Adult acquired flatfoot deformity, primarily posterior tibial tendon dysfunction, in many cases can be successfully managed with conservative treatment modalities including early immobilization, long-term bracing, physi?cal therapy, and anti-inflam?matory medications. Adult acquired flatfoot deformity (AAFD), the painful flatfoot deformity in adults, is a major cause of disability for a patient and can be a challenge for foot and ankle specialists.
As discussed above, many different problems can create a painful flatfoot. Damage to the posterior tibial tendon is the most common cause of AAFD. The posterior tibial tendon is one of the most important tendons of the leg. It starts at a muscle in the calf, travels down the inside of the lower leg and attaches to the bones on the inside of the foot. The main function of this tendon is to support the arch of your foot when you walk. If the tendon becomes inflamed or torn, the arch will slowly collapse. Women and people over 40 are more likely to develop problems with the posterior tibial tendon. Other risk factors include obesity, diabetes, and hypertension. Having flat feet since childhood increases the risk of developing a tear in the posterior tibial tendon. In addition, people who are involved in high impact sports, such as basketball, tennis, or soccer, may have tears of the tendon from repetitive use. Inflammatory arthritis, such as rheumatoid arthritis, can cause a painful flatfoot. This type of arthritis attacks not only the cartilage in the joints, but also the ligaments that support the foot. Inflammatory arthritis not only causes pain, but also causes the foot to change shape and become flat. The arthritis can affect the back of the foot or the middle of foot, both of which can result in a fallen arch. An injury to the tendons or ligaments in the foot can cause the joints to fall out of alignment. The ligaments support the bones and prevent them from moving. If the ligaments are torn, the foot will become flat and painful. This more commonly occurs in the middle of the foot (Lisfranc injury), but can also occur in the back of the foot. Injuries to tendons of the foot can occur either in one instance (traumatically) or with repeated use over time (overuse injury). Regardless of the cause, if tendon function is altered, the forces that are transmitted across joints in the foot are changed and this can lead to increased stress on joint cartilage and ligaments. In addition to tendon and ligament injuries, fractures and dislocations of the bones in the midfoot can also lead to a flatfoot deformity. People with diabetes or with nerve problems that limits normal feeling in the feet, can have collapse of the arch or of the entire foot. This type of arch collapse is typically more severe than that seen in patients with normal feeling in their feet. In addition to the ligaments not holding the bones in place, the bones themselves can sometimes fracture and disintegrate without the patient feeling any pain. This may result in a severely deformed foot that is very challenging to correct with surgery. Special shoes or braces are the best method for dealing with this problem.
Symptoms shift around a bit, depending on what stage of PTTD you?re in. For instance, you?re likely to start off with tendonitis, or inflammation of the posterior tibial tendon. This will make the area around the inside of your ankle and possibly into your arch swollen, reddened, warm to the touch, and painful. Inflammation may actually last throughout the stages of PTTD. The ankle will also begin to roll towards the inside of the foot (pronate), your heel may tilt, and you may experience some pain in your leg (e.g. shin splints). As the condition progresses, the toes and foot begin to turn outward, so that when you look at your foot from the back (or have a friend look for you, because-hey-that can be kind of a difficult maneuver to pull off) more toes than usual will be visible on the outside (i.e. the side with the pinky toe). At this stage, the foot?s still going to be flexible, although it will likely have flattened somewhat due to the lack of support from the posterior tibial tendon. You may also find it difficult to stand on your toes. Finally, you may reach a stage in which your feet are inflexibly flat. At this point, you may experience pain below your ankle on the outside of your foot, and you might even develop arthritis 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
Non-surgical treatment consists of custom orthoses and or special bracing devices along with supportive measures aimed at reducing the symptoms. While non-surgical treatment helps the majority of patients with PTTD, progressive cases may require surgical treatment including soft tissue tendon transfers, osteotomies and lastly fusion.
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.