# Mid‐term performance of a unicompartmental knee prosthesis

## TL;DR

This study shows that a unicompartmental knee prosthesis provides good long-term results with high survival rates and low complications.

## Contribution

The study provides new evidence supporting unicompartmental knee arthroplasty as a viable option with high survivorship and functional outcomes.

## Key findings

- Midterm patient-reported outcomes showed significant and sustained improvements through 5 years.
- Kaplan–Meier survivorship was 98.1% at 5 years with low revision rates.
- Radiolucencies did not significantly affect outcomes, and complications were rare.

## Abstract

The objective of this study was to report midterm patient‐reported outcomes (PROs) and survivorship of the Medacta MOTO Medial® Unicompartmental prosthesis (Medacta International, Castel San Petro, Switzerland) and surgical technique.

This prospective, multicentre study included 207 adults aged 43–85. Of these, 170 reached 2‐year and 90 reached 5‐year follow‐up. PROs included the forgotten joint score (FJS), Oxford knee score (OKS) and knee injury and osteoarthritis outcome score (KOOS) subscales: Pain, Symptoms, ADL, Sport and QOL. Stress radiographs were divided into three types, quantifying the amount of medial space opening and deformity correction. Data were collected at preoperative, intraoperative, 4 weeks, 6 months, 1‐year, 2‐year and 5‐year. Complications, revisions and Kaplan–Meier survivorship were analysed.

All PROs showed statistically significant improvements starting at 6 months and maintained through 5‐year. Pre‐operative standing full‐length x‐rays, averaged 6.5° varus. The average change in mechanical axis was less than 1° at 5‐year. No difference in PROs was found between patients with (N = 63) and without (N = 27) radiolucencies. Only two cases with radiolucencies progressed to revision. There was one superficial infection and four revisions to the total knee arthroplasty. No thromboembolic, instability or arthrofibrosis complications occurred. Kaplan–Meier survivorship was 98.5% at 2‐year and 98.1% at 5‐year.

Unicompartmental knee replacement with implant system that allows surgical flexibility and independent balancing is a surgical option with promise of excellent functional outcomes, low complication rates and high survivorship (98.1% at 5‐year). These results challenge previous studies indicating high revision rates and support the utilisation of unicompartmental arthroplasty for properly indicated patients.

Level II, prognostic studies.