peroneal tendonitisPeroneal tendonitis is an inflammation of the peroneal tendons. These tendons become inflamed as a result of repetitive strain most common in athletes. The peroneal tendons rub against bone causing them to thicken in response to this action.
The peroneal tendons are located on the lateral side of the ankle (side furthest from the midline of your body). One is the peroneus longus (long tendon) and the other is the peroneal brevis (short tendon). When these two tendons become inflamed they may cause pain around the backside of the ankle, over the lateral side of the heel where they course under a prominent bump in your heel bone. 
Individually the tendons also have their own unique path to pain when they're inflamed. Pain can occur where the short tendon inserts in the base of your fifth metatarsal bone. It can also occur where the long tendon dives under the foot and inserts into the first metatarsal bone.  

What These Tendons Do

The peroneal tendons help to transfer your weight from the outside of the foot over to the great toe during push off, assist your calf muscles in flexing your foot, and keep your ankle stable during activities like running or jumping.


In addition to repetitive strain, peroneal tendonitis is caused by:
  • Chronic ankle sprains associated with a high-arched foot
  • Direct injury to the tendons
  • Severe flatfoot
  • Fractures and spurs
  • Damage or rupture of the ligament that holds the tendons behind the ankle.
  • Lack of adequate warm-up before exercise
  • Unsupportive footwear


Peroneal tendonitis can be either acute (occurs suddenly such as an ankle sprain) or chronic (occurs over a longer period of time such as injury as a result of severe flatfoot). 
Symptoms include:
  • Pain in the ankle that worsens during physical activity
  • Swelling in the ankle
  • Ankle warm to the touch
  • Pain with ankle rotation
  • Sharp or aching feeling along the tendons on the outside of the ankle or the outside of the 5th toe.
  • Unstable ankle


The diagnosis is made by clinical examination where the two muscles are tested against resistance, direct pressure to the tendon, ultrasound, and MRI exam. The podiatrist will check for pain, instability, weakness, and signs of an ankle sprain.


Initial treatment is aimed at the reduction of inflammation through rest and immobilization, icing, and anti-inflammatory medications. This is followed by casting with custom orthotics to control foot motion, bracing, and physical therapy. Regenerative medicine such as platelet-rich plasma and cold laser treatments such as MLS laser can also be helpful in longer term healing of this condition.


To prevent peroneal tendonitis, it’s important to include the following as part of your training regimen:
  • Supportive shoes appropriate for your sport
  • Adequate stretching including exercises such as Dynamic Warm-ups for Runners .
  • Pay attention to the surfaces you run on to avoid ankle sprains; fields should be cleared of any possible hazards before play begins.
  • Strengthening exercises for the ankle

What is Foot and Ankle Tendonitis and How Is It Treated?

For an appointment with one of our Seattle podiatrists, call 206-368-7000 or request an appointment online.

Dr. Rion Berg
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A podiatrist in North Seattle treating families for over 40 years.