The posterior tibialis muscle originates on the bones of the leg (tibia and fibula). This muscle then passes behind the medial (inside) aspect of the ankle and attaches to the medial midfoot as the posterior tibial tendon. The posterior tibial tendon serves to invert (roll inward) the foot and maintain the arch of the foot. This tendon plays a central role in maintaining the normal alignment of the foot and also in enabling normal gait (walking). In addition to tendons running across the ankle and foot joints, a number of ligaments span and stabilize these joints. The ligaments at the medial ankle can become stretched and contribute to the progressive flattening of the arch. Several muscles and tendons around the ankle and foot act to counter-balance the action of the posterior tibial tendon. Under normal circumstances, the result is a balanced ankle and foot with normal motion. When the posterior tibial tendon fails, the other muscles and tendons become relatively over-powering. These muscles then contribute to the progressive deformity seen with this disorder.
Flat feet causes greater pressure on the posterior tibial tendon than normal. As the person with flat feet ages, the muscles, tendons and ligaments weaken. Blood supplies diminish as arteries narrow. These conditions are magnified for obese patients because of their increased weight and atherosclerosis. Finally, the tendon gives out or tears. Most of the time, this is a slow process. Once the posterior tibial tendon and ligaments stretch, body weight causes the bones of the arch to move out of position. The foot rotates inward (pronation), the heel bone is tilted to the inside, and the arch appears collapsed. In some cases, the deformity progresses until the foot dislocates outward from the ankle joint.
Not everyone with adult flatfoot has problems with pain. Those who do usually experience it around the ankle or in the heel. The pain is usually worse with activity, like walking or standing for extended periods. Sometimes, if the condition develops from arthritis in the foot, bony spurs along the top and side of the foot develop and make wearing shoes more painful. Diabetic patients need to watch for swelling or large lumps in the feet, as they may not notice any pain. They are also at higher risk for developing significant deformities from their flatfoot.
There are four stages of adult-acquired flatfoot deformity (AAFD). The severity of the deformity determines your stage. For example, Stage I means there is a flatfoot position but without deformity. Pain and swelling from tendinitis is common in this stage. Stage II there is a change in the foot alignment. This means a deformity is starting to develop. The physician can still move the bones back into place manually (passively). Stage III adult-acquired flatfoot deformity (AAFD) tells us there is a fixed deformity. This means the ankle is stiff or rigid and doesn???t move beyond a neutral (midline) position. Stage IV is characterized by deformity in the foot and the ankle. The deformity may be flexible or fixed. The joints often show signs of degenerative joint disease (arthritis).
Non surgical Treatment
Non-surgical treatment includes rest and reducing your activity until the pain improves. Orthotics or bracing help support the tendon to reduce its pull along the arch, thus reducing pain. In moderate to severe cases, a below knee cast or walking boot may be needed to allow the tendon to rest completely and heal. Physical therapy is an integral part of the non-surgical treatment regimen to reduce inflammation and pain. Anti-inflammatory medication is often used as well. Many times evaluation of your current shoes is necessary to ensure you are wearing appropriate shoe gear to prevent re-injury.
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.