In short
The two peroneal tendons run behind the outer ankle bone and stabilise the outside of the ankle and foot. They can become painful and thickened (tendinopathy), develop splits or tears, or slip out of their groove (subluxation). Symptoms are pain and swelling behind the outer ankle, weakness, a feeling of instability or clicking. Rest in a boot, physiotherapy and bracing help many people; surgery repairs tears, deepens the groove or corrects an underlying high-arched foot.
What are the peroneal tendons?
Peroneus longus and peroneus brevis run down the outside of the leg, curve behind the fibula (the outer ankle bone) and attach to the foot. Brevis attaches to the base of the fifth metatarsal; longus passes under the foot to the base of the first metatarsal. They turn the foot outwards and protect against rolling the ankle.
Types of problem
- Tendinopathy: pain and thickening from overload
- Split tears, most often of peroneus brevis
- Subluxation or dislocation: the tendons snap out of the groove behind the fibula, often after an injury
- Problems where peroneus longus wraps around the cuboid, sometimes involving a small bone in the tendon (os peroneum)
What causes them?
- Ankle sprains and chronic ankle instability
- A high-arched foot with the heel tilted inwards, which overloads the tendons
- Repetitive sport, especially running and cutting movements
- A shallow groove behind the fibula or a torn retinaculum that normally holds the tendons in place
What are the symptoms?
- Pain and swelling behind and below the outer ankle bone
- Weakness pushing the foot outwards
- A feeling of instability
- Clicking or snapping behind the ankle if the tendons are slipping
Treatment without surgery
- A walking boot for a few weeks to settle acute pain
- Physiotherapy: peroneal strengthening and balance work
- Bracing for sport
- Insoles with a lateral wedge for a high-arched foot
Surgery
- Tendon repair (tubularisation) of split tears, or tenodesis of a badly damaged tendon to its neighbour
- Groove deepening and retinaculum repair for slipping tendons
- Ligament repair for associated ankle instability
- Heel realignment (calcaneal osteotomy) when a high-arched foot is the cause
Common questions
Are peroneal tendon problems linked to ankle sprains?
Yes. Peroneal tendon injuries often happen alongside ankle sprains and chronic ankle instability, and are easily missed. If pain continues behind the outer ankle months after a sprain, the tendons should be checked.
Do I need a scan?
Ultrasound, which can watch the tendons moving, or MRI is usually used to confirm a tear or a tendon slipping out of its groove.
Talk it through with a specialist
Consultations at Spire Liverpool, Salford and the Isle of Man. New patients £250.
Consultant Foot and Ankle Surgeon, MB BCh, PhD, FRCS (Tr&Orth), FRCS (Glasg), SFHEA, FFSTEd. GMC 6074953. Hunterian Professor, Royal College of Surgeons of England.
Page last reviewed 25 October 2026. This information is general and does not replace an assessment.
Prof Mason's published research on this topic
Peer-reviewed papers by Prof Mason and his colleagues. Links open the paper or its PubMed record.
- Pearse R, Stringer H, Redfern J, Patel S, Cullen N, Mason LW, Welck M, Malhotra K. Position, size and orientation of the peroneus longus tubercle in patients with cavovarus feet. The Foot, 2026.
- Ardakani A, Rudran B, Stringer H, Mason L, Welck M, Malhotra K. The position, orientation, and relative size of the fibularis longus tubercle in normal patients: a weightbearing CT assessment. Clinical Anatomy, 2024.
- Usuelli FG, Mason LW, Maccario C, Grassi M, Ballal M, Molloy A. Lateral ankle and hindfoot instability: a new clinical based classification. Foot and Ankle Surgery, 2014.