Persons with chronic hip joint pain exhibit reduced hip muscle strength

STUDY DESIGN: Controlled Laboratory Cross-Sectional Study OBJECTIVES: To assess strength differences of the hip rotator and abductor muscle groups in young adults with chronic hip joint pain (CHJP) and asymptomatic controls. A secondary objective was to determine if strength in the uninvolved hip of those with unilateral CHJP differs from asymptomatic controls. BACKGROUND: Little is known about the relationship between hip muscle strength and CHJP in young adults. METHODS: 35 participants with CHJP and 35 matched controls (18 to 40 years of age) participated. Using hand-held dynamometry, strength of the hip external rotators (ERs) and internal rotators (IRs) was assessed with the hip flexed to 90° (ERs90°, IRs90°) and 0° (ERs0°, IRs0°). To assess ER and IR strength, the hip was placed at the end-range of external rotation and internal rotation, respectively. Strength of the hip abductors (ABDs) was assessed in sidelying, with the hip in 15° of abduction. Break tests were performed to determine maximum muscle force and the average torque was calculated using the corresponding moment arm. Independent samples t-tests were used to compare strength values between the 1) involved limb in participants with CHJP and corresponding limb in the matched controls and 2) the uninvolved limb in participants with unilateral CHJP and corresponding limb in the matched controls. RESULTS: Compared to controls, participants with CHJP demonstrated weakness of 16–28%, (P<0.01) in all muscle groups tested in the involved hip. The uninvolved hip of 22 subjects with unilateral CHJP demonstrated weakness of 18% and 16% (P<0.05) in the ERs0° and ABDs, respectively when compared to the corresponding limb of the matched controls. CONCLUSION: Our results demonstrate that persons with CHJP have weakness in the hip rotator and hip abductor muscles. Weakness also was found in the uninvolved hip of persons with CHJP