The results of unicompartmental knee arthroplasty are controversial. We report our first year's experience of unicompartmental knee arthroplasty using minimally invasive Oxford Uni®.

57 knees from 49 patients who had undergone operation from January 2002 to December 2002 were reviewed. The mean age was 65 years (46-77). There were 5 males and 44 females. The mean follow-up period was 28 months (24-31). The preoperative diagnosis was 50 cases of osteoarthritis, 5 cases of avascular necrosis of the medial femoral condyle and 2 cases of chondrocalcinosis. The clinical results were evaluated preoperatively and at the final follow up using the HSS knee score and the range of motion of knee. At the final follow up, ability of the patient to assume the squatting position was checked. The tibiofemoral angle was measured preoperatively and postoperatively.

The tibiofemoral angle was improved varus 1.3o preoperatively to valgus 4.8° postoperatively. The HSS knee score was 67.7 (52-80) preoperatively and 94.6 (88-100) at the final follow up. The mean preoperative flexion contracture was 6.3° (0-15) and 1.7° (0-5) at the final follow up. The active full flexion of the knee was possible in all patients within 2 months after surgery. The squatting position was possible in forty patients within 6 months after surgery. Complications were encountered in four cases with a meniscal bearing dislocation. One case was converted to a total knee arthroplasty and three cases were changed with thicker bearings.

Minimally invasive unicompartmental knee arthroplasty using Oxford Uni® is suitable surgical method for a unicompartmental knee lesion. It provides a short recovery period, excellent pain relief, and is compatible with the Korean life style. However, a meniscal bearing dislocation during the follow-up period is an important complication.