Peroneal Tendonitis is an uncommon problem with the tendons on the outside of the rearfoot. The problem in most cases happens in runners in which the loads on these structures are therefore higher. There are 2 peroneal muscles on the of the lower limb whose tendons pass across the outside of the ankle joint with one tendon attaching on the lateral side of the foot at the base of the fifth metatarsal. The other tendon passes under the foot to connect to an area close to the center of the arch of the foot. The muscles have many different actions, however a major one is to counteract the ankle rolling outwards and ending up with a ankle sprain. Since they work hard during this task, the burden on the tendons could be too much for the tendon to tolerate and they are susceptible to peroneal tendinopathy.
Typically the condition starts off with pain either above or just beneath the outside ankle bone without or with some swelling. In some the swelling develops later. With ongoing activity the pains gets more constant and gradually worse. A typical feature in those with peroneal tendinopathy is a low supination resistance. This means that it is easy for the ankle to supinate or roll laterally. This will cause the peroneal tendons to be very active, so if you then combine it with higher level of sports activity, then the tendon is at higher risk for an overuse injury.
Dealing with peroneal tendinopathy generally starts with minimizing the strain by lessening physical activity levels as well as the use of footwear wedging or foot inserts to pronate or tip the feet inwards so the muscle doesn't have to function as hard. Ice and anti-inflammatory drugs can also help decrease the discomfort and inflammation. Over the medium to long term raising load by the way of exercise ought to be placed on the tendon in order that it can adapt to the strains placed on it. In some circumstances, surgery is indicated.