Tibialis Posterior Tendon Dysfunction

The foot is one of the most complicated and important areas of the body in regards to alignment of its twenty-eight bones. It is through the foot and ankle that the weight of the body, and sometimes as much as five times body weight when exercising, must be transmitted from a vertical position in the leg, to a horizontal position in the foot.

This is carried out though a number of very complicated motions through the foot that allows the quick yet gradual reduction of force. It is these motions that allow us to ambulate gracefully, and not as though we were walking on two concrete blocks.

When the foot fails to function in correct alignment, other areas of the foot and/or leg take on more stress and strain, resulting in severe pain and sometimes deformity.

Ideally, the heel bone should be aligned directly beneath the leg. The weight of the body is transmitted through the joints of the body, beginning with the heel bone, as this is the bone which first strikes the ground. The muscles and tendons act as levers, allowing fluid motion of the bones to which they attach.

In some individuals, either due to genetics, injury, overweight, or improperly fitting shoes, the heel bone can be aligned in a way that prohibits the fluid transmission of force through the foot and leg. This is experienced in a number of ways, including pain and/or swelling in the inside area of the arch or ankle, severe chronic leg fatigue or pain, pain directly beneath the outside (side of the little toe) ankle bone, pain with prolonged walking or standing, progressive loss of arch height, and/or inability to maintain a walking distance that was once easily maintained, or an inability to keep up with peers of equal fitness.

When the heel bone becomes malaligned, the soft tissues (ligaments and tendons) on each side of the foot and ankle begin to lose their primary function of pulleys allowing motion of the bones, and carry on a function of support. The entire weight of the body including the transmission of the force of walking is then carried through these tissues, resulting in pain and degeneration of these areas.

One tendon of particular importance is that of the tibialis posterior tendon. The muscle to which the tendon is attached begins in the deep back portion of the leg below the knee, and forms a tendon just above the ankle. It stops, or inserts, into the hard nodular bone just below and distal to the inside (side of the big toe) ankle bone at the top of the arch. This muscle functions to maintain the height of the arch and assist in pushing off the balls of the toes. It is this tendon that carries the large majority of stress and strain when the heel bone becomes out of align, and often times will give out. Gravity pushes the weight of the body down while the tendon desperately tries to keep the arch up.

Alignment of the knees also contributes to the development of this problem. People (most commonly female) who are "knock kneed", technically called genu valgum, where the knees area angled in towards each other, are especially prone to developing arch problems. The position of the knees causes the center of gravity to fall closer to the center of the body as opposed to over the heels. This can be illustrated by standing with the knees touching and dropping a pencil from the knee cap to the floor. The pencil usually will not hit the foot in individuals who are knock-kneed, illustrating the tendency of the body weight to fall in this fashion as well.

Diagnosis of tibialis posterior tendon dysfunction (TPD) involves a combination of clinical pain while pushing on specific areas of the foot and leg, observation of the foot and leg while standing and walking, and observation of the foot while performing specific tests. Pain is most often encountered while pushing along the course of the tendon beginning from behind the inside ankle bone and coursing in a straight line toward the big toe, ending at the previously mentioned nodule of bone. There is often swelling and occasionally redness in the area as well. There can also be pain in the front of the inside ankle bone, as well as pain directly beneath the outside ankle bone.

In addition, while having the patient face away from you, examine the alignment of the heel to the leg. A relatively straight line should be able to be drawn from the ground, up the back of the heel, and up the leg. With the patient sitting, hold the foot by the heel. With the opposite hand, push up under the ball of the little toe until the ankle is 90o to the leg, as when standing. A straight line should be able to be drawn from the shin of the leg out the ball of the second toe. Patients with TPD often result with the line from the shin ending far inside of the big toe.

Finally, with the patient's back to you, ask them to stand on the balls of both feet. Then ask them to stand on the balls of one foot at a time with the opposite foot picked entirely off of the ground. Patients with TPD will often have pain if not a complete inability to perform either of these maneuvers.

So what can be done for this problem? The absolute WORSE thing to do if pain is experienced in this area is to take a pain medication to mask the pain. The second WORSE thing to do is to have this area injected with a steroid. A steroid acts to reduce inflammation but it also temporarily puts cells to sleep. This can greatly increase the potential for this tendon to rupture should the deformity still be present after a steroid injection.

Treatment options are all geared at reducing the strain on this tendon, primarily by externally supporting the arch. In addition to oral anti-inflammatory medication, some type of external support in the arch is crucial. This can include a rudimentary arch pad, orthotics, or a cast. In some cases, depending on the severity of the condition, surgery is required to reduce the deformity.

If the condition is left untreated, the pain and flatfoot deformity is likely to get worse. Eventually, degenerative changes occur in the joints of the rear portion of the foot, and pain will likely begin in this area, should this develop.

By and large, a thorough evaluation and aggressive, conservative treatment is the key to treating this often debilitating problem.

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