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Last revised by Dr Yuranga Weerakkody on 20 Mar 2022

Sprain refers to an injury of ligaments and capsules and should not be confused with the strain which refers to an injury to muscles and their tendons. These terms should not be used interchangeably.


Knee, ankle and acromioclavicular joints are the most common location of the ligamentous sprain.


Some authors classify sprain into the following grades

  • grade 1 
    • stretching +/- minimal tearing (no macroscopic rupture)
    • heals completely without any instability
  • grade 2 
    • larger but incomplete tearing/partially disrupted fibers
    • leads to the weakened ligament which predisposes to the recurrent injuries
  • grade 3 
    • complete tearing/rupture
    • leads to chronic joint instability

Radiographic features

The imaging modalities for the diagnostic workup and grading of the sprain are ultrasound and MRI which show following features:

  • thickened and hypoechoic ligament with an area of discontinuity in the fibers.
  • edema along the injured ligament.
  • hemorrhage

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Cases and figures

  • Case 1: ulnar collateral ligament sprain
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