Over 60 Million Americans suffer from Adult Acquired Flatfoot (AAF), otherwise known as Posterior Tibial Tendon Dysfunction or PTTD. This condition generally occurs in adults from 40-65 years of age, and it usually only occurs in one foot, not both. The Posterior Tibial (PT) Tendon courses along the inside part of the ankle and underneath the arch of the foot. It is the major supporting structure for the arch. Over time, the tendon becomes diseased, from overuse, and starts to lose it's strength. As a result, the arch begins to collapse, placing further strain on the PT Tendon, leading to further decrease in tendon strength, which causes further collapse of the arch. This is described as a progressive deformity because it will generally get worse over time.
As the name suggests, adult-acquired flatfoot occurs once musculoskeletal maturity is reached, and it can present for a number of reasons, though one stands out among the others. While fractures, dislocations, tendon lacerations, and other such traumatic events do contribute to adult-acquired flatfoot as a significant lower extremity disorder, as mentioned above, damage to the posterior tibial tendon is most often at the heart of adult-acquired flatfoot. One study further elaborates on the matter by concluding that ?60% of patients [presenting with posterior tibial tendon damage and adult-acquired flatfoot] were obese or had diabetes mellitus, hypertension, previous surgery or trauma to the medial foot, or treatment with steroids?.
Depending on the cause of the flatfoot, a patient may experience one or more of the different symptoms here. Pain along the course of the posterior tibial tendon which lies on the inside of the foot and ankle. This can be associated with swelling on the inside of the ankle. Pain that is worse with activity. High intensity or impact activities, such as running, can be very difficult. Some patients can have difficulty walking or even standing for long periods of time. When the foot collapses, the heel bone may shift position and put pressure on the outside ankle bone (fibula). This can cause pain on the outside of the ankle. Arthritis in the heel also causes this same type of pain. Patients with an old injury or arthritis in the middle of the foot can have painful, bony bumps on the top and inside of the foot. These make shoewear very difficult. Occasionally, the bony spurs are so large that they pinch the nerves which can result in numbness and tingling on the top of the foot and into the toes. Diabetics may only notice swelling or a large bump on the bottom of the foot. Because their sensation is affected, people with diabetes may not have any pain. The large bump can cause skin problems and an ulcer (a sore that does not heal) may develop if proper diabetic shoewear is not used.
In the early stages of dysfunction of the posterior tibial tendon, most of the discomfort is located medially along the course of the tendon and the patient reports fatigue and aching on the plantar-medial aspect of the foot and ankle. Swelling is common if the dysfunction is associated with tenosynovitis. As dysfunction of the tendon progresses, maximum pain occurs laterally in the sinus tarsi because of impingement of the fibula against the calcaneus. With increasing deformity, patients report that the shape of the foot changes and that it becomes increasingly difficult to wear shoes. Many patients no longer report pain in the medial part of the foot and ankle after a complete rupture of the posterior tibial tendon has occurred; instead, the pain is located laterally. If a fixed deformity has not occurred, the patient may report that standing or walking with the hindfoot slightly inverted alleviates the lateral impingement and relieves the pain in the lateral part of the foot.
Non surgical Treatment
Footwear has an important role, and patients should be encouraged to wear flat lace-up shoes, or even lace-up boots, which accommodate orthoses. Stage I patients may be able to manage with an off the shelf orthosis (such as an Orthaheel or Formthotics). They can try a laced canvas ankle brace before moving to a casted orthosis. The various casted, semirigid orthoses support the medial longitudinal arch of the foot and either hold the heel in a neutral alignment (stage I) or correct the outward bent heel to a neutral alignment (stage II). This approach is meant to serve several functions: to alleviate stress on the tibialis posterior; to make gait more efficient by holding the hindfoot fixed; and thirdly, to prevent progression of deformity. Devices available to do this are the orthosis of the University of California Biomechanics Laboratory, an ankle foot orthosis, or a removable boot. When this approach has been used, two thirds of patients have good to excellent results.
For those patients with PTTD that have severe deformity or have not improved with conservative treatments, surgery may be necessary to return them to daily activity. Surgery for PTTD may include repair of the diseased tendon and possible tendon transfer to a nearby healthy tendon, surgery on the surrounding bones or joints to prevent biomechanical abnormalities that may be a contributing factor or both.