Posterior Tibial Tendon Tear/Adult Aquired

What is it?

A flat foot, or pes plano valgus, is a deformity that involves the arch of the foot. Patients will often present with a flattening and collapsing of the arch of the one foot only on the involved side of tendon tear. There is too much motion in the joints of the foot (mainly the subtalar joint) leading to the foot collapsing over time. The motion in the joints that move the foot from a higher arch to a lower arch is called pronation. Those patients that have too much motion in the direction of the arch falling have too much pronation motion that leads to a flat foot. The heel bone (calcaneus) will rotate on the joint and point outwards (valgus). Over time arthritis in the joints can develop due to the excessive motions and strain through the foot and ankle. Some patients have a fixed rigid flat foot that has no motion. These are more complicated and more painful situations. Not all patients with flat feet have pain or dysfunction. Not all patients with flat feet need correction. It can occur in children and adults.

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Causes:

Flat feet are generally passed by genetics. However, there are cases where trauma and overuse of the foot can lead to collapse of the arch. The posterior tibial tendon is a very strong tendon that helps to hold the arch. If this tendon is damaged, becomes weakened, or tears then the arch will begin to fall over time causing pain and dysfunction (posterior tibial tendon dysfunction). A tight Achilles tendon (equinus) is am major deforming force leading to a collapsed arch. When the Achilles is tight, the heel is off the ground more often and the foot must compensate by flattening to reach the ground. Increased weight and improper shoe gear can also lead to pes planus.

Symptoms:

Most patients will complain about a general fatigue and discomfort in the foot and ankle after long periods of standing and use of the feet. Some patients will have pain along the course of the posterior tibial tendon as well as where the tendon connects to the arch of the foot. There may be an inability to walk without a great deal of pain. Most of the pain will be in the middle of the foot and along the joints that support the arch.

Diagnosis:

A thorough examination of the entire lower extremity and the foot and ankle will be performed to evaluate a flat foot. It is important to identify the area of the foot that the collapse is stemming from. The amount of flexibility to the deformity will be evaluated. The more rigid the deformity the more complex the treatment becomes. Gait analysis will be beneficial as well. X-rays will be taken to evaluate the location of the bones and the condition of the joints and the amount of collapse. MRI’s may be needed to examine the amount of damage to the tendons.

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X-ray showing a foot with a normal arch. Notice the normal angles and relationships of the bones and joints with each other.
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X-ray showing a flat foot. Notice the angles of the deformity with the relationship of the bones with each other. The heel bone is angled too close to the ground. The ankle bone is angled too much towards the ground.

Treatment:

The first line of treatment is with custom functional foot orthotics. In patients with a flexible deformity, supporting the arch with an custom arch support will take the strain off the joints and muscles as well as bringing the heel into a more corrected position perpendicular to the ground. Wider shoe gear will also accommodate the pain and motion of the foot. In many cases special braces can be used when the pain is increased and surgery is not advised. In most cases with chronic pain and dysfunction, surgical reconstruction of the flat foot is warranted.

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Picture showing a functional foot orthotic supporting the arch. Picture showing a custom molded functional brace that will aid in function with a damaged posterior tibial tendon.

There are many ways to surgically correct the flat foot. In most surgical cases, there will be a need to do both tendon work and bone work. In some cases the heel bone can be shifted in a more proper position, bringing the subtalar joint into better position and lifting the arch. This is done in several different ways. Some cases, especially those with arthritis, will need fusion of one or more of the joints to lock them into the proper position. Some patients will need to have a repair and shortening of the posterior tibial tendon or even adding or transferring another tendon to the arch of the foot. Those patients with a short Achilles tendon (equinus) will need a lengthening of the Achilles tendon. This is usually done endoscopically with a small incision in the back of the calf and a camera attached to a scalpel. Some patients will have to have a combination of procedures in order to correct the deformity and bring back function to the foot and ankle.

Picture showing damaged PT tendon. Notice the healthy tendon just below the PT. This tendon will be used for the transfer. Picture showing the harvesting of the tendon that will be transferred. The cut end of the tendon is in the forceps.
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Picture showing the drill hole being made into the bone of the arch in order to anchor the tendon into the bone. Picture showing the implant used to anchor the transferred tendon into the bone.
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Picture showing the completed transfer of the tendon. The new tendon is at the arrow’s tip.
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X-ray showing a flat foot. Notice the angles of the deformity with the relationship of the bones with each other. In the upper x-ray, the heel bone is angled too close to the ground. The ankle bone is angled too much towards the ground. In the Lower x-ray, the ankle bone is angled too far from the center of the 2nd toe and the center of the foot.
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X-ray showing a flat foot after reconstruction. Notice the angles of the deformity with the relationship of the bones with each other. In the upper x-ray, the heel bone is now angled farther away from the ground. The ankle bone is now angled less towards the ground. In the Lower x-ray, the ankle bone is now angled closer to the center of the 2nd toe and the center of the foot.

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