Introduction

In 1803 Monteggia was the first to describe peroneal tendon dislocation in a female ballet dancer. These tendons dislocate if the superior peroneal retinaculum ruptures, frequently due to an inversion/dorsiflexion trauma of the foot with the tendons contracted, or if the superior peroneal retinaculum is congenitally absent or weak. A non concave fibular groove predisposes for dislocation. Another cause is explained through the cartilaginous rim, located laterally from the fibular groove that adds to the overall depth of the groove. In case this rim is absent or flat, the tendons are more likely to dislocate. 

Endoscopic peroneal groove deepening is a new technique to treat recurrent dislocation caused by a shallow peroneal groove.

Anatomy

The peroneal muscles are located in the lateral compartment of the leg, also known as the peroneal compartment. Both muscles are innervated by the superficial peroneal nerve and the peroneal and medial tarsal arteries supply the muscles with blood through separate vinculae. The peroneus brevis tendon is situated dorsomedially to the peroneus longus tendon from its proximal aspect up to the fibular tip, where it is relatively flat. Just distal to this tip, the peroneus brevis tendon becomes rounder, and crosses the round peroneus longus tendon. The distal posterolateral part of the fibula forms a sliding channel for the two peroneal tendons. This malleolar groove is formed by a periosteal cushion of fibrocartilage that covers the bony groove. Posterolaterally the tendons are held into position by the superior peroneal retinaculum.

History & Physical Examination

Pathology of the peroneal tendons often co-exists with a lateral ankle sprain. The diagnosis of peroneal tendon pathology can therefore be difficult in a patient with lateral ankle pain. The anterior drawer test and varus stress test are applied routinely to detect laxity of the ankle ligaments. In acute cases the detailed history should include reconstruction of the trauma mechanism. The presence of associated conditions such as rheumatoid arthritis, psoriasis, hyperparathyroidism, diabetic neuropathy, calcaneal fracture, fluoroquinolone use, and local steroid injections is important since these can all increase the prevalence of peroneal tendon dysfunction. A diagnostic differentiation must be made with fatigue fractures or fractures of the fibula, posterior impingement of the ankle, and lesions of the lateral ligament complex. Post-traumatic or post-surgical adhesions and irregularities of the posterior aspect of the fibula (peroneal groove) can also be responsible for symptoms in this region.

In case of tendinopathy, there is crepitus and recognizable tenderness over the tendons on palpation. Swelling, tendon dislocation and signs of tenosynovitis can be found at the lateral aspect of the posterior ankle. In case of peroneal tendon dislocation, patients typically complain of lateral instability, giving way and sometimes a popping or snapping sensation over the lateral aspect of their ankle. On physical examination the tendons can be subluxated by active dorsiflexion and eversion which provokes the pain. 

Diagnostic Imaging

If the Ottawa ankle rules do not show abnormalities it should be questioned whether to apply additional investigation in the acute phase following an inversion trauma. However when there is suspicion of peroneal tendon pathology, additional diagnostics should be applied. Also if posterolateral ankle pain persists after the initial trauma, diagnostic imaging should be considered. Routine weight-bearing radiographs in the antero-posterior and lateral direction are advised in these cases to rule out (avulsion) fractures, spurs, calcifications or ossicles. 
Peroneal tendon dislocation is a clinical diagnosis, nevertheless it is frequently accompanied by a tendon rupture. Additional investigations such as MRI and ultrasonography may be helpful in diagnosing (partial) tears of the tendon of peroneus brevis or longus. Both are considerably accurate and precise, nevertheless ultrasonography cost- effectively is preferable.

Axial and coronal T2 images of MR-scan; along the peroneus brevis tendon, a higher signal intensity can be seen centrally, indicating a partial rupture.

Post-operative rehabilitation

The patient can be discharged the same day of surgery and weightbearing is allowed as tolerated. Apply an ankle brace for 6 weeks. The patient is instructed to perform active dorsiflexion of the ankle to the neutral position (knee slightly bent). This exercise should be performed 2 or 3 days times per hour for the first days after surgery. For the first 6 weeks no active eversion movements should be made. The patient is instructed to elevate the foot when not walking to prevent edema. The dressing is removed 3 days post-operative. Brace then can be applied. Normal walking without crutches at 4 - 5 days post surgery. Patients with limited range of motion are directed to a physiotherapist. Running can on avarage be expected at 8 weeks post surgery. Sport resumption can on average be expected at 10 weeks post surgery. 

Recommended Literature

Van Dijk CN, Kort N.Tendoscopy of the peroneal tendons.
Arthroscopy. 1998 Jul-Aug;14(5):471-8.

Verheyen CP, Bras J, van Dijk CN. Rupture of both peroneal tendons in a professional athlete. A case report. Am J Sports Med. 2000 Nov-Dec;28(6):897-900.

Scholten PE, van Dijk CN. Tendoscopy of the peroneal tendons. Foot Ankle Clin. 2006 Jun;11(2):415-20, vii.