Posterior Tibial Tendon Dysfunction (PTTD) / Adult acquired flat foot

A progressive debilitating inflammation/degeneration of the muscle in the shin called the tibialis posterior leading to adult-acquired flat foot deformity. Over time if uncorrected it may lead to joints becoming rigid as the tendon problems affect the areas around them.

IMPORTANT NOTE: degeneration of the tendons starts a long time before the disease becomes noticeable to the person!   


Flat foot (pes planus) foot type puts people at risk along with knee problems like “knock-knee” (genu valgum).  

The tibialis posterior muscle is the main muscle to hold up the arch and helps the body move forward to the other foot when walking

This muscle can be forced to work harder than it should because of the way the certain bodies are constructed. This can lead to tiny tears in the muscle or tendon and can eventually lead to muscle and ligament failure. 

If not managed early enough this problem can lead to deformities such as:

  • Duck-footing (Out-toeing).
  • Rolling in.
  • Arch flattening.   
  • Tight calf muscles.

Risk factors

  • Middle aged women (up to 10% prevalence) 
  • Young athletes 
  • Arthritis  
  • Extra bones in the foot
  • Pes planus foot type (flat foot) 
  • Hypermobility  
  • Overuse 
  • Hypertension (high blood pressure) 
  • Obesity 
  • Diabetes 
  • Previous trauma 
  • Steroid use 


NSAID’s (Ibuprofen & Nurofen) and changes to activities/exercise and then based on adapted based on which stage:

Stage I

  • Immobilization with CAM (Moon boot) 3-4 weeks depending on severity
  • Footwear changes
  • Stretching as required of associated muscles
  • Muscle strengthening and rehabilitation thereafter
  • Orthotics
  • Surgery if not improved after 3-4 months.

Stage II-IV

  • As above but with surgical consultation and with different complexity of surgery depending on the severity of the condition. Ranging from heel bone reduction with tendon repair and reattachment to ankle fusion and re-alignment.

Clinical presentation / diagnostic indicators:

  • Previous damage to the area (up to 50%)  
  • Pain and swelling of the inside aspect of foot and ankle exacerbated by activity (see image on the left)
  • Standing on toes can be painful (or walking up and down stairs) 
  • Reduced balance 
  • Inability to perform one-sided heel raise on the affected side  
  • Reduced ankle mobility 
  • Reduced strength / painful when movements are resisted by an assistant 
  • Painful passive foot out-turning  
  • Diagnosis can be confirmed on Ultrasound, Xray can be helpful in showing the extent of the deformity and for pre-surgery assessment 

Other similar conditions to rule out:

  • Tarsal coalition (abnormal bony-bridging between two normally disconnected bones)
  • Inflammatory arthritis
  • Charcot arthropathy (rare breakdown of the ankle bones and joints)
  • Neuromuscular disease (rare problems with the nerves that affect muscles and prevent them from functioning normally)
  • Trauma to ligaments holding the foot together


  • Stage I: Posterior tibial tendon intact and inflamed, no deformity, mild swelling
  • Stage II: Posterior tibial tendon dysfunctional, flat foot but the foot joints still moveable when assessed by the podiatrist, commonly unable to perform a heel raise
  • Stage III: Arthritic changes in the joints around the ankle and the joints are immoveable on assessment
  • Stage IV: Tilting of the bone inside the ankle leading to ankle arthritic deterioration