The peroneal tendons run behind the outside of the ankle and help control eversion, lateral ankle stability and foot loading during walking, running and cutting. Tendinopathy can cause pain behind or below the lateral malleolus, but not every case of lateral ankle pain is simple tendon overload.
Peroneus brevis split tears, peroneus longus tears, tendon subluxation, chronic lateral ankle ligament injury, sural nerve irritation and os peroneum pathology can produce overlapping symptoms. A snapping or clicking tendon also raises a different diagnostic question than uncomplicated tendinopathy.
At Novo Soft Tissue in the Denver Tech Center, Dr. Scott King begins by determining which structure is actually producing the symptoms, then assesses tendon loading, ankle stability and whether dynamic ultrasound or MRI is needed before selecting progressive loading, shockwave therapy, mechanical support, imaging or referral.
What Is Peroneal Tendinopathy?
Peroneal tendinopathy is a load-related disorder of the peroneus brevis and/or peroneus longus tendon, typically producing posterolateral ankle or lateral-foot pain that increases with tendon loading.
Both tendons pass behind the lateral malleolus in a shared groove held in place by the superior peroneal retinaculum. The peroneus brevis then attaches at the base of the fifth metatarsal on the outer edge of the foot. The peroneus longus turns under the foot near the cuboid, where some people have a small accessory bone called the os peroneum, and continues across the sole toward the first ray on the inner side of the foot.
Not Every Case of Lateral Ankle Pain Is Peroneal Tendinopathy
- Peroneal tendinopathy: posterolateral ankle pain along the tendon course, worse with eversion and push-off loading, running, uneven surfaces or cutting, with localized tenderness.
- Peroneal tendon tear: consider with persistent focal pain, weakness, swelling, mechanical symptoms, a prior inversion injury, long-standing tendon symptoms or failure to progress.
- Subluxation or instability: consider with snapping, clicking or a feeling of the tendon moving behind the lateral malleolus, especially when symptoms are reproduced with movement or began with a forceful dorsiflexion and eversion injury.
- Lateral ligament pathology: consider after inversion sprains, with giving way or instability and symptoms over the ATFL and CFL region in front of and below the ankle bone.
- Sural nerve irritation: burning, tingling or altered sensation along the outer heel and foot rather than load-related tendon pain.
- Os peroneum and peroneus longus problems: more distal pain under the outer foot near the cuboid, with a longus-specific loading pattern.
A chronic peroneal tendon tear can mimic tendinopathy. Split tears of the peroneus brevis are particularly important because they may produce persistent posterolateral ankle pain without an obvious acute rupture event. That does not mean every long-standing tendon symptom contains a tear. Peroneal instability also does not always mean the tendons visibly jump over the fibula: it can occur within the tendon sheath. The differences are explained in peroneal tendinopathy vs. tendon tear or subluxation.
What We Examine
- Precise pain location and tenderness along the peroneus brevis and longus
- Swelling around the tendons
- Resisted eversion and plantarflexion-eversion, and eversion strength
- Single-leg loading, calf raises, balance and gait
- Snapping or clicking, and any tendon movement behind the fibula during motion
- Lateral ankle ligament stability
- Hindfoot posture and foot alignment
- The fifth metatarsal base, cuboid and os peroneum region
- Neural symptoms that suggest sural nerve involvement
No single resisted test definitively diagnoses tendinopathy. The pattern across these findings determines whether the tendon is likely just overloaded or whether imaging is needed to look for a tear or instability.
Foot and hindfoot alignment can influence peroneal loading, particularly when a varus pattern repeatedly shifts demand toward the lateral border of the foot. Many people with peroneal tendon pain have ordinary alignment, so this is assessed rather than assumed.
When Is Imaging Needed?
Uncomplicated, load-related tendon pain that matches the exam often does not need imaging at first. Imaging becomes more useful when a tear or instability is suspected, symptoms are atypical, or progress stalls.
Ultrasound and MRI answer somewhat different questions. Dynamic ultrasound is especially valuable when the complaint is snapping or positional instability, while MRI can be useful when a broader structural assessment is needed. Neither test replaces the examination.
