Risk factors for noncontact ankle sprains in high school athletes: the role of hip strength and balance ability.

Background: Ankle sprains are among the most common sports injuries.

Hypothesis: Poor balance as measured on a balance board and weakness in hip abduction strength are associated with an increased risk of noncontact ankle sprains in high school athletes.

Study Design: Cohort study; Level of evidence, 2.

Methods: One hundred sixty-nine high school athletes (101 male athletes, 68 female athletes) from football, men's basketball, men's soccer, women's gymnastics, women's basketball, and women's soccer were observed for 2 years. Balance in single-limb stance on an instrumented tilt board and hip flexion, abduction, and adduction strength (handheld dynamometer) were assessed in the preseason. Body mass, height, generalized ligamentous laxity, previous ankle sprains, and ankle tape or brace use were also documented.

Results: There were 20 noncontact inversion ankle sprains. Balance ability (P = .72), hip abduction strength (P = .66), hip adduction strength (P = .41), and hip flexion strength (P = .87) were not significant risk factors for ankle sprains. The incidence of grade II and grade III sprains was higher in athletes with a history of a previous ankle sprain (1.12 vs 0.26 per 1000 exposures, P < .05). A higher body mass index in male athletes was associated with increased risk (P < .05). The combination of a previous injury and being overweight further increased risk (P < .01).

Conclusion: Balance as measured on a balance board and hip strength were not significant indicators for noncontact ankle sprains. The apparent high injury risk associated with the combination of a history of a previous ankle sprain and being overweight in male athletes warrants further examination.