Posterior tibial tendon dysfunction, also known as adult acquired flatfoot, is a common cause of pain and flattening of the arch of the foot that occurs with age. The posterior tibial tendon is a large and very important tendon on the medial or inner side of the ankle. It supports the arch and inverts the foot. Tendonitis or dysfunction is caused by repetitive irritation that occurs with walking and weight bearing. Left untreated, this condition can worsen over time, causing pain and deformity (a very flat foot). It usually occurs in one foot, but it can develop in both feet. It is different from painless flexible flatfeet, often seen in adolescents and children, because the pain and condition worsens over time.
The underlying cause of adult acquired flatfoot disorder is uncertain. It has been linked to certain ankle injuries and genetics. The irritated tendon stretches and loses its elasticity and ability to function. As a result, the arch flattens further. Over time, this can affect the biomechanics of the ankle the joints, leading to degenerative changes of the cartilage, also known as arthritis.
• Pain in the ankle, hind foot, and arch that worsens with increased activity.
• Swelling or deformity of the ankle, particularly on the inner ankle.
• Difficulty with balance, walking, and jumping on one leg.
The diagnosis is typically made by the patient’s story and the physical exam. X-rays do not show the tendon, but if done while standings, x-rays can show the flattening of the arch. The location of the pain, the shape and flexibility of the foot all come into play when making a diagnosis and indicate how advanced the problem has become. MRI can confirm the degree of damage to the tendon and can help guide management.
Early treatment attempts to stop the cycle of tendon damage and arch flattening. Depending on the severity of the condition, rest, braces, and walking boot immobilization may be recommended. Non-steroidal, anti-inflammatory drugs and properly fitting shoes may help reduce pain as well. Shoes with arch supports over the counter or custom orthotics (shoe inserts) help. Physical therapy exercises are also part of the treatment.
Surgery will be considered if the disorder is severe and limits the patient’s daily activities.
However, surgery is rarely helpful in the early stages of the disease. In cases of severe muscle tightness, a muscle lengthening procedure is controversial but shown in some research to prevent progression. Tendon transfer with bone realignment is a surgical treatment that restores function and reduces pain, but the recovery is significant. Triple arthrodesis is a fusion procedure that is right for certain patients where the deformity is severe and has led to joint damage. Recovery time from surgery depends on the specific procedure and the patient’s age and functional level.