Infrapatellar fat pad excision hampers intraosseous supply to the patella.

The reported rate of patello femoral instability (tilting, subluxation, dislocation etc.) is as high as 31% (Bindglass et al). Some contemporary steps are used as a modification to the previous surgical technique and an implant with a properly oriented and a deep trochlear groove.this has resulted in the newer low incidence of instability, which is less than 1%( Grace et al 1988, Rand in1994). These are: -

· Proper removal of all the osteophytes.

· Proper measurment of patellar thickness.

· Presice reaming of patellar implant bed.

· Measuring of patellar thickness with implant in situ.

· Mediallized positioning. And,

· Use of cement.

In 1991 Reuben JD et al studied effect of patella thickness on patella strain they inferred that TKA system should include instrumentation that allows precise restoration of overall patellar thickness. Maintaining a bony patellar thickness of at least 15mm will only produce better results. They also concluded that patellar complications following total knee arthroplasty have begun to emerge as a major cause of failure.

Levitsky KA et al in a seven and a half year long term follow up in 1993 inferred that in patients meeting the selection criteria, TKA without resurfacing the patella provided satisfactory long term results and a high degree of patient satisfaction with an absence of mechanical complications and no reoperations.

In 1994 Harwin SF et al opined that successful femoropatellar resurfacing can be accomplished with minimal complications if the following technical considerations are met: 5-7 degrees of valgus alignment; medial placement of patellar component, taking care not to increase either the AP diameter of the knee or the thickness of the patella; avoiding internal rotation either in the tibia or in the femor and proper soft tissue balance. If anything goes wrong, patello-femoral complication is a usual outcome.

Arnold MP et al in their study of patellar substitution in total knee prosthesis in 1998 concluded that using a blood supply preserving approach and a biomechanically adequate implant TKA without patellar replacement gives excellent long term results. They showed in a long-term follow up study of TKA that the patello-femoral joint is an important problem after TKA.

Harvin in 1998 studying patellofemoral complications in symmetrical TKA gave excellent results with newer anatomic designs. The complication rate was as low as 1.4% and reoperation rate 0.56%.

Feller JA et al studying patellar resurfacing versus retention in 1996 concluded that stair climbing ability was significantly better in the patellar retention group. Although there were no complications related to patellar resurfacing, in the medium term follow up, they did not find any significant benefit from re-surfacing the patella during TKA for osteoarthritis, if it was not severely deformed.

Matsuda S et al analysed the effect of femoral component design and contact stresses with an unresurfaced patella in 2000. They opined that design features of the patello-femoral portion of TKA component are important factors that affect contact stresses in the patellofemoral joint. These features will likely affect the clinical results of TKA with an unresurfaced patella.

Poll FE et al in 2000 researched on walking, chair rising and stair climbing after total knee arthroplasty in patients with patellar resurfacing versus non-resurfacing using temporal-spatial parameters and kinematic and kinetic variables at the knee joint. Analysis of variance (ANOVA) was tested. There were no significant differences in the biomechanics of walking, stair climbing or chair rising between patients after TKA with and without a resurfaced patella. They did not find any advantage of resurfacing the patella.

Kelly MA in his article on Patellofemoral complications following total knee arthroplasty in 2001 was of the opinion that the diagnosis and treatment of the more-frequent complications should be studied in detail. Although these complications may be successfully treated, most may be largely avoided with proper surgical technique and prosthetic component design.

Churchill et al in his paper on the influence of femoral rollback on patellofemoral contact loads in 2001were of the opinion that increasing the femoral roll back in flexion is thought to reduce the patello-femoral contact load in total knee arthroplasty. Posterior cruciate ligament (PCL) substituting TKA produced greatest and the most reproducible roll back. Moving the tibial post posteriorly, further increase the roll back. Increased roll back correlated with reduced patellar load. Quadriceps loads were reduced by increasing the roll back but to a smaller degree. The roll back primarily affects patellar load rather than the quadriceps efficiency.

Stiehl JB et al while studying kinematics of the patellofemoral joint in total knee arthroplasty.in year 2001 were of the opinion that kinematic abnormalities of the prosthetic patellofemoral joint may reduce the effective extensor movement after TKA.

