Systematic review of medial versus lateral survivorship in unicompartmental knee arthroplasty

• The medial UKA five-, 10- and 15-year survivorship are 93.9%, 91.7% and 88.9%.
• The lateral UKA five, 10- and 15-year survivorship are 93.2%, 91.4% and 89.4%.
• Survivorship of medial and lateral UKA does not significantly differ.
• Registry-based studies report a lower survivorship than cohort-based studies.

BackgroundUnicompartmental knee arthroplasty (UKA) has gained popularity in patients with isolated unicompartmental osteoarthritis. To our knowledge no systematic review has assessed and compared survivorship of medial and lateral UKA. We performed a systematic review assessing medial and lateral UKA survivorship and comparing survivorship in cohort studies and registry-based studies.MethodsA search was performed using PubMed, Embase and Cochrane systems. Ninety-six eligible studies reported survivorship, of which fifty-eight reported medial and sixteen reported lateral UKA survivorship. Nineteen cohort studies and seven registry-based studies reported combined medial and lateral survivorship.ResultsThe five-year, ten-year and fifteen-year medial UKA survivorship was 93.9%, 91.7% and 88.9%, respectively. Lateral UKA survivorship was 93.2%, 91.4% and 89.4% at five-year, ten-year and fifteen-year, respectively. No statistical difference between both compartments was found. At twenty years and twenty-five years survivorship of medial UKA was 84.7% and 80%, respectively, but no studies reported lateral UKA survivorship at these follow-up intervals. Survivorship of cohort studies was not significantly higher compared to registry-based studies at five years (94.3 vs. 91.7, respectively, p = 0.133) but was significantly higher at ten years (90.5 vs. 84.1, p = 0.015).ConclusionThis is the first systematic review that shows no difference in the five-, ten- and fifteen-year survivorship of medial and lateral UKA. We found a lower survivorship in the registry-based studies compared to cohort studies.Level of evidenceSystematic Review of level IV studies.