Posterior Tibial Tendon Dysfunction (Adult Flatfoot)
Posterior tibial tendon dysfunction (PTTD) is the most common cause of a flat foot that develops in adulthood. Caught early, it usually responds well to non-surgical care.
What PTTD is
The posterior tibial tendon runs behind the inner ankle bone and helps hold up the arch. When it becomes inflamed, stretched or torn, the arch gradually collapses — producing what doctors call adult-acquired flatfoot. It is more common in women, in people over 40, and in those with obesity, diabetes or high blood pressure.
Symptoms
- Pain and swelling along the inner ankle and arch
- An arch that is flattening, often in one foot first
- The heel drifting outward and "too many toes" visible from behind
- Difficulty doing a single-leg heel raise on the affected side
- Pain that worsens with activity and standing
The stages
Clinicians describe PTTD in stages. Early on the tendon is inflamed but the foot still moves normally and the flatfoot is flexible. As it progresses the deformity becomes fixed and the hindfoot stiffer, and in late stages the ankle joint can be affected. Earlier stages respond far better to non-surgical care, which is why prompt assessment matters.
Treatment
Early treatment focuses on offloading the tendon: rest from aggravating activity, supportive shoes, custom orthotics or an arch-supporting brace, and a course of strengthening exercises guided by a physiotherapist. A walking boot may settle a painful flare. When the deformity is fixed or non-surgical care fails, reconstructive surgery is considered.
When to see a professional
See a podiatrist or orthopaedic specialist if one arch is flattening, the inner ankle aches and swells, or you cannot rise onto your toes on one foot. Early diagnosis can prevent a flexible, treatable flatfoot from becoming a rigid one.
Frequently asked questions
- Is PTTD the same as flat feet?
- Not quite. Many people have lifelong flat feet without problems. PTTD is a flatfoot that develops in adulthood because the supporting tendon is failing, and it tends to be painful and progressive.
- Can PTTD be treated without surgery?
- Yes, especially in the early, flexible stages — with orthotics, bracing, supportive shoes and strengthening. Surgery is reserved for advanced or unresponsive cases.
- What is the single-leg heel raise test?
- Standing on the affected foot and trying to rise onto your toes. Difficulty or pain doing so is a classic sign of posterior tibial tendon dysfunction.
Sources & further reading
- Posterior tibial tendon dysfunction, orthoinfo.aaos.org
- Acquired flatfoot deformity, www.mayoclinic.org
- Adult flat foot, www.apma.org