Adult acquired flatfoot deformity (AAFD) is a progressive flattening of the foot arch, primarily caused by the deterioration of the posterior tibial tendon located in the lower leg. AAFD is also referred to by several other names such as posterior tibial tendon dysfunction, posterior tibial tendon insufficiency, and dorsolateral peritalar subluxation. This condition can evolve from initial stages involving pain and swelling along the posterior tibial tendon to eventual complete collapse of the arch and development of arthritis in the hindfoot and ankle.

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Anatomy

The posterior tibial muscle originates from the lower leg bones (tibia and fibula) and transitions into the posterior tibial tendon, which extends behind the inside of the ankle and attaches to the navicular bone along the foot's instep. This tendon is crucial for maintaining the foot arch during standing and walking.

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Apart from the tendons spanning ankle and foot joints, numerous ligaments stabilize these joints. Over time, these ligaments at the inner ankle may become stretched, contributing to the progressive flattening of the arch.

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Various muscles and tendons around the ankle and foot counterbalance the posterior tibial tendon's action. However, when this tendon fails, other muscles become relatively dominant, leading to the progressive deformity characteristic of AAFD.

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Symptoms

Individuals with AAFD commonly experience pain, deformity, and/or swelling around the ankle or hindfoot. Initially, pain and swelling along the posterior tibial tendon behind the inner ankle are typical symptoms.

As the condition progresses, foot and ankle deformities may arise, including:

• Progressive flattening of the arch

• Outward shifting of the heel, misaligning it from the leg

• Rotational deformity of the forefoot

• Tightening of the Achilles tendon

• Development of arthritis

• Deformity of the ankle joint

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At certain stages, pain may shift from the inner to the outer ankle as the heel shifts outward, causing pinching of structures on the outer ankle.

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Causes

Posterior tibial tendon dysfunction is the primary cause of AAFD, often stemming from gradual wear and tear rather than a specific event or injury. It is more prevalent in individuals with flat feet from birth or due to other factors, as the increased stress on the posterior tibial tendon and ligaments within the foot and ankle leads to progressive deformity. Weight also influences the condition's progression, with significant weight loss potentially improving symptoms.

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Diagnosis

AAFD diagnosis typically involves assessing symptoms, physical examination, and X-rays. Dr. Kamel evaluates pain location, foot shape, hindfoot joint flexibility, and gait to diagnose and determine the disorder's severity.

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Treatments

Treatment options depend on symptoms, goals, deformity severity, and arthritis presence. Non-surgical approaches such as rest, immobilization, orthotics, braces, and physical therapy may suffice for some patients. Immobilization with a boot can alleviate tendon stress and reduce inflammation in early-stage disease, followed by transition to arch supports or orthotics. Flatfoot reconstruction surgery may be necessary for advanced cases, involving procedures such as tendon and ligament lengthening, tendon transfers, bone realignment, or joint fusion, tailored to the patient's condition and goals.

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Recovery

Recovery duration varies based on treatment modality, ranging from several weeks to months. Full improvement may take 1-2 years after surgery. Whether long-term orthotic or brace use is necessary depends on the severity of deformity and tendon damage.