Rajagiri Evolution of Total Knee Arthroplasty design.pptx

A quick recap into the evolution of knee arthroplasty designs

1. EVOLUTION OF TKA DESIGN LIBIN THOMAS MANATHARA Rajagiri Hospital

2. INTERPOSITIONAL ARTHROPLASTY In 1860, Verneuil suggested joint reconstruction by soft tissue interposition Pig bladder, nylon, fascia lata, prepatellar bursa, and cellophane were some of the materials used But none of the results were promising

3. RESECTION ARTHROPLASTY In 1860 Ferguson increased mobility by creating a new subchondral surface after resection of the entire joint Usually performed on knees that had ankylosis and deformity secondary to tuberculosis or other infectious processes The results of this procedure were also satisfactory

4. INTERPOSITION AND RESURFACING PROSTHESIS Boyd in 1938, Campell in 1940, Cabitzain 1950, Kraft and Levinthal in 1954 replaced only femoral part of the joint Burman in 1944, Kiaer in 1963, Macintosh in 1956 replaced the tibial surface

5. MacIntosh ARTHROPLASTY In 1958 MacIntosh introduced his interventions of hemiarthroplasty for treating varus or valgus knee He implanted a tibial acrylic plateau in order to correct deformities restoring stability and reducing pain

6. INTERPOSITION AND RESURFACING PROSTHESIS Vitallium (used in hip arthroplasty) was introduced in knee replacement by MacIntosh, but owing to early loosening it was not popularized He introduced the flexion-extension gap concept for gaining ligament balance by using spacers

7. HINGED PROSTHESIS In 1951, a hinged prosthesis was developed by Walldius Acrylic was used initially and later on was replaced by metal The technique to use this prosthesis was easy to perform

8. HINGED PROSTHESIS A ll soft tissue and ligaments were removed Then the intramedullary stem was aligned It provided mechanical and structural stability In 1950s and 1960s hinged TKA gave a satisfactory outcome

9. HINGED PROSTHESIS L imitations- use of a simple hinged prosthesis to replace the native knee joint (which has complex movements) This resulted in high failure rates due to early loosening (overloading of prosthesis- bone interface)

10. HINGED PROSTHESIS The Guepar prosthesis was developed which shifted the axis of rotation posteriorly (also a hinged type) It too failed because the knee is a complex joint

11. A NEW FRONTIER? In t he 1970s new implant designs came up which are based on concepts still relevant today One design tried to reproduce the normal knee kinematics by trying to recreate the normal anatomy Other models concentrated on function primarily than anatomy by concentrating on mechanics of knee

12. ADVANCES IN MATERIAL SCIENCES In 1963- original polyethylene In 1971, methyl methacrylate- FDA approval for use as “bone cement”

13. POLYCENTRIC KNEE ARTHROPLASTY Based Charnley’s low friction arthroplasty concept, in 1971, Gunston used metallic femoral condyle runners on polyethylene troughs on the tibial plateau Collaterals and cruciate ligaments were preserved in Gunston’s knee arthroplasty

14. POLYCENTRIC KNEE ARTHROPLASTY T here was significant pain relief in short-term follow up But it failed due to inadequate fixation to the native bone

15. GEOMEDIC KNEE- MAYO CLINIC D eveloped by Dr. Coventry with Mr. Averill Cruciate ligaments were preserved But there was implant losing due to alteration in knee kinematics

16. FREEMAN- SWNASON KNEE D eveloped by a surgeon- Dr. Michael Freeman and Professor of Mechanical Engineering SAV Swanson in 1973 Conceptually, it is not only concentrated on mechanical stability but also on conserving the anatomy

17. GOALS Efforts should be made to reduce the risk of loosening There should NOT be complete congruence between femoral and tibial components of the prosthesis There should be minimum friction between the components

18. GOALS Any moment limiting hyperextension should NOT be sudden but rather should be gradual The fitting of prosthetic components to the native bone should be in such a manner that the load distribution is over the largest area of bone–prosthesis interface

19. GOALS Removal of bone during TKA should be minimum and should be similar to the bone removed during arthrodesis It should keep big, flat cancellous surface for implantation A rescue procedure should be available easily

20. GOALS Dead space between the components should be as little as possible in order to avoid the possible risk of infection Long intramedullary stem and intramedullary cement should be minimal to avoid infection

21. GOALS There should be efforts to minimize the generation of debris to as little as possible This concept led to use of as large as possible metal-on-plastic bearing surfaces to reduce surface stress

22. GOALS There should be availability of standard insertion techniques The implanted prosthesis should at least provide a range of motion from 5° of hyperextension to 90° of flexion.

