Posterior ankle impingement syndrome

Posterior ankle impingement (PAI) syndrome is one of the impingement syndromes involving the ankle. It is classically described in ballet dancers.

Pathophysiology

Thought to occur from repetitive ankle plantar flexion.

Predisposing anatomical factors
  • Stieda process
  • os trigonum
  • fracture involving lateral tubercle of posterior process of talus
  • prominent superior surface of calcaneal tuberosity
  • prominent down slope of posterior tibial articular surface
  • any abnormal calcification/ossification posterior to the ankle

Radiographic features

MRI ankle
  • may demonstrate posterolateral capsular thickening and synovitis involving an intact posterior talofibular ligament 
  • there may be tenosynovitis involving the flexor hallucis longus (FHL)
  • may show one or more of the predisposing anatomical factors
  • accompanying bone contusion may be present involving the lateral talar tubercle

Signal characteristics of the affected region include:

  • T1: low signal in areas of bony bruising
  • T2/STIR: high signal posterior to ankle in areas of bone bruising
  • PD/PD fat saturated: high signal posterior to the ankle
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Article Information

rID: 10754
Synonyms or Alternate Spellings:
  • Os trigonum syndrome
  • talar compression syndrome
  • PAI syndrome
  • Posterior ankle impingement (PAI) syndrome

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Cases and Figures

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