TENDOSCOPY OF THE PERONEAL TENDONS

Peroneal tendon pathology frequently coexists with or results from chronic lateral ankle instability. These disorders often cause chronic ankle pain in runners and ballet dancers.³ Post-traumatic lateral ankle pain is common, but peroneal tendon pathology is not always recognized as a cause of these symptoms. In a study by Dombek and coworkers, only 60% of peroneal tendon disorders were accurately diagnosed at the first clinical evaluation.⁴

Pathology consists of tenosynovitis, tendon dislocation or subluxation, and (subtotal) rupture or snapping of one or both of the peroneal tendons. It accounts for most symptoms at the posterolateral aspect of the ankle. Other causes of posterolateral ankle pain are rheumatoid synovitis, bony spurs, calcifications or ossicles, pathology of the posterior talofibular ligament (PTFL), or disorders of the posterior compartment of the subtalar joint. Posterior ankle impingement can manifest as posterolateral ankle pain.⁵

The primary indication for treating pathology of the peroneal tendons is pain.⁶ If conservative treatment fails, the surgical intervention involves débridement of the tendons, fibular groove deepening in case of recurrent peroneal tendon dislocation, and an adequate and precise determination of the location and extent of tendon ruptures. Van Dijk introduced a tendoscopic approach to treat a wide variety of peroneal tendon disorders, and the subsequent patient follow-up was published in 2006.⁷ The tendoscopic technique is safe and produces good or excellent clinical outcomes, making it a good alternative to open surgical approaches.

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.⁸^,⁹ The peroneus brevis tendon is situated dorsomedial to the peroneus longus tendon from its proximal aspect up to the fibular tip, where it is relatively flat. Just distal to this lateral malleolus 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.¹⁰ Posterolaterally, the tendons are held into position by the superior peroneal retinaculum.⁷^,¹¹

The peroneal tendons act as lateral ankle stabilizers. In chronic ankle instability, more strain is put on these tendons, resulting in hypertrophic tendinopathy, tenosynovitis, and ultimately in tendon tears.⁷

In 1803, Monteggia was the first to describe peroneal tendon dislocation in a female ballet dancer.¹² These tendons dislocate if the superior peroneal retinaculum ruptures, frequently because of an inversion or dorsiflexion trauma of the foot with the muscles contracted, or if it is congenitally absent or weak.¹¹ A nonconcave fibular groove predisposes to dislocation. The cartilaginous rim, located laterally from the fibular groove, adds to the overall depth of the groove.¹³ If this rim is absent or flat, the tendons are more likely to dislocate.¹⁴

Patient Evaluation

History and Physical Examination

Tendinopathy of the peroneal tendons often coexists with a lateral ankle sprain, and the diagnosis of peroneal tendon pathology in a patient with lateral ankle pain can be difficult.¹⁵ 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, because they can increase the degree of peroneal tendon dysfunction.¹⁶ The differential diagnosis includes fatigue fractures or fractures of the fibula, posterior impingement of the ankle, and lesions of the lateral ligament complex. Post-traumatic or postoperative adhesions and irregularities of the posterior aspect of the fibula (i.e., peroneal groove) also can be responsible for symptoms in this region.

Patients with tendinopathy have 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.

Patients with peroneal tendon dislocation 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.¹⁷

Diagnostic Imaging

If the Ottowa ankle rules do not indicate abnormalities, applying diagnostics in the acute phase after an inversion trauma should be questioned. However, when peroneal tendon pathology is suspected, additional diagnostics should be applied, and when posterolateral ankle pain persists after the initial trauma, diagnostic imaging should be considered. Routine weight-bearing radiographs in the anteroposterior and lateral directions are advised in these cases to rule out avulsion fractures, spurs, calcifications, or ossicles.

Peroneal tendon dislocation is a clinical diagnosis, and it is frequently accompanied by a tendon rupture. Additional investigations such as magnetic resonance imaging (MRI) and ultrasonography may be helpful in diagnosing partial tears of the tendon of peroneus brevis or longus.¹⁸ Both modalities are considerably accurate and precise, although ultrasonography is more cost effective.¹⁹

Treatment

Conservative Management

Conservative management should be attempted first. This includes activity modification, footwear changes, temporary immobilization, and corticosteroid injections. Lateral heel wedges can take the strain off the peroneal tendons, which may allow healing.¹⁶

Surgical Technique

The patient is placed in the lateral decubitus position. Alternatively, the patient can be placed in the supine position with the foot in endorotation. A support can be placed under the leg, allowing the ankle to be moved freely. Before anesthesia is administered, the patient is asked to evert the foot so that the peroneal tendons can be visualized clearly. Their course is drawn on the skin, and the locations of the portals are marked (Fig. 16-1). The surgery can be performed under local, regional, epidural, or general anesthesia. After exsanguination, a tourniquet is inflated around the thigh of the affected leg.

FIGURE 16-1 The patient is placed in the lateral decubitus position. Alternatively, the patient can be placed in the supine position with the foot in endorotation. A support can be placed under the leg, allowing the ankle to move freely. The patient is asked to evert the foot, which usually allows the peroneal tendons to be visualized clearly. Its course is drawn on the skin (white line), and the location of the portals is marked (black areas).

A distal portal is made 2 to 2.5 cm distal to the posterior edge of the lateral malleolus. An incision is made through the skin, and the tendon sheath is penetrated with an arthroscopic shaft with a blunt trocar. A 2.7-mm, 30-degree arthroscope is then introduced.

The inspection starts approximately 6 cm proximal to the posterior tip of the fibula, where a thin membrane splits the tendon compartment into two separate tendon chambers. More distally, the tendons lie in one compartment. A second portal is made 2 to 2.5 cm proximal to the posterior edge of the lateral malleolus under direct vision by placing a spinal needle directly over the tendons (Fig. 16-2). Through the distal portal, a complete overview of both tendons can be obtained.

FIGURE 16-2 A, Peroneal tendoscopic image shows a left ankle with the arthroscope in the distal portal, and both tendons are clearly visualized. Peroneus longus tendon (1), peroneus brevis tendon (2), tendon sheath (3). B, Peroneus longus tendon (1), peroneus brevis tendon (2), tendon sheath (3), the location of the proximal portal is determined under direct vision with a spinal needle (4). C, Peroneus longus tendon (1), peroneus brevis tendon (2), tendon sheath (3), the definite portal is created with a retrograde knife directly over the tendons (5).

By rotating the arthroscope over and between both tendons, the entire compartment can be inspected (Fig. 16-3). When a total synovectomy of the tendon sheath has to be performed, it is advisable to make a third portal more distal or more proximal than the portals described previously. When a rupture of one of the tendons is seen, endoscopic synovectomy is performed, and the rupture is repaired through a mini-open approach.