The patello-femoral joint in total knee arthroplasty: is the design of the trochlea the critical factor?

We report the outcome after 10 years of a prospective study of two cohorts of patients undergoing total knee reconstruction treated with patellar replacement (centre A, n=124) or without (centre B, n=143). The same tibio-femoral components were used in all knees. The cohorts were demographically similar. The clinical outcome and the patello-femoral revision rates were the same in the two cohorts. Analgesia was required for anterior knee pain in one patient with replacement and in one without. In the replacement group patello-femoral survival on a best-case scenario was 100% at 10 years, and on a worst-case scenario 96%; one of the nonreplaced patellae had been resurfaced for pain by 10 years. In view of the satisfactory and similar outcomes with and without replacement the authors suggest that an appropriate design for the prosthetic trochlea, rather than the replacement or otherwise of the patella, is the main determinant of patello-femoral outcome in total knee reconstruction. Thus patella replacement may be optional. Desirable trochlea design features are described.