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Hip abduction, external rotation strength may predict noncontact ACL injury
Of 501 athletes, noncontact ACL injuries had an overall annual incidence of 3%.
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In competitive athletes, study results showed baseline hip abduction and hip external rotation strength were predictors of future noncontact ACL injury status.
“We measured hip strength in a large group of athletes and we tracked them over the years to look at ACL injuries, and those who ended up tearing their ACL had weaker hip muscles than those who did not,” Christopher M. Powers, PT, PhD, of the University of Southern California, told Orthopedics Today. “What it suggests is reduced hip strength may be a risk factor for noncontact ACL injuries.”
Contact vs noncontact
Powers and his colleagues measured isometric hip strength in 501 competitive athletes who participated in various sports before the start of the competitive season. ACL injury status during the sport season was recorded and injured athletes were classified by the mechanism of injury (noncontact vs. contact). A logistic regression was conducted after the season to determine whether baseline hip strength predicted future noncontact ACL injury.
Overall, 15 noncontact ACL injuries were documented, an annual incidence of 3%. A significant association was observed between both reduced hip external rotation strength and reduced hip abduction strength and an increased risk of noncontact ACL injury. Results showed for each 1-unit decrease, the odds of sustaining a noncontact ACL injury increased by 23% in hip external rotation and by 12% in hip abduction strength.
According to receiver operating characteristic curve analysis, athletes who later sustained an ACL injury were independently distinguished between athletes who remained uninjured by hip external rotation strength test, and hip abduction strength tests measured in preseason. External rotation strength less than or equal to 20.3% of body weight or abduction strength less than or equal to 35.4% of body weight were the clinical cutoffs established by Powers and his colleagues to define high risk.
“There have been studies that have shown hip strength is related to movement patterns that have been associated with ACL injury risk, so this further supports the concept of lack of proximal stability being a potential risk factor,” Powers said.
Hip strength
He noted although this group were all competitive athletes, their findings may be limited to the general population. Powers and his colleagues are working on identifying other lower extremity injuries that could be attributed to a lack of hip strength.
“For example, we just did another study looking at hip strength related to ankle sprains and found a similar predictability,” Powers said. – by Casey Tingle
- Reference:
- Khayambashi K, et al. Am J Sports Med. 2016;doi:10.1177/0363546515616237.
- For more information:
- Christopher M. Powers, PT, PhD, FACSM, FAPTA, can be reached at the University of Southern California, Division of Biokinesiology and Physical Therapy, 1540 E Alcazar St. CHP-155, Los Angeles, CA 90089; email: powers@usc.edu.
Disclosure: Powers reports no relevant financial disclosures.