Background: To assess whether primary repair of proximal ACL tears in the delayed setting leads to similar clinical and functional outcomes as compared to ACL repair in the acute setting.
Methods: All patients with proximal tears with good tissue quality treated in the acute (≤3 weeks post-injury) and delayed setting (>3 months post-injury) were retrospectively reviewed at minimum 2-year follow-up. Ipsilateral reinjury or reoperation and contralateral injury rates were recorded. Functional outcomes were evaluated using the Lysholm, modified Cincinnati, Single Assessment Numeric Evaluation, International Knee Documentation Committee subjective, Forgotten Joint Score-12, Anterior Cruciate Ligament-Return to Sport after Injury scale, and satisfaction scores. Finally, time to return to work, time to discontinue brace-usage, time to running, and time to return to sports were reviewed. Group differences were compared using chi-square tests and Mann-Whitney U tests.
Results: Sixty-nine patients were included, of which 34 (49%) were treated acutely and 35 (51%) in the delayed setting. Besides time from injury to surgery, patient demographics were similar between groups (all p > 0.1). There were three reinjuries (9%) in the acute group and four in the delayed (11%; p > 0.999). Reoperation, complication, and contralateral injury rates were similar between groups (all p > 0.1), while functional outcomes were also comparable (all p > 0.05).
Conclusion: This study found that acute and delayed primary ACL repair results in similar clinical and functional outcomes at short to mid-term follow-up. Therefore, the most important factors for repair surgery success seem to be tissue quality and tissue length, rather than acuity of the surgery.
Level of evidence: Level III, retrospective comparative cohort study.
Keywords: Acute; Anterior cruciate ligament; Clinical outcomes; Delayed; Functional outcomes; Knee; Primary repair.
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