MID-TERM RESULTS OF OXFORD MEDIAL UNICOMPARTMENTAL KNEE ARTHROPLASTY

Abstract

Purpose: To analyze the clinical and radiographic results of patients treated by Oxford minimally invasive unicompartmental knee arthroplasty.

Materials and Methods: We have operated 166 patients 188 knees of minimally invasive unicompartmental knee arthroplasty(Oxford Uni^®) from January 2002 to December 2005. The mean ages was 65.3 (44–82) years and 16 cases of male and 150 cases of female. The mean follow-up period was 57 (36–77) months. Preoperative diagnosis were osteoarthritis in 166 cases, avascular necrosis of medial femoral condyle in 20 cases and chondrocalcinosis in 2 cases. The clinical results were evaluated using the HSS knee score and the range of motion of knee preoperatively and at the final follow up. At the final follow up, the ability of the patient to assume the squatting and cross-leg position were checked. The tibiofemoral angle was measured preoperatively and postoperatively. Component loosening, radiolucent lines were checked.

Result: The HSS knee score was 67.5 (52–86) preoperatively and 89.9 (59–100) at the final follow up. The mean preoperative flexion contracture was 6.5° (0–20) and 0.81 (0–5) at the final follow up. Active full flexion was possible within postoperative 2 months. The squatting position was possible in 133 patients (80.1%) and the cross-leg position was possible in 152 patients (91.6%). The tibiofemoral angle was improved varus 1.5° to valgus 4.8°. Complication occurred in 14 cases (7.4%). Meniscal bearing dislocation in 8 cases (4.3%). Tibial components loosenig in 3 cases (1.6%). Femoral components loosening in 2 cases (1.1%). The average time of meniscal bearing dislocation was 11.3 (3–24)months postoperatively. Six cases returned to the predislocation level of activity with the insertion of thicker bearings and 2cases required TKR conversion.

Conclusion: Minimally invasive unicompartmental knee arthroplasty(Oxford Uni^®) provides rapid recovery, good pain relief and excellent function quite suitable to Korean life-style. But given the high complicate rate in mid-term results. Oxford Uni^® gives less reliability compared with TKR.