Hip Joint Loading During Walking Is Associated With Cartilage Defect Severity in Young Adult Football Players With Hip/Groin Pain.

Understanding factors associated with early hip osteoarthritis (OA) in young active adults may facilitate hip OA prevention. We investigated the cross-sectional association between hip contact force (HCF) during walking and cartilage defect severity, accounting for cam morphology size (alpha angle), hip pain severity, sex, age, and walking speed, in football players with hip/groin pain. One hundred and twenty-one football players (18-50 years; 26 women) with > 6-month hip/groin pain and no radiographic OA underwent MRI and a Dunn 45° radiograph. Outcome: Scoring Hip Osteoarthritis with MRI (SHOMRI) score for cartilage defect severity (0-20), categorized into three SHOMRI groups: (a) SHOMRI = 0; (b) SHOMRI = 1-3; and (c) SHOMRI = 4+. Movement and ground force data were captured whilst participants walked at their self-selected pace. Musculoskeletal modeling was used to calculate HCF for one stride cycle. The exposure variable was HCF impulse (body weight times seconds [BW.s]). Differences in HCF impulse based on SHOMRI group (for the most symptomatic hip) were assessed using linear models, controlling for alpha angle, sex, age, walking speed, hip pain, and contralateral hip pain status. Resultant HCF impulse was significantly higher for participants in the 0 versus 4+ SHOMRI group (mean difference; 95%CI: 0.142BW.s; 0.028-0.256 for swing and 0.106BW.s; 0.029-0.184 for stance) and 0 versus 1-3 SHOMRI group (0.071 BW.s; 0.016-0.125 for swing). Participants with more severe cartilage defects walked with lower hip joint loading, and other variables (e.g., alpha angle size, hip pain severity, age) contributed little to this relationship. Hip joint under-loading could be a possible target for hip OA prevention.