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Ultrasound imaging and guided hydrodilatation for the diagnosis and treatment of internal snapping hip syndrome

Dear Editor, A 42-year-old male started jogging and weight training half a year ago. He described that he also suffered audible sounds with intermittent pain over his right inguinal area during hip flexion and extension thereafter. Since the discomfort was relieved by medication and physical modalities, he was referred for an ultrasound (US) examination for the affected hip. Static US imaging showed no effusion over the right anterior hip recess with normal echotexture of the iliopsoas muscle and tendon. Dynamic US examination was first performed by placing the transducer in the short-axis plane with the hip flexed and abducted (Figure 1A). When the hip returned to the neutral position, the iliopsoas tendon was observed to abruptly glide medial to the iliacus muscle above the iliofemoral ligament (Figure 1B, Video S1). A flash of the iliopsoas tendon was visualized during repeated hip flexion and extension (Figure 1C, Video S1). US guided hydrodilatation with a mixture of 5 mL 50% dextrose and 5 mL 1% lidocaine was introduced between the iliacus muscle and iliopsoas tendon (Figure 1D, Video S1). The snapping phenomenon immediately improved after the injection (Video S1). An exercise program incorporating hip stretching and core muscle strengthening was then given and there was no symptom recurrence at the 3-month follow-up. Snapping hip syndrome affects 5%-10% in the general population. Its prevalence is higher in the young physically-active group