In 2002 Ogon M et al in a 10 to 16.3 year follow up on patella resurfacing concluded that patellar complications were more often found in the resurfaced group than in the group without resurfacing. The results indicate overall no advantage of patella resurfacing compared with patella retention in the long run.

In 2003 Holt et al studied the role of patellar resurfacing in TKA. The study made a final conclusion that patello-femoral complications can be diminished with improved surgical techniques and better implant designs.

Barrack et al in his study all patellae should be resurfaced during primary total knee arthroplasty in 2003 was of the opinion that patello-femoral contact areas are higher and contact stresses are lower in the native patella compared with resurfaced patella after TKA. He also said that every study to date has suggested that kinematics are more abnormal when patella is resurfaced than when it is retained. Laboratory and clinical data indicate that not resurfacing the patella is a viable if not a preferable option in most TKA patients.

Burnett et al tried to find out indications for patellar resurfacing in TK in 2004 concluded that the management of patella in TKA traditionally has been one of the three options: always resurface, never surface or selectively resurface the patella. They also concluded that anterior knee pain before and after TKA much not always be presumed to be secondary to patello-femoral resurfacing / non-resurfacing etiology and other factors may play a role in the dynamic development of anterior knee pain after TKA. The decision to resurface the patella in TKA remains controversial, and the results of long term randomized controlled trails will improve the understanding of this complex issue in the future.

A meta-analysis of patellar replacement in TKA was done by Nizard et al published in 2005 March. They said that it is unclear from individual randomized studies whether the patella should be replaced during total knee replacement. They did a meta-analysis to provide quantitative data to compare patellar resurfacing with nonresurfacing during total knee arthroplasty. Only randomized, controlled trials reported between January 1966 and August 2003 comparing patellar replacement with patella retention were included for a total of 12 studies. The resurfaced patella performed better, and we found an increased relative risk (defined by the ratio of the risk of the event in the resurfaced group on the risk of the event in the nonresurfaced group) for reoperation, for significant anterior knee pain, and for significant pain during stair climbing when the patella was left unresurfaced. No differences were observed between the two groups for International Knee Society function score, Hospital for Special Surgery score, and for patient satisfaction. Many confounding factors were present, such as component design, surgeon experience, and technical aspects of the surgery. They concluded that forming a definitive conclusion was difficult because of these factors.

COMPLICATIONS

Kakkar et al in 1969 used venography and serial fibrinogen imaging to evaluate the progress of calf vein thrombi in a group of postoperative patients. They found that 23% of the calf vein thrombi propagated to proximal veins.

In 1979 Garner published a study of 220 total condylar arthroplasties, 49 knees did not have primary wound healing or had some wound drainage. Cultures were taken out of 41 knees, 35 were negatives. The most frequent organism was staphylococcus epidermidis. There was only one deep infection in which there was secondary infection of the skin flap from mixed organisms. The author concluded that early wound drainage was not related to periprosthetic infection.

Rand et. al. in 1980 observed that stress fracture adjoining the components usually occur in the Patella apart from femur or tibia. The lateral femoral condyle stress fracture usually occurs after stripping of the lateral condyle for fixed valgus deformity caused by avascularity of the bone. Stress fracture of the tibia with medial sinkage and displacement of the tibial component has also been seen in rheumatoid patients.

Hirsh & Bhalla et. al in 1981 reported 4 cases of Supra Condylar Fracture after anterior notching. They were the first to propose that a notch in the anterior cortex of the femur during placement of component may pre-dispose to fracture.

In 1982 Rose HA; Hood et al shared there experienced in lateral popliteal(common peroneal) nerve palsy after TKA. A total of 2626 TKA were performed at the HSS from 1974 to 1980. There were 23 peroneal nerve palsies after both TKAs, which were done 5 months apart. The pre-operative deformities were varus in 5 knees, neutral alignment in 7 knees, and valgus in 11 knees. In addition some degree of flexion contracture was found in 14 patients being severe in 9. Five patients underwent exploration and release of the nerve and a nerve palsy developed in spite of this precaution. These explorations were done in patients with serve flexion contractures (30 & 80 degrees). Time and presentation were variable from recovery room to 6^th postoperative day. 17 required foot drop brace. Six patients did not require anything.

