HSS Ultrasound Case 73

Clinical History 38 year-old man with chronic left posterior lateral ankle pain and snapping sensation.

The patient was referred for an ultrasound (US) to assess for peroneal tendon pathology.

Ultrasound of the Month – Case 73

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Ultrasound of the Month – Case 73

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Findings Transverse US image of the left ankle reveals a thickened and retracted superior peroneal retinaculum (SPR) and anterior subluxation of the left peroneus brevis tendon from the peroneal groove. There is no edema or tenosynovitis to suggest acute injury. Comparative US image of the asymptomatic right ankle reveals normal position of the right peroneus longus and brevis tendons in the peroneal groove.

Ultrasound of the Month – Case 73

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Diagnosis: Chronic left superior peroneal retinaculum rupture and anterior subluxation of the peroneus brevis tendon.

Discussion The superior peroneal retinaculum (SPR) extends from the lateral periosteum of the lateral malleolus and attaches posteriorly on the Achilles and/or calcaneus.

A normal SPR acts to keep the peroneal tendons in place within the peroneal groove at the posterior aspect of the lateral malleolus.

A chronically torn SPR can result in recurrent peroneal tendon subluxation or dislocation, presenting as painful lateral ankle snapping or popping usually when walking up or down stairs.

Ultrasound can efficiently evaluate for peroneal tendon subluxation or dislocation using real-time and dynamic imaging.

Conservative management involves cast immobilization. If symptoms persist, surgical repair is highly successful.

Ultrasound of the Month – Case 73

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