Acquired Flat Foot Deformity

Overview
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. 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. Most 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.

Causes
The cause of posterior tibial tendon insufficiency is not completely understood. The condition commonly does not start from one acute trauma but is a process of gradual degeneration of the soft tissues supporting the medial (inner) side of the foot. It is most often associated with a foot that started out somewhat flat or pronated (rolled inward). This type of foot places more stress on the medial soft tissue structures, which include the posterior tibial tendon and ligaments on the inner side of the foot. Children nearly fully grown can end up with flat feet, the majority of which are no problem. However, if the deformity is severe enough it can cause significant functional limitations at that age and later on if soft tissue failure occurs. Also, young adults with normally aligned feet can acutely injure their posterior tibial tendon from a trauma and not develop deformity. The degenerative condition in patients beyond their twenties is different from the acute injuries in young patients or adolescent deformities, where progression of deformity is likely to occur.

Symptoms
The first stage represents inflammation and symptoms originating from an irritated posterior tibial tendon, which is still functional. Stage two is characterized by a change in the alignment of the foot noted on observation while standing (see above photos). The deformity is supple meaning the foot is freely movable and a ?normal? position can be restored by the examiner. Stage two is also associated with the inability to perform a single-leg heel rise. The third stage is dysfunction of the posterior tibial tendon is a flatfoot deformity that becomes stiff because of arthritis. Prolonged deformity causes irritation to the involved joints resulting in arthritis. The fourth phase is a flatfoot deformity either supple (stage two) or stiff (stage 3) with involvement of the ankle joint. This occurs when the deltoid ligament, the major supporting structure on the inside of the ankle, fails to provide support. The ankle becomes unstable and will demonstrate a tilted appearance on X-ray. Failure of the deltoid ligament results from an inward displacement of the weight bearing forces. When prolonged, this change can lead to ankle arthritis. The vast majority of patients with acquired adult flatfoot deformity are stage 2 by the time they seek treatment from a physician.

Diagnosis
In diagnosing flatfoot, the foot & Ankle surgeon examines the foot and observes how it looks when you stand and sit. Weight bearing x-rays are used to determine the severity of the disorder. Advanced imaging, such as magnetic resonance imaging (MRI) and computed tomography (CAT or CT) scans may be used to assess different ligaments, tendons and joint/cartilage damage. The foot & Ankle Institute has three extremity MRI?s on site at our Des Plaines, Highland Park, and Lincoln Park locations. These extremity MRI?s only take about 30 minutes for the study and only requires the patient put their foot into a painless machine avoiding the uncomfortable Claustrophobia that some MRI devices create.

Non surgical Treatment
Depending on the stage of the deformity and patient?s functional goals, various treatment options are available. Some patients improve with conservative care which includes rest and immobilization, shoe modifications, orthoses and bracing, or physical therapy. Surgery might be warranted for advanced stages of the condition. Often a combination of procedures including tendon and muscle augmentation, tendon transfers, realigning of bones or fusion of certain joints might be necessary in more advanced cases. Your doctor will evaluate and recommend an individualized plan of care with your specific needs in mind.

Surgical Treatment
If initial conservative therapy of posterior tibial tendon insufficiency fails, surgical treatment is considered. Operative treatment of stage 1 disease involves release of the tendon sheath, tenosynovectomy, debridement of the tendon with excision of flap tears, and repair of longitudinal tears. A short-leg walking cast is worn for 3 weeks postoperatively. Teasdall and Johnson reported complete relief of pain in 74% of 14 patients undergoing this treatment regimen for stage 1 disease. Surgical debridement of tenosynovitis in early stages is believed to possibly prevent progression of disease to later stages of dysfunction.