Pearls On Treating Peroneal Tendon Dislocation

Jeffrey Bowman DPM MS

The peroneus longus and peroneus brevis tendons are prone to dislocation due to athletic activities and other factors. This makes it imperative to have a grasp of treatment options.

First, here is a quick review of anatomy. The peroneus longus courses behind the fibula towards the base of the fifth metatarsal before making a quick turn and continuing through the plantar central portion of the foot. It inserts onto the lateral side of the first metatarsal base. The peroneus longus functions to stabilize the first metatarsal to the second metatarsal and also plantarflexes the first metatarsal.

The peroneus brevis follows the same course as the longus but instead of turning at the base of the fifth metatarsal, it actually inserts onto the base. Its main function is to be the major evertor of the foot, but it also causes some dorsiflexion. Note that these tendons course beneath the retinaculum, which is designed to help keep the tendons in their natural anatomical position.

Tendon dislocation may result from a myriad of athletic activities. Snow skiing is the most common cause, accounting for one in every 200 tendon dislocations.1 Other athletic activities that can lead to tendon dislocation include football, rugby, basketball, water skiing, dance, gymnastics, mountain climbing and combat training.1 Golf isn’t looking like too bad a sport now, is it? Indirect causes of tendon dislocation are much more common than direct causes.

Chronic subluxation may often be present in those with recurrent ankle sprains.2 Finally, dislocation may stem from neuromuscular abnormalities such as paralysis and polio.2

A Closer Look At The Mechanism Of Injury

Peroneal tendon dislocation results from a sudden and “rapid dorsiflexory force across the ankle with subsequent simultaneous, violent, reflex contraction of the peroneal tendons and ankle joint plantarflexors.”1,3 Violent contracture of the peroneal tendons with the foot in a supinated position, with the ankle also being dorsiflexed, can also cause dislocation.1-3

Retinacular rupture rarely occurs. In fact, the retinaculum is typically “stripped off the fibular insertion or avulsed with a small fleck of fibular cortex.”2 Eckert and Davis developed a classification scheme to determine the severity of injury as well as incidence of occurrence, based on observations that they noted during surgical repair:4

In stage 1, the retinaculum is elevated off the lateral malleolus with the tendons now located between the fibula and retinaculum. This occurs in 51 percent of patients with peroneal retinaculum injuries .

In stage 2, the fibrocartilaginous ridge is elevated with the retinaculum attached and the tendons displaced beneath this ridge. This occurs in 33 percent of patients.

In stage 3, a small portion of the lateral malleolus is avulsed off and the tendons now located beneath this fragment of bone. This occurs in 16 percent of patients.

As you can see, the more severe stage 3 is much less common.On physical exam pain is more localized to the posterior aspect of the fibula, which is opposite of ananterofibular ligament injury. Patients may complain of a snapping sensation over the lateral malleolus.5 The tendons can be actively subluxed/dislocated in the office with resisted dorsiflexion and eversion of the foot or circumduction of the ankle and foot in a clockwise and counterclockwise fashion.The peroneus brevis can develop partial tears due to continued dislocation over the lateral malleolus.5

X-ray, computed tomography (CT) and magnetic resonance imaging (MRI) may all be adjuncts to clinical evaluation in the diagnosis. The MRI may help diagnose any underlying injury to the tendon substance itself.Note: it is always important to examine the opposite foot.

Finding An Appropriate Treatment Option

Conservative treatment consists of a below knee cast for five to six weeks. The literature reports a 50 percent success rate with conservative treatment.1,2 Some studies report a 14 to 56 percent success range.3

One oftentimes determines whether surgery is necessary according to the severity of the injury.1-3 Direct repair of the retinaculum to the periosteum of the fibula is the treatment of choice for acute injuries.

Chronic injuries may require a little more ingenuity.Treatment options include reattachment of the retinaculum with reinforcement using tendon transfers or rerouting the peroneal tendons.

Another option to treat chronic dislocations is fibular groove deepening. If this groove is too shallow, it may aid in the dislocation process.6 By deepening this groove, you alter and increase the stability of the peroneal tendons.2

Also consider bone block procedures. These osteotomies can reform and deepen the fibular groove.

References

1. McGlamry ED, Banks AS, Downey MS. Foot and Ankle Surgery, third edition, volume 2. Lippincott, Williams and Wilkins, Philadelphia, 2001.

2. Coughlin MJ, Mann RA, Saltzman CL (eds.) In Surgery of the Foot and Ankle, eighth edition, volume 2. Mosby, St. Louis.

3. Easley ME, Wiesel SW. Operative Techniques in Foot and Ankle Surgery. Lippincott, Williams and Wilkins, Philadelphia, 2010.

4. Eckert WR, Davis EA Jr. Acute rupture of the peroneal retinaculum. J Bone Joint Surg Am. 1976; 58(5):670-672.

5. Ogawa BK, Thordarson DB, Zalavras C. Peroneal tendon subluxation repair with an indirect fibular groove deepening technique. Foot Ankle Int. 2007; 28(11):1194-7.

6. Adachi N, Fukuhara K, Kobayashi T, et al. Morphologic variations of the fibular malleolar groove with recurrent dislocation of the peroneal tendons. Foot Ankle Int. 2009; 30(6):540-544.

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