Posterior Tibial Tendon Dysfunction

What is it?

The posterior tibial tendon is a strong cord that joins a calf muscle to the bones of your foot. (A tendon is the tissue that links muscle to bone.) It runs behind the bony bump on the inside of your ankle, attaches under the sole of your foot and helps hold up your arch.

Posterior tibial tendon dysfunction (PTTD) happens when this tendon becomes strained, stretched or worn. It becomes painful and stops doing its job well. Over time the arch along the inside of your foot can get flatter.

PTTD is a common cause of adult acquired flatfoot, which means a foot that has become flat in adulthood. About 3 per cent of adults have an adult acquired flatfoot, though figures vary with how the condition is defined. It is usually described as a condition that gets worse over time if it isn't managed.

Who does it affect?

Anyone can get PTTD, but it is most common in women aged 40 and over. It is reported to be about 3 times more common in women than in men.

Most people who develop it already have flat feet. Other things linked with it are being overweight, high blood pressure, diabetes, rheumatoid arthritis and an earlier injury to the tendon.

Signs and symptoms

The usual first signs are pain and mild swelling along the tendon, behind the inner ankle bone. The pain may spread into the inside of the middle of your foot. It is often felt during activity and again after you have rested.

You may find that high-impact activity such as running becomes very hard. Some people have trouble walking or standing for a long time. Other signs can include warmth, redness or stiffness behind or under the inner ankle or along the arch.

As the condition goes on, your heel may roll inwards and your foot may look flatter. You might also notice pain on the outer side of your ankle as the foot collapses.

What causes it?

The tendon usually starts to wear before you notice any symptoms. It can then become inflamed, torn or worn out. Part of the tendon behind the inner ankle bone has a low blood supply, which may make it more prone to damage.

Extra strain on the tendon can cause tiny tears. Things that add strain include:

• flat feet, or feet that roll inwards a lot
• very flexible joints
• being overweight
• a sudden change in how hard or how long you exercise
• a change of shoes or equipment
• stiff or weak calf muscles

An injury to the tendon can also start it. Flat feet and a poorly working tendon seem to feed into each other: each can make the other worse.

How is it diagnosed?

Your podiatrist will ask about your pain, your activity, your shoes and your health. They will look at your arch, heel and forefoot while you stand. They will feel along the tendon behind your inner ankle bone and ask you to rise up on the toes of one leg (a single leg heel raise).

In the early stage, the main signs are tenderness, pain and swelling around the tendon. In the next stage, the arch has flattened but the foot can still be moved back into shape, and a single leg heel raise is difficult. Your podiatrist will also check whether your foot is still flexible or has become stiff, because that changes the advice you are given.

Other conditions can look similar or happen alongside it. These include inflammatory arthritis, nerve and muscle conditions, and tendon problems after an ankle fracture. Flatfoot caused by rheumatoid arthritis may not respond to treatment in the same way, so your podiatrist will ask about your health history and any past ankle injuries.

Treatment

Care usually starts without surgery. The best results are for people in the early and middle stages.

Looking after it at home

Wear the orthoses or supportive insoles your podiatrist gives you, and do the exercises they set. Short-term rest helps the tendon settle in the early stages, so ease off activities that bring on the pain. Avoid sudden jumps in how hard or how long you exercise.

Treatment from your podiatrist

Orthoses are the main treatment. Orthoses made for you, with support under the inside of the arch, reduce pain more than flat insoles or standard treatment in the early and middle stages. They take some of the force off the tendon and give it time to heal.

Exercise alongside orthoses seems to improve the results. Which exercises work best isn't yet clear, but regular check-ups with your podiatrist are better than going it alone.

If the tendon is very sore in the early stage, your podiatrist may suggest a short time in a walking boot or cast to rest it. A walking boot causes less muscle wasting than a plaster cast.

Other options

Injections aren't recommended for this problem. A steroid injection beside the tendon on the inner side can make it tear (rupture). A steroid injection might be considered if you also have an inflammatory condition such as rheumatoid arthritis, but it is unlikely to be used first.