They identified following factors contributing to common peroneal nerve palsy:

1. Stretching of nerve in valgus and flexion contracture;

2. Fascial compression of the nerve and its vascular supply;

3. Direct pressure from dressing;

4. Rare Idiopathic case.

In 1984 Insall divided Patellar problems associated with TKA in 3 categories

1. Patellar Fracture & loosening of Prosthetic components

2. Soft tissue catching or crepitus due to overgrowth of synovial tissue and sometimes associated with pain

3. Patellar instability in form of subluxation and dislocation.

Ranawat et al in 1984 reviewed 241 knees for complications of total condylar knee and laid down treatment of patellofemoral complications.

1. Dislocations and Subluxation: - caused by mal alignment of femoral or tibial components especially tibial or lateral tightness in a valgus knee. It should be treated with revision of mal aligned component and positioning it in a correct plane. For lateral retinaculum tightness, lateral release and medical advancement should be done.

2. Fracture of patella: - caused by mainly a) decreased circulation caused by extensive lateral release and excision of infra patella fat pad and b) improper tension in quadriceps due to improper selection of the size of patella. This complication is treated by cast in extension for 3-4 weeks. If SLR not possible then surgically replace of retinaculum and patellar repair or patellectomy. Preserving the soft tissue around patellar and proper alignment of the implant can prevent this complication.

3. Loose patellar implant: -Treatment of choice is revision if bone stock present otherwise one may remove the component and sculpture the undersurface for a smooth finish.

They said that these complications could be prevented if following criteria are used:

1. Correct alignment of TKA in all 3 planes.

2. Lateral release whenever there is tilt of patella and when there is a tendency for sublaxion, dislocation with positive “thumb test” at 90 degree of flexion.

3. Correct alignment of tibial component in relation to tibial tubercle.

4. Correct size in relation to anteroposterior dimension of femur.

5. Blood supply preservation by minimal soft tissue obstruction.

6. The subchondral bone of the lateral face should be maintained to provide strength.

Merkow in 1985 treated 12 knees (11 patients) with symptomatic lateral dislocation of Patella after TKA. He said that Patellar problems ranged from 5 to 30%. All the patients were women. The cause for dislocation was trauma in 3 knees, incorrect tracking after replacement in 6, and mal–rotation of tibial component in 3.The design of implant did not appear to be a factor causing dislocation in this group. Dislocation was treated by proximal alignment of quadriceps in 10 knees, lateral retinacular release alone in 1, and revision of Tibial and femoral components in 1. After follow up for 34 months the results were excellent.

Rush et al did a study in 1987 he followed up cases of TKA operated in Australia by means of a questionnaire to the surgeons and reported 13 cases of vascular injury. Four with injury to poplitial artery, one with arterio-venous fistula involving the lateral genicular artery, eight with acute ischemia resulting from superficial femoral or popliteal artery thrombosis the authors suggested that it was the tourniquet which caused the thrombosis. They recommended not to us tourniquet in presence of extensive calcification of proximal artery and poor peripheral pulse.

Laskin & Schols in 1987 published a report of medial capsular release in severe varus knees. They described 4 knees with instability of 68 severe varus deformities, which required medial capsular release. Asymmetric instability is the most frequent variant of instability in extension. It is caused mostly because of inadequate medial release in varus knees. Insall & others also agree and state that they accept very little medial laxity after valgus correction, but they accept lateral laxity after varus correction provided that the alignment could not be brought back to neutral with the components inserted. If this is present then further medial release should be done. All the knees done by Laskin had appeared stable at the time of operation. One knee had stability improved by inserting a thicker tibial component and in one a probable neuropathic joint may have caused instability. One knee was unsuccessfully revised by a ligament reconstruction and the fourth knee required revision to a more constraint prosthesis.

Rand et al in 1987 found the incidenee of arterial insufficienay to be only 0.03% in 9022 TKA performed between 1974-1986.

Johnson et al in 1988 compared midline and parapatellar skin incisions for flap mobility and its effect on blood supply to the skin. They demonstrated a reduction in blood supply in the lateral region of the skin incisions about the knee through measurements of transcutaneous oxygen.

