Posterior Tibial Tendon Dysfunction: the tendon that holds up the arch.

Posterior tibial tendon dysfunction (PTTD) is irritation and then degeneration of the posterior tibial tendon, which runs behind the inner ankle bone and is the main dynamic support of the arch. As the tendon weakens, it can no longer hold the arch up, and the foot gradually flattens and rolls inward.

It usually starts as inner-ankle pain and swelling and progresses over time. The single most important point is that it is staged: caught early, while the tendon is irritated but the foot is still flexible, it is treated with simple supportive measures. Left to progress, the flatfoot can become fixed and stiff, which is much harder to treat. That is why catching it early matters.

Symptoms

Typical findings include:

• Pain and swelling along the inner ankle and arch
• A gradually flattening arch, often in one foot first
• Difficulty standing on tiptoe on the affected side
• Pain that shifts to the outer ankle as the deformity advances

Why catching it early matters

Early on, the tendon is irritated but the foot is still flexible, and the arch can still be supported and the tendon protected. As the condition advances, the flatfoot becomes progressively fixed, the joints stiffen, and the problem shifts from a tendon to a deformity. The earlier it is recognized, the simpler and more effective the treatment, which is why inner-ankle pain with a flattening arch should not be ignored.

How it is diagnosed

The diagnosis is largely clinical, based on inner-ankle tenderness, a flattening arch, and difficulty rising onto the toes. Standing X-rays show the alignment of the foot and how far the deformity has progressed, and MRI or ultrasound assesses the tendon itself when needed.

Non-surgical treatment

Early-stage dysfunction, while the foot is flexible, responds to:

• An orthotic or a brace to support the arch and offload the tendon
• Physical therapy to strengthen the tendon and surrounding muscles
• Anti-inflammatory measures to settle the irritation
• A period of relative rest from aggravating activity

Surgical treatment

Progressive collapse that does not respond to conservative care may need reconstruction. Depending on the stage, this can combine a tendon transfer to restore active support of the arch with bony realignment (osteotomy) to correct the flatfoot, and occasionally fusion when the deformity is fixed and the joints are arthritic. The aim is a stable, well-aligned, comfortable foot.

Recovery timeline

Recovery depends on the stage and the treatment:

1. Non-surgical
   A brace or orthotic with therapy over several weeks to months, with the best results when started early.
2. After reconstruction, weeks 0 to 6
   Protected immobilization and limited weight-bearing while the repair and any bone work heal.
3. Months 3 to 6 and beyond
   Progressive strengthening and a graded return to walking and activity as the foot rebuilds support.

What patients commonly misunderstand

Two things to understand:

• A 'fallen arch' with inner-ankle pain is not just cosmetic. A newly flattening, painful arch in an adult often means the posterior tibial tendon is failing. Recognized early, while the foot is flexible, it is treated simply. Ignored, it can progress to a fixed deformity.
• Earlier treatment means simpler treatment. The condition is staged. In the early stages an orthotic, therapy, and anti-inflammatory measures often suffice. Once the flatfoot becomes fixed, correction is a bigger undertaking, which is why catching it early matters.

This page is general educational content authored by Dr. Lee. It is not a substitute for individual medical advice. Every patient's case is different, book a consultation to discuss yours.