Adult flatfoot (adult acquired flatfoot) or posterior tibial tendon dysfunction (PTTD) is a common pathology presented to foot and ankle specialists. PTTD is characterized by a valgus (everted) hindfoot, flattening of the longitudinal arch of the foot (collapse) and abduction of the forefoot. This is a progressive deformity that begins flexible and can become rigid over time. The posterior tibial tendon (PT) is one of the main supporting structures of the foot arch. Changes within this tendon cause flattening of the foot. There are four stages of this deformity that begins flexible and progressives, with no treatment, to a rigid deformity and with time may involve the ankle joint. Patients usually present with pain in the foot or ankle stating the ankle is rolling. Its also common for patients to state they have difficulty walking barefoot. Pain is exacerbated after physical activities. Pain is usually isolated to the inside of the foot along the course of the PT tendon.
Damage to the posterior tendon from overuse is the most common cause for adult acquired flatfoot. Running, walking, hiking, and climbing stairs are activities that add stress to this tendon, and this overuse can lead to damage. Obesity, previous ankle surgery or trauma, diabetes (Charcot foot), and rheumatoid arthritis are other common risk factors.
The symptoms of PTTD may include pain, swelling, a flattening of the arch, and an inward rolling of the ankle. As the condition progresses, the symptoms will change. For example, when PTTD initially develops, there is pain on the inside of the foot and ankle (along the course of the tendon). In addition, the area may be red, warm, and swollen. Later, as the arch begins to flatten, there may still be pain on the inside of the foot and ankle. But at this point, the foot and toes begin to turn outward and the ankle rolls inward. As PTTD becomes more advanced, the arch flattens even more and the pain often shifts to the outside of the foot, below the ankle. The tendon has deteriorated considerably and arthritis often develops in the foot. In more severe cases, arthritis may also develop in the ankle.
Posterior Tibial Tendon Dysfunction is diagnosed with careful clinical observation of the patient?s gait (walking), range of motion testing for the foot and ankle joints, and diagnostic imaging. People with flatfoot deformity walk with the heel angled outward, also called over-pronation. Although it is normal for the arch to impact the ground for shock absorption, people with PTTD have an arch that fully collapses to the ground and does not reform an arch during the entire gait period. After evaluating the ambulation pattern, the foot and ankle range of motion should be tested. Usually the affected foot will have decreased motion to the ankle joint and the hindfoot. Muscle strength may also be weaker as well. An easy test to perform for PTTD is the single heel raise where the patient is asked to raise up on the ball of his or her effected foot. A normal foot type can lift up on the toes without pain and the heel will invert slightly once the person has fully raised the heel up during the test. In early phases of PTTD the patient may be able to lift up the heel but the heel will not invert. An elongated or torn posterior tibial tendon, which is a mid to late finding of PTTD, will prohibit the patient from fully rising up on the heel and will cause intense pain to the arch. Finally diagnostic imaging, although used alone cannot diagnose PTTD, can provide additional information for an accurate diagnosis of flatfoot deformity. Xrays of the foot can show the practitioner important angular relationships of the hindfoot and forefoot which help diagnose flatfoot deformity. Most of the time, an MRI is not needed to diagnose PTTD but is a tool that should be considered in advanced cases of flatfoot deformity. If a partial tear of the posterior tibial tendon is of concern, then an MRI can show the anatomic location of the tear and the extensiveness of the injury.
Non surgical Treatment
The adult acquired flatfoot is best treated early. Accurate assessment by your doctor will determine which treatment is suitable for you. Reduce your level of activity and follow the RICE regime. R – rest as often as you are able. Refrain from activity that will worsen your condition, such as sports and walking. I – ice, apply to the affected area, ensure you protect the area from frostbite by applying a towel over the foot before using the ice pack. C – compression, a Tubigrip or elasticated support bandage may be
applied to relieve symptoms and ease pain and discomfort. E – elevate the affected foot to reduce painful swelling. You will be prescribed pain relief in the form of non-steroidal antiinflammatory medications (if you do not suffer with allergies or are asthmatic). Immobilisation of your affected foot – this will involve you having a below the knee cast for four to eight weeks. In certain circumstances it is possible for you to have a removable boot instead of a cast. A member of the foot and ankle team will advise as to whether this option is suitable for you. Footwear is important – it is advisable to wear flat sturdy lace-up shoes, for example, trainers or boots. This will not only support your foot, but will also accommodate orthoses (shoe inserts).
Surgical correction is dependent on the severity of symptoms and the stage of deformity. The goals of surgery are to create a more functional and stable foot. There are multiple procedures available to the surgeon and it may take several to correct a flatfoot deformity. Usually surgical treatment begins with removal of inflammatory tissue and repair of the posterior tibial tendon. A tendon transfer is performed if the posterior tibial muscle is weak or the tendon is badly damaged. The most commonly used tendon is the flexor digitorum longus tendon. This tendon flexes or moves the lesser toes downward. The flexor digitorum longus tendon is utilized due to its close proximity to the posterior tibial tendon and because there are minimal side effects with its loss. The remainder of the tendon is sutured to the flexor hallucis longus tendon that flexes the big toe so that little function is loss.