Summary
A prospective cohort study describing patient characteristics and outcomes following non-operatively treated ACL injured patients registered in the Norwegian Knee Ligament Registry from 2017 to 2023.
Abstract
Background
Anterior cruciate ligament (ACL) injuries impair knee function and quality of life, regardless of treatment option. Research on non-operatively treated patients is limited, despite an estimated 50% of patients being managed non-operatively in Norway. Randomized controlled trials (RCTs) show comparable functional, clinical and patient-reported outcomes following both non-operative and surgical treatment options, however half of non-operatively treated patients eventually undergo delayed ACL reconstruction. While some cohort studies suggest delayed ACL reconstruction may increase the risk of meniscal and cartilage injuries, evidence beyond the few RCTs is based on small prospective cohorts or retrospective studies which are prone to bias. The knowledge gap regarding non-operatively treated patients with ACL injuries limits our understanding of its associated risks and outcomes, and hampers clinicians’ ability to identify which patients may benefit from non-operative treatment. Since neither treatment option achieves optimal outcomes for all patients, more knowledge regarding non-operative treatment option is required to enable evidence-based treatment recommendations and informed shared decision-making.
Aim
The aim of this study was to describe patient characteristics and outcomes following ACL injuries initially treated non-operatively in patients registered in the Norwegian Knee Ligament Registry during the period from 2017 to 2023.
Methods
Patients with primary ACL injuries treated non-operatively were prospectively registered in the Norwegian Knee Ligament Register (from 2017 to 2023). Female patients < 14 and male patients < 16 were excluded. Data recorded included the following; baseline characteristics, injury details, patient-reported outcomes (Knee injury and Osteoarthritis Outcome Score, KOOS) and surgical details if delayed ACL reconstruction was performed. Survival of non-operative treatment was analyzed with Kaplan-Meier graphs. Factors associated with delayed ACL reconstruction were assessed using cox regression analysis.
Results
Of the 485 patients included (mean age 35 (SD 12), 25% < 25 years), 93% (n=452) were physically active in sports pre-injury. At two years follow-up, 63% remained non-operatively treated. Of those patients undergoing delayed ACL reconstruction (n=178), 56% (n=100) underwent concurrent meniscal repair. Instability was the main reason for ACL reconstruction (85%, n=75). Younger patients, those active in pivoting sports pre-injury, and those with meniscal injuries at baseline, were more likely to undergo ACL reconstruction (HR 1.95, 1.54, and 1.63, respectively), and no difference between genders were observed (HR 0.88, p-value 0.4). There were no statistically significant differences in KOOS scores between the non-operatively treated and ACL reconstructed patients at 2- and 5-year follow-up.
Conclusion
ACL injured patients treated non-operatively represent all age groups and are typically active pre-injury. Of the initially non-operatively treated ACL injured patients registered during the inclusion period, 63% remained non-operatively treated at two years follow-up. Patients that were < 25 years old, those engaged in pivoting sports pre-injury, and those patients with baseline meniscal injuries, were all statistically at higher risk of undergoing delayed ACL reconstruction than their counterparts. KOOS was comparable between non-operatively treated and delayed ACL reconstructed patients.