Understanding the Adult Flatfoot Deformity

Adult Acquired Flatfoot Deformity is one of the most common acquired pathologies of the adult foot. Most often it results due to dysfunction of the tibialis posterior tendon. Other causes include inflammatory arthritis, trauma, neuromuscular causes and Charcot arthropathy.

Why is the Posterior Tibial Tendon (PTT) Important

  • The PTT converts a flexible valgus hindfoot at heel strike to a rigid Varus alignment at toe off phase of the gait cycle. So now the entire length of the foot acts as a rigid lever that lifts and propels the body during the last phase of the gait cycle.
  • With progressive dysfunction of the posterior tibial tendon-
  1. The medial longitudinal arch collapses,
  2. The subtalar joint everts,
  3. The heel bends in an outward direction.


  • Initially there is pain & swelling on the inner or medial aspect of the foot accompanied with swelling
  • As the deformity progresses there is pain on the outer aspect of the foot due to sub fibular impingement
  • Increasing difficulty in wearing shoes and worsening of pain on activity or even prolonged standing
  • Too Many Toes’ Sign – with advanced deformity and outward rotation of the forefoot, more of the lateral toes become visible when viewed from behind

Treatment options:

·         Physical therapy
·         Stretching and strengthening exercises
·         Anti-inflammatory medications
·         Orthotics

Stage and progression of the flatfoot deformity determines the degree and duration of the conservative treatment. The patient should be encouraged to lose weight, modify repetitive loading activities, and use orthotic, supportive insoles.