Hip Biomechanics During a Single-Leg Squat: Five Key Differences Between People With Femoroacetabular Impingement Syndrome and Those Without Hip Pain.

Abstract

STUDY DESIGN\nCross-sectional, case-controlled, laboratory-based study.\n\n\nBACKGROUND\nPeople with femoroacetabular impingement (FAI) syndrome have different hip joint biomechanics than hip-healthy people during a double-leg squat. However, information on biomechanics during a single-leg squat is limited.\n\n\nOBJECTIVES\nTo compare hip joint biomechanics between people with FAI syndrome and people without hip pain during double-leg and single-leg squats.\n\n\nMETHODS\nFourteen people with FAI syndrome (cam, n=7; pincer, n=1; mixed, n = 6) and 14 people without hip pain participated in this study. Three-dimensional biomechanics data were collected while all participants performed a double-leg and a single-leg squat. Two-way mixed model analyses of variance (ANOVAs) were used to assess GROUP by TASK interactions for hip joint angles, thigh and pelvis segment angles, hip joint internal moments, and squat performance variables. Post-hoc analyses for all variables with a significant GROUP by TASK interaction were performed to identify between GROUP differences for each task.\n\n\nRESULTS\nThere were significant GROUP by TASK interactions for peak hip joint (P = 0.014, η2 = 0.211) and thigh segment (P = 0.009, η2 = 0.233) adduction angles, and for peak hip joint abduction (P = 0.002, η2 = 0.308) and extension (P = 0.016, η2 = 0.203) internal moments. There were no significant GROUP by TASK interactions for squat performance variables.\n\n\nCONCLUSION\nBiomechanical differences at the hip between people with FAI syndrome and without hip pain were exaggerated during a single-leg squat compared to a double-leg squat task.\n\n\nLEVEL OF EVIDENCE\nDiagnosis, level 4. J Orthop Sports Phys Ther, Epub 23 Jul 2019. doi:10.2519/jospt.2019.8356.