Adult-acquired flatfoot is a challenging condition to treat. It is defined as a symptomatic, progressive deformity of the foot caused by loss of supportive structures of the medial arch. It is becoming increasingly frequent with the aging population and the obesity epidemic. Patients commonly try to lose weight by exercising to improve the condition. This often leads to worsening of symptoms and progression of the disorder. Early recognition of this complex disorder is essential, if chronic pain and surgery are to be avoided.

 

Another common term for this condition is Posterior Tibial Tendon Dysfunction (PTTD).  There is a cause-effect relationship between pronation, flatfoot deformity and subsequent tenosynovitis of the posterior tibial tendon. Mechanical irritation of the tendon may lead to synovitis, partial tearing and eventually full rupture of the tendon. Other structures, including ligaments and the plantar fascia, have also been shown to contribute to the arch collapsing. As the deformity progresses, these structures have been shown to attenuate and rupture as well. In later stages, subluxation of various joints lead to a valgus rearfoot and transverse plane deformity of the forefoot. These deformities can become fixed and irreducible as significant osteoarthritis sets in.

 

Clinicians need to recognize the early stage of this syndrome which includes pain, swelling, tendonitis and disability. The musculoskeletal portion of the clinical exam can help determine the stage of the disease. It is important to palpate the posterior tibial tendon and test its muscle strength. This is tested by asking patient to plantarflex and invert the foot. Joint range of motion is should be assessed as well. Stiffness of the joints may indicate longstanding disease causing a rigid deformity.

 

 A weightbearing examination should be performed as well. A complete absence of the medial longitudinal arch is often seen. In later stages the head of the talus bone projects outward to the point of a large "lump" in the arch. Observing the patient's feet from behind shows a significant valgus rotation of the heel. From behind, the "too many toes" sign may be seen as well. This is when there is abducution of the forefoot in the transverse plane allowing the toes to be seen from behind. Dysfunction of the posterior tibial tendon can be assessed by asking the patient to stand on his/her toes on the affected foot. If they are unable to, this indicates the disease is in a more advanced stage with the tendon possibly completely ruptured.

 

Diagnostic testing is often used to diagnose the condition and help determine the stage of the disease. The most common test done in the office setting are weightbearing X-rays of the foot and ankle. These assess joint alignment and osteoarthritis. If tendon tearing or rupture is suspected, the gold standard test would be MRI. The MRI is used to check the tendon, surrounding ligament structures and the midfoot and hindfoot joints. An MRI is essential if surgery is being considered.

 

Conservative treatment also depends on the stage of the disease. Early on, the pain and swelling with no deformity can be treated with rest, ice, compression, elevation and non-steroidal anti-inflammatory medication. Usually OTC orthotic inserts are recommended with stability oriented athletic shoes. If this fails or the condition is more advanced, immobilization in a rigid walking boot is recommended. This rests the tendon and protects it from further irritation, attenuation, or tearing. If symptoms are greatly improved or eliminated then the patient may return to a supportive shoe. To protect the patient from reoccurrence, different types of devices are recommended. The most common device is orthotics. Usually custom-made orthotics are preferable to OTC. They are reserved for early staged PTTD. Advanced stages may require a more aggressive type orthotic or an AFO (ankle-foot orthosis). There are different types of AFO's. One type has a double-upright/stirrup attached to a footplate. Another is a gauntlet-type with a custom plastic interior surrounded be a lace-up leather exterior. Both require the use of a bulky type athletic or orthopedic shoes. Patient compliance is always challenging with these larger braces and shoes.

 

If conservative treatment fails to provide relief of pain and disability then surgery is considered. Numerous factors determine whether a patient is a surgical candidate. They include age, obesity, diabetes, vascular status, and the ability to be compliant with post-operative care. Surgery usually requires a prolonged period of nonweightbearing immobilization. Total recovery ranges from 3 months to one year. Clinical, x-ray, and MRI examination are all used to select the appropriate surgical procedure.

 

 

 

Daniel L. Wiernik, DPM

Board Certified in Foot Surgery and Reconstructive Rearfoot/Ankle Surgery