Persistent Pain After Ankle Sprain: Is A Peroneal Tendon Injury The Cause?
In a follow-up to the last column (see “A Guide To Treating Ankle Sprains From Start To Finish, pg. 92, June issue), I would like to discuss common secondary injuries that often occur in relation to ankle injuries, especially sprains. One of the most common and often misdiagnosed secondary complications of ankle sprains is a tear or injury to the peroneal tendon(s). Since the tendons are in such close proximity to the lateral ankle and the lateral ankle is most often injured during a sprain, there is a tendency to perceive the two painful regions as one. Accordingly, some pay less attention to the peroneal tendons than the lateral collateral ligaments. This is not to say that it is simple to differentiate an ankle sprain with or without peroneal injury at the initial visit. However, if the patient continues to have pain two to three weeks after an initial sprain, practitioners should consider the peroneal tendons as a possible cause of pain. The cause of peroneal injury with ankle sprains is not truly and fully understood. What is understood is that the peroneal tendons act as evertors of the ankle and also act as mild stabilizers of the medial column and first ray through the attachment of the peroneus longus to the base of the first metatarsal. The peroneal tendons are most commonly stretched with inversion of the ankle. Accordingly, they are most prone to injury with an inversion type of injury. However, in our institute research, we have found three potential causes of peroneal injury.
How Can Peroneal Tendon Injuries Occur?
The first is the most common finding of injury to the peroneal tendon or peroneal retinaculum during an inversion injury. The peroneus brevis tendon is pushed between the peroneus longus and the fibula, and the inversion may snap the tendon against the side of the fibula. This results in a retinaculum tear and linear tear of the peroneal tendon. A second cause of injury is from a severe fixed strain on the peroneal tendon while the foot is in a fixed position. We have noted that this injury commonly occurs with skiing injuries, snowboarding injuries, horseback riding injuries and water skiing injuries. In all such cases, the foot is in a locked position of full dorsiflexion and eversion in the buckle. During the injury, the foot has an isometric overload of the peroneal tendon resulting in tear. The difference in this type of tear is that it is often more severe with a potential complete tear or severe split tearing. This may involve either the peroneus brevis or longus tendon, although the brevis is more commonly injured. The last and probably most common presentation is in the case of chronic ankle instability with a poorly treated ankle injury. The peroneal tendons are under constant strain to try to stabilize the lateral ankle instability, and the brevis tendon begins to fray from the overload. This leads to a longitudinal tear or split longitudinal tear. This type of injury is a chronic low-grade injury that responds well to surgery. It is essential in all cases of peroneal injury to consider instability of the ankle as a primary cause and treat the underlying instability of the ankle, if present, at the same time as the peroneal repair.