The peroneal tendons run on the outside of the ankle just behind the bone called the fibula. Tendons connect muscle to bone and allow them to exert their force across the joints that separate bones. Tendinitis implies that there is inflammation in the tendon. Tendinosis means there is enlargement and thickening with swelling of the tendon. This usually occurs in the setting of overuse, meaning a patient or athlete does a repetitive activity that irritates the tendon over long periods of time.
The history is very important in the setting of peroneal tendinosis. As noted above, these are overuse injuries. People with peroneal tendinosis typically have either tried a new exercise or have markedly increased their activities. Characteristic activities include marathon running or others which require repetitive use of the ankle. Patients will usually present with pain right around the back of the ankle. There is usually no history of a specific injury.
As discussed above, improper training or rapid increases in training and poor shoewear can lead to peroneal tendinosis. Also, patients who have a hindfoot varus posture, or high arch, may be more susceptible. This is because in those patients, the heel is slightly turned inwards which requires that the peroneal tendons work harder. Their main job is to evert or turn the ankle to the outside, which fights against the varus position. The harder the tendons work, the more likely they are to develop tendinosis.
There are two peroneal tendons that run along the back of the fibula (Figures 1 and 2). The first is called the peroneus brevis. The term “brevis” implies short. It is called this because it has a shorter muscle and starts lower in the leg. It then runs down around the back of the bone called the fibula on the outside of the leg and inserts (i.e. connects) to the fifth metatarsal.. The peroneus longus takes its name because it has a longer course. It starts higher on the leg and runs all the way underneath the foot to insert on the bottom of the first metatarsal. Both tendons, however, share the major job of everting or turning the ankle to the outside. The tendons are held in a groove behind the back of the fibula and have a roof made of ligamentous-type tissue over the top of them called a “retinaculum.”
Symptoms of peroneal tears and peroneal tendinitis include pain along the lateral part of the foot and ankle up to the 5th metatarsal bone, as well as pain with eversion of the foot.
A thorough subjective and objective examination from a can be sufficient to diagnose peroneal tendonitis.
X-rays do not reveal soft tissue abnormalities; however, they are useful for excluding arthritis, bone abnormalities such as pes cavus, or fractures.
In cases where other injuries may need to be ruled out, or conservative treatment is failing, an MRI scan or ultrasound investigation can e used for detecting all types of peroneal lesions.
Conservative treatments include rest, ice, compression elevation as well as bracing and physical therapy. If these modalities fail to help after several weeks an MRI or ultrasound may be ordered to better evaluate the extent of tendon inflammation and tearing. A tear in the tendon, depending on how thick and long may need to be surgically fixed. This is done by making an incision over the area of the tendon that is torn and using sutures to repair the tendon. At CMD we also make use of amniotic membrane wraps that help promote healing and decrease adhesions and scar tissue that may form around the tendon.
After surgery you would be placed in a splint with no weight bearing for about 2 weeks. After 2 weeks you can advance to range of motion and ambulating with a boot. At 4 weeks you would begin aggressive physical therapy to get you back to full strength and range of motion.