Minimally invasive lateral unicompartmental knee replacement: Early results from an independent center using the Oxford fixed lateral prosthesis

The aim of the present study was to assess clinical outcome as well as short-term survivorship of fixed-bearing lateral unicompartmental knee replacement (UKR) from a non-designer centre using the Oxford Fixed Lateral prosthesis.

This single-centre retrospective cohort study reports the short-term results of 51 consecutive patients (52 knees) after fixed-bearing lateral UKR with a minimum follow-up of one year. Survivorship analysis was performed with different endpoints and clinical outcome was measured using the Oxford Knee Score (OKS), objective American Knee Society Score (AKSS-O), range-of-motion (ROM), visual analog scale for pain (VAS), Tegner activity score and UCLA score.

There was no revision surgery, defined as exchange of at least one of the components resulting in a survival rate of 100% at two years. Three patients required further surgical treatment resulting in a survival rate of 94.2% (95% confidence interval (CI): 83.2–98.1%) with the endpoint ‘any reoperation’. Outcome scores, VAS and ROM showed a statistically significant improvement at final follow-up (P < .001). The OKS improved from 26.4 ± 6.9 (12–41) preoperatively to 39.7 ± 8.4 (15–48), the AKSS-O from 54.3 ± 15.3 (18–90) to 82.2 ± 15.6 (40–100), the American Knee Society Functional Score from 56.4 ± 21.3 (10–100) to 83.1 ± 20.2 (five to 100) and the ROM from 123.5 ± 13.5 (90–140) to 134 ± 10.3 (95–150).

Early results of fixed-bearing lateral UKR using the Oxford-Fixed-Lateral prosthesis were encouraging with a significant improvement in pain and knee function as well as an excellent survivorship of 100% at a mean follow-up of two years. Further follow-up is necessary to evaluate the long-term effectiveness of this device and the surgical technique.

Level IV, retrospective cohort study.