Tibialis posterior tendon is the tendinous extension of the same muscle, which originates at back of leg. This tendon passes behind medial malleolus (bony prominence at medial aspect of ankle) and attached to the navicular bone (near instep of foot inner aspect) of midfoot. Its main function is to maintain the medial foot arch (inner longitudinal curve) and stabilize heel with midfoot during push off phase or fore foot weight baring during walking and thus prevents collapse of mid foot and also helps calf muscle to exert its puss off force while walking.
Blood supply of tibialis posterior tendon near medial malleolus area is precarious and is prone to degeneration in individuals in whom the tendon is overloaded. Degenerated tendon become weak and also may get torn. This results in weakness or total loss of tibialis posterior tendon function. This can result in collapse of foot arch and flat foot deformity, difficulty in heel raise and standing, walking. After initiation of tendon degeneration, it can progress through different stages, starting from simple synovitis around tendon to complete disruption of the tendon ending with degenerative fixed deformity of foot.
There is no exact cause but are different co existing factors are associated with the incidence of tibialis posterior tendon dysfunction. Usually fatty female of 4rth decade are more commonly affected. Presence of DM and HTN also increases the incidence. Presence of congenital flat foot deformity and traumatic mid foot injury can also cause tibialis tendon dysfunction.
During the initial period of tendon degeneration, it presents with pain and swelling behind medial malleolus, difficulty in walking, standing and push off. Gradually foot shape starts changing, its arch start collapsing as tendon starts get elongation and weak and finally following rupture of the tendon arch collapses completely. Although foot remains flexible and its arch can be recreated at this stage but with time all the joints around hindfoot and midfoot get degenerated and deformity gets fixed
Treatment of tibialis posterior tendon dysfunction mostly conservative with foot orthosis and physical rehabilitation during the initial phase of the disease. Although role of surgical intervention at this stage cannot be ignored. Surgical treatment at initial stages are aimed to prevent progression of disease and improve function of foot. In late stage with painful fixed deformed foot, surgical treatment is the only reasonable option.
