To identify the demographic and operative factors that determine outcome in supracondylar femoral osteotomy for lateral compartment osteoarthritis of the knee.

Clinical and radiologic review of a nonrandomized, consecutive one-surgeon series.

A university-affiliated, elective surgical referral centre.

Forty-nine consecutive patients with unicompartmental osteoarthritis of the knee, involving the lateral compartment, and of sufficient severity that the alternative surgical procedure would be total knee replacement.

Supracondylar varus osteotomy stabilized with a blade plate.

Knee function measured by the Knee Society Score and time to conversion to total knee replacement.

A Knee Society Score greater than 80 was obtained in 81% of patients, but in the function portion of the measurement only 30% had a similar score. After discarding the patients who died, life-table analysis demonstrated the predicted survival before conversion to total knee replacement to be 87% at 7 years. There was no correlation with patient age or sex, femorotibial angulation, amount of correction or time after the intervention. Removal of the fixation device improved the clinical result.

The role of supracondylar femoral osteotomy remains poorly defined, but the procedure can delay total knee replacement for considerable time in appropriate patients.