Hip Abductor Muscle Weakness in Individuals with Gluteal Tendinopathy

KIM ALLISON, BILL VICENZINO, TIM V. WRIGLEY, ALISON GRIMALDI, PAUL W. HODGES, KIM L. BENNELL

To compare hip abductor muscle strength between individuals with symptomatic, unilateral gluteal tendinopathy (GT) and asymptomatic controls. Fifty individuals with GT aged between 35 and 70 years, and 50 sex- and age-comparable controls were recruited from the community. Maximal isometric strength (torque normalized to body mass) of the hip abductors was recorded in supine using an instrumented manual muscle tester. A two-way mixed analysis of covariance (ANCOVA), with covariates of self-reported pain during testing and pain limiting maximum effort, was used to compare hip abductor strength of the symptomatic and asymptomatic hip between GT and control individuals. Data were expressed as mean and standard deviation, with the pairwise comparisons expressed as mean differences and 95% confidence intervals. Individuals with GT demonstrated significantly lower hip abductor torque of both their symptomatic and asymptomatic hip than healthy controls (both p<0.05) with mean strength deficits of 0.35 Nm/kg (32%) on the symptomatic hip and 0.25 Nm/kg (23%) on the asymptomatic hip. In individuals with GT, the symptomatic hip was significantly weaker than the asymptomatic hip with a mean strength deficit of 0.09 Nm/kg (11%) (p<0.05). People with unilateral GT demonstrate significant weakness of the hip abductor muscles bilaterally when compared with healthy controls. Although it is not clear whether hip weakness precedes GT or is a consequence of the condition, the findings provide a basis to consider hip abductor muscle weakness in the treatment plan for management of GT.