St. Georg sledge for medial compartment knee replacement. 461 arthroplasties followed for 4 (1-17) years.

We evaluated the long-term outcome of 461 medial compartment knee arthroplasties operated at one orthopedic center from 1974 to 1993 through survivorship analysis. Prospective assessment was based on clinical examinations using a modified Bristol knee-scoring system and complete radiographical knee survey. 92% had good or excellent results on objective scoring, and range of motion averaged 112 degrees. 3 criteria were applied to indicate failure: 1) revision or recommended revision, 2) severe-to-moderate pain or revision, 3) lost to follow-up. 20 arthroplasties were revised or recommended to be revised at mean 5.5 years. The incidence of failure due to progression of arthrosis in the unreplaced compartment was low (< 2%). Loosening or wear occurred in 6 cases (1.5%), 2 of which developed fracture of implant. With revisions only as end-point to failure, the survival was 87% at 10 years (95% CI 81%-93%, effective number at risk = 133). In addition to revisions, 19 knees were considered to have failed, as moderate-to-severe pain was noted at follow-up and the survival was reduced to 74% at 10 years with pain or revision as endpoint (95% CI 65%-82%, effective number at risk = 105). We conclude that unicompartmental knee arthroplasty gives long-term pain relief in elderly patients with medial compartment arthrosis.