Posterior tibial tendon dysfunction

What is posterior tibial tendon dysfunction, and how common is it?

Posterior tibial tendon dysfunction (PTTD) is a painful, strained tendon on the inside of your ankle. The tibialis posterior tendon runs behind the inside ankle bone, attaches under the sole of your foot and helps hold your arch up¹. When it's strained it causes pain and inflammation, and over time the arch along the inside of your foot becomes flatter². That's why PTTD is a common cause of adult acquired flatfoot (a flat foot that develops in adulthood)³. You may also see it called tibialis posterior tendinopathy.

Adult acquired flatfoot affects about 3% of adults⁴. PTTD is usually thought of as a condition that progresses, though how it plays out over time isn't fully known³.

What causes it, and who gets it?

It most often starts when the tendon wears down and becomes inflamed or torn⁵. Extra load on the tendon can cause tiny tears. Examples are flat feet or feet that roll inwards, very flexible joints, being overweight, a sudden change in exercise, a change of shoes, and stiff or weak calf muscles⁶.

Most people who develop it already have flat feet⁷. Anyone can get it, but it's common in women over 40², and it's reported as about 3 times more common in females⁸. High blood pressure, obesity, diabetes, rheumatoid arthritis and a past injury to the tendon are also listed as risk factors⁵. These are links rather than proven causes, so having one doesn't mean you'll develop it.

What does it feel like, and how is it diagnosed?

You'll typically feel pain and mild swelling along the tendon behind your inner ankle bone, sometimes spreading into the inner arch. It's usually felt during activity and after rest⁵. Running or other high-impact activity can become very difficult, and some people find long periods of walking or standing hard⁹. Later, the heel can roll inwards, the foot looks flatter and you may notice a 'too many toes' sign⁶. As the foot collapses, pain can also appear on the outside of the ankle⁹.

Diagnosis is based on an examination. A podiatrist or doctor will look at your standing arch and heel, press along the tendon and ask you to rise onto your toes on one leg. Tenderness, pain and swelling around the tendon point to early disease. Difficulty with that single-leg heel raise, with a flexible flatfoot, points to a later stage¹⁰. A flat foot caused by rheumatoid arthritis may not respond to treatment in the same way, which is one reason a proper examination matters¹⁰.

What helps first?

Supportive insoles or orthoses (shoe inserts made to support the arch) are the core of first-line care. Personalised arch-support orthoses eased pain more than flat insoles in early-stage disease, and adding exercise seemed to improve the effect¹¹. They also reduce forces on the tendon². How much they help, and which exercises work best, isn't clear yet¹¹, so it helps to have a podiatrist guide you and review progress.

For a painful early-stage tendon, a short period in a boot or cast lets it rest².

Injections into the tendon aren't recommended¹². Injecting the inner side of the tendon carries a major risk of it rupturing¹³. A steroid injection is unlikely to be a first choice unless the problem is linked to an inflammatory condition⁸.

What helps if that isn't enough?

If self-management and first-line care haven't settled it, your podiatrist or GP can refer you to an orthopaedic foot and ankle surgeon⁵. A referral is for an opinion. It isn't a promise that surgery is the right option⁸. It helps to note what you've tried, for how long and what happened, so the referral is clear.

How long does it take to settle, and can it come back?

How long recovery takes isn't clear yet, and no best way to stop it returning has been shown, whether footwear, exercise or weight loss. What is clear is that early care is worthwhile. Left unmanaged, the condition can lead to a fixed flatfoot⁵. As it progresses, painful arthritis, stiffness and pain at rest or at night can develop, and the foot shape can no longer be corrected¹³. Untreated, the tendon can also rupture and need surgery⁶.

Having new inner ankle or arch pain checked early, and reviewed over time, is a sensible step. Keep an eye out for an arch that's becoming less flexible, new night or rest pain, or a foot shape that's getting worse.