PATELLOFEMORAL ARTHROPLASTY (PFA) FOR PAT ELLOFEMORAL ARTHRITIS - A RETROSPECTIVE STUDY OF 50 IMPLANTS

Material and methods 51 prosthesis were performed in 47 patients and w ere studied in order to assess long term results. One patient was lost for follow up. The diagnosis was: primitive arthritis in 48 knees and post traumatic arthritis in 3 knees. 25 knees had patellofemoral subl uxation. 16 patients had been previously operated on patellofemoral jo int. The average age at the time of surgery was 60.5 years and follow up time averaged 3 years. 22 prosthesis had more than 4 years follow-u p. The operations were performed using a lateral approach with tibial tubercle osteotomy and lateral patellar retinaculum release. The troch lear component was asymetric and made of chrome cobalt alloy; the pate llar component was shaped in polyethylene. Both components were cement ed. Results Using the Guepar scoring system, 41 (82 per cent) PFA were rated excellent or good and 9 poor. Post operative roentgenograms dem onstrated patellofemoral alignment in all knees, even in cases of preo perative patellar subluxation, without tilting of the patella. Follow up roentgenograms demonstrated progressive but moderate deterioration of the tibio femoral joint in 9 cases. In 3 cases, more severe tibio f emoral arthritis were treated by T.K.R one to three years after P.F.A. In one of these knees, we discovered an asymptomatic loosening of tro chlear component. The last 6 poor results were always due to persisten t pain. Discussion The purpose of this study was to assess the results of P.F.A and to clarify the indications. It appears that the 82 per c ent success rate of this study may be compared with the results of lit erature. All the authors have found P.F.A. to be a viable solution, pr eferable to patellectomy (even in older patients) or isolated patellof emoral realignment. The clinical and radiological results did not dete riorate with time. Persistent patellofemoral malalignment was not obse rved in this study thanks to the use of a lateral approach. The presen ce of tibio femoral arthritis adversly affected the outcome, but accel erated changes on the tibio femoral joint after P.F.A were not observe d.