Adult-acquired flatfoot or collapsed arch occurs because the large tendon on the inside of the ankle - the posterior tibial tendon - becomes stretched out and no longer supports the foot?s arch. In many cases, the condition worsens and and the tendon thickens, becoming painful, especially during activities. Flatfoot or collapsed arch is also known as posterior tibial tendon dysfunction. This condition is different than having flat feet since birth (known as congenital flatfoot), although sometimes these patients develop similar symptoms and require similar treatments.
Posterior tibial tendon dysfunction is the most common cause of acquired adult flatfoot. Sometimes this can be a result of specific trauma, but usually the tendon becomes injured from wear and tear over time. This is more prevalent in individuals with an inherited flat foot but excessive weight, age, and level of activity are also contributing factors.
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.
The diagnosis of posterior tibial tendon dysfunction and AAFD is usually made from a combination of symptoms, physical exam and x-ray imaging. The location of pain, shape of the foot, flexibility of the hindfoot joints and gait all may help your physician make the diagnosis and also assess how advanced the problem is.
Non surgical Treatment
Nonoperative therapy for posterior tibial tendon dysfunction has been shown to yield 67% good-to-excellent results in 49 patients with stage 2 and 3 deformities. A rigid UCBL orthosis with a medial forefoot post was used in nonobese patients with flexible heel deformities correctible to neutral and less than 10? of forefoot varus. A molded ankle foot orthosis was used in obese patients with fixed deformity and forefoot varus greater than 10?. Average length of orthotic use was 15 months. Four patients ultimately elected to have surgery. The authors concluded that orthotic management is successful in older low-demand patients and that surgical treatment can be reserved for those patients who fail nonoperative treatment.
Surgical intervention for adult acquired flatfoot is appropriate when there is pain and swelling, and the patient notices that one foot looks different than the other because the arch is collapsing. As many as three in four adults with flat feet eventually need surgery, and it?s better to have the joint preservation procedure done before your arch totally collapses. In most cases, early and appropriate surgical treatment is successful in stabilizing the condition.