Flippe G in 1988 demonstrated that stress fracture of Hip after TKA might occur if the patient was not ambulatory before the operation. The complication could be avoided by prolonged used of crutches or a walker.

Landy and Walker in 1988 examined 90 retrieved knee prosthesis with implant time of upto 10 years. Polyethylene wear was much greater than seen in wear studies of acetabular components. Abrasions burnishing and deformation was seen in approximately 90% of the components. Cement particles embedded in the surface were found in about one-half. Delamination, the most severe form of polyethylene degradation was found in 37%. The authors concluded that UHMWPE is a questionable material for Total Knee Implants. However, currently a suitable alternative is not available.

Johnson et al in 1988 showed that there is significantly better incidence of primary wound healing in TKR skin flaps with improved techniques in tissue management and when the skin incision is made slightly medial parapatellar. The author also studied effect of Continued Passive Motion. They recommended not to be exceeded 40-degrees of flexion in first few days.

Galinet in 1988 said that a persistent flexion contracture is usually the result of incorrect bone cuts at surgery or failure to strip & divide posterior capsule. Usually there is an inadequate amount of bone which is cut from the distal femur, if the component is fixed without balancing the flexion and extension gaps with spacer, it gets tempting to overcome the flexion contracture by excising more bone form the upper tibia; however if this is done the flexion gap will get enlarged, the result will be dislocation with a PCL substituting design. They recommend cutting the distal femur for avoiding this complication.

Vince in 1989, did a 10-12 year follow up of Total condylar prosthesis. All had one-piece polyethylene tibial insert with a 3.5 cm central peg, all were cemented. They observed 3 Tibial loosening and one femoral component loosening. All the tibial component loosening were positioned in Varus.

Hsu & Walker in 1989 in an experimental study showed that the ideal position for a kinematic prosthesis was 7 degrees of femorotibial Valgus with the tibial component positioned at 90 degrees to long axis of Tibia. In this situation the component is loaded with a 51% to 49% distribution between medial and lateral plateaus. They concluded that adduction and abduction motions during gait cycle would produce different loading patterns in patients. Malalignment and malposition should be related to mechanical loosening and perhaps the main cause of it.

Agliette in 1989 showed that postoperative range of motion depends on many factors of which pre-existing range of motion is the most important. A knee that is very stiff to begin with, is difficult to mobilize satisfactorily because of quadriceps contracture and fibrosis of capsule. Even if an adequate ROM is achieved on the table it may not be present post-operatively. For this reason very stiff or ankylosaed knee should be approached with caution and with expectation that 45 to 60 degree of flexion is the likely end result,

Birt et. al in 1990 stated that mobile bearing designs such as Oxford Knee and Low contact stress design are theoretically least reliable to polyethylene wear.

Haas et al in 1990 studied 1329 patients with 1697 knee arthroplasties. Deep vein thrombosis was found in 808 patients (61%); 52% had thromboembolism of the calf veins and 8% had that of the proximal veins. The lung scans of 60 patients (4.5%) were positive and symptomatic pulmonary embolism occurred in 14 patients (1.1%). All his patients received aspirin as prophylaxis.

Haas et al in 1990 compared compression devices with aspirin after unilateral and bilateral TKA. In the unilateral group the incidence of DVT in the compression group was 22% versus 47% in aspirin group. In bilateral group incidents of DVT in comparison group was 48% versus 68% in aspirin group. The author recommended use of comparison devices for unilateral TKA.

Fahmy et al in 1990 demonstrated human intramedullary femoral canal pressure between 500 and 1000 mm of Hg generated by using standard alignment rod techniques in TKR. He said venting the canal did not lower the canal pressure significantly, only over drilling the femoral canal and gently placing the rod maintained the intra medullary pressures in the normal limits. He said that use of pneumatic tourniquet doesn’t protect against fat embolism and with popularity of intra medullary guides the incidence of fat embolism may increase.

Monto et al in 1990 review of literature reported 19 cases of fat embolism with 9 deaths, 15 of which were associated with long stem, cemented prosthesis such as GUEPAR hinge. Four cases were associated with total condylar arthroplasty.

