Dynamic sonographic evaluation of peroneal tendon subluxation

Peroneal tendon subluxation is a major cause of posttraumatic lateral ankle pain. Because peroneal subluxation often occurs only when the foot is dorsiflexed and everted, findings on static imaging studies may appear to be normal. We therefore evaluated the effectiveness of sonography in revealing peroneal tendon subluxation in patients performing stress maneuvers.

From June 2001 to June 2003, 13 consecutive patients (10 females and three males; mean age, 30.4 years; age range, 16-66 years) in whom peroneal tendon subluxation was clinically suspected were scanned with a high-frequency linear array transducer by an experienced sonologist. The ankles in 10 asymptomatic volunteers were also scanned. Sequential axial and longitudinal sonograms of the peroneus longus and peroneus brevis tendons at rest were obtained and evaluated for tendinitis and tendon tears. Real-time axial sonograms were then obtained while the foot was dorsiflexed and everted. Of the 13 patients, 12 had sonographic findings of peroneal tendon subluxation and underwent surgical exploration. The sonographic and surgical reports of these 12 patients were compared.

All 12 patients with sonographic findings of peroneal tendon subluxation were subsequently found to have subluxation at surgery. The positive predictive value of dynamic sonography for peroneal tendon subluxation was therefore 100%. Sonography revealed peroneus brevis tendon tears in five patients and a peroneus longus tear in one; all findings were confirmed at surgery, with no false-positive sonograms. Only four of the 20 asymptomatic ankles showed subluxation, and none had any other tendon abnormalities.

Sonography is an effective technique for diagnosing peroneal tendon subluxation, as well as associated tears of the peroneal tendons.