Surgery

If home care and treatment from your podiatrist haven't worked, your podiatrist can refer you to a foot and ankle surgeon. This is for the surgeon's opinion, not a promise of an operation. Before you are referred, your podiatrist will check the blood flow in your foot, including your pulses, because it matters for any surgery.

If the tendon is left untreated it can tear and may then need surgery.

Recovery

The outlook is better when PTTD is found and treated early. Orthoses can ease pain, and exercise alongside them seems to help further. How long recovery takes varies, and no set timeframe has been shown.

Left untreated, the arch can keep flattening until the foot becomes stiff and can't be moved back into shape. Painful arthritis can then develop, with stiffness and pain at rest or at night, and walking is much harder. A foot that has stiffened or is getting worse should be seen by a foot and ankle surgeon.

Preventing it

The tendon often wears for a long time before you feel it, so catching it early matters. See your podiatrist about new pain on the inside of your ankle or arch rather than waiting.

You can't change every risk factor, but some of the strains linked with PTTD are within your control. These include sudden increases in exercise, a sudden change of shoes, stiff or weak calf muscles and extra weight. If you already have flat feet, or have diabetes, high blood pressure or rheumatoid arthritis, ask your podiatrist to check your feet.

When to see a podiatrist

Book an appointment if

You have new pain or swelling on the inside of your ankle or arch, your arch seems to be getting flatter, your heel is rolling inwards, or home care and insoles haven't helped.

Seek prompt assessment if

Call your local emergency number if your foot or leg suddenly turns cold and pale or blue, with pain or numbness, or if you suddenly can't move your leg or foot. Also call if you have a foot infection and feel very unwell, with confusion or slurred speech, severe shivering or muscle pain, severe breathlessness, mottled or discoloured skin, or little or no urine, as this could be sepsis. Go to the nearest emergency department if your ankle or foot is at an odd angle after an injury.

See your GP or another doctor today if you have: sudden pain with a pop or snap; a new significant injury to your leg, foot or ankle; a new flat foot after an injury; or a foot or ankle you can't put weight on (avoid putting weight on it until it has been examined). See a doctor today too if your foot is red, hot and swollen, especially if you have diabetes, as a Charcot foot (a serious foot problem linked to diabetes) can look like this. The same goes for significant swelling, or a change in colour or temperature, in your foot or ankle or going up your leg. Also see a doctor today if you have a high temperature, feel hot and shivery or unwell, or have night sweats that are out of the ordinary, as these can be signs of infection. If your GP can't see you today, go to an urgent care clinic or an after-hours GP.

See your GP soon if: your foot pain keeps you awake at night or hurts at rest, especially if your foot has become stiff and flat; your foot shape is getting worse; you have a lump in your foot or ankle; you have lost weight and can't explain why; or you are under 16 and have new or worsening symptoms.

Frequently asked questions

Is PTTD the same as adult acquired flatfoot?

They are closely linked and often describe the same condition. PTTD means the tendon is painful and not working well. Adult acquired flatfoot is a wider term for a foot that has flattened in adulthood. You may also hear tibialis posterior tendon dysfunction, or progressive collapsing foot deformity, which is a newer name.

Can it come back after it settles?

It isn't yet clear how often PTTD returns. It also isn't clear whether footwear, exercise or weight loss stop it coming back. If your inner ankle or arch pain returns, or your arch seems to be flattening again, book an appointment with your podiatrist early.

Further reading

• Tibialis posterior tendinopathy - My Joint Health Hub NHS
• Posterior tibialis tendon dysfunction (PTTD) NHS
• Surgery to repair / reconstruct the tibialis posterior tendon NHS
• Tibialis posterior tendon dysfunction or insufficiency or adult acquired flat foot deformity NHS
• A Patient's guide to Adult Acquired Flatfoot Deformity Tibialis Posterior Tendon Dysfunction :: Royal National Orthopaedic Hospital NHS