The dysfunction and function of the mid-foot ( arch ) of the foot is critical to normal walking and as well as running gait and biomechanics. The support of the arch of the foot is looked after by a number of things, for example the shape of the bones, the ligaments, the muscles and the plantar fascia. One of several crucial muscles in the dynamic stability of the arch of the feet are the posterior tibial muscle. This is a powerful muscle that is in the lower leg. The tendon of this muscle passes down the inside of the ankle joint and attaches below the bones that make up the mid-part of the arch of the feet, so this particular muscle is so important for stabilizing the arch. In some people, this muscle seems to lose it ability to support the foot, resulting in a condition known as Posterior tibial tendon dysfunction or adult acquired flat foot.
This condition usually starts off with a moderate discomfort in the midfoot or medial side of the ankle joint and the arch of the foot gradually collapses and the rearfoot rolls inwards (pronates). This is all due to the muscle not being able to do its job properly. If treatment is not started, then the pain and disability gets worse. In its end stages it usually is quite disabling and painful. It eventually has a significant impact on quality of life and the ability to walk. It is quite fatiguing because so much energy is necessary to walk with posterior tibial tendon dysfunction.
Since the long term consequences of this problem may be so debilitating, it is crucial that it must be detected as early as possible and therapy started. The longer the delay the harder it is to treat. In the early phases, the only real adequate treatment usually are quite hard or stiff foot orthotics. Weather resistant be firm as the forces that are lowering the feet are so great that they need to be countered. A softer orthotic will do nothing. A high top hiking or basketball type shoe or sneaker is also useful at stabilising the rearfoot. If this isn't adequate then more complex ankle supports will be the next step. If this fails or the therapy is started too late, then surgical intervention is actually the only suitable treatment at this late stage.