The posterior tibial tendon is the terminus of the posterior tibial muscle. This tendon is one of the main supporting structures for the arch of the foot. When the tendon’s function is impaired, its ability to support the arch becomes compromised which can result in a flattening of the foot. This is also called “adult acquired flatfoot.”
The posterior tibial tendon is usually damaged from overuse. Often the symptoms occur in situations that demand function of the tendon (ex. Walking, running, jogging, etc).
Your flatfoot would be evaluated to determine causes for the condition. This would incorporate taking an inventory of muscle strength, obtaining a through history of symptoms, and assessing for the severity of the condition. X-rays are typically ordered to evaluate the arch and the integrity of the joints. An MRI can be helpful at times to look at the posterior tibial tendon in more detail.