Hamstrings and Quadriceps Weaknesses Following Anterior Cruciate Ligament Reconstruction Persist Up to 6 Months After Return-to-Sport: An Angle-specific Strength Analysis.

The study only measured concentric isokinetic strength at a single speed (60 degrees/second), so findings cannot be directly compared to functional tests or eccentric strength assessments. Rehabilitation programmes were not standardised and were delivered by private physiotherapists, so variability in prior care may influence strength outcomes. Return to sport clearance was based on subjective surgeon assessment rather than objective criteria, which may not reflect current best-practice guidelines. The sample size was small (20 at baseline, 16 at follow-up), and the follow-up period was only six months, so the long-term persistence of these deficits and their relationship to re-injury risk remains unclear. The ACL reconstruction group was significantly older than the control group (24.0 vs 21.8 years), though the authors argue this small age difference is unlikely to impact strength results.

The authors report no conflicts of interest. Funding was provided by FWO Flanders and internal funding from KU Leuven.

Do not assume that normal peak strength values indicate a safe return to sport. This study shows that significant hamstrings weaknesses exist at deeper flexion angles that peak tests miss, and these deficits persist for at least six months after returning to play without additional targeted rehabilitation.