# Femur tibial rotation in patients undergoing bilateral versus unilateral ACL reconstruction: A propensity score matched analysis

## TL;DR

This study found that patients who had surgery for two torn ACLs had more internal tibial rotation compared to those with one ACL surgery.

## Contribution

The study provides new evidence on tibial rotation differences between bilateral and unilateral ACL reconstruction using a matched analysis.

## Key findings

- Bilateral ACLR patients had a mean SEA-PTC angle of -8.6°, significantly greater than the -5.2° in unilateral ACLR patients.
- The SEA-PTC angle in the bilateral group was about 1.5 times greater than in the unilateral group.
- The difference in tibial rotation was statistically significant (p = 0.043).

## Abstract

The aim of the present study was to compare the tibial rotation between patients who have undergone unilateral versus bilateral ACL reconstruction (ACLR).

Patients who underwent primary bilateral ACLR at our institution from the years 2010 to 2022 were retrospectively identified (n = 49). Exclusion criteria were: simultaneous injury (n = 2), not available magnetic resonance imaging (MRI) or surgical report (n = 13), or were older than 50 at the time of first ACL injury (n = 11). Twenty‐three patients were eligible for matching. A retrospective database analysis of consecutive unilateral primary ACL from 2019 to 2021 (n = 572) was performed. Patients with previous knee surgery, lateral collateral ligament and/or posterior cruciate ligament and/or posterolateral corner injury and fractures around the knee were excluded from the study. Those who had undergone unilateral ACLR with < 3‐year follow‐up were further excluded. Twenty‐three patients of case were matched with 96 unilateral ACL control by age, gender, body mass index and Tegner activity level. Two orthopaedic knee surgeons who were blinded measured the femur tibial rotation by measuring surgical epicondylar axes—posterior tibial condyles angle (SEA‐PTC angle) on MRI scans.

Propensity score matching analysis yielded 19 pairs of bilateral and unilateral ACLR. The mean SEA‐PTC angle in the bilateral ACLR group was −8.6° ± 3.9°. Specifically, the SEA‐PTC angle was −8.5° ± 3.4° and −8.7° ± 4.4° for right and left knee respectively. The mean SEA‐PTC angle in unilateral ACLR group was −5.2° ± 5.8°. The SEA‐PTC differed statistically between groups (p = 0.043).

Patients who underwent bilateral ACLR had a significantly greater internal tibial rotation on MRI compared with those who underwent unilateral ACLR. Specifically, the mean of SEA‐PTC of bilateral group was about 1.5 times greater among those of unilateral ACLR.

Level III, case–control study.