Differences in patellar tracking and knee kinematics among three different total knee designs.

Patellar complications are the primary reason for reoperation of the current condylar type designs. The aim of this study was to compare patellar tracking of various knee implant designs: Genesis II NexGen, and the P.F.C. Sigma Modular Knee System regarding trochlear groove center curvature. Nine unembalmed whole cadaveric lower extremities were used. The quadriceps and hamstrings were dissected into their individual muscles and loads were applied onto the muscles proximally based on the cross sectional area of the muscles. The three-dimensional kinematics of the patellofemoral and tibiofemoral joint of the intact knee were measured using a 3Space tracking system. Three implants (one from each company) were implanted onto the same cadaveric knee in random order consecutively. This was done to ensure consistency of the soft tissue constraints in influencing the amount of patellar tracking. Patellar rotation, patellar tilting, patellar lateral shift and patellar displacement in relation to groove center were measured. There was no significant difference between the intact knee and the various implants regarding patellar rotation and lateral shift. However, all three prosthetic designs showed a significant degree of lateral tilting when compared with the intact knee. At 60 degrees knee flexion, the normal patella was tilted laterally to 0.44 degree +/- 2.15 degrees as compared with the Genesis II patella at 4.75 degrees +/- 4.81 degrees, the NexGen patella at 4.85 degrees +/- 4.81 degrees, and the P.F.C. Sigma patella at 4.89 degrees +/- 3.79 degrees lateral tilt. There was no difference between the intact knee compared with the resurfaced patella in patellar displacement in relation to the groove center. This study suggests the relatively similar kinematic behavior between the implant designs as compared with the intact knees. However, additional modification of implant geometry may be required to help decrease the amount of patellar tilt.

[1]  S. Hirokawa,et al.  Three-dimensional mathematical model analysis of the patellofemoral joint. , 1991, Journal of biomechanics.

[2]  T. van Eijden,et al.  A mathematical model of the patellofemoral joint. , 1986, Journal of biomechanics.

[3]  J. N. Grace.  Patellar insatability after total knee arthroplasty , 1988 .

[4]  J Passick,et al.  Recurrent infection of a total hip arthroplasty associated with radiation-induced ulcerative colitis. A case report. , 1989, The Journal of arthroplasty.

[5]  T P Andriacchi,et al.  Patellar component failure in cementless total knee arthroplasty. , 1988, Clinical orthopaedics and related research.

[6]  R Nagamine,et al.  Effect of rotational malposition of the femoral component on knee stability kinematics after total knee arthroplasty. , 1995, The Journal of arthroplasty.

[7]  R Nagamine,et al.  Patellar tracking measurement in the normal knee , 1995, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[8]  R Huiskes,et al.  The three‐dimensional tracking pattern of the human patella , 1990, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[9]  Extensor mechanism complications following total knee arthroplasty. , 1987, The Journal of arthroplasty.

[10]  J. Reuben,et al.  Effect of patella thickness on patella strain following total knee arthroplasty. , 1991, The Journal of arthroplasty.

[11]  F. H. Gunston,et al.  Complications of polycentric knee arthroplasty. , 1976, Clinical orthopaedics and related research.

[12]  R. Gustilo,et al.  Technique of patellar resurfacing in total knee arthroplasty , 1988 .

[13]  L. S. M. Gomes,et al.  Patellar prosthesis positioning in total knee arthroplasty , 1988 .

[14]  K. An,et al.  The effects of tibial rotation on patellar position , 1994 .

[15]  Importance of soft tissue integrity on biomechanical studies of the patella after TKA. , 1996, Journal of biomechanical engineering.