Lateral Ankle Injuries That Need Prompt Assessment
An acute injury with a snap or pop, rapid swelling, visible or palpable tendon displacement, marked weakness, or inability to continue playing after a forced dorsiflexion and eversion movement may be an acute peroneal tendon dislocation or tear. That is not routine tendinopathy and calls for prompt imaging and orthopedic evaluation.
How Treatment Is Selected
Load Management
Provocative lateral loading, such as uneven trails, cutting or high running volume, is modified temporarily. Unnecessary complete rest is avoided.
Progressive Peroneal Loading
Progressive loading is the foundation for uncomplicated tendinopathy. Rehabilitation should progressively rebuild the peroneal tendons’ ability to tolerate eversion, plantarflexion, single-leg loading and higher-speed lateral demand. That usually means progressing eversion strength, plantarflexion and eversion control, single-leg loading and balance, then running, cutting and sport-specific demand.
Radial or Focused Shockwave
Radial or focused shockwave may be considered as an adjunct for selected persistent tendon pain once a major tear or instability has been excluded. Direct peroneal-specific evidence is limited, so it is not presented as a stand-alone treatment. Shockwave may be directed to symptomatic tendon tissue. It does not mechanically stabilize a subluxating tendon.
Manual Treatment
Manual treatment may address adjacent calf and ankle soft tissue or mobility restrictions where clinically appropriate. It does not repair a split tendon tear or stabilize a subluxating tendon.
Footwear and Mechanical Support
Footwear changes or an orthotic are considered only when alignment or a recurrent lateral loading pattern gives a reason, such as cavovarus mechanics or symptoms clearly modified by foot position. When external mechanical support is indicated, Novo can use Sole Supports custom orthotics as part of the load-management strategy. Support does not repair a tendon tear.
Imaging
Dynamic ultrasound is used when snapping or subluxation is suspected, and MRI when a tear or broader structural pathology is suspected.
Referral
Referral to a foot and ankle specialist is appropriate with recurrent tendon dislocation, persistent snapping, a substantial tear, acute traumatic instability, major weakness, progressive symptoms, or failure to improve with appropriate conservative management.
You do not need to decide which treatment you need before your visit. All four tools are compared on the services page, and shockwave at Novo is explained on shockwave therapy in Denver. Pain on the inside of the ankle is covered on the posterior tibial tendinopathy page, and pain at the front of the ankle on the tibialis anterior tendinopathy page.
What Research Says
- Peroneal disorders are heterogeneous: a recent systematic review of peroneal tendoscopy reinforces that peroneal disorders span tendinopathy, tenosynovitis, tendon tears, stenosis and intrasheath subluxation, several distinct problems that can produce similar lateral ankle symptoms (Tham, 2026).
- Dynamic ultrasound for instability: in an early surgical-correlation study, all 12 patients with a positive dynamic-ultrasound diagnosis of peroneal tendon subluxation had the diagnosis confirmed at surgery (Neustadter, 2004). In another series, dynamic ultrasound revealed tendons switching positions within the sheath in 14 patients with painful snapping who had no visible subluxation, all confirmed at surgery (Raikin, 2008).
- Tears: the newest diagnostic meta-analysis of 12 studies found pooled ultrasound sensitivity of 93% for peroneus brevis tears and 94% for peroneus longus tears, compared with 73% and 60% for MRI, with high specificity for both. However, the studies were heterogeneous and at high risk of bias, so the authors could not confidently declare either modality superior (Ghandour, 2025).
- Subluxation: in a small, selected surgical cohort of 21 patients, ultrasound was 100% sensitive for subluxation compared with 66% for MRI, while MRI was slightly more accurate for tears (Melville, 2024).
- Shockwave: direct peroneal-specific evidence is limited to case reports with combined treatments.
This is why Novo first determines whether the problem is tendinopathy, tear or instability before selecting treatment.
Tendinopathy vs. tear or subluxation → · Shockwave evidence review →
Sources: Ghandour et al., Eur Radiol 2025 · Melville et al., J Clin Med 2024 · Neustadter et al., AJR 2004 · Raikin et al., J Bone Joint Surg Am 2008 · Tham et al., J Orthop 2026 · Culebras Almeida & Schwitzguebel, Life 2026
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