OXFORD UNICOMPARTMENTAL KNEE ARTHROPLASTY. 2 TO 12 YEAR RESULTS IN A DISTRICT GENERAL HOSPITAL SETTING

Abstract

We report the outcome of 135 knees with medial compartment osteoarthritis treated by Oxford meniscal-bearing unicompartmental arthroplasty. They have been performed in a Distict General hospital by a single surgeon. All the knees had an intact anterior cruciate ligament, a correctable varus deformity and the lateral compartment was uninvolved or had minor osteoarthritic changes. At review 29 knees were in patients who had died and 106 were in those who were still living. The mean elapsed time since operation was 5.82 years (range 2–12 yrs).

Using revision as the end point the outcome for every knee was established. Five knees have been revised, giving a cumulative prosthetic survival rate at ten years of 94.04% (95% confidence interval 84.0 to 97.8). The causes for revision were aseptic loosening in three, progressive valgus deformity in one and dislocation of the bearing in one. Knee rating and patient function were assessed using the modified Knee Society Scoring system. The mean Knee score was 92.2 (51–100), and mean Functional score was 76.2 (51–100). 90% of the patients did not require blood transfusion. Two patients had deep vein thrombosis and three knees had superficial wound infection that responded to antibiotics. Intraoperatively, one patient had fracture of the proximal tibia which was fixed with two partially threaded cancellous screws.

92% of patients were fully satisfied with the procedure and 91% of them said that they would undergo a similar procedure in the opposite knee.

The implant survival is comparable to that reported by the designers of the prosthesis and not significantly different from those for total knee replacement. Uni-compartmental knee replacement with all its advantages offers a viable alternative in patients with medial gonarthrosis. Appropriate patient selection and good surgical technique are the key factors.