Overview Painful progressive flatfoot, otherwise known as tibialis posterior tendonitis or adult-acquired flatfoot, refers to inflammation of the tendon of the tibialis posterior. This condition arises when the tendon becomes inflamed, stretched, or torn. Left untreated, it may lead to severe disability and chronic pain. People are predisposed to tibialis posterior tendonitis if they have flat feet or an abnormal attachment of the tendon to the bones in the midfoot. Causes Many health conditions can create a painful flatfoot, an injury to the ligaments in the foot can cause the joints to fall out of alignment. The ligaments support the bones and prevent them from moving. If the ligaments are torn, the foot will become flat and painful. This more commonly occurs in the middle of the foot (Lisfranc injury), but can also occur in the back of the foot. In addition to ligament injuries, fractures and dislocations of the bones in the midfoot can also lead to a flatfoot deformity. Symptoms Pain along the inside of the foot and ankle, where the tendon lies. This may or may not be associated with swelling in the area. Pain that is worse with activity. High-intensity or high-impact activities, such as running, can be very difficult. Some patients can have trouble walking or standing for a long time. Pain on the outside of the ankle. When the foot collapses, the heel bone may shift to a new position outwards. This can put pressure on the outside ankle bone. The same type of pain is found in arthritis in the back of the foot. Asymmetrical collapsing of the medial arch on the affected side. Diagnosis Diagnostic testing is often used to diagnose the condition and help determine the stage of the disease. The most common test done in the office setting are weightbearing X-rays of the foot and ankle. These assess joint alignment and osteoarthritis. If tendon tearing or rupture is suspected, the gold standard test would be MRI. The MRI is used to check the tendon, surrounding ligament structures and the midfoot and hindfoot joints. An MRI is essential if surgery is being considered. Non surgical Treatment Orthotic or anklebrace, Over-the-counter or custom shoe inserts to position the foot and relieve pain are the most common non-surgical treatment option. Custom orthotics are often suggested if the shape change of the foot is more severe. An ankle brace (either over-the-counter or custom made) is another option that will help to ease tendon tension and pain. Boot immobilization. A walking boot supports the tendon and allows it to heal. Activity modifications. Depending on what we find, we may recommend limiting high-impact activities, such as running, jumping or court sports, or switching out high-impact activities for low-impact options for a period of time. Ice and anti-inflammatory medications. These may be given as needed to decrease your symptoms. Surgical Treatment Flatfoot reconstruction (osteotomy). This is often recommended for flexible flatfoot condition. Flatfoot reconstruction involves cutting and shifting the heel bone into a more neutral position, transferring the tendon used to flex the lesser toes (all but the big toe) to strengthen the posterior tibial tendon, and lengthening the calf muscle. Fusion (also known as triple arthrodesis). Fusion involves fusing, or making stiff, three joints in the back of the foot the subtalar, talonavicular, and calcaneocuboid joints, to realign the foot and give it a more natural shape. Pins or screws hold the area in place until it heals. Fusion is often recommended for a rigid flatfoot deformity or evidence of arthritis. Both of these surgeries can provide excellent pain relief and correction.