If you have flat feet, you have lots of company: around 25 percent of Americans have pes planus, the medical term for flat feet, according to Dr. Bruce Sangeorzan of the University of Washington. For most people, flat feet cause no symptoms other than wearing out their shoes faster on the inner side of the sole. You can inherit flat feet or develop them in adulthood. Damage to the posterior tibial tendon in the lower part of the leg can cause flat feet and pain in the lower part of the leg, above the arch of the foot.
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Function of the Posterior Tibial Tendon
Adult-acquired flatfoot generally occurs as a result of damage to the posterior tibial tendon, which helps hold up the arch of the foot. The tendon attaches to the calf muscle in the lower part of your leg, running down towards the ankle and then curving in to attach to the navicular bone, located in the middle of the inner aspect of the foot. When you walk, the tendon pulls up on the navicular bone, which helps form the arch of the foot.
Damage to the Tendon
When you damage the posterior tibial tendon, it stretches and sags, which allows the navicular bone to move out of position. Many factors can affect the tendon. Being overweight, overuse or repetitive stress, trauma or degeneration over time can all cause damage to the tendon. Symptoms most often occur in middle-aged or older adults. Diseases such as diabetes and high blood pressure also increase your risk. Steroid injections in the area can also weaken the tendon. As small or large tears appear in the tendon, inflammation develops as your body attempts to heal the area.
Inflammation in the posterior tibial tendon causes pain that goes from your foot up your lower leg along the tendon. You might feel pain behind the ankle bone or higher up on your leg. In some cases, your leg might swell along the tendon. The pain in the tendon might change your gait ---the way you walk. Your foot may roll inward, or pronate, when you walk. This puts more strain on other parts of your leg, including your hip and knee, which can lead to pain in those areas.
Most doctors start with conservative treatment to heal a damaged posterior tibial tendon, using rest, ice, compression, elevation and non-steroidal anti-inflammatory medications to reduce swelling and inflammation and allow the tendon to repair itself. A temporary walking cast gives the area time to heal without inflicting more damage. Custom orthotics that fit in your shoe can help correct your gait by mechanically holding up your foot in a normal arch pattern. Physical therapy can also help strengthen the damaged tendon. If you have a severe tear in the tendon, you might need surgical repair.