Condition

Peroneal tendonitis

Overview

Peroneal tendonitis is an overuse pathology characterised by inflammation and irritation of the peroneal tendons, which run along the lateral aspect of the lower leg and ankle. These tendons play a key role in stabilising the foot and controlling eversion during gait. The condition is commonly observed in runners, individuals with high-arched (cavus) foot types, and patients who have recently increased training load or altered footwear.

Symptoms & Causes

Patients typically report:

Lateral ankle or foot pain, often exacerbated by weight-bearing activity
Localised swelling or tenderness along the peroneal tendons
Discomfort during resisted eversion or single-leg loading
Sensations of ankle instability, particularly on uneven surfaces
Symptoms that ease with rest but recur on resumption of activity

Undiagnosed or untreated peroneal tendonitis may progress to chronic tendinopathy or lead to compensatory gait alterations, increasing the risk of further lower-limb injury.

Aetiology & Contributing Factors

Common underlying factors include:

Sudden increases in training volume or intensity
Repetitive overloading associated with running or lateral-movement sports
High-arched or supinated foot types
Inadequate footwear or worn-out running shoes
Previous ankle sprains leading to mechanical instability

How is it Diagnosed?

Diagnosing Peroneal Tendonitis involves a combination of clinical assessment, movement testing, and if needed imaging. Because lateral ankle pain can stem from several conditions, an accurate diagnosis is essential for effective treatment.

1. Clinical History

A podiatrist or clinician will begin by understanding your symptoms and activity levels. Key questions often include:

When did the pain start?
Have you recently increased running or training intensity?
Do you have a history of ankle sprains or instability?
What activities make the pain worse (e.g. walking, running, uneven ground)?

This helps identify whether the condition is linked to overuse or biomechanical stress.

2. Physical Examination

A hands-on assessment is crucial and typically includes:

Palpation (touch): Tenderness along the outer ankle where the peroneal tendons run
Swelling check: Localised inflammation behind the outer ankle bone
Resisted eversion test: Pain when pushing the foot outward against resistance
Single-leg loading: Discomfort when standing or balancing on one foot
Range of motion: Assessing ankle mobility and control

These findings strongly indicate irritation of the peroneal tendons.

3. Gait & Biomechanical Assessment

At clinics like Foot Factor Orthotics & Podiatry, a detailed gait analysis is often performed to identify underlying causes:

Over-supination (high-arched foot type)
Poor foot mechanics during walking or running
Abnormal loading patterns on the lateral ankle

This step is key to preventing recurrence.

4. Imaging (If Required)

Imaging is not always necessary but may be used in persistent or unclear cases:

Ultrasound: Detects tendon inflammation, thickening, or tears
MRI: Provides detailed images of soft tissue, useful for ruling out tendon tears or other conditions
X-ray: Helps exclude fractures or bony abnormalities

5. Differential Diagnosis

Because symptoms overlap with other conditions, clinicians will rule out:

Sinus Tarsi Syndrome
Lateral ankle ligament sprains
Peroneal tendon subluxation (tendon slipping)
Stress fractures of the foot or ankle

Foot Factor provides Expert Podiatry Treatment Tailored to You.

At Foot Factor, our podiatrists specialise in diagnosing and treating foot pain with precision and expertise. With advanced gait analysis, bespoke orthotics, and sports-focused podiatry care, we don’t just identify the problem—we provide a targeted solution to get you back to moving pain-free. Book a consultation today and take the first step toward lasting relief.