Functional testing provides unique insights into the pathomechanics of femoroacetabular impingement and an objective basis for evaluating treatment outcome.

Femoroacetabular impingement (FAI) has been recognized as a significant clinical problem. While hip reshaping surgery for treating FAI has had positive clinical outcomes, there remains a need for objective functional outcomes of FAI treatment. We tested the hypothesis that during walking and stair climbing significant changes in hip kinematics would occur following hip reshaping surgery that indicate restoration of normal function post-operatively. Hip and pelvic kinematics were collected for 17 FAI patients pre- and 1 year post-operatively and compared to 17 healthy matched controls. Prior to surgery, FAI patients had significantly reduced hip internal rotation and hip sagittal plane range of motion during walking (p = 0.01, p < 0.001, respectively) and stair climbing (p = 0.01, p < 0.001, respectively) as compared with controls. Post-operatively, these motions were restored to normal during walking (p = 0.70, p = 0.46, respectively), but remained significantly reduced in the FAI patients during stair climbing (p = 0.03, p < 0.001, respectively). These results have important implications for understanding the functional pathomechanics of FAI and providing an objective basis for evaluating treatment outcome. The stair climbing results indicate that problems still exist in the hip joint for activities requiring higher ranges of hip motion and suggest a basis for exploring future improvements for the treatment of FAI.