A tendon is tissue that connects muscle to bone and lies across joints, providing the ability to bend and slightly rotate joints. The tibia is the larger of the two bones of the lower leg, the one that can easily be palpated from the kneecap downward. "Posterior" refers to the back of the body or to a body part located on the backside of the body in the anatomical position. The posterior tibial tendon is the tissue that attaches to muscle in the calf of the lower leg, passes down on the back side of a bone called the medial malleolus, which is the round, bony knot or protrusion on the inside of the ankle, and attaches to the navicular bone in the foot. This bone is located closer to the heel than the toes.
Among the functions of the posterior tibial tendon are to maintain the navicular bone in its proper position, to keep the arch up and to support a person when he or she is stepping off onto his or her toes during walking. The posterior tibial tendon can become stretched, torn and inflamed as a result of trauma to the lower leg or ankle and as a result of diseases and health conditions. One of the most common symptoms of a problem with the posterior tibial tendon is pain in the inner ankle and discomfort when walking. Signs of problems with this tendon almost always include the gradual disappearance of the inner arch on the bottom of the affected foot. A condition known as flat foot occurs when the natural arch is lost because of a problem with the posterior tibial tendon.
Another conditions that can affect the posterior tibial tendon is posterior tibial tendinitis, which is inflammation of the tissue. The condition can quickly cause microscopic tears that further weaken the structure leading to stretching and more tearing until the complete collapse of the arch results. People who suspect that they might be suffering from a problem with the posterior tibial tendon might actually be able to see physical signs that indicate malfunction. For example, when standing behind someone who has developed a condition with this structure, sometimes the fourth and fifth toes on the foot affected by a problem with this tendon can be viewed, but the foot without such a problem will not show these toes.
There are specific groups of people who tend to run a higher risk of suffering from problems with the posterior tibial tendon. They include females older than 50, obese people, diabetics, people who have high blood pressure and individuals who have inflammatory diseases such as rheumatoid arthritis. Others who might be prone to problems with the tendon are people who use local steroid injections and those who have had injuries or surgery on the lower leg.