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Adult Acquired Flatfoot

What is Adult Acquired Flatfoot?

Adult Acquired Flatfoot Deformity (AAFD) refers to a condition in which the arch of the foot collapses, causing the sole to turn outward due to foot-related complications. While many individuals with flat feet can find relief through orthotics, braces, and physical therapy, surgery becomes a viable option when these measures fail to alleviate pain and improve the condition.

What does Adult Acquired Flatfoot feel like?

Patients with AAFD commonly experience soreness, contortion, and inflammation of the ankle or hindfoot. Dysfunction of the posterior tibial tendon, a major contributor to AAFD, can lead to various foot and ankle problems.

Depending on the underlying issue, a patient’s flatfoot condition can manifest in different forms, including but not limited to the following:

  • Pain and swelling: An achy feeling can be noticed along the inner side of the foot and ankle, where the posterior tibial tendon is located. This might also lead to increased swelling in that area.
  • Pain that worsens with activity: Engaging in high-impact activities such as running can be quite challenging. Some patients might find it difficult to walk or stand for extended periods.
  • Pain on the outside of the ankle: When the foot loses its arch and the heel bone moves out of alignment, pressure can build up on the outer ankle bone (fibula), resulting in discomfort. Similarly, arthritic inflammation in the heel can trigger a similar painful sensation.
  • Pain from old injuries: People who have experienced an earlier injury or have arthritis in the middle of the foot could develop painful bony protrusions on the top and inner parts of their feet. This can make wearing shoes very uncomfortable. In some cases, these bony protrusions might press on nerves, leading to numbness that spreads to the top of the foot and down into the toes.
  • Diabetes-related symptoms: In individuals with diabetes, an abnormally large bump or swelling on the foot might serve as an initial warning sign. Interestingly, due to reduced sensitivity, this bump might not cause any pain. However, without regularly using appropriate footwear for diabetics, this bump could result in skin problems and even ulcers.

What causes Adult Acquired Flatfoot?

Several factors contribute to AAFD:

Posterior Tibial Tendon Dysfunction (PTTD)

The primary culprit in AAFD is the posterior tibial tendon. Originating from a calf muscle, this tendon runs down the inner lower leg before anchoring to the inner side of the foot. It’s one of the leg’s most vital tendons, supporting the foot’s arch as you walk.

However, inflammation or tearing can weaken the tendon, causing the arch to gradually collapse. Individuals over 40 and women are more susceptible to posterior tibial tendon issues. Being overweight, diabetic, or having hypertension increases the risk further. People born with flat feet, especially those engaging in strenuous activities like basketball, soccer, or tennis, are also prone to tendon tears due to repetitive strain.


Inflammatory arthritis, such as rheumatoid arthritis, is an underlying cause of painful flatfoot. It not only damages joint cartilage but also weakens the ligaments that maintain proper foot alignment. This condition not only causes discomfort but also deformity, often impacting the midfoot and back areas, leading to arch collapse.


Injuries to the ligaments in the foot can result in joint misalignment. These ligaments, which support and stabilise bones, can become torn, resulting in flatfoot deformity and significant pain, particularly in the midfoot area or Lisfranc injury. Additionally, bone fractures or dislocations can contribute to foot flattening.

Diabetic Collapse (Charcot Foot)

Individuals with diabetes or nerve conditions that affect foot sensation are at higher risk for severe arch collapse. They might experience ligament breakdown, bone fractures, or disintegration without feeling discomfort. Surgical treatment is challenging for this condition, making special shoes or braces more effective in providing support.

What are the non-surgical options for Adult Acquired Flatfoot?

Orthotics, braces, and physical therapy can significantly assist in managing the symptoms of flatfoot for many individuals. If these options haven’t provided significant relief, surgery might be considered an effective solution to reduce pain and correct any deformities.

What are the surgical options for Adult Acquired Flatfoot?

When non-surgical methods are ineffective, surgery can be considered. The specific method used depends on how severe the condition is and what the patient wants to achieve. Surgery can involve various approaches, such as lengthening ligaments and muscles, removing inflamed tendon lining, moving tendons, reshaping bones, using implants to realign the foot, and even fusing joints.

If the condition is in its early stages, treatment usually combines tendon and ligament procedures with additional osteotomies (bone reshaping) to correctly reposition the foot.

For more advanced cases involving fixed deformities or arthritis, fusion surgeries may be recommended. These surgeries involve eliminating the joint that connects two bones. While this effectively corrects deformities and provides added stability, it’s important to note that such treatments can result in reduced flexibility and restricted foot movement.

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For further inquiries or to arrange a consultation, please contact Professor Al Muderis’ office at +61 2 88829011 or book an appointment online.