Adults with an acquired flatfoot
deformity may present not with foot deformity but almost uniformly with
medial foot pain and decreased function of the affected foot. Patients whose acquired flatfoot is associated with a more generalised medical problem tend to receive their diagnosis and are referred
appropriately. However, in patients whose ?adult acquired flatfoot deformity? is a result of damage to the structures supporting the medial longitudinal arch, the diagnosis is often not made early.
These patients are often otherwise healthier and tend to be relatively more affected by the loss of function resulting from an acquired flatfoot deformity. The most common cause of an acquired
flatfoot deformity in an otherwise healthy adult is dysfunction of the tibialis posterior tendon, and this review provides an outline to its diagnosis and treatment.
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.
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.
Starting from the knee down, check for any bowing of the tibia. A tibial varum will cause increased medial stress on the foot and ankle. This is essential to consider in surgical planning. Check the
gastrocnemius muscle and Achilles complex via a straight and bent knee check for equinus. If the range of motion improves to at least neutral with bent knee testing of the Achilles complex, one may
consider a gastrocnemius recession. If the Achilles complex is still tight with bent knee testing, an Achilles lengthening may be necessary. Check the posterior tibial muscle along its entire course.
Palpate the muscle and observe the tendon for strength with a plantarflexion and inversion stress test. Check the flexor muscles for strength in order to see if an adequate transfer tendon is
available. Check the anterior tibial tendon for size and strength.
Non surgical Treatment
It is imperative that you seek treatment should you notice any symptoms of a falling arch or PTTD. Due to the progressive nature of this condition, your foot will have a much higher chance of staying
strong and healthy with early treatment. When pain first appears, your doctor will evaluate your foot to confirm a flatfoot diagnosis and begin an appropriate treatment plan. This may involve rest,
anti-inflammatory medications, shoe modifications, physical therapy, orthotics and a possible boot or brace. When treatment can be applied at the beginning, symptoms can most often be resolved
without the need for surgery.
Until recently, operative treatment was indicated for most patients with stage 2 deformities. However, with the use of potentially effective nonoperative management , operative treatment is now
indicated for those patients that have failed nonoperative management. The principles of operative treatment of stage 2 deformities include transferring another tendon to help serve the role of the
dysfunctional posterior tibial tendon (usually the flexor hallucis longus is transferred). Restoring the shape and alignment of the foot. This moves the weight bearing axis back to the center of the
ankle. Changing the shape of the foot can be achieved by one or more of the following procedures. Cutting the heel bone and shifting it to the inside (Medializing calcaneal osteotomy). Lateral column
lengthening restores the arch and overall alignment of the foot. Medial column stabilization. This stiffens the ray of the big toe to better support the arch. Lengthening of the Achilles tendon or
Gastrocnemius. This will allow the ankle to move adequately once the alignment of the foot is corrected. Stage 3 acquired adult flatfoot deformity is treated operatively with a hindfoot fusion
(arthrodesis). This is done with either a double or triple arthrodesis - fusion of two or three of the joints in hindfoot through which the deformity occurs. It is important when a hindfoot
arthrodesis is performed that it be done in such a way that the underlying foot deformity is corrected first. Simply fusing the hindfoot joints in place is no longer acceptable.