Hip muscle weakness and reduced joint range of motion in patients with femoroacetabular impingement syndrome: a case-control study.

BACKGROUND: Femoroacetabular impingement (FAI) syndrome is a hip joint motion-related clinical disorder characterized by abnormal contact between the hip joint structures. Abnormal hip morphology and joint pain may impair the hip joint range of motion (ROM) and muscle function. However, FAI effects on hip joint ROM and muscle strength remain controversial.

OBJECTIVES: The purpose of this study was to compare hip joint ROM and muscle strength between FAI syndrome patients and healthy controls.

METHODS: Twenty FAI syndrome male patients and 20 healthy male controls (CG) matched for age (FAI=28±6 years; CG=27±5 years), body mass (FAI=81±12kg; CG=80±13kg) and height (FAI=177±6cm; CG=178±6cm), participated in the study. Hip joint ROM for flexion, internal rotation and external rotation were assessed through goniometry. Maximal isometric strength for hip flexion, extension, abduction and adduction were evaluated through hand-held dynamometry.

RESULTS: Hip joint ROM was significantly lower in FAI syndrome patients compared with CG for passive flexion (-4%; effect size - ES=0.65), active internal rotation (-42%; ES=1.60), active external rotation (-28%; ES=1.46) and passive external rotation (-23%; ES=1.63). FAI patients' hip extensors (-34%; ES=1.46), hip adductors (-33%; ES=1.32), and hip flexors (-25%; ES=1.17) were weaker compared to the CG subjects.

CONCLUSIONS: FAI syndrome patients presented both hip muscle weakness and reduced joint ROM compared to match CG.