Mid-term outcomes of mobile-bearing lateral unicompartmental knee arthroplasty

This research was undertaken to evaluate Oxford Domed Lateral unicompartmental knee replacement (UKR) survival and clinical and radiological outcomes. The study also considered the influence of body mass index (BMI) on results and proposed contralateral healthy knee anatomic femorotibial angle (AFTA) as a predictor of postoperative knee alignment.

A retrospective evaluation of 41 primary Oxford Domed Lateral UKR performed in 41 patients in the same institution was undertaken on a patient group comprising of 10 men and 31 women with a mean age of 63 years (range: 38-81 years). A minimum follow-up of two years was required.

The total revision rate was one out of 41 patients (2.4%), with a mean follow-up of 49 months (range: 25-84 months). One patient presented with a traumatic medial dislocation of the bearing after 15 months (resulting in an overall dislocation rate of 2.4%). The visual analogue scale (VAS) and the Oxford knee score (OKS) demonstrated significant postoperative improvement (P < 0.001). Survival at five years, with revision for any reason as the endpoint, was 97.5%. No significant correlation was observed between BMI and postoperative flexion angle, radiologically measured parameters, or pre- and postoperative VAS and OKS. Significant correlation was found (r = 0.77, P < 0.001) between postoperative and contralateral healthy knee anatomic femorotibial angles.

The Oxford Domed Lateral UKR presents a low dislocation rate and excellent mid-term clinical and functional results. Contralateral healthy knee AFTA appears to be a predictor of postoperative knee alignment.