The adult acquired flatfoot (AAF) is a progressive, symptomatic (painful) deformity resulting from gradual stretch (attenuation) of the tibialis posterior tendon as well as the ligaments that support the arch of the foot. Although the posterior tibialis tendon plays a significant role, this pathology has recently been recognized as involving failure of other interosseous ligaments, such as the spring ligament. Due to the complexity of this pathology, posterior tibial tendon dysfunction (PTTD) is now referred to as adult acquired flatfoot. Severe flatfoot associated with AAF can lead to other problems, such as plantar fascial tension, tendon pain, rearfoot subluxation, and ankle osteoarthritis.
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.
Many patients with this condition have no pain or symptoms. When problems do arise, the good news is that acquired flatfoot treatment is often very effective. Initially, it will be important to rest and avoid activities that worsen the pain.
Perform a structural assessment of the foot and ankle. Check the ankle for alignment and position. When it comes to patients with severe PTTD, the deltoid has failed, causing an instability of the ankle and possible valgus of the ankle. This is a rare and difficult problem to address. However, if one misses it, it can lead to dire consequences and potential surgical failure. Check the heel alignment and position of the heel both loaded and during varus/valgus stress. Compare range of motion of the heel to the normal contralateral limb. Check alignment of the midtarsal joint for collapse and lateral deviation. Noting the level of lateral deviation in comparison to the contralateral limb is critical for surgical planning. Check midfoot alignment of the naviculocuneiform joints and metatarsocuneiform joints both for sag and hypermobility.
Non surgical Treatment
Conservative treatment also depends on the stage of the disease. Early on, the pain and swelling with no deformity can be treated with rest, ice, compression, elevation and non-steroidal anti-inflammatory medication. Usually OTC orthotic inserts are recommended with stability oriented athletic shoes. If this fails or the condition is more advanced, immobilization in a rigid walking boot is recommended. This rests the tendon and protects it from further irritation, attenuation, or tearing. If symptoms are greatly improved or eliminated then the patient may return to a supportive shoe. To protect the patient from reoccurrence, different types of devices are recommended. The most common device is orthotics. Usually custom-made orthotics are preferable to OTC. They are reserved for early staged PTTD. Advanced stages may require a more aggressive type orthotic or an AFO (ankle-foot orthosis). There are different types of AFO’s. One type has a double-upright/stirrup attached to a footplate. Another is a gauntlet-type with a custom plastic interior surrounded be a lace-up leather exterior. Both require the use of a bulky type athletic or orthopedic shoes. Patient compliance is always challenging with these larger braces and shoes.
When conservative care fails to control symptoms and/or deformity, then surgery may be needed. The goal of surgical treatment is to obtain good alignment while keeping the foot and ankle as flexible as possible. The most common procedures used with this condition include arthrodesis (fusion), osteotomy (cutting out a wedge-shaped piece of bone), and lateral column lengthening. Lateral column lengthening involves the use of a bone graft at the calcaneocuboid joint. This procedure helps restore the medial longitudinal arch (arch along the inside of the foot). A torn tendon or spring ligament will be repaired or reconstructed. Other surgical options include tendon shortening or lengthening. Or the surgeon may move one or more tendons. This procedure is called a tendon transfer. Tendon transfer uses another tendon to help the posterior tibial tendon function more effectively. A tendon transfer is designed to change the force and angle of pull on the bones of the arch. It’s not clear yet from research evidence which surgical procedure works best for this condition. A combination of surgical treatments may be needed. It may depend on your age, type and severity of deformity and symptoms, and your desired level of daily activity.