High early revision rate with the FPV patello-femoral unicompartmental arthroplasty

Unicompartmental patellofemoral arthroplasties are uncommon however numbers are increasing and there are a variety of new prostheses available. The Femoro-Patella Vialla (FPV, Wright Medical) device was the second most commonly used patellofemoral unicompartmental prosthesis in the 2012 British National Joint Register. There are however no published outcomes data for this device.

52 consecutive cases were studied prospectively using Oxford Knee Score and American Knee Society Scores pre-operatively and at follow up to a minimum of two years.

Overall Oxford Knee Scores improved from 30 points pre-operatively (36.6%) to 19 points (60%) at one-year. American Knee Society Knee scores improved from 51 points pre-operatively to 81 points at one-year. Function scores improved from 42 points pre-operatively to 70 points at one-year. 13 (25%) patients had an excellent outcome with pain abolished and near normal knee function. 11 (21%) patients gained very little improvement and scored their knees similar or worse to their pre-operative state. There were no infective or thromboembolic complications. Seven cases have been revised to a total knee replacement for on-going pain in six cases and progression of arthritis in the tibio-femoral compartments in one case. The patellar button was found to be very poorly fixed in all cases that were revised.

Early results with the FPV prosthesis demonstrate that successful outcomes can be achieved however the results were unpredictable and a significant minority of patients had on-going symptoms that they found unacceptable. The early revision rate was high in this series.