23. GOALS There should be some restriction of free rotation Soft tissue should restraint excessive range of motion in all directions, especially by collateral ligaments

24. FREEMAN SWANSON KNEE Even today majority of these concepts are valid 2 controversies First is the role of PCL Secondly the necessity to replace the patellofemoral joint and patellar resurfacing

25. DUOCONDYLAR PROSTHESIS In mid 1970s-was introduced to try and mimic the normal anatomy of knee joint The femoral component had two unicondylar prosthesis which were connected anteriorly via bridge and were wider This articulated with two flat tibial instruments

26. TOTAL CONDYLAR PROSTHESIS Insall et al. (1974) developed Total Condylar (TC) prosthesis concentrating on the concept of functional TKA (similar to the Freeman-Swanson) Pathbreaking It gave longevity of implant Dependable and easily reproducible results

27. INSALL AND GUNSTON TOTAL CONDYLAR PROSTHESIS C onsidered as the first “modern prosthesis” In this model cruciate ligaments were not retained The femoral condyles had a change in radius curvature posteriorly and condyles were made symmetrical

28. INSALL AND GUNSTON TOTAL CONDYLAR PROSTHESIS To aid in patellar tracking there was flange and trough anteriorly In order to give mediolateral stability, there was a short post replacing the tibial eminence In order to avoid the anterior subluxation, there was addition of a central post to engage femur during flexion in TC II

29. TOTAL CONDYLAR PROSTHESIS Although due to loosening resulting from more forces from this central post its use was discontinued early but it laid foundation to PS design Other design models that were based on TC design were Press-Fit Condylar (PFC) and PFC Sigma (DePuy)

30. TIMELINE 1974 The first metal baseplate for tibia with different polyethylene inserts was designed by Dr. Eftekhar. Tibial poly came initially in 6, 10, and 15 sizes 1975 Dr. Pappas and Buechel around the same time developed the New Jersey Knee which was named low contact stress (LCS) due to mobile bearing and rotating platform which was the first of its kind

31. TIMELINE 1975 The origin of CR-TKA occurred when Dr. Merril Ritter suggested a change into the tibial component of TC prosthesis by cutting the posterior inlet to preserve posterior cruciate ligaments 1978 By making a Posterior-Stabilized design, the limitation of the Total Condylar prosthesis was changed by the Insall–Burstein prosthesis

32. POSTERIOR STABILISED TKA It created a femoral roll back at 70° by engagement of central cam on femur and posterior part of tibial post thus shifting the point of contact posteriorly This Insall–Burstein knee gave the inspiration to the current PS design

33. POSTERIOR STABILISED TKA Patellar dislocation was one of the major drawbacks of Insall–Burstein knee To correct it the future models had asymmetrical anterior flange, which improved patellofemoral tracking

34. POSTERIOR STABILISED TKA With the use of posterior- stabilized prosthesis, it was realized that only cruciate excision was not enough The advantages and disadvantages of PCL retention versus substitution is a matter of debate even today after many years of its use

35. POSTERIOR STABILISED TKA The ligaments should be well balanced if PCL is retained PCL retention had several hurdles like chance of PCL rupture causing instability in flexion, difficulties in balancing ligaments

36. POSTERIOR STABILISED TKA These problems led to the discovery of deep-dish polyethylene inserts, which have become part of many CR prosthesis These inserts restrict anterior translation of femur over tibia due to their conforming articular surface in coronal and sagittal planes

37. POSTERIOR STABILISED TKA The main aim of Posterior-Stabilized (PS) TKA is to produce mechanical alignment In PS-TKA, contact point of femur and tibia is shifted posteriorly during 40°–90° knee flexion by using post and cam mechanism on tibia and femur, respectively

38. CRUCIATE RETAINING TKA In CR-TKA to restrict the anterior translation of femur over tibia during knee flexion, the native PCL is used and hence it does not have cam and post mechanism in the prosthesis Studies conducted to compare CR-TKA with retaining PCL to CR-TKA without PCL showed decreased kinematics of the knee reduced posterior translation of LFC and anterior translation of MFC with absent PCL, proving the vital role of PCL in knee kinematics

39. CRUCIATE RETAINING TKA M ajor risk is that the soft tissue in arthritic knee is usually attenuated and may not function This making patients prone to losing kinematic function on a long term if PCL fails Some studies show that the femoral roll back produced by CR-TKA is less consistent wrt PS-TKA

40. HIGHLY CONGRUENT LINER (ANTERIOR STABILISED) In this prosthesis, there is no post and cam mechanism and PCL is sacrificed Here stability and kinematic control are offered by Highly Congruent Liner (HCL) giving highly conforming articular geometry MFC acts as a pivot center by being fairly immobile, whereas during flexion LFC moves posteriorly causing femoral roll back and external rotation

