Posterior tibial tendon dysfunction (PTTD), sometimes referred to as adult acquired flat foot deformity is a musculoskeletal condition whereby the tendon of the tibialis posterior becomes dysfunctional. The tibialis posterior muscle activates during gait to stabilise the arch of the foot and to help slow down and control pronation as the foot strikes the ground. Therefore, when the tendon becomes dysfunctional the arch of the foot is more likely to flatten and over pronation becomes more likely. When this occurs the foot becomes more unstable as the midfoot is subject to mechanical overloading, both from body weight and the contraction of the calf muscles which causes a powerful pronation moment. As a result of these abnormal stresses, ligaments and soft tissue structures in the foot can stretch and deform over time (acquire a flat foot).
Risk factors include pre-existing flat foot, age, obesity, female gender, sedentary lifestyle, diabetes high blood pressure, previous trauma and inflammatory diseases.
Stage 1: No deformity, Mild weakness (able to complete single leg heel raise)
Stage 2: Flexible flat foot deformity Significant weakness (difficulty to complete single leg heel raise)
Stage 3: Fixed flat foot deformity Complete inability to perform a single leg heel raise
Stage 4: Fixed flat foot with valgus (foot rolled in) position Arthritis of the Ankle
The aim of Orthotic treatments for PTTD is to decrease the patient’s pain, allow for increased activity and function, maintain a neutral foot and ankle position and prevent or postpone progression of deformity. Orthotics can be used successfully for a majority of PTTD patients.
Orthotic treatment choices for PTTD vary based on the clinical presentation, symptoms and patient activity level. Patients can be grouped into two categories: those with an acute presentation and those with chronic symptoms.
The photo on the right shows how an orthotic can be used to maintain the architechture of the foot and help to protect against it flattening.