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.

It is usually a unilateral phenomenon. Bilateral posterior ankle impingement syndrome has been described but is rare 5.

Patients usually present with a sharp pain at the back of the ankle upon plantar flexion. The pain might persist for some time after such a movement. 

Thought to occur from repetitive ankle plantar flexion leading to soft tissue compression, synovitis, capsulitis and eventually scarring 6

  • Stieda process
  • os trigonum
  • fracture involving lateral tubercle of the posterior process of the talus
  • prominent superior surface of calcaneal tuberosity
  • prominent downslope of the posterior tibial articular surface
  • any abnormal calcification/ossification posterior to the ankle
  • may demonstrate posterolateral capsular thickening and synovitis involving an intact posterior talofibular ligament (PTFL)
  • 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 tubercle of the posterior talar process
  • localized fluid and/or edema in the posterior joint recesses
  • T1: low signal in areas of bone bruising
  • T2/STIR: high signal posterior to ankle in areas of bone bruising
  • PD/PD fat saturated: high signal posterior to the ankle

Article information

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

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Cases and figures

  • Figure 1: illustration of causes
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  • Case 1
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  • Case 2
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  • Case 3
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