What is PTTD?
Posterior tibial tendon dysfunction is an inflammation and/or overstretching of the posterior tibial tendon, which helps support the arch. PTTD interferes with the tendon's job, which often results in a flattening of the foot.

Symptoms of PTTD
Initial symptoms of PTTD may include pain, swelling, flattening of the arch, and an inward rolling of the ankle. PTTD is a progressive condition, however, and as it gets worse, symptoms will likely change.

• As the arch begins to flatten, there might still be pain on the inside of the foot and ankle. At this point, though, the foot begins to turn outward, and the ankle rolls inward.
• As the condition advances, the arch continues to flatten and the pain usually moves to the outside of the foot, below the ankle. At this point, the tendon has deteriorated significantly and arthritis has likely developed in the the foot, or in more severe cases, the ankle.

Causes of PTTD
Overuse is the common cause of PTTD, with symptoms usually occurring after running, walking, hiking, or climbing stairs.

The first image shows the position of the posterior tibial tendon, while the second demonstrates how the foot's position shifts while in the intermediate and advanced stages.