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.
In many cases, adult flatfoot causes no pain or problems. In others, pain may be severe. Many people experience aching pain in the heel and arch and swelling along the inner side of the foot.
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
Initial treatment is based on the degree of deformity and flexibility at initial presentation. Conservative treatment includes orthotics or ankle foot orthoses (AFO) to support the posterior tibial
tendon (PT) and the longitudinal arch, anti-inflammatories to help reduce pain and inflammation, activity modification which may include immobilization of the foot and physical therapy to help
strengthen and rehabilitate the tendon.
For more chronic flatfoot pain, surgical intervention may be the best option. Barring other serious medical ailments, surgery is a good alternative for patients with a serious problem. There are two
surgical options depending on a person?s physical condition, age and lifestyle. The first type of surgery involves repair of the PTT by transferring of a nearby tendon to help re-establish an arch
and straighten out the foot. After this surgery, patients wear a non-weight bearing support boot for four to six weeks. The other surgery involves fusing of two or three bones in the hind foot below
the ankle. While providing significant pain relief, this option does take away some hind foot side-to-side motion. Following surgery, patients are in a cast for three months. Surgery is an effective
treatment to address adult-acquired flatfoot, but it can sometimes be avoided if foot issues are resolved early. That is why it is so important to seek help right away if you are feeling ankle pain.
But perhaps the best way to keep from becoming flatfooted is to avoid the risk factors altogether. This means keeping your blood pressure, weight and diabetes in check.