Peroneal tendonitis is a common yet often under-recognized cause of lateral ankle pain, particularly in athletic populations and individuals with biomechanical abnormalities of the foot and ankle. The condition involves inflammation or degeneration of the peroneal tendons—specifically the peroneus longus and peroneus brevis—as they course posterior to the lateral malleolus and insert into the foot. Given their essential role in dynamic ankle stability and foot function, pathology affecting these tendons can significantly impair gait and athletic performance.
The peroneal tendons originate from the lateral compartment of the leg. The peroneus longus arises from the proximal fibula and lateral tibial condyle, while the peroneus brevis originates more distally from the fibular shaft. Both tendons pass through the retrofibular groove, secured by the superior peroneal retinaculum, before diverging distally. The peroneus brevis inserts onto the tuberosity of the fifth metatarsal, whereas the peroneus longus courses plantarward across the cuboid and inserts at the base of the first metatarsal and medial cuneiform. Functionally, these tendons act to evert the foot and contribute to plantarflexion, while also providing lateral ankle stability, particularly during the stance phase of gait.
Peroneal tendonitis typically arises from repetitive overuse, resulting in microtrauma and subsequent inflammation or tendinopathy. It is frequently observed in runners, especially those who train on uneven surfaces or perform excessive hill running. Sudden increases in training intensity, duration, or frequency are well-established risk factors. Biomechanical contributors play a significant role; individuals with cavovarus foot alignment are particularly predisposed due to increased lateral column loading and chronic tensile stress on the peroneal tendons. Additionally, lateral ankle instability following previous sprains can lead to compensatory overactivation of the peroneal muscles, further exacerbating tendon overload.
Clinically, patients with peroneal tendonitis present with lateral ankle pain that may radiate distally along the course of the tendons. Pain is typically exacerbated by activity, particularly during resisted eversion or passive inversion of the foot. Swelling and tenderness posterior to the lateral malleolus are common findings, and in some cases, crepitus may be appreciated, suggesting tenosynovitis. Chronic cases may demonstrate tendon thickening or weakness in eversion strength. It is important to differentiate peroneal tendonitis from other causes of lateral ankle pain, such as lateral ligament sprains, sinus tarsi syndrome, or fractures of the fifth metatarsal.
Diagnostic evaluation is primarily clinical but may be supplemented by imaging in ambiguous or refractory cases. Ultrasound provides a dynamic, cost-effective modality for assessing tendon integrity, detecting tenosynovitis, and identifying subluxation. Magnetic resonance imaging (MRI) offers superior soft tissue contrast and is particularly useful in evaluating tendon tears, degenerative changes, or associated pathology such as retinacular injury. Imaging is especially indicated when symptoms persist despite conservative management or when surgical intervention is being considered.
Management of peroneal tendonitis is predominantly conservative and focuses on reducing inflammation, correcting biomechanical contributors, and gradually restoring function. Initial treatment typically includes activity modification, rest, and the use of nonsteroidal anti-inflammatory drugs (NSAIDs) where appropriate. Cryotherapy and compression may help manage acute inflammation. Immobilization in a walking boot may be indicated in more severe cases to allow tendon healing.
A key component of treatment involves addressing underlying biomechanical abnormalities. Foot orthoses can be particularly beneficial, especially in patients with cavus or varus alignment. Devices designed to increase lateral forefoot support and reduce excessive supination can offload the peroneal tendons. Lateral wedging or modifications to improve pronatory moments may be considered, depending on the individual’s gait pattern. Footwear modifications, including the use of stable, cushioned shoes with adequate lateral support, are also important in mitigating excessive tendon stress.
Rehabilitation plays a critical role in recovery and prevention of recurrence. Physiotherapy programs typically focus on progressive strengthening of the peroneal muscles, proprioceptive training, and correction of movement patterns. Eccentric loading exercises have shown efficacy in the management of tendinopathies and may be incorporated into rehabilitation protocols. Additionally, addressing proximal kinetic chain deficits, such as hip abductor weakness or poor neuromuscular control, can reduce compensatory loading at the ankle.
In cases where conservative treatment fails, or when structural abnormalities such as tendon tears or subluxation are present, surgical intervention may be warranted. Procedures may include tendon debridement, repair of longitudinal splits, or reconstruction of the superior peroneal retinaculum. Postoperative rehabilitation is essential to restore strength and function, with gradual return to activity over several months.
Prevention of peroneal tendonitis centers on appropriate training practices, biomechanical optimization, and early intervention. Gradual progression of training loads, adequate recovery periods, and cross-training can help minimize overuse injuries. Screening for and addressing biomechanical risk factors, particularly in high-risk populations such as runners, is essential. Education on proper footwear selection and terrain considerations can further reduce the risk of tendon overload.
Peroneal tendonitis is a multifactorial condition that reflects the interplay between mechanical loading, anatomical predisposition, and activity demands. A thorough understanding of the underlying biomechanics and risk factors is essential for accurate diagnosis and effective management. With appropriate conservative care, most patients achieve favorable outcomes; however, recognition of refractory cases and timely referral for advanced imaging or surgical consultation is critical. For clinicians, particularly those involved in sports medicine and podiatry, a comprehensive and individualized approach remains the cornerstone of successful treatment and long-term prevention.