• Emmeline Shih, SPT, CSCS


Tibialis posterior dysfunction is a common condition that can lead to an acquired flat foot deformity. The posterior tibialis is the primary dynamic stabilizer of the medial longitudinal arch which helps to invert and plantarflex the foot resulting in a “locking” of the midtarsal joints and helping the foot become a rigid lever for push off during the gait cycle. It also helps the gastrocnemius be more efficient. If there dysfunction to the posterior tibialis, the surrounding ligaments and capsules become weaker and increase in laxity which can lead to an acquired flat foot deformity and the overuse of foot intrinsics.


Common reasons for posterior tibialis dysfunction include overuse, trauma, flat foot, ligamentous laxity, high heels, lack of ankle/foot ROM and imbalance of lower extremity musculature. Typical patients presenting with posterior tibialis tendon dysfunction include novice runners/triathletes, women 40 or older and individuals with flat feet. Risk factors include diabetes mellitus, obesity and hypertension.


Individuals will report pain along the instep o