Background and Purpose. An estimated 100,000 anterior cruciate ligament (ACL) injuries occur each year in the United States. With the rising costs of health care associated with surgery and rehabilitation, a better understanding of the predisposing factors that lead to the higher prevalence of female non-contact ACL injuries compared to their male counterparts is critical. This study evaluated the isometric strength ratios of the muscles acting in the transverse and frontal plane of the hip in female athletes with and without non-contact ACL injury.
Methods. Isometric muscle strength of the adductors/abductors (Add/Abd) and the external rotators/internal rotators (ER/IR) of the hip were evaluated with a hand-held dynamometer that was mounted upon an examination table customized specifically to meet the needs of this study. Thirty-five female subjects participated in this study, n=16 athletes had previously sustained a non-contact ACL injury, and n=19 served as uninjured athletic controls.
Results. Results from the current study indicated no difference upon comparison of the isometric hip muscle strength ratios of the dominant versus non-dominant lower extremities of uninjured female athletes for Add/Abd (p=0.75), and ER/IR (p=0.76). There were also no differences apparent in the muscle recruitment patterns when comparing the ACL-injured lower extremity of the experimental group to that of the like-dominant lower extremity of the athletic control group. Lastly, side-to-side comparison of the injured groups involved versus uninvolved lower extremity also revealed no significant difference for the Add/Abd (p=0.91), and for the (ER/IR p=0.61) of the hip.
Conclusion and Discussion. Findings from this study revealed no significant difference in the antagonistic isometric muscle strength ratios of the muscles acting in the frontal and transverse plane of the hip upon comparison of non-contact ACL injured and uninjured female athletes participating in basketball, volleyball, and soccer. Further research is warranted to explore dynamic strength testing and determine if proximal strength imbalances of the hip are a predisposing factor for the large number of non-contact ACL injuries within female athletes.
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