We compared the medium-term outcomes of age and gender matched patients with unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). We retrospectively reviewed the pain, function and total knee society scores (KSS) for 602 UKAs and age and gender matched TKAs between 2001 and 2013. Function scores remained significantly better in UKAs from preoperative until 3 years follow up. The change of function scores was not significantly different. TKAs performed better than UKAs for pain scores. Total KSS for both groups were not significantly different in the study. Fewer medical complications were reported in UKA group. 6.30% of UKAs and 2.99% of TKAs were revised. The theoretical advantages of UKA were not borne out, other than in immediate postoperative complications.