(Peroneal Tendon Subluxation)

Persistent pain and a feeling of “popping” to the outside portion of the ankle bone or fibula after an ankle injury may be indicative of peroneal tendon dislocation.

The peroneus brevis and peroneus longus are considered lateral compartment muscles of the leg that function to stabilize the foot during walking. The peroneus brevis muscle attaches to the fifth metatarsal bone and the peroneus longus attaches on the bottom of the foot on the first metatarsal bone. Both of these muscles work to stabilize the foot during different portions of the walking cycle. The peroneus brevis is the main tendon that helps maintain the heel bone in a straight position. Both of the peroneal tendons course along the backside of the fibula bone just before the ankle joint in a closed canal that is supported by the peroneal retinaculum. The peroneal retinaculum is a ligament that holds the peroneal tendons in place just behind the fibula.

Suspicion for peroneal tendon dislocation must be high in anyone having persistent pain and a feeling of “popping” after an ankle injury. During an ankle sprain a tremendous amount of force and stretch is place on the peroneal tendons as they course behind the fibula on outside of the ankle. The force generated by twisting the ankle and the subconscious firing of these muscles to help correct the foot at the time of injury can cause tearing to the tendons but it can also cause a tearing of the peroneal retinaculum.

Symptoms may be intermittent activity dependant pain above the level of the ankle joint just behind the fibula as well as visible dislocation of the fibula from behind the fibular groove over the outside portion of the fibula. Swelling to the region may or may not be present.

The examination is the most important diagnostic tool to establish the diagnosis. Reproducible pain to the peroneal retinaculum as well as visible dislocation of the peroneus brevis tendon during manual muscle testing is key features to the exam.

X-rays are of limited value unless there is an associated “chip” or avulsion fracture to the fibula bone. MRI’s are often times indicated but may be very difficult to find the retinacular injury.

Conservative treatment is usually geared toward the treatment of an acute ankle sprain with ice, anti-inflammatory medications and compression. The use of an ankle brace or CAM boot can be used to stabilize the ankle initially after an acute ankle injury. Upon the diagnosis of peroneal tendon subluxation the use of a compressive ankle brace that can be worn within the shoe is often times helpful. Ice and anti-inflammatory medications can also be used to help manage the symptoms.

Surgical care is often times indicated because repetitive dislocation of the peroneal tendons can lead to tendon tearing or attenuation. Surgical care is directed at repairing any coexistent attenuation of the peroneal tendons as well as repairing the peroneal retinaculum by attaching the ligament to the fibula bone with bone anchors. Often times the groove behind the fibula is deepened to help maintain the peroneal tendons in their anatomic position.

Post surgical care includes three weeks of a non weight bearing cast with advancement into a removable CAM boot for an additional three weeks. Passive motion of the ankle and soft tissue mobilization is often times begun in formal physical therapy beginning three weeks after surgical repair. Successful outcomes of peroneal retinacular surgical repairs are generally high with expected return to all normal activities around twelve to sixteen weeks post operatively.

Most ankle injuries are met with full recovery. If ongoing pain to the fibula region with a feeling of “popping” noted during activity peroneal retinacular injury must be suspected.

Peroneal Tendon Dislocation is caused by the rupture of the peroneal retinacular ligament which acts to hold the peroneal tendons behind the ankle bone. This injury generally occurs following an ankle sprain.