Survivorship of Fixed-Bearing Lateral Unicompartmental Knee Arthroplasty: Minimum 10-Year Follow-up of a Single-Center Cohort.

BACKGROUND: Lateral unicompartmental knee arthroplasty (UKA) accounts for only 5 to 10% of all UKA procedures, and outcome data beyond 10 years remain limited. The purpose of this study was to evaluate the survivorship of fixed-bearing lateral UKA in a consecutive cohort of patients who had a minimum follow-up of 10 years.

METHODS: This retrospective single-center cohort study included 78 patients (85 knees) who underwent fixed-bearing lateral UKA from 2006 to 2015. Kaplan-Meier survival analysis was performed with revision for any reason as the endpoint. Survivorship was assessed at five, 10, and 15 years. Patients who died during follow-up without revision were censored at the time of death.

RESULTS: Kaplan-Meier revision-free survivorship was 91.7% at five years and 90.6% at both 10 and 15 years. There were eight revisions (9.4%). The most common cause of failure was progression of osteoarthritis in other compartments (62.5%), followed by aseptic loosening (25.0%) and periprosthetic fracture (12.5%). Most failures occurred within the first five postoperative years.

CONCLUSION: Fixed-bearing lateral UKA demonstrated excellent long-term survivorship, with revision-free survival of 90.6% at 10 and 15 years. Failures occurred predominantly during the early postoperative period and were most often related to progression of osteoarthritis in other compartments. When appropriate indications are respected, lateral UKA represents a durable and reliable alternative to total knee arthroplasty for patients who have isolated lateral compartment osteoarthritis.