Deficits in muscle strength are not seen following recovery from augmented primary repair of anterior cruciate ligament tears

Objectives: Anterior cruciate ligament (ACL) repair for proximal tears, where the ligament is re-attached and augmented with suture tape, can negate the need for graft harvest, thereby maintaining native anatomy. Autograft harvest has been associated with persistent deficits in lower limb muscle strength after recovery from ACL reconstruction. The aim of this study is to compare lower limb muscle strength following ACL repair and reconstruction. Methods: Nineteen ACL repair patients augmented with suture tape and nineteen ipsilateral semitendinosusgracilis autograft ACL reconstruction patients (both mean 4 years postoperatively) were recruited, along with twenty healthy volunteers. Patient-reported outcome measures (PROMs) were obtained using the Knee Injury and Osteoarthritis Outcome Score (KOOS), Lysholm, and Tegner scores. Maximal isometric quadriceps and hamstring strength at 90 degrees knee flexion were measured using a fixed Myometer after a warm-up and three maximal-effort contractions. Results: Mean hamstring strength of the reconstructed legs was lower than that of healthy volunteers by 0.29 Nm/ kg. The hamstring strength ratio of the operated side to the uninjured side was greater in the repair (95% +/- 13) than in the reconstruction (81% +/- 18) group. There were no statistically significant differences between sides for quadriceps peak torque or for hamstrings in the volunteer or repair group. PROMs scores for the reconstruction group were significantly lower than volunteers across all domains and lower than repair for KOOS activities of daily living and Lysholm scores. Conclusion: Hamstring weakness seen following ACL reconstruction is not evident following ACL repair with suture tape augmentation. Strength asymmetry could contribute to re-injury risk and influence functional performance, while altered loads affect knee biomechanics and may lead to osteoarthritis progression. The absence of these deficits in the repair group demonstrates a potential benefit of this technique when used in appropriate patients. Level of evidence: II.