# Comparative Outcomes of Synchronous Anterior Cruciate Ligament (ACL) Reconstruction With Medial Unicompartmental Knee Replacement (UKR) in ACL-Deficient Knees Versus Conventional UKR in ACL-Competent Knees: A Systematic Review and Meta-Analysis

## TL;DR

This study compares outcomes of combining ACL reconstruction with knee replacement versus standard knee replacement, finding similar results in patient satisfaction and implant survival.

## Contribution

The study introduces a novel approach of combining ACL reconstruction with UKR, showing functional equivalence to conventional UKR in ACL-intact knees.

## Key findings

- Both groups showed high postoperative satisfaction with patient-reported outcome measures.
- Implant survivorship was comparable between the two groups, ranging from 87.5% to 100%.
- A small but statistically significant OKS difference favored the intervention group, though not clinically meaningful.

## Abstract

Medial unicompartmental knee replacement (UKR) is a joint-preserving alternative to total knee arthroplasty for patients with isolated medial compartment osteoarthritis. Historically, anterior cruciate ligament (ACL) deficiency has been considered a contraindication to UKR due to concerns over implant failure and instability. However, synchronous ACL reconstruction with UKR has emerged as a potential solution, aiming to restore joint stability while preserving native biomechanics. This review evaluates whether outcomes differ between synchronous ACL reconstruction with UKR and conventional UKR in ACL-intact knees.

A systematic review was conducted following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Sixteen studies were included, comprising 1842 knees, 312 in the intervention group, and 1530 in the comparator group. Eligible studies reported outcomes such as Oxford Knee Score (OKS), Knee Society Score (KSS), implant survival, revision rates, and complications. Meta-analysis was performed using a random-effects model to account for heterogeneity.

Both groups demonstrated substantial improvements in patient-reported outcome measures (PROMs), with OKS, Knee injury and Osteoarthritis Outcome Score (KOOS), and KSS scores indicating high postoperative satisfaction. Implant survivorship ranged from 87.5% to 100% in the intervention group and 92-95% in the comparator group. A statistically significant mean OKS difference of 1.6 points favoured the intervention group (p=0.0251), though this fell below the minimal clinically important difference threshold, suggesting functional equivalence.

Synchronous ACL reconstruction with UKR offers comparable outcomes to conventional UKR in ACL-intact knees. This approach may be particularly beneficial for younger, active patients with ACL deficiency. Further prospective studies are needed to validate long-term efficacy and refine patient selection.