Posterior tibial tendonitis: symptoms, treatment, and when to worry
Last updated September 3, 2026.
Posterior tibial tendon dysfunction is when the tendon that holds up your arch becomes inflamed or stretched, causing pain along the inner ankle and a slowly collapsing arch. It is the commonest cause of adult-acquired flatfoot. Caught early it responds to insoles and exercises; left alone it can progress to a rigid flatfoot.
What does it look like?
Early on: pain and swelling along the inner ankle and arch, worse with walking, running, or standing for long periods. As the tendon weakens, the arch begins to drop and the heel drifts outward, and the classic sign emerges: standing on tiptoe on that foot alone is painful or impossible. In later stages the foot turns visibly flat, the ankle rolls inward, and arthritis can follow. It usually affects one foot, typically in middle age, more often in women.
What actually helps?
- Act early: the stage you treat at decides the outcome. Pain along the inner ankle with a normal arch is the window where conservative treatment works best.
- Support the arch: firm insoles or an ankle brace take the load off the failing tendon. In early flares, a boot for a few weeks rests it properly.
- Strengthen the tendon: physio exercises targeting the posterior tibial tendon, heel raises progressing to single-leg versions, rebuild its capacity. This is the core long-term treatment.
- Reduce the strain: weight loss where relevant, supportive footwear instead of flat flimsy shoes, and activity modification during flares all lower the tendon's daily load.
- Surgery for the advanced stages: reconstruction, tendon transfer, or fusion procedures exist for collapsed or rigid flatfoot that has stopped responding to conservative care.
When is it an emergency?
Tendon problems are not emergencies, but do not sit on these: a sudden pop with instant inability to push off the foot can be a tendon rupture needing prompt assessment, and pain with a hot, red, swollen ankle plus fever suggests infection rather than tendon trouble. A foot shape that changes visibly over weeks also deserves prompt review, because early treatment of this condition is so much more effective than late. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
What is the difference between posterior tibial tendonitis and dysfunction?
Tendonitis implies the tendon is inflamed, which fits the early painful stage. Dysfunction is the broader term, because the real problem is often the tendon degenerating and stretching rather than simple inflammation, and that is what lets the arch fall. The modern name, posterior tibial tendon dysfunction, covers the whole arc from inner ankle pain to adult-acquired flatfoot.
Can posterior tibial tendon dysfunction heal without surgery?
Early stages very often do. Firm arch support, a period of relative rest or a boot in flares, and a dedicated strengthening program for the tendon resolve or stabilize many cases, particularly while the foot is still flexible. Later stages with a rigid collapsed arch are the ones that drift toward surgery. The single best predictor of avoiding surgery is how early treatment starts.
Why can't I do a single-leg heel raise?
That is the tendon's signature test. Rising on tiptoe is the posterior tibial tendon's exact job, and a healthy one does it easily on one leg. When the tendon is stretched or torn, the heel raise is weak, painful, or impossible, and the heel fails to roll inward as it should. Clinicians use precisely this test, counting clean single-leg heel raises, to stage the condition and track recovery.
Will my flat foot get better?
If the flattening is recent and the foot is still flexible, yes, support and strengthening can restore a functional arch and stop progression. If the foot has become rigid, the deformity is structural, and conservative treatment manages pain and function rather than rebuilding the arch. Flexible versus rigid is the key distinction your clinician tests, and it sets the treatment path.
What shoes and insoles actually help?
Firm, supportive shoes with structure through the midfoot, not soft or minimal ones, paired with insoles that support the arch and cup the heel. Custom orthotics add heel posting that physically corrects the inward roll for more significant cases. An ankle-foot brace is the step up when insoles alone are not enough. The goal is mechanical: take the daily load off the failing tendon.
Is this the same as plantar fasciitis?
Different structure, different pain map. Plantar fasciitis hurts under the heel and along the arch's underside, classically with the first morning steps. Posterior tibial tendon dysfunction hurts along the inner ankle and arch, worsens with activity rather than first steps, and comes with arch collapse and failed heel raises. Both respond to support and loading programs, but they are distinct diagnoses.