Tibialis posterior tendon is the tendinous extension of the same muscle, extend from leg to middle of foot. Before reaching foot tendon passes behind medial malleolus (bony prominence at medial aspect of ankle) and then 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 heel lift off.

Tendon get degenerated due to different reason and makes it weak. It is a progressive disease so after initiation of tendon degeneration, it can progress through different stages, starting from simple synovitis around tendon to complete disruption of the tendon and its consequences. This results in weakness or total loss of tibialis posterior tendon function. This eventually cause collapse of foot arch and flat foot deformity. This condition is also called Adult Acquired Flat Foot. Depending on the natural course and progression this condition can be divided into three stage

Stage 1: Stage of synovitis, no deformity

Stage 2: Stage of tendon degeneration & elongation, flexible deformity

Stage 3: Stage of  tendon degeneration & rupture, fixed deformity

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. There is no exact cause but are different risk 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.

This condition passes through different phases and shows different set of presentation. 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.

If you feel pain and swelling at medial aspect of foot near instep or at behind the medial prominence of ankle associated with difficulty in standing, walking and heel raise, you should visit a specialist foot & ankle surgeon.

He will evaluate your clinical symptom to locate the source of pain and will confirm by local examination. Clinical evaluation is significant for diagnosis. He may also examine your foot for any deformity and weakness of the tendon. He will ask you to get weight bearing x-ray of your foot to quantify the deformity. MRI is required in early stage to confirm diagnosis as well as extent of tendon degeneration. Both x-ray and MRI is required for staging the disease for treatment planning.

Treatment depends on stage of the disease. In early stage treatment aimed to prevent the progression and consequence of the disease. In later stage deformity correction, improve foot function and pain relief are the goal. Both conservative and operative treatments are indicated with their advances and limitation.

Conservative treatment in early stage is aimed to symptomatic relief and offloading the diseased tendon with rest, icing, NSAIDs and arch support. In late stage heel stabilizing orthotics are used to maintain foot shape and improve its function. UCBL a specially designed orthotic for adult acquired flat feet is recommended. Local infiltration with PRP has also being tried with guarded result.

Recommendation of surgical treatments varies widely for different stage of disease depending on the treatment goal.

• Tendinosocpy and debridement in stage 1 disease
• Open tendon debridement and repair in stage 1 disease
• Open tendon debridement and repair augmented with calcaneal osteotomy in Stage 2 disease
• FHL tendon transfer with calcaneal osteotomy in stage 2 disease

Triple arthrodesis in stage 3 disease