THE UNREPLACED COMPARTMENTS AFTER UNICONDYLAR KNEE REPLACEMENT - A 5-YEAR MEAN FOLLOW-UP OF 33 KNEES

The status of unreplaced compartments at the time of unicondylar knee replacement has not been evaluated in terms of its influence on overal l outcome and progression of disease in these compartments. Thirty-thr ee unicondylar knee replacements in 28 patients (mean age 65 years, SD 8.2) with unicompartmental osteoarthritis were evaluated after a mean follow-up period of 5.1 years (range 3-6.5). Intra-operative appearan ce of the unreplaced compartments was correlated with clinical and rad iographic findings. Mean pre-operative Hospital for Special Surgery sc ore was 54 +/- 11 and at final review was 81 +/- 6. Femoro-tibial anat omical axis was restored to within 5-degrees of neutral. Symptoms attr ibutable to the patello-femoral joint remained unchanged in 29 knees ( 79%) and there was no radiographic deterioration in 15 knees (47%). Th irty-two knees (97%) had no symptoms in the unreplaced femoro-tibial c ompartment, and 29 (88%) showed no radiographic changes of disease pro gression. In the unreplaced femoro-tibial compartment, there was signi ficant difference in terms of symptoms and radiographic appearance at final review in patients with near-normal cartilage compared to those with partial-thickness erosion. Mild fibrillation and partial-thicknes s erosion of patellar articular cartilage did not correlate with outco me. These findings demonstrate that there is little progression of dis ease in unreplaced compartments in the medium term and have relevance in the selection of patients for unicondylar knee replacement.