Intrinsic risk factors for hip and groin pain in professional male football players

Submission note: A thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Allied Health, College of Science, Health and Engineering, La Trobe University, Bundoora, Victoria.

Background Hip or groin pain causes significant time-loss in football. Factors such as muscle strength, range of motion, and bony shape (morphology), have potential to increase the risk of this injury. This thesis investigated the association between factors identified from screening, and time-loss hip or groin injury in professional male football players. Methods A systematic review investigated the factors differentiating athletes with and without groin pain to inform the screening test battery. A total of 575 football players underwent musculoskeletal, and X-ray screening specific for hip or groin pain during two consecutive seasons. Injury and exposure surveillance (training and match play) was conducted prospectively. Baseline data were analysed for two cross-sectional studies with the normal profiles for hip strength and range of motion, and the prevalence of bony morphological variants determined. Two prospective studies examined the epidemiology and intrinsic risk factors for hip or groin injury. Results Dominance, previous groin injury and ethnicity had no clinically relevant effect on normal strength and range of motion profiles. Cam morphology (asphericity of the femoral head neck junction) was very common (60% hips, 72% players), but acetabular overcoverage and undercoverage were uncommon ( less than 13% players). Cam morphology prevalence was lower in East Asian football players. High burden of groin injury was found, at an incidence of 1.0 per 1000h (95% CI 0.9-1.1) and 21% (IQR 10-28%) of players experienced groin injury each season. Each club could expect 6.6 groin injuries (IQR 2.9-9.1) and 85 days lost per season (IQR 35-215 days). Adductor-related groin pain was the most common entity (68%). Previous groin injury (HR= 1.8; 95% CI 1.2-2.7) and higher than normal eccentric adduction strength increased risk for hip or groin injury (HR=1.6; 95%CI 1.0-2.5). Lower than normal eccentric adduction strength increased risk for adductor-related injuries (HR =1.7; 95%CI 1.0-3.0). However, these associations were not strong enough to identify an ‘at-risk’ individual and therefore, not useful screening tests to predict injury. Bony hip morphology was not associated with groin injury risk. Conclusions This thesis found that musculoskeletal screening is most useful to detect current hip or groin symptoms, rather than detecting the individual “at-risk” of future groin injury. Hip adduction strengthening may prevent adductor-related groin injury, but is likely to be more effective if implemented at the group, rather than individual level. There is no indication for X-ray screening of bony hip morphology in asymptomatic male football players.

Thesis with publications.