Caroline Emilie van Woensel Kooy, Rune Bruhn Jakobsen, Anne Marie Fenstad,
Andreas Persson, Lars Engebretsen , Håvard Moksnes, Guri Ranum Ekås

Abstract

Objective To describe the nationwide population of anterior cruciate ligament (ACL) injured patients initially managed non-operatively, quantify the proportion undergoing delayed ACL reconstruction (ACLR) and describe both intraoperative findings and patient-reported outcomes.

Methods Primary ACL injuries treated non-operatively were prospectively registered in the Norwegian Knee Ligament Register (2017–2023). We collected baseline characteristics, injury details, surgical details if delayed ACLR was performed and patient-reported outcomes (Knee injury and Osteoarthritis Outcome Score, KOOS). Treatment survival was analysed with Kaplan-Meier curves, and factors associated with ACLR were assessed with Cox regression.

Results Of 485 patients included (mean age at injury (SD) 35 (12), 25%<25 years), 93% (n=452) were physically active in sports preinjury. At 2 years, 63% remained non-operatively treated. Of the delayed ACLR patients (n=178), 56% underwent concurrent meniscal repair, and 18% partial resection. Instability was the main reason for ACLR (85%). Patients younger than 25 years, those active in pivoting sports preinjury and those with meniscal injuries at baseline were more likely to undergo delayed ACLR (HR (95% CI) 1.95 (1.2 to 3.2), 1.54 (1.1 to 2.2) and 1.63 (1.2 to 2.2), respectively. Both non-operative and delayed ACLR patients showed moderate impairment on KOOS Sport/Recreation and Quality of Life subscales at 2-year follow-up (mean scores 69.8 vs 61.0 and 68.6 vs 63.4), with no statistically significant between-group differences.

Conclusion In this active population of ACL injured patients treated non-operatively, two-thirds remained non-operatively treated at 2 years. Younger patients, those engaged in pivoting sports preinjury and those with baseline meniscal injuries had higher risks of undergoing delayed ACLR. KOOS scores were similar between non-operative and delayed ACLR patients.