Dynamic Ultrasonography of the Deep External Rotator Musculature of the Hip: A Descriptive Study

Background: No detailed reports exist describing the methodology of ultrasound image acquisition of the deep external rotator muscles of the hip. Because gluteal pain and sciatica are common, ultrasound may be a useful dynamic imaging adjunct in the evaluation of these patients. Objective: To describe dynamic ultrasonography of the deep external rotator muscles of the hip for diagnostic purposes. Design: Descriptive. Setting: University radiology department. Participants: Participants (n = 25; 14 male) without gluteal pain or sciatica were enrolled (mean age 27.6 +/- 4.7 years; mean body mass index 26.0 +/- 4.1 kg/m(2)). Methods: Ultrasonographic cine clips oriented to the long axis of each deep external rotator muscle were captured. In addition, cine clips of the piriformis tendon and obturator internus tendon were obtained. Cine clips were analyzed approximately 1 week after completion of image acquisition independently by 2 blinded raters. Main Outcome Measures: A 5-point Likert scale to evaluate the diagnostic utility of the ultrasound image. Results: The modal Likert scores for rater 1 were as follows: piriformis muscle = 4; piriformis tendon = 4; superior gemellus muscle = 3; obturator internus muscle = 4; obturator internus tendon = 4; inferior gemellus muscle = 4; quadratus femoris muscle = 4. The modal scores for rater 2 were: piriformis muscle = 4; piriformis tendon = 3; superior gemellus muscle = 4; obturator internus muscle = 3; obturator internus tendon = 4; inferior gemellus muscle = 3; quadratus femoris muscle = 4. Conclusion: Dynamic ultrasonography may be useful to image the hip deep external rotator musculature for diagnostic purposes and therefore aid in the evaluation of gluteal pain and sciatica. Future work should investigate the reliability and validity of ultrasonography in the evaluation of pathology of these muscles.