This is the most common cause of the adult flat foot. This occurs when one or both arches collapse. The posterior tibial tendon starts in the calf, stretches down behind the inside of the ankle and attaches to bones in the middle of the foot. This tendon helps hold your arch up and provides support as you step off on your toes when walking. This tendons primary function is to decelerate the inside arch of the foot from rolling in too much. If it becomes inflamed, over-stretched or torn, you may experience pain on the inner ankle and gradually lose the inner arch on the bottom of your foot, leading to flatfoot.

Signs and symptoms of posterior tibial tendon dysfunction include:

• Gradually developing pain on the outer side of the ankle or foot.

• Loss of the arch and the development of a flatfoot.

• Pain and swelling on the inside of the ankle.

• Tenderness over the midfoot, especially when under stress during activity.

• Weakness and an inability to stand on the toes.

• The forefoot, or front part of the foot may point away from the rear part of the foot and leg, and this may go from a flexible condition to a fixed or rigid position.

Diabetics, overweight, and patients with arthritis people are particularly at risk.

Left untreated, posterior tibial tendon dysfunction could lead to arthritis in the hind foot. Pain could increases and spread to the outer side of the ankle.

Treatment includes rest, over-the-counter nonsteroidal anti-inflammatory drugs, and immobilization of the foot for 6 to 8 weeks with a rigid below-knee cast or boot to prevent overuse. In more severe conditions,, a brace from the leg to the foot may be necessary. Surgery is often the last resort but can help reestablish a normal foot position and prevent a crippling deformity from occuring.