Abstract
Introduction: Patella maltracking is dependent on multifactorial reasons. We have been able to identify one of major and important factor being the rotational alignment of the femoral component. The other subtle variable factors that have a cumulative effect on the tracking of the patella is recognized, which is not the major thrust this study.
Methods and Materials: This is a prospective study on a total of 200 TKR. The first subset of 100 done by the same surgeon and same type of prosthesis and the same sequence of all femoral cuts followed by the tibial cut.
Thus, the rotation of the femoral component was referenced from the posterior condyles.
The second subset of 100 cases, the distal femoral cut was followed by the tibial resection. The susequent femoral resection was referenced from the tibial cut. Thus the rotation of the femoral component was dependent on the tibial axis, and not on the posterior femoral condyles, which in deficient condyles can lead to a significant rotational error.
Conclusion: In the first subset the incidence of lateral release were 3% and 10% asymptomatic patellar tilt.
In the second subset, where the femoral rotation was referenced from the tibial axis, excluding the severe valgus knees, the incidence of lateral release was 0% with asymptomatic patellar tilt of 6%. since all other factors were unchanged i.e. patella replacement, rotation of the tibial prosthesis, same prosthesis, the single variable factor being the femoral rotation leads us to conclude that femoral rotation is a major in appropriate patellar tracking. As a corollary ‘Patellar tracking is the index of orientation, sizing of all components of the prosthesis and soft tissue balance’.
The abstracts were prepared by Professor Jegan Krishnan. Correspondence should be addressed to him at the Flinders Medical Centre, Bedford Park 5047, Australia.
