Between 1975 and 2OO1, Five Hundred unicompartmental kne arthroplasties (UKA) were performed by a surgeon (M.R.C.) In more than 6O% of the cases it was an internal UKA for knee degenerative arthritis. Axis deformity was noted in 43,2% of the cases, with a genu varum in 33,6% of the cases. Isolated necrosis of the medial femoral condyle was noted in 6 cases (1,2%) and 13 cases (2,6%) showed with sequellae of a trauma. A Single procedure was performed in 425 knees. Bilateral arthroplasty was done in in 15% of the cases. Epidemiology of the series shows that the left knee was operated in 46.6% and right one in 53.4% of the cases. The Average age was 7O.6 for male and 71.8 for the female patients. 7O.4% of the patients were Female and 29.6% were Male. Several types of implants were used: The Marmor knee in 295 cases, the Miller-Galante (75 cases), Cartier (75 cases) Oxford III (5O cases), but also the Mansat and PCA prosthesis.

Methods and Results: Retrospective study with patients assessed in 2 separate series in 2OOO and 2OO6. Analysis of the results was performed using the Lequesne score, the Mansat protocole and the Hungerford functional score for the most recent cases. The results were excellent and good in 87% of the cases. Walking improoved in over 9O% of the cases. No primary or late infection was noted in this series and no severe post-operative complications. Prosthesis removal and change was performed in 9% of the cases, mainly for loosening or for polyethylene degradation.

Discussion and Conclusions: This study confirms the good results with the UKA and allows to understand the reasons for failure, to notify the differences between Lateral and Medial UKA

The correct indication should take in account the persistance of the ACL and of a mild knee deviation in the frontal axis.