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Overview
Adult-acquired flatfoot (AAF) is the term used to describe the progressive deformity of the foot and ankle that, in its later stages, results in collapsed and badly deformed feet. Although the condition has been described and written about since the 1980s, AAF is not a widely used acronym within the O&P community-even though orthotists and pedorthists easily recognize the signs of the condition because they treat them on an almost daily basis. AAF is caused by a loss of the dynamic and static support structures of the medial longitudinal arch, resulting in an incrementally worsening planovalgus deformity associated with posterior tibial (PT) tendinitis. Over the past 30 years, researchers have attempted to understand and explain the gradual yet significant deterioration that can occur in foot structure, which ultimately leads to painful and debilitating conditions-a progression that is currently classified into four stages. What begins as a predisposition to flatfoot can progress to a collapsed arch, and then to the more severe posterior tibial tendon dysfunction (PTTD). Left untreated, the PT tendon can rupture, and the patient may then require a rigid AFO or an arthrodesis fixation surgery to stabilize the foot in order to remain capable of walking pain free.


Causes
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
The first stage represents inflammation and symptoms originating from an irritated posterior tibial tendon, which is still functional. Stage two is characterized by a change in the alignment of the foot noted on observation while standing (see above photos). The deformity is supple meaning the foot is freely movable and a ?normal? position can be restored by the examiner. Stage two is also associated with the inability to perform a single-leg heel rise. The third stage is dysfunction of the posterior tibial tendon is a flatfoot deformity that becomes stiff because of arthritis. Prolonged deformity causes irritation to the involved joints resulting in arthritis. The fourth phase is a flatfoot deformity either supple (stage two) or stiff (stage 3) with involvement of the ankle joint. This occurs when the deltoid ligament, the major supporting structure on the inside of the ankle, fails to provide support. The ankle becomes unstable and will demonstrate a tilted appearance on X-ray. Failure of the deltoid ligament results from an inward displacement of the weight bearing forces. When prolonged, this change can lead to ankle arthritis. The vast majority of patients with acquired adult flatfoot deformity are stage 2 by the time they seek treatment from a physician.

Diagnosis
It is of great importance to have a full evaluation, by a foot and ankle specialist with expertise in addressing complex flatfoot deformities. No two flat feet are alike; therefore, "Universal" treatment plans do not exist for the Adult Flatfoot. It is important to have a custom treatment plan that is tailored to your specific foot. That starts by first understanding all the intricacies of your foot, through an extensive evaluation. X-rays of the foot and ankle are standard, and MRI may be used to better assess the quality of the PT Tendon.

Non surgical Treatment
Stage one deformities usually respond to conservative or non-surgical therapy such as anti-inflammatory medication, casting, functional orthotics or a foot ankle orthosis called a Richie Brace. If these modalities are unsuccessful surgery is warranted.


Surgical Treatment
In cases where cast immobilization, orthoses and shoe therapy have failed, surgery is the next alternative. The goal of surgery and non-surgical treatment is to eliminate pain, stop progression of the deformity and improve mobility of the patient. Opinions vary as to the best surgical treatment for adult acquired flatfoot. Procedures commonly used to correct the condition include tendon debridement, tendon transfers, osteotomies (cutting and repositioning of bone) and joint fusions. (See surgical correction of adult acquired flatfoot). Patients with adult acquired flatfoot are advised to discuss thoroughly the benefits vs. risks of all surgical options. Most procedures have long-term recovery mandating that the correct procedure be utilized to give the best long-term benefit. Most flatfoot surgical procedures require six to twelve weeks of cast immobilization. Joint fusion procedures require eight weeks of non-weightbearing on the operated foot - meaning you will be on crutches for two months. The bottom line is, Make sure all of your non-surgical options have been covered before considering surgery. Your primary goals with any treatment are to eliminate pain and improve mobility. In many cases, with the properly designed foot orthosis or ankle brace, these goals can be achieved without surgical intervention.