Overview of Peroneal Tendon Issues

Clincal picture of dislocating peroneals in ankle neutral.

Many patients that we treat at our office have chronic ankle instability in the form of lateral tendon dislcocations, or chronic ankle sprains. Many times these patients are unclear as to how important these tendons are to the overal stability and function of the ankle joint. With abnormal tendon gliding and ligamentous attenuations and ruptures, these tendons may also become painful with patients who have chronic ankle sprains. This is a comprehensive overview of this pathology and treatment options to help out with the understanding of these clinical scenarios.

History of the Procedure
Disorders of the peroneal tendons have been reported infrequently. Monteggia described peroneal tendon subluxation in 1803, and this entity seems to be more commonly encountered than are disruptions of the peroneus longus or brevis alone. Nonetheless, peroneus brevis disorders have been described more often in the literature, with peroneus longus problems gaining more recent attention. However, much of the literature regarding both tendons is in the form of case reports.

Problem
The peroneal muscles make up the lateral compartment of the leg and receive innervation from the superficial peroneal nerve. The peroneus longus muscle originates from the lateral condyle of the tibia and the head of the fibula. The tendon of peroneus longus courses behind the peroneus brevis tendon at the level of the ankle joint, travels inferior to the peroneal tubercle, and turns sharply in a medial direction at the cuboid bone. The tendon inserts into the lateral aspect of the plantar first metatarsal and medial cuneiform.
A sesamoid bone called the os peroneum may be present within the peroneus longus tendon at about the level of the calcaneocuboid joint. The frequency with which an os peroneum occurs is controversial, with many supporting the idea that one is always present. However, the os peroneum may be ossified in only 20% of the population. The peroneus longus serves to plantar flex the first ray, evert the foot, and plantar flex the ankle.

The peroneus brevis originates from the fibula in the middle third of the leg. Its tendon courses anterior to the peroneus longus tendon at the ankle. It courses over the peroneal tubercle and inserts onto the base of the fifth metatarsal. The peroneus brevis everts and plantar flexes the foot.

Problems may arise in either of the tendons alone, or both may be involved with subluxation. The hallmark of disorders of the peroneal tendons is laterally based ankle or foot pain. Whether the problem is tendinous degeneration or subluxation, the clinical manifestation is pain. With time, loss of eversion strength may occur.

Problems arising with the peroneus longus include tenosynovitis and tendinous disruption (acute or chronic). The os peroneum may be involved with the degenerative process or as a singular disorder and can be fractured or fragmented. Longitudinal tears of the peroneus longus are uncommon but have been reported.
Longitudinal tears of the tendon are the most common problem seen with the peroneus brevis tendon. These may be single or multiple. Tendinitis and tenosynovitis also may occur.

Subluxation of both peroneal tendons may occur following an acute traumatic episode or may be of a more chronic nature.

Frequency
Disorders of the peroneal tendons are less common than other tendon problems involving the Achilles or posterior tibial tendons. However, it is impossible to estimate their true frequency in the United States or abroad.

Etiology
The precise etiology of peroneal tendon disorders depends somewhat on the specific problem being addressed. All disorders may result following a traumatic episode, direct or indirect, with a lateral ankle sprain being the most common trauma. Brandes and Smith have reported that 82% of patients with primary peroneus longus tendinopathy had a cavo-varus hindfoot.3 The presence of an os peroneum also has been postulated to predispose to peroneus longus rupture. Ruptures likewise have been reported to occur secondary to rheumatoid arthritis and psoriasis, as well as diabetic neuropathy, hyperparathyroidism, and local steroid injection.4,5,6
Longitudinal splits in the peroneus brevis tendon appear to result from mechanical factors. Repetitive or acute trauma causes the attritional ruptures. These ruptures may result from an incompetent superior peroneal retinaculum that allows the peroneus brevis to rub abnormally against the fibula.

Overcrowding from a peroneus quartus muscle also has been reported. The blood supply to the tendon has been shown to be adequate.

Subluxation of the peroneal tendons results from disruption of the superior peroneal retinaculum and usually involves avulsion of the retinaculum from its fibular insertion. The mechanism of injury typically involves an inversion injury to the dorsiflexed ankle with concomitant forceful contraction of the peroneals. Some patients have a more chronic presentation and cannot recall a traumatic episode. Congenital dislocations also have been reported. An inadequate groove for the peroneals in the posterolateral fibula may be a cause of subluxation as well.

Pathology of the longus and brevis tendons almost always occurs concurrently. Brandes and Smith noted a 33% incidence of concomitant problems.

Pathophysiology
Brandes and Smith have described and classified primary peroneus longus tendinopathy.3 They present 3 anatomic zones in which the tendon can be injured. Zone A is the level of the superior peroneal retinaculum. Zone B is the level of the inferior peroneal retinaculum. Zone C is the level of the cuboid notch. In their series, complete ruptures were most likely in zone C, while partial ruptures were more common in zone B. In the same study, surgical findings were classified into 3 groups. Group I pathology had no frank rupture but did have adhesions or thickening of the tendon. Group II pathology consisted of partial tears with some continuity of the tendon. Group III had complete ruptures with complete loss of continuity. All group III pathology occurred in zone C.

Other attempts have been made to classify peroneal tendon pathology. Sobel et al have presented a classification for tears of the peroneus brevis tendon as follows:7,8


•Grade 1 - Flattened tendon
•Grade 2 - Partial-thickness split less than 1 cm in length
•Grade 3 - Full-thickness split less than 2 cm in length
•Grade 4 - Full-thickness split more than 2 cm in length
Eckert and Davis have classified superior peroneal retinaculum (SPR) pathology as follows:9


•Grade I - SPR elevated from fibula
•Grade II - Fibrocartilaginous ridge elevated from fibula with SPR
•Grade III - Cortical fragment avulsed with SPR

Presentation
The patient with peroneal tendon pathology typically complains of laterally based ankle or hindfoot pain. The pain usually worsens with activity. However, presentation and diagnosis often are delayed. Patients may or may not recall a specific episode of trauma. Brandes and Smith reported that only 9 of 22 patients with primary peroneus longus tendinopathy recalled an inciting event and that the event was an average of 4.3 months prior to presentation.
Peroneal tendon subluxation or dislocation may present acutely following a traumatic injury to the ankle. However, it is not uncommon for these to present later with an uncertain history of trauma. Patients also may complain of snapping or popping in the ankle.

On physical examination, there usually is tenderness to palpation along the course of the peroneal tendons. Edema also may be present. These disorders require a high level of suspicion. Even frank dislocations may be missed if not specifically evaluated.

A provocative test for peroneal pathology has been described. The patient's foot is examined hanging in a relaxed position with the knee flexed 90º. Slight pressure is applied to the peroneal tendons posterior to the fibula. The patient is then asked to forcibly dorsiflex and evert the foot. Pain may be elicited, or the tendons may be felt to sublux.

Indications
The primary indication for treating these disorders is pain. Nonsurgical treatment usually is attempted first. Failure of conservative measures is an indication for operative intervention.

Operative Considerations

With physical therapy, MRI, and need for primary or secondary repair will be determined based on overal health of the patient, as well as how effective nonsurgical measures have been. If the pain and resolution is not fully noted through physical therapy and bracing one should consider the possiblity of repair. If there are tendon tears associated with the pathology, repair is recommended. If an associated low muscle (peroneus quartius) or ruptured retinaculum is identified, repair is also likely required. We are experts in this pathology, and treat this regularly, and I feel a proper evaluation for this condition will be beneficial to anyone with recurrent ankle sprains, as well as pain in the lateral ankle.