Good nough in 1990 demonstrated that most blood loss in surgery of TKR is not during the operation, but occurs post operatively through suction drainage. They also said that reinfusions of drains are useful but one must be prepared for additional BT especially in bilateral cases.

Dislocations & subluxations are reported in posterior- stabilized implants especially insall-burstien posterior stabilized and insall-burstien II and kinemax design. They are more common with pre-operative valgus alignment. Cohen reported a series of subluxation of PS TKA. Gebhard did similar study of 2 patients.

Insall et al in a series of total condylar arthroplasty in 1990, reported 7 cases of skin necrosis or wound separation, three required secondary closure and two required secondary graft. They said that skin necrosis is particularly likely in previously operated knees, especially when midmedial or midlateral incisions are already present. The use of such previous incisions involves raising a substantial flap. They advocated using the most lateral scar when multiple longitudinal scars are present.

Asp and Rand in 1990 studied 8998 arthplasties, of which 26 were Post Operative common peroneal nerve (CPN) palsies. Palsies were complete in 18 and incomplete in eight. 23 of the patient had both motor and sensory deficits, three had only motor. At 5-year follow-up, recovery was complete for 13 palsies and partial for 12. They said that complete recovery was more likely in those palsies that were incomplete initially.

Martin and Whiteslide in 1990 studied instability of the knee and effect of the joint line elevation after TKA. They said that symmetric instability in extension caused whenever the thickness of the components is less than the extension gap or either by miscalculation of bony cuts or improper ligament tensioning could be corrected by using a thicker tibial component. This causes alteration of the joint mechanics by moving the joint axis proximally, an action that has secondary effects on ligament tension and stability as well as patellar function by creating a low lying patella.

Buecchel FF in 1990 gave technique for lateral release in severe Valgus knees. He stated that after lateral release, lateral laxity should be compensated for by externally rotating the femoral component.

Naranja et al in 1990 studied 37 knees that were either surgically fused or ankylosed and had a TKA performed. The results included and average 7 degrees of extension and 62 degrees of flexion. Total complication rate was 57%. A satisfactory outcome (no pain & unlimited ambulation distance) was obtained in only 10 patients (27%). They concluded that the lack of consistent adequate motion and the complication rate might suggest that the surgeons should reconsider the risk and benefits of this difficult procedure.

Krackow & Weiss in 1990 described a technique to correct Genu Recurvatum. They said that it occurs generally in patients with rheumtoid arthritis and muscle Paralysis. If the knee does not hyper extend at conclusion of surgery it will not develop genu recurvatum. In this technique the origins of the collateral ligaments are transferred proximally and posteriorly. Whereby the cam action of the prosthesis prevents recurvatum.

First reported series of Osteolysis as complication was in 1992 by Peters and Engh. They reported 16% incidence in 174 consecutive TKAs. They also said that presentation of Osteolysis is variable with most patients are asymptomatic. Some may present with boggy synovitis. There might be diffused pain with activity especially in patients where Tibial implant is not stable. They proposed radiographic criteria to diagnose Osteolysis; absence of cancellous bone trabaculae and geographic demarcation by a shell of bone are some of these.

Bindelglass; Cohen et al. in 1993 studied patellar tilt and subluxation in TKA and their relation to pain, fixation, implant design. They reported that petellar subluxation could occur both in settings of patellar re-surfacing or retention. In patellar subluxation incidence rate was as high as 31%, in patients in whom re-surfacing was done.

Lombardi et. al in 1993 analyzed the incidence of dislocation in 3032 primary knees implanted with insall-burstien prosthesis series. The incidence of this problem was very rare with the original IBPS prosthesis (0.2% or 1 in 494). However, with the advent of IB -II prosthesis, the problem became more apparent (2.5% or 1 in 40). Knees that dislocated were found to have achieved statistically significant higher flexion (118 degrees) as compared with control knees (105) (p<0.001%). In addition they tended to achieve higher flexion angles rapidly in the post-operative period.

This resulted in the modification of the spine, which was made longer and was shifted anteriorly. This modification reduced the incidence of dislocation (0.2% or 1 in 656).