41. HIGHLY CONGRUENT LINER (ANTERIOR STABILISED) This motion is guided by the liner using high articular congruence MFC is holed in place by medial side concavity which is spherical, whereas LFC is allowed to glide posteriorly during flexion because lateral side is like slot And to prevent anterior translation of femur anterior lip poly is raised

42. BICRUCIATE RETAINING TKA As opposed to the PS, CR, and HCL which are mechanical design variation, Bicruciate Retaining prosthesis (BCR-TKA) is an anatomical variation design and its similar to unicondylar prosthesis In this design we try to recreate the patients’ normal joint line, i.e. an average 3° of varus Tension of soft tissue, articular geometry, contraction of muscle guides the knee motion usually

43. BICRUCIATE RETAINING TKA Knee kinematics can be driven powerfully if the collateral ligaments and ACL and PCL ligaments are all being preserved even without balancing And hence in order to reduce articular congruence, the liner is completely flat This avoids the kinematic difference, i.e. pulling of a ligament in one direction and liner pulling knee motion in another direction

44. BICRUCIATE RETAINING TKA This contributed to early failure of anatomic knee models As compared to standard TKA, BCR-TKA as a procedure is more challenging as soft tissues need to be preserved Similar to UKA, BCR-TKA also has strict guidelines with respect to selecting patients- there should be minimal deformity, ligaments should be intact

45. MOBILE BEARING vs FIXED BEARING TKA The fixed bearing (FB) conventional TKA has stood the test of time Long-term studies showing great results were mostly conducted on elderly patients (low activity levels) Now TKA is shifting to a younger age group (high functional demand), so mobile bearing (MB) inserts are suggested

46. MOBILE BEARING vs FIXED BEARING TKA MB were designed to minimize the possible wear and eventual loosening associated with FB In FB complex, multidirectional motion is converted to unidirectional motion in between two bearing surfaces Whereas by increasing contact area and reducing the contact stress MB allows a more congruent surface

47. MOBILE BEARING vs FIXED BEARING TKA MB had the challenge to reduce the wear between tibial baseplate and Polyethylene (PE) insert In order to allow the desired locking in tibial base- plate, FB were made of titanium alloy which failed to give a smooth surface for PE whereas MB tibial base plates were made of highly polished cobalt–chromium alloy

48. MOBILE BEARING vs FIXED BEARING TKA Due to more physiological sagittal gait kinematics, MB increased knee flexion and knee range of motion MB had an added advantage of self-correcting any mismatch between tibia and femur and thus giving a better result with respect to patellofemoral mechanics and thus reducing anterior knee pain and patellar clunk syndrome

49. MOBILE BEARING vs FIXED BEARING TKA In spite of the advantages, MB came with a potential risk of PE dislocation due to mobility between tibial baseplate and the insert 0–9.3% incidence has been reported for PE dislocation

50. MOBILE BEARING vs FIXED BEARING TKA Oxford Unicompartmental Knee (Biomet, Warsaw, IN, USA) is the first commonly used MB model It was introduced in 1976 and used till date After that Low Contact Stress (LCS, formerly New Jersey Knee, DePuy, Warsaw, IN, USA) followed

51. NON CEMENTED vs CEMENTED PROSTHESIS Non-cemented fixation in TKA was developed in 1980 due to concern about the tolerance of bone cement fixation over long term It was initially invented by Hungerford et al. as a porous-coated anatomic design

52. NON CEMENTED vs CEMENTED PROSTHESIS Surface topography on this prosthesis helps the bone ingrowth in it They are usually coated or textured so that on the surface of implant new bone is formed

53. NON CEMENTED vs CEMENTED PROSTHESIS And till the bone ingrowth occurs screws or pegs are used to stabilize the prosthesis As compared to cemented prosthesis, uncemented is dependent on bone ingrowth- requires a longer healing period

54. NON CEMENTED vs CEMENTED PROSTHESIS Due to aseptic loosening and bone loss, there were higher failure rates with non-cemented implants as compared to cemented ones Since non-cemented implants have not been used for that long it is difficult to have a comparison with cemented implants

55. CONSTRAINED CONDYLAR KNEE PROSTHESIS There are ligament attenuation resulting in laxity and imbalance along with bone loss in revision TKA giving poorer outcomes Soft tissue defect causing the coronal plane movement is restricted by constrained condylar knee prosthesis

56. CONSTRAINED CONDYLAR KNEE PROSTHESIS Tangential anterior-posterior stress across prosthesis interface is reduced by CCK by allowing change of center of rotation during flexion When CCK was used excessive constraint was a major concern resulting in early loosening and failure

57. THANK YOU Libin Thomas Manathara RAJAGIRI HOSPITAL