Frontal plane lower extremity alignment in adolescent athletes with chronic hip adductor-related groin injury symptoms: A case-control study

To compare trunk and lower extremity frontal plane projection angles (FPPA) during single leg squat (SLS) performance, perceived hip and groin function and symptoms, and isometric hip strength of adolescent athletes with chronic hip adductor-related groin injury (HARGI) symptoms and age, gender, and sport-matched healthy subjects.Case-control study.Junior Olympic Development Training Centre.Twenty-six athletes at 59.1 ± 60 weeks (range = 12-208 weeks) post-index grade II HARGI injury who had continued sport training (injury group) and 26 control group subjects.SLS trunk, hip, and knee FPPA, isometric hip strength standardized to bodyweight, and Copenhagen Hip and Groin Outcome Scores (HAGOS).The injury group had greater bilateral knee FPPA, and greater injury side hip FPPA during maximum SLS. Injury group HAGOS subscale scores were lower than control group scores. Hip abductor, adductor, external rotator, and internal rotator strength was lower at the injury side of the injury group compared to the matched control group limb. Forward stepwise multiple regression analysis of the injury group found that 50% of injury side knee FPPA was predicted by hip internal rotator strength and time post-index HARGI; and 47% of injury side hip FPPA was predicted by other side hip flexor strength and the HAGOS function, sport and recreation subscale score (p = 0.002).Greater injury side hip and bilateral knee FPPA during maximum SLS, lower self-reported hip symptom and function scores, and less injury side hip abductor, adductor, external rotator and internal rotator strength suggests that adolescent athletes with chronic HARGI symptoms are at an increased risk for sustaining a non-contact knee injury. Impaired hip internal rotator strength at the side of the chronic HARGI was related to increased knee FPPA, and impaired hip flexor strength at the other side of the HARGI was related to increased hip FPPA. Findings support using SLS performance testing in this athlete group to help determine safe return to sport training readiness.