Unicompartmental knee arthroplasty compares favorably to total knee arthroplasty in the same patient.

There are several surgical management options for medial knee arthritis, and it is often difficult to decide whether a unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA) is appropriate. Few studies have compared UKAs and TKAs in the same patient. We identified 23 patients with osteoarthritis who had a TKA on one side and a UKA on the other. The preoperative values of the 2 knees were not statistically different. Strict criteria were used to determine whether a UKA could be performed (functional anterior cruciate ligament, minimal deformity, and minimum changes in other compartments). Preoperative radiographs were reviewed to confirm that the knee undergoing TKA had medial compartment disease only. Knee Society scores, radiographic analysis, and patient preferences were recorded for all patients. Average follow-up was 46 months (range, 7.2-148 months) and 42 months (range, 11.5-59.8 months) for TKA and UKA, respectively. We found little or no difference in outcomes between the 2 procedures, except for an improved range of motion with the UKA compared with the TKA (123 degrees +/-9 degrees vs 119.8 degrees +/-7 degrees, respectively). Knee Society scores improved from 45.9 to 89.7 in UKA and from 42.4 to 90.3 in TKA. Of the 23 patients, 11 expressed no preference between either knee and 12 preferred the unicompartmental knee; no patient preferred the total knee. With appropriate patient selection, UKAs are a successful option for patients with osteoarthritis.