Evidence checked as of October 2026. Written by The Wellness Team.
What is peroneal tendon pain?
The two peroneal tendons run behind the bony bump on the outside of the ankle and help stabilise it when you walk, run or change direction. Pain along that line can come from tendinopathy, which is irritation and degeneration of the tendon, from tenosynovitis, from a partial or complete tear, or from the tendons slipping out of position. These look similar from the outside and are managed differently.
Typical features are pain and swelling behind or just below the outer ankle bone, worse with activity and often stiff first thing. Some people feel a snap or click, or a sense that the ankle gives way. A sprain that never fully settled is a common backstory.
How is it diagnosed?
A careful examination and the story of the problem come first. Ultrasound is useful because it shows the tendon in motion, so it can reveal swelling, a split in the tendon or a tendon that slips. MRI is used when the picture is unclear or a tear is suspected. Imaging should answer a question the examination has raised. It should not be the starting point for every ankle ache, because many tendons look abnormal on a scan in people with no pain.
What does the evidence say about treatment?
A review in the Journal of the American Academy of Orthopaedic Surgeons states that non-surgical treatment should always be the first step. That means a short period of rest, a corrective orthotic where the foot alignment contributes, then progressive strengthening of the peroneal tendons and the muscles around them. An international expert consensus published in Knee Surgery, Sports Traumatology, Arthroscopy agrees that conservative treatment is the treatment of choice for most acute peroneal problems, and notes that the evidence on outcomes is limited and varied.
When symptoms persist despite a proper rehabilitation programme, or a significant tear is found, referral to a foot and ankle surgeon is appropriate. Procedures range from tendon debridement and repair to tendoscopy, which uses a small camera. Systematic reviews of tendoscopy report encouraging short-term results, based on small numbers of patients.
Where does PRP fit?
Honestly, as an option that is not proven. The same orthopaedic review notes that PRP has been reported by several authors but its effect on peroneal tendon healing has not been confirmed. Evidence for PRP across lower limb tendons is mixed. A Canadian health technology review found inconsistent results and unclear injection protocols, and a 2026 meta-analysis of randomised trials in Achilles tendinopathy found no significant benefit over placebo at three or six months.
That does not mean PRP can never help one person. It means the claim should be modest, the discussion should be open, and PRP should be considered after a good rehabilitation attempt, not instead of one. Steroid injection around these tendons is generally avoided because of the risk of weakening them.
What should you ask before any injection?
Ask which structure is the target, whether the diagnosis has been confirmed on ultrasound or MRI, what the evidence is for your specific problem, and how success will be measured. A sensible plan includes a rehabilitation programme, a review at about three months and a clear point at which you would see a surgeon.
How can The London PRP Clinic by The Wellness help?
We start with the diagnosis. An assessment looks at the ankle, the foot alignment and the loading pattern that caused the problem, and uses ultrasound where it will change the plan. PRP is offered at £450 a session where it is a reasonable option, with the limits of the evidence explained first.
Discuss your ankle with the clinic: https://www.thelondonprpclinic.com/contact-best-prp-clinic-london
Review current services: https://www.thelondonprpclinic.com/services
When should you seek urgent help?
See a doctor promptly if you cannot put weight on the foot, the ankle looks deformed, you heard a pop with immediate weakness, or the leg becomes hot, red and swollen with fever. Calf pain and swelling with breathlessness or chest pain need emergency care.
Evidence and limits
Peroneal tendon disorders, review in JAAOS. https://doi.org/10.5435/jaaos-d-18-00623
International expert consensus on acute peroneal tendon pathology. https://doi.org/10.1007/s00167-018-4971-x
PRP for chronic lower limb tendinopathies, Canadian Journal of Health Technologies. https://doi.org/10.51731/cjht.2023.681
Peroneal tendon pathologies, review of non-operative and operative treatment. https://pmc.ncbi.nlm.nih.gov/articles/PMC8696808/
Corticosteroid injection in chronic tendon lesions, review noting no good evidence of benefit and tendon-weakening effects in animal studies. https://pmc.ncbi.nlm.nih.gov/articles/PMC1120980/
This is general information, not personal medical advice or a promise of results.