Acquired Adult Flatfoot Deformity (AAFD), or Pes Planus, refers to a condition characterized by a progressive flattening or collapse of the arch of the foot. It generally occurs when the posterior tibial tendon, a muscle that attaches the ankle and the midfoot, becomes dysfunctional. This tendon is largely responsible for maintaining the foot’s alignment, arch and a proper gait. AAFD is termed progressive because the process of flattening occurs over a period of time and starts affecting the other soft tissues in the ankle as well as foot. The condition may start with pain in the ankle and lead to permanent deformity or development of Arthritis if not treated.


  • Sudden injury to the posterior tibial tendon/ Posterior Tibial Tendon Dysfunction (PTTD)
  • Existing Flatfoot that further stresses the ligaments and tendons
  • Wear and tear of the soft tissues in the foot or ankle
  • Inflammatory Arthritis not only affects the joints but also the ligaments leading to a fallen arch and painful Flatfoot.
  • Injury to the foot ligament, fracture/dislocation of the midfoot bone


  • Change in alignment of the foot/flattened arch
  • Pain while walking, running or standing for long duration
  • Most of the toes are visible from the back of the foot
  • Limp walk
  • Swelling and tenderness over the inner ankle
  • Longstanding history of pain in the inner or outer ankle
  • Improper alignment of heel and leg
  • Deformity of the forefoot


The orthopedic doctor will be able to assess the problem by looking at the feet when the patient stands. People with AAFD have feet that appear splayed out wherein most of the toes are visible from the back of the foot and the arch is noticeably flattened. Diagnostic tests may include:

  • Single leg-heel rise test – This test requires the patient to stand on one leg and raise the heel above the ground a couple of times. Ability to do so indicates that the posterior tibial is still intact.
  • X-ray of the foot while bearing the complete bodyweight helps to establish the extent of deformity.


Acquired Adult Flatfoot Deformity can generally be treated through non-surgical methods by supporting and strengthening the tendons or ligament.Surgical intervention is required only when these non-operative measures fail to restore the foot arch and balance. Depending on the degree and functional requirement of the patient, a specific or combination of procedures can be used for treatment. These may include:

  • Rest and avoidance of strenuous activities
  • Immobilization of the foot with a cast for a specific time period
  • Orthotic inserts can be prescribed to support the hindfoot
  • Wearing an ankle brace
  • Weight loss to prevent pressure on the soft tissues and ligaments
  • Surgical intervention to lengthen the ligament or muscle
  • Surgical replacement of the affected tendon with another tendon
  • Surgical realignment of bones
  • For diagnosis and treatment of Acquired Adult Flatfoot, visit OrthoTexas.