UNDERSTANDING ADULT ACQUIRED FLATFOOT DEFORMITY

By: Sara John, C.Ped (C)., C.Ped Tech (C)

Adult Acquired Flatfoot Deformity (AAFD) describes a progressive flattening of the medial longitudinal arch resulting in pain and swelling along the medial foot and ankle, difficult walking and standing for long periods, changes to the foot’s appearance as the condition advances, and decreased function of the affected foot.

Dysfunction of posterior tibialis tendon that runs on the inner side of the ankle is a common cause of Adult Acquired Flatfoot Deformity. The loss of active and passive pull of the tendon alters the normal biomechanics of the foot and ankle. Overstretching or rupture of the tendon results in tendon and muscle imbalance of the foot leading to AAFD.

Damage to the nerves, ligaments, or tendons of the foot causing partial dislocation of the joints, bone fracture, neurological condition causing weakness, rheumatoid arthritis, diabetes, high blood pressure, prolonged use of steroids, and obesity are some of the other contributing factors to the development of this condition.

At first, there may be pain and swelling along the medial side of the foot where the posterior tibialis tendon travels from the back of the leg under the medial ankle bone to the foot. As it progresses, there will be pain on the lateral side of the foot as well. Pain in the leg when standing for long periods, trouble rising up on toes, unable to participate fully in sports and other recreational activities are other symptoms.

There are four stages of adult acquired flatfoot deformity. The severity of the deformity determines the stage.

Stage 1 - Medial ankle pain, swelling, inflamed tendon and mild weakness. There is flatfoot position but without deformity. Pain and swelling from tendinitis is common in this stage.

Stage 2 – Medial ankle pain, swelling, elongated tendon, marked weakness and flexible deformity. The deformity is starting to develop. The physician can still move the bones back into place manually (passively).

Stage 3 – Medial and lateral ankle pain, marked weakness, fixed deformity - the ankle is stiff or rigid and does not move beyond a neutral position, and there is some degeneration of subtalar joint.

Stage 4 – This stage is characterized by deformity in the foot and ankle. Signs of degenerative changes are noted.

Early recognition plays an important part in prevention of AAFD. The history, physical examination, Xray and MRI are important tools in diagnosing this condition. The wear pattern on the shoes offers some clues.

Goals of treatment include reducing clinical symptoms, improving alignment, pain relief and prevent the progression of the deformity. Conservative treatment include off the shelf or custom made orthotics in order to align the foot, and deep structured footwear with strong heel counter for comfort and better compliance with orthotics. Bracing is effective in controlling the deformity by stabilizing the ankle and improving gait mechanics.

Physical therapy is recommended to stretch and strengthen the foot and leg muscles. Surgical intervention is needed when conservative care fails to control the symptoms or deformity.