Intrinsic risk factors for groin injuries among male soccer players: a prospective cohort study.

BACKGROUND This study was conducted to determine if risk factors for groin injuries among male soccer players could be identified. HYPOTHESIS Previous groin injuries, reduced function scores, age, findings on clinical examination, and low isometric groin strength are associated with increased risk of new groin injuries. STUDY DESIGN Cohort study; Level of evidence, 3. METHODS A total of 508 players representing 31 amateur teams were tested during the 2004 preseason for potential risk factors for groin injury through a questionnaire on previous injury and function score (Groin Outcome Score [GrOS]) and a clinical examination of the groin. Generalized estimating equations were used in univariate analyses to identify candidate risk factors, and factors with a P value <.10 were then examined in a multivariate model. RESULTS During the soccer season, 61 groin injuries affecting 55 legs (51 players) were registered. The total incidence of groin injuries was 0.6 injuries per 1000 playing hours (95% confidence interval [CI], 0.4-0.7), 0.3 injuries per 1000 training hours (95% CI, 0.2-0.4), and 1.8 injuries per 1000 match hours (95% CI, 1.2-2.5). In a multivariate analysis, previous acute groin injury (adjusted odds ratio [OR], 2.60; 95% CI, 1.10-6.11) and weak adductor muscles as determined clinically (adjusted OR, 4.28; 95% CI, 1.31-14.0) were significantly associated with increased risk of groin injuries. A multivariate analysis based only on acute time-loss injuries revealed the 40-m sprint test result (adjusted OR, 2.03 for 1 standard deviation change [injured group faster]; 95% CI, 1.06-3.88; P = .03) and functional testing of the rectal abdominal muscles (adjusted OR, 15.5 [painful in 19% of the players in the injured group compared to 16% in the uninjured group]; 95% CI, 1.11-217; P = .04) as significant risk factors. CONCLUSION A history of acute groin injury and weak adductor muscles are significant risk factors for new groin injuries.