Kraay and Woolson et al in 1993 popularized the use of ultrasonography (USG) in detection of thromboembolism. They said that sensitivity and specificity of ultrasonography is approaching those of the gold standard in detection: contrast venography. The sensitivity of USG is between 89% to 100%, the specificity between 95% to 100%, accuracy between 97% to 99%. However these numbers apply to thigh clots only between inguinal ligament and popletial vein.

Insall et al 1993 stated their policy of manipulation of the knee during the 6^th and 12^th postoperative week, if knee flexion is not achieved greater than 75 degrees or more. In a series of 400 knees there were only 2 complications, one supra-condylar fracture, one patellar tendon avulsion. Both these complications appeared early in their experience, when the value of muscle relaxing agents was not appreciated. They said that this complication could be avoided if quadriceps are completely paralysed using spinal or general anesthesia.

Maynard in 1994 demonstrated that majority of thrombosis is formed in the intra operative or immediate postoperative period. Therefore warfarin is not effective in preventing these clots. They also demonstrated that all thrombosis propagated into or above the popliteal vein despite warfarin therapy initiated at the time of initial positive venogram.

Lotke et al in 1996 determined that proximal Deep vein thrombosis occurs only in 5% to 8% of the TKA and THA. This is in agreement with many other authors such as Haas et al, Hull et al and Landy et al. he also emphasized on a newer technology for DVT: the magnetic resonance venography (MRV). It’s major advantage is that it is non invasive and it can detect clots in the pelvic veins while other diagnostic modalities like Doppler and contrast venography cannot. However they found only 45% sensitivity of MRV and the recommended further evaluation of the modality. In addition author also showed that warfarin if given as prophylaxis has a low potential for excessive bleeding if careful control is maintained.

Monte et al in 1996 reviewed the literature of common peroneal nerve palsy after TKA. He reported the cumulative prevalence to be 0.58%. There were 12,784 patients out of which 74 had CPN palsy.

Montgomerry et al in 1998 examined 71 patients with 82 TKA in stiff knees. All had pre-operative arc of motion of less then 50 degrees; the average pre-operative knee score was 38; average pre-operative arc of motion was 36 degree; average flexion contracture was 22 degree; and average maximum flexion was 58 degrees. Post operatively the average knee score was 80; average post-operative arc of motion was 93 degree; and average maximum flexion was 94 degrees. Post operatively no knee had a flexion contracture greater than 10 degrees. They concluded that TKA in ankylosed knees could lead to significant improvement in range of motion and pain. This study was in contrast with that of other authors and general belief.

In 2000 Lesh ML; Gurvinder Deol et. al. did a bio-mechanical study on 12 knees and studied the consequence of anterior femoral notching in TKA and its affect on peri-prosthetic supra condylar fracture of the femur. They demonstrated that notching of anterior femoral cortex significantly lessens the load to failure (from 11813 newtons to 9690 newtons) following TKA and influences subsequent fracture patterns. They said that the prevalence of inadvertent anterior notching is 3.5% to 26.9% and that of supra condylar fracture ranges from 0.30% to 4.2%.

Insall and Brassad in 2000 cited that Deep Vein Thrombosis occurs in approximately 50 % of unilateral cases and 75% of bilateral cases in TKA when no prophylaxis is used. They said that although DVT occurs in calf veins, emboli do not arise from this region. Unlike the situation in total hip replacement, isolated proximal vein thrombosis does not seem to occur after knee surgery despite the possible trauma from a pneumatic tourniquet. The authors reported three deaths in first 400 arthroplasties in Hospital for special surgery (HSS). They also said that major risk for fatal pulmonary embolism, after TKA may be in the 3 rd and 4^th week after surgery.

Insall et al in 2000 said that excessive bleeding which can contribute to postoperative wound drainage must be controlled. They recognized 2 areas of particular concern: - The posterior lateral corner at the level of tibia, which is supplied by the lateral inferior genicular artery and the area were the insertion of the PCL on the tibia. They also said that in case a haematoma is formed then range of motion and CPM exercises should be stopped. Compression bandage should be given and wound should be observed, in case of increasing swelling it should be opened. When leakage through incision occurs it is best to evacuate haematoma surgically. They forbid probing and squeezing the haematoma that can cause retrograde contamination.