Flat foot is a pretty common condition of the foot, but most of the time simply having a lower arch or flatter foot is not necessarily a problem. What is a problem is if it is progressive and becomes painful, then it is known as posterior tibial tendon dysfunction or adult acquired flatfoot. In these cases the arch of the foot becomes progressivly lower and the heel rolls inwards. This is usually accompanied with pain in the arch of the foot and in the ankle region. Those with this also find walking is a lot harder and walking consumes a lot of energy leading to a lot of fatigue.
The cause of posterior tibial tendon dysfunction is not totally clear, but it is a problem in which the posterior tibial tendon and muscle can not just do the job that it is designed for. The primary role of the posterior tibial tendon is to hold up the arch of the foot and stop the heel rolling inwards. For some reason the muscle and tendon complex can not just do their job any more, leading to the progressive nature of this problem.
The treatment of posterior tibial tendon dysfunction is somewhat urgent and needs to be addressed as early as it possibly can. This is because the condition is progressive and it will reach a stage where conservative measures do not work and surgery is the only option. While the surgical outcomes are generally satisfactory, they do involve the fusion of some joints to prevent the condition getting worse, that does have some long term limitations on gait and function, so is best avoided. To avoid the surgical intervention, treatments needs to be started early. This will involve foot orthotics that are very supportive and angle the foot back in the right direction. Exercises are also recommended, but should never be used instead of foot orthotics, as they are crucial to stop this problem from progressing.