Last updated: May 26, 2011
Many terms are in use to describe a painful progressive flatfoot. Posterior tibial tendon dysfunction is one term to describe a dropped arch in adults. Other terms include posterior tibial tendon insufficiency and adult acquired flatfoot.
The term adult acquired flatfoot is a reasonable term because it allows a broader recognition of causative factors not only limited to the posterior tibial tendon an event where the posterior tibial tendon looses strength and function. Other causes can include a traumatic ligament rupture and/or progressive arthritis of key midfoot joints that can settle out of position flattening the arch.
Most flat feet are not painful particularly those flat feet seen in children. In the adult acquired flatfoot pain occurs because soft tissues (tendons and ligaments) have been torn or the arthritic joints can become symptomatic. The deformity progresses or worsens because once the vital ligaments and posterior tibial tendon are lost; nothing can take their place to hold up the arch of the foot.
The painful progressive adult acquired flatfoot affects women four times as frequently as men. It occurs in middle to older age people with a mean age of 60 years. Often people who develop the condition already have flat feet. A change occurs in one foot where the arch begins to flatten more than before with pain and swelling developing on the inside of the ankle. Why this event occurs in some people (female more than male) and only in one foot remains poorly understood. Contributing factors increasing the risk of adult acquired flatfoot are diabetes hypertension and obesity.
The adult acquired flatfoot secondary to posterior tibial tendon dysfunction is diagnosed in a number of ways.
The most accurate diagnosis is made by a skilled clinician utilizing observation and hands on evaluation of the foot and ankle. The affected foot appears more pronated and deformed compared to the unaffected foot. Muscle testing will show a strength deficit. An easy test to perform in the office is the single foot raise.
A patient is asked to step with full body weight on the symptomatic foot keeping the unaffected foot off the ground. The patient is then instructed to "raise up on the tip toes" of the affected foot. If the posterior tibial tendon has been attenuated or ruptured the patient will be unable to lift the heel off the floor and rise onto the toes. In less severe cases the patient will be able to rise on the toes but the heel will not be noted to invert as it normally does when we rise onto the toes.
X-rays can be helpful but are not diagnostic of the adult acquired flatfoot. Both feet - the symptomatic and asymptomatic - will demonstrate a flatfoot deformity on x-ray. Careful observation may show a greater severity of deformity on the affected side.
Magnetic Resonance Imaging (MRI) can show tendon injury and inflammation but cannot be relied on with 100% accuracy and confidence. The technique and skill of the radiologist in properly positioning the foot with the MRI beam are critical in demonstrating the sometimes obscure findings of tendon injury around the ankle. Magnetic Resonance Imaging (MRI) is expensive and is not necessary in most cases to diagnose posterior tibial tendon injury. Ultrasound has also been used in some cases to diagnose tendon injury but this test again is usually not required to make the initial diagnosis.
The adult acquired flatfoot is best treated early. There is no recommended home treatment other than the general avoidance of prolonged weightbearing in non-supportive footwear until the patient can be seen in the office of the foot and ankle specialist.
Early on in this condition the inflammation and tendon injury will respond to rest protected ambulation in a cast as well as anti-inflammatory therapy. Follow-up treatment with custom-molded foot orthoses and properly designed athletic or orthopedic footwear are critical to maintain stability of the foot and ankle after initial symptoms have been calmed.
Once the tendon has been stretched the foot will become deformed and visibly rolled into a pronated position at the ankle. Non-surgical treatment has a significantly lower chance of success. Total immobilization in a cast or Camwalker may calm down symptoms and arrest progression of the deformity in a smaller percentage of patients. Usually long-term use of a brace known as an ankle foot orthosis is required to stop progression of the deformity without surgery.
A new ankle foot orthosis known as the Arizona Brace has proven to show significant success in treating Stage II posterior tibial dysfunction and the adult acquired flatfoot. This is a custom molded brace connected to a custom corrected foot orthotic device that fits well into most forms of lace-up footwear including athletic shoes. The brace is light weight and is cosmetically appealing.
In cases where cast immobilization orthoses and shoe therapy have failed surgery is the next alternative. The goal of surgery and non-surgical treatment is to eliminate pain stop progression of the deformity and improve mobility of the patient. Opinions vary as to the best surgical treatment for adult acquired flatfoot. Procedures commonly used to correct the condition include tendon debridement tendon transfers osteotomies (cutting and repositioning of bone) and joint fusions.
Patients with adult acquired flatfoot are advised to discuss thoroughly the benefits vs. risks of all surgical options. Most procedures have long-term recovery mandating that the correct procedure be utilized to give the best long-term benefit. Most flatfoot surgical procedures require six to twelve weeks of cast immobilization. Joint fusion procedures require six weeks of non-weightbearing on the operated foot - meaning you will be on crutches for this amount of time.
The bottom line is: Make sure all of your non-surgical options have been covered before considering surgery. Your primary goals with any treatment are to eliminate pain and improve mobility.