Gluteus maximus impairment in femoroacetabular impingement: a tensiomyographic evaluation of a clinical fact.

INTRODUCTION: the aim of the present study is to evaluate the mechanical and contractile properties of the gluteus maximus (GM) muscle in patients with femoroacetabular impingement (FAI). Our hypothesis is that the clinical observation of GM pain would be evidenced by tensiomyographic impairment in muscle function.

MATERIALS AND METHODS: A prospective, cross-sectional, intra-group comparative study was conducted to assess the neuromuscular changes of lower extremity muscles in patients with FAI. Fifty-one patients with clinical and radiographic diagnosis of FAI for at least 3 months were included. The rectus femoris (RF), adductor magnus (AM), and GM of both lower extremities of all patients were evaluated with tensiomyography (TMG). The values of TMG of the affected lower extremity were compared to those of the healthy contralateral side. The parameters obtained in this study were maximal displacement (Dm), and contraction time (Tc).

RESULTS: The Tc of the injured GM was significantly higher compared to the healthy side (p = 0.01). There were no significant side-to-side differences in the Dm of the GM (p = 0.13), either in the Tc and Dm of the RF (p = 0.15 and p = 0.8, respectively) and AM (p = 0.25 and p = 0.75, respectively).

CONCLUSIONS: FAI is associated with impairment of contraction time in the GM of the injured compared to the healthy side. Impairment of the GM may be monitored to evaluate response to conservative or surgical treatment.