Peroneal tendonitis is a common yet often misunderstood source of pain on the outside of the ankle. It frequently affects runners, athletes, and individuals who subject their feet to repetitive strain. While it can be a frustrating injury that sidelines even the most active people, understanding its causes, recognizing its symptoms, and following a structured treatment plan are the keys to a full recovery.
Understanding the Peroneal Tendons and the Onset of Tendonitis
To understand peroneal tendonitis, one must first appreciate the critical role of the peroneal tendons. These are two strong, cord-like structures on the outside of the ankle: the peroneus longus and the peroneus brevis . They connect the muscles of the lower leg to the bones of the foot, running side-by-side behind the bony bump on the outside of the ankle, known as the lateral malleolus . Their primary job is to stabilize the foot and ankle, particularly during weight-bearing activities. They are responsible for turning the foot outward (eversion) and maintaining balance, especially on uneven surfaces .
Peroneal tendonitis is, at its core, an inflammatory condition affecting these tendons . However, it is often more accurately described as a continuum of overuse injuries. In its early stages, it presents as acute inflammation (tendonitis), but if left untreated, it can progress to a chronic, degenerative condition known as tendinosis, where the tendon structure begins to break down . The most common culprit is overuse—a rapid increase in training intensity, duration, or frequency that overwhelms the tendon’s ability to repair itself . This is particularly common in new runners or those returning to sport after a break .
Causes and Risk Factors: Who Is Most at Risk?
The causes of peroneal tendonitis are multifactorial, often stemming from a combination of activity-related stress and underlying biomechanical issues. Repetitive activities that involve constant shifting and lateral movement, such as basketball, soccer, and tennis, place significant demand on these tendons, making them susceptible to irritation . Furthermore, a single traumatic event, like an ankle sprain, can set the stage for tendonitis. When the ankle is rolled inward, the peroneal tendons are forcibly stretched to counteract the motion, which can cause microtears and inflammation that fails to fully resolve .
Beyond activity, an individual’s foot structure plays a pivotal role. People with high-arched feet (cavus foot) are particularly prone to this condition . A high arch often leads to a hindfoot varus posture, where the heel is slightly turned inward. This alignment places chronic, increased strain on the peroneal tendons as they work harder to stabilize the ankle . Similarly, individuals with tight calf muscles are at a higher risk, as limited flexibility in the calves alters normal ankle biomechanics and stresses the peroneal tendons . Other contributing factors include improper or worn-out footwear that fails to provide adequate support, obesity which increases load on the tendons, and simply the aging process, as tendon health naturally declines over time .
Recognizing the Symptoms and the Path to Diagnosis
The primary symptom of peroneal tendonitis is pain and swelling along the outside of the ankle, often tracking from just below the lateral malleolus toward the outer part of the foot . The pain is typically insidious, starting as a dull ache that intensifies with activity—such as running, pushing off, or even just walking—and subsides with rest . In some cases, individuals may notice a popping or clicking sensation in the tendon, particularly if the tendons are unstable or subluxing (slipping out of their normal position) . The area may also feel warm to the touch and appear puffier than the uninjured ankle .
Diagnosing peroneal tendonitis can be challenging, as its symptoms often mimic those of a lateral ankle sprain. In fact, one study suggests that nearly 60% of cases are initially misdiagnosed . A healthcare provider will begin with a thorough physical exam, palpating the tendons to pinpoint tenderness and assessing range of motion and strength . To confirm the diagnosis and rule out other issues like fractures, arthritis, or tendon tears, imaging studies are often necessary. While X-rays can rule out bone problems, an MRI or musculoskeletal ultrasound provides detailed images of the soft tissues, allowing the physician to assess the extent of inflammation, degeneration, or tearing within the tendons .
Conservative Treatment: The First Line of Defense
The vast majority of peroneal tendonitis cases respond well to conservative, non-surgical treatment, with symptoms often improving within three to four weeks . The initial phase focuses on reducing acute pain and inflammation. This is commonly achieved through the RICE protocol (Rest, Ice, Compression, and Elevation) and the use of non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen . In more acute cases, a period of immobilization in a walking boot may be necessary to completely offload the tendon and allow inflammation to subside .
Once the acute pain is controlled, the cornerstone of recovery is physical therapy. A structured rehabilitation program is essential not just for healing, but for preventing recurrence. Physical therapy typically progresses through several stages:
- Flexibility and Range of Motion: Gentle stretching of the calf muscles, such as the wall calf stretch and soleus stretch, helps alleviate tension on the peroneal tendons .
- Strengthening: As pain allows, patients advance to strengthening exercises. This often starts with isometric holds and progresses to resistance band exercises, such as resisted ankle eversion, which directly targets the peroneal muscles .
- Balance and Proprioception: Exercises like single-leg stands help retrain the ankle to respond to uneven surfaces, improving stability and reducing the risk of future injury .
In addition to exercise, a physical therapist may recommend supportive measures like ankle bracing or taping during activity, and assess the patient’s footwear. For individuals with high arches, a supportive shoe with a neutral last may be more beneficial than one with aggressive arch support . Custom orthotics can also be prescribed to correct biomechanical imbalances .
When Surgery Becomes Necessary
Surgery for peroneal tendonitis is reserved for cases where a lengthy trial of conservative treatment (typically four to six months) has failed to provide relief, or in the presence of a significant tendon tear . The specific surgical procedure depends on the extent of the damage. For simple, chronic inflammation without a major tear, a procedure called a synovectomy may be performed to debride (clean out) the inflamed tissue around the tendon . If the tendon is torn, the surgeon may need to repair it by removing the damaged portion and suturing the healthy ends together .
In complex cases involving recurrent instability or severe anatomical issues, the surgery may be more involved. This could include deepening the shallow groove in the fibula where the tendons sit to prevent them from snapping out of place, or even reconstructing a tendon using a graft if the damage is too severe for a primary repair . For patients with high arches that contribute to the problem, a corrective foot reconstruction surgery may be recommended at the same time to protect the repaired tendons from future stress . Post-surgical recovery is extensive, often requiring several weeks in a cast followed by a lengthy course of physical therapy to regain strength and mobility .
Peroneal tendonitis is a painful condition that can significantly impact an individual’s mobility and quality of life. It arises from a complex interplay of overuse, biomechanical predisposition, and sometimes acute injury. While the path to recovery requires patience, the prognosis is excellent. By understanding the importance of listening to one’s body, respecting the early signs of pain, and engaging in a comprehensive treatment plan that includes relative rest and targeted physical therapy, most people can expect a full return to their desired activities. The goal of treatment is not only to alleviate the immediate pain but to address the underlying causes—be it muscle weakness, poor flexibility, or inappropriate footwear—to build stronger, more resilient ankles for the long term.