Posterior Tibial Tendon Dysfunction

Overview

what it is and why it matters

Posterior tibial tendon dysfunction (PTTD), also called adult-acquired flatfoot, is the gradual failure of a tendon that runs along the inside of your ankle and holds up the arch of your foot. As the tendon weakens, stretches out, and eventually tears through, the arch on the inside of your foot flattens, your heel angles outward, and your forefoot drifts toward the outside. Looking at the foot from behind, you can see extra toes peeking out on the outside (the classic too-many-toes sign).

It is most common in women over 40, people carrying extra weight, anyone with high blood pressure or diabetes, and people whose work has them on hard floors all day.

Symptoms

what you may notice

Pain along the inside of the ankle and arch, an aching or burning that starts behind the inner ankle bone and runs along the inside of the foot.
Arch flattening on one side, you notice one foot is becoming flatter than the other, and your old shoes start wearing unevenly.
Cannot rise onto tiptoes on the affected foot, standing on one leg, you either cannot push up onto your toes at all or it feels weak and painful.
Heel drifting outward, looking at your feet from behind, extra toes peek out on the outside of the affected foot (the "too-many-toes sign").
Fatigue and aching after standing or walking, the inside of your ankle and foot tire quickly and throb after time on your feet.

Diagnosis

exam first, imaging second

Your provider does a focused physical exam of the foot and ankle, checking the arch, how the heel sits, and how well you can rise onto your toes on the affected side. Standing X-rays of the foot measure how much the arch has collapsed and how far the heel has drifted outward. An MRI shows how badly the tendon itself has degenerated. Your provider grades how far the condition has progressed, from early to advanced, and that stage guides treatment.

How We Treat It

what we try first, in order

Most people with PTTD start with non-operative care. The treatments below are listed in the order we usually introduce them. Bracing comes first to support the failing arch, and which brace you get depends on how far the disease has progressed.

Ankle-foot orthosis (AFO) / custom orthotic

A custom insert, a snug arch-and-heel cup for early stages, or a more rigid ankle-foot brace for advanced disease, supports the failing arch and stops the heel from drifting outward.

Physical therapy

Physical therapy focuses on strengthening the failing tendon with slow, controlled work and stretching the tight calf muscles that pull the heel outward.

Activity modification

Cut back on running, jumping, and long stretches of standing on hard surfaces; they all overload the failing tendon.

When Surgery Is on the Table

if non-operative care isn't enough

Surgery is for early-stage disease that has not responded to bracing and rehab, and for the more advanced stages where the arch has collapsed too far for braces alone to hold. The operation usually combines a tendon transfer (using a healthy nearby tendon to take over) with bony cuts that reshape the foot's alignment.

Frequently Asked

questions we hear in clinic

What is posterior tibial tendon dysfunction?

It is the gradual failure of a tendon that runs along the inside of your ankle and holds up the arch of your foot. As the tendon weakens, stretches out, and eventually tears through, the arch on the inside of your foot flattens, the heel angles outward, and the forefoot drifts toward the outside. That is why it is also called adult-acquired flatfoot.

What is the "too-many-toes sign"?

When the heel drifts outward and the forefoot turns out, looking at the foot from behind shows extra toes peeking out on the outside of the affected foot. It is one of the patterns that points toward this diagnosis.

Why can't I rise onto my tiptoes on that foot?

Rising onto your toes relies on the posterior tibial tendon. When the tendon is failing, you usually cannot rise onto your tiptoes at all on that side, or it is weak and painful. How well you can do this is one of the things your provider checks during the exam.

What imaging will I need?

Standing X-rays of the foot from three angles measure how much the arch has collapsed and how far the heel has drifted outward. An MRI shows how badly the tendon itself has degenerated. Your provider grades how far the condition has progressed, from early to advanced, and that stage guides treatment.

What is tried before surgery?

Most people start with non-operative care: a brace or custom orthotic to support the failing arch (a snug arch-and-heel cup for early stages, a more rigid ankle-foot brace for advanced disease), physical therapy to strengthen the tendon and stretch the tight calf, and cutting back on running, jumping, and long stretches of standing on hard surfaces.

When is surgery needed, and what does it involve?

Surgery is for early-stage disease that hasn't responded to bracing and rehab, and for the more advanced stages where the arch has collapsed too far for braces alone to hold. The operation usually combines a tendon transfer, using a healthy nearby tendon to take over, with bony cuts that reshape the foot's alignment.