Background: A high percentage of female athletes who sustain an anterior cruciate ligament (ACL) rupture suffer serious long-term consequences such as osteoarthritis and disability. Thus, identification of risk factors has high clinical relevance in the prevention of ACL rupture. Hypothesis Noninjured athletes with low knee flexor electromyography (EMG) preactivity and high knee extensor EMG preactivity during sidecutting are at increased risk of future ACL rupture.
Study design: Cohort study (prognosis); Level of evidence, 2.
Methods: Fifty-five elite female athletes (team handball and soccer) aged 24 +/- 5 years with no history of ACL injury were tested for EMG preactivity of vastus lateralis and medialis, rectus femoris, semitendinosus, and biceps femoris during a standardized side-cutting maneuver. The incidence of ACL ruptures was registered in the following 2 match seasons.
Results: During the subsequent 2 match seasons, 5 athletes sustained a confirmed noncontact ACL rupture. Before injury, all 5 players displayed a neuromuscular pattern that differed from the noninjured players, characterized by reduced EMG preactivity for the semitendinosus (ST) and elevated EMG preactivity for the vastus lateralis (VL) (P < .01). On the basis of these findings, a high-risk zone was defined as one standard deviation above the mean VL-ST difference. In our population, 5 of 10 subjects with a VL-ST difference in this zone sustained an ACL injury during the study period.
Conclusion: In the present study, currently noninjured female athletes with reduced EMG preactivity of the ST and increased EMG preactivity of the VL during side cutting were at increased risk of future noncontact ACL rupture. Our data indicate that a high-risk zone can be used to identify noninjured players at high risk of future ACL rupture. Consequently, individual preventive efforts can be introduced in time. However, large prospective studies are needed to confirm this finding before definitive clinical recommendations can be made.