Flat foot is quite a common problem of the foot, but most of the time merely having a lower mid-foot (arch) or flatter foot is not always a problem. What is a concern is if it is progressive and becomes painful, then it's called posterior tibial tendon dysfunction or adult acquired flatfoot. In such cases the arch of the foot becomes progressively flatter and the rearfoot rolls inwards. This is usually accompanied with pain in the arch of the foot and in the ankle area. Those with this also find walking is a lot more difficult and walking consumes a lot of energy leading to a lot of fatigue.The cause of posterior tibial tendon dysfunction is not really totally, but it is an issue where the posterior tibial tendon and muscle can't just do the task that it is designed for. The main role of the posterior tibial tendon is to support the arch of the foot and prevent the heel rolling inwards. For some reason the muscle and tendon unit can't just do their job any more, resulting in the progressive nature of this condition.
The management of posterior tibial tendon dysfunction is sort of urgent and really should be dealt with as early as it possibly can. This is because the disorder is progressive and it will reach a stage where conservative measures don't work and surgery is the only alternative. While the surgical outcomes are usually acceptable, they do consist of the fusion of some joints to prevent the condition getting worse, that comes with some long term limitations on gait and function, so is best avoided. In order to avoid the surgical treatment, treatments should be started early. This will likely consist of foot supports that are really supportive and angle the foot back in the right position. Exercises are also encouraged, but should never be used instead of foot orthotics, as they are critical to stop the flat foot from getting worse.