Adult Acquired Flat Foot

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What is adult acquired flat foot (posterior tibial tendon dysfunction)?

At OrthoArizona, posterior tibial tendon dysfunction is one of the most common causes of pain in the inner half of the ankle or foot. The posterior tibial tendon connects the tibialis posterior muscle in the calf to the inner half of the foot. It helps support the arch of the foot and helps the foot turn inward. The tendon may lose its ability to support the arch and this leads to pain, and ultimately deformity, of the foot or ankle. It is one but not the only cause of a “fallen arch.”

What causes posterior tibial tendon dysfunction?

The posterior tibial tendon can become dysfunctional or insufficient as a result of acute inflammation, injury, or slowly over time. The condition is described as chronic if it developed slowly over a period of months or years.  In this case, the tendon will become thickened over months as the body tries to inefficiently heal chronic tearing of the tendon. We describe this similar to leaving a bungee cord out in the Arizona sun for the summer and then attempting to use it in the fall. The bungee cord would develop small cracks or tears in it and is unlikely to have the same function. Like the bungee cord, the tendon typically never regains normal function once it begins to tear and thickens. However, there are some patients who can expect the pain to resolve even though they may not have the same strength or alignment.

Who gets posterior tibial tendon dysfunction?

While it can be seen in younger patients, at OrthoArizona, we typically see this diagnosis in middle age or older patients. We also see it present in our patients who may be overweight or have diabetes. It is not typically seen in patients who have had “high arches” all of their lives.

What are the symptoms of posterior tibial tendon dysfunction?

The main complaint we see in our patients is pain. The pain usually begins on the inner half of the foot and ankle. This may be due to inflammation or tearing of the tendon. There is also pain from the increased force on other medial structures as they become stretched.

As the condition worsens, the patient can develop deformity in the foot or ankle called a “fallen arch” or flat foot. As the flat foot deformity worsens, pain also is noticed on the outer half of the foot or ankle. We usually describe it as a stretching pain or tearing pain on the inner half and an impinging (or pinching) pain on the outer half as the bony alignment of the foot changes.

In addition to pain, many of our patients also have swelling, especially on the inner part of the ankle or foot.

How is posterior tibial tendon dysfunction diagnosed?

Diagnosis is usually by obtaining a patient history and performing physical exam along with foot/ankle X-rays obtained while the patient is standing. The physical exam is probably the most important factor at the time of initial diagnosis. Advanced imaging, such as MRI or CT, is usually reserved for surgical planning or to rule out other conditions.

How is posterior tibial tendon dysfunction treated?

Our initial treatment is almost non-surgical. The first goal is to try to calm down any acute inflammation and pain with anti-inflammatory medications and some form of immobilization. Rest and icing are also incorporated. If we can get some of the more recent pain and inflammation to resolve, then we can work on treating the chronic tendon dysfunction. This is often done with a combination of orthotic inserts and braces. Physical therapy may be utilized. We usually reserve the custom braces/insert for those who have significant deformity or those who did not have success with cheaper off-the-shelf products.

Surgical treatment is reserved for those patients who fail conservative measures. Early in the disease process, some patients without deformity (“fallen arch” or a flat foot) may notice pain relief by cleaning up the tendon.  Once patients develop deformity, treatment is often broken down into either motion sparing procedures or fusions.  The end goal is pain relief and this is often achieved by having a more stable foot and ankle. In certain patients, cleaning up the tendon and transferring a healthy tendon in conjunction with cutting and realigning bones can obtain this. In other patients, stability is achieved by fusing bones. Please see our article on fusions for more information on this.

Posterior tibial tendon dysfunction is a very complex problem to treat. It is very important to discuss treatment goals and options with your provider. Additionally, while patients see improvement after 4-5 months postoperative, many patients continue to improve for up to 12 months after surgical treatment.

*This information is not intended as a substitute for the medical recommendations of your medical provider. Please consult your physician regarding advice about a particular medical condition.