Biomechanical deficiencies in women with semitendinosus-gracilis anterior cruciate ligament reconstruction during drop jumps

Objective:To compare landing mechanics and neuromuscular recruitment strategies between women with semitendinosus-gracilis anterior cruciate ligament reconstruction (SG-ACLr) and noninjured women during double- and single-legged drop jumps.

Design:Cross-sectional biomechanical study.

Setting:Single university-based biomechanics laboratory.

Participants:Fourteen women 1-5 years post-SG-ACLr and 16 noninjured women participated in this study.

Methods:After anthropometric measurements, warm-up, and familiarization procedures, participants performed 5 trials of a double- and single-legged drop jumps.

Main outcome measurements:Dynamic knee valgus was measured as the distance between knee joints during the landing phase of the double-leg drop jumps. Medial knee displacement was the outcome considered during the landing phase of the single-leg drop jumps. For both drop jump tasks, neuromuscular recruitment was evaluated through rectified normalized electromyographic activity of the quadriceps and hamstrings (amplitude and latency), and quadriceps/hamstrings electromyographic co-contraction ratio.

Results:Although the SG-ACLr group demonstrated a tendency toward a greater dynamic knee valgus during both drop jumps, these differences did not reach statistical significance. EMG data revealed different neuromuscular strategies for each group, depending on the specific jump.

Conclusions:These findings suggest that women with SG-ACLr have a tendency toward greater dynamic knee valgus that could predispose to additional knee injuries. Rehabilitation specialists need to be aware of existing kinematic and neuromuscular deficiencies years after SG-ACLr. Taking this into consideration will aid in prescribing appropriate interventions designed to prevent re-injury.