Summary

In patients with non-acute ACL injuries initially managed with rehabilitation, lower baseline KOOS4 scores and higher pre-injury activity levels were associated with a greater likelihood of undergoing subsequent ACL reconstruction.

Abstract

Objective

To identify baseline factors associated with the decision to undergo subsequent anterior cruciate ligament (ACL) reconstruction after initial rehabilitation in patients with non-acute ACL injury, using data from the ACL Surgery Necessity in Non-Acute Patients (ACL SNNAP) trial.

Methods

This post hoc analysis focused on patients randomised to initial rehabilitation in the ACL SNNAP multicentre trial. We examined the association between baseline variables—sex, age, time since injury, Knee Injury and Osteoarthritis Outcome Score (KOOS4), and pre-injury Tegner activity score—and the likelihood of undergoing surgery within 18 months. Univariate logistic regression was used to screen variables, followed by multivariate regression to identify significant predictors.

Results

Of 160 patients randomised to rehabilitation, 159 were included in the analysis after one withdrawal. Among them, 41% (n = 65) underwent ACL reconstruction within 18 months, while 38% (n = 61) completed rehabilitation without surgery. Sex, age, and time since injury were not significantly associated with the likelihood of surgery. Lower KOOS4 scores were associated with greater odds of surgery (odds ratio [OR] per unit increase: 0.979; 95% CI: 0.961 to 0.997; p = 0.0229), while higher pre-injury Tegner scores were associated with increased likelihood of surgery (OR per unit: 1.203; 95% CI: 1.028 to 1.408; p = 0.0215).

Conclusions

In patients with non-acute ACL injury initially managed with rehabilitation, lower baseline KOOS4 scores and higher pre-injury activity levels were associated with greater odds of undergoing subsequent ACL reconstruction. These findings may support shared decision-making and early surgical referral for patients with greater symptoms and higher pre-injury activity demands.

Trial registration: Current Controlled Trials ISRCTN10110685; ClinicalTrials. gov Identifier: NCT02980367.

Funding: This (ACL SNNAP) award was funded by the National Institute of Health and Care Research (NIHR), Health Technology Assessment programme (NIHR award ref: 14/140/63).