Tibialis posterior tendinosis is wear and tear of the tendon that passes behind and around the inner side of the ankle (tibialis posterior tendon).

The tibialis posterior tendon helps to maintain the normal arch of the foot. The usual cause of tibialis posterior tendinosis is an excessive ongoing strain caused by a problem with the way the ankle moves. Most often, the person has a low arch, and the foot tends to turn outward when walking, often because the person is overweight. Tendon dysfunction may further contribute to flattening of the arch. The tendon may tear completely, sometimes suddenly in a young person.

Early on, people have occasional pain behind the inner ankle. In time, the pain becomes severe, and swelling occurs. Normal standing and walking become more difficult. Standing on the toes is usually painful and may be impossible if the tendon is completely torn.

Doctors can often base the diagnosis on the person's symptoms and the results of an examination. However, sometimes magnetic resonance imaging (MRI) is necessary to confirm the diagnosis and to see the extent of tendon damage.

Devices placed in the shoe (orthoses) and ankle braces worn with supportive shoes or boots are usually sufficient. Complete rupture may require surgery for a person to regain normal function. Surgery is especially important in young active people with tears that develop suddenly.

Last full review/revision December 2012 by Kendrick Alan Whitney, DPM