Rehabilitation exercise progression for the gluteus medius muscle with consideration for iliopsoas tendinitis: an in vivo electromyography study.

BACKGROUND It is common for hip arthroscopy patients to demonstrate significant gluteus medius muscle weakness and concurrent iliopsoas tendinitis. Restoration of gluteus medius muscle function is essential for normal hip function. HYPOTHESIS A progression of hip rehabilitation exercises to strengthen the gluteus medius muscle could be identified that minimize concurrent iliopsoas muscle activation to reduce the risk of developing or aggravating hip flexor tendinitis STUDY DESIGN Descriptive laboratory study. METHODS Electromyography (EMG) signals of the gluteus medius and iliopsoas muscles were recorded from 10 healthy participants during 13 hip rehabilitation exercises. The indwelling fine-wire EMG electrodes were inserted under ultrasound guidance. The average and peak EMG amplitudes, normalized by the peak EMG amplitude elicited during maximum voluntary contractions, were determined and rank-ordered from low to high. The ratio of iliopsoas to gluteus medius muscle activity was calculated for each exercise. Exercises were placed into respective time phases based on average gluteus medius EMG amplitude, except that exercises involving hip rotation were avoided in phase I (phase I, initial 4 or 8 weeks; phase II, subsequent 4 weeks; phase III, final 4 weeks). RESULTS A continuum of hip rehabilitation exercises was identified. Resisted terminal knee extension, resisted knee flexion, and double-leg bridges were identified as appropriate for phase I and resisted hip extension, stool hip rotations, and side-lying hip abduction with wall-sliding for phase II. Hip clam exercises with neutral hips may be used with caution in patients with hip flexor tendinitis. Prone heel squeezes, side-lying hip abduction with internal hip rotation, and single-leg bridges were identified for phase III. CONCLUSION/CLINICAL RELEVANCE This study identified the most appropriate hip rehabilitation exercises for each phase to strengthen the gluteus medius muscle after hip arthroscopy and those to avoid when iliopsoas pain or tendinitis is a concern.