Obesity does not influence the outcome after unicompartmental knee arthroplasty.

We retrospectively reviewed all 147 medial UKA's placed between 2001 and 2011 with a minimum follow-up of two years. The VAS for pain and satisfaction, the New Knee Society Score (KSS) for satisfaction and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were used as patient reported outcomes (PROs). Pre-operative and follow-up radiographs of the knee were assessed. The survival rate with a median follow-up of 5.0 years is 87%. No significant difference in survival, PROs or radiographical results were seen between the obese and non-obese group. Mid-term survival, radiographical results and PROs of a UKA are not influenced by obesity. Obesity in patients with medial compartment knee osteoarthritis should not form a contra-indication when selecting patients for a UKA.