What are the Peroneal Tendons?
In this section Cypress Foot and Ankle expert Dr. Christopher Correa discusses peroneal tendon injuries and how they relate to chronic lateral ankle pain. The peroneal tendons are a pair of tendons that run from the lateral calf and ankle, behind the posterior lateral malleolus and lateral foot. One tendon inserts at the base of the 5th metatarsal and the other courses across the plantar foot attaching to the base of the 1st metatarsal. Both tendons aid in eversion of the foot and provide lateral stability. When the foot is non weight bearing this motion means moving the foot outward (laterally) and upward.
When weight bearing these muscles are the primary muscles responsible for preventing the ankle from inverting (turning in or what is a motion typically associated with an ankle sprain). This role makes these tendons the major muscle group preventing ankle sprains. Because of this during an ankle sprain event this leads them to undergo extreme strain trying to prevent a sprain while it happens. While the vast majority of ankle sprains heal without any lasting issues, posterior lateral ankle pain that persists beyond 3 weeks following injury is not normal and could indicate a possible peroneal tendon tear among other things.
Tearing of the Peroneal Tendons and Lateral Ankle Pain
Because these tendons play a major part instability of the ankle, when damage of the tendons occur it often presents as persistent pain and swelling at the posterior lateral ankle accented with occasional sharp increased episodes of pain. When the peroneal tendons tear, they do not often rupture into two separate pieces but rather form longitudinal splits along the striations of the tendon causing elongation and flattening of the tendon. If left alone for long enough the tendons can attenuate to the point where they completely tear, though this is not a quick process. Pain also arises from inflammation of the lining of the tendon sheath known as the synovium. When the synovium becomes inflamed and enlarged it takes up room in the tendon sheath further increasing pain and swelling.
Causes/ Types of Peroneal Tendon Injury
There are a few ways these tendons can tear. In one case a boney process (lump) on the outside of the heel bone (calcaneus) known as the peroneal tubercle can be naturally enlarged in some people. This enlarged tubercle can put pressure on one or both of the tendons leading to tearing over time much like wearing a rope on the edge of a counter. Fixing this issue usually requires surgical removal of the bone spur and repair of the damaged tendon.
A second method happens during an inversion injury or ankle sprain. During the extreme force of the inversion ankle sprain if the retinaculum does not tear. In this case the peroneus longus applies a high level of force directly on the peroneus brevis. This leads to compression of the peroneus brevis between the back of the fibula and the peroneal longus tendon causing flattening and tearing of the brevis. This flattening leads to fraying of the tendon and elongation which, once started, can get worse over time. This contributes to persistent pain and swelling at the posterior lateral ankle. Immobilization and physical therapy can help reduced symptoms but many times surgical repair of the tendon is necessary.
Normal Cross-sectional anatomy below
Crushing of the peroneus brevis against fibula by peroneus longus
Inversion ankle sprains can also occasionally lead to failure and tearing of the peroneal retinaculum, the band of tissue responsible for holding the peroneal tendons in place behind the ankle. As the retinaculum approaches its insertion to the fibula it inserts to a cartilaginous connector which then blends into the periosteoum - the fibrous boney outer coating of the bone. While there are three separate ways the retinaculum can fail, the most common way I have seen is separation of the cartilaginous connector from the bone leading to a delamination of the periosteum creating a pocket. If this retinaculum is damaged it can cause the peroneal tendons to dislocate around the edge of the posterior lateral fibula creating a painful snapping feeling behind the ankle. The sharp posterior lateral fibula can cause damage to the tendon if left untreated for a long time. Often times to patient can actually feel the dislocation of the tendons when it happens. Correction of this issue often requires surgical repair.
Whether it is after an injury or not, if you are experiencing persistent ankle pain give the experts at Select Foot and Ankle Specialists a call today and take the first step towards recovery!