Trough line sign

Dr Ian Bickle and Radswiki et al.

The trough line sign is a sign of posterior shoulder dislocation on AP films. 

In a posterior dislocation, the anterior aspect of the humeral head becomes impacted against the posterior glenoid rim. With sufficient force, this causes a compression fracture on the anterior aspect of the humeral head. This compression fracture is analogous to the Hill-Sachs compression fracture seen with anterior shoulder dislocation of the glenohumeral joint. 

Frontal radiographs reveal two nearly parallel lines in the superomedial aspect of the humeral head.

Share article

Article information

rID: 12244
Section: Signs
Synonyms or Alternate Spellings:

Support Radiopaedia and see fewer ads

Cases and figures

  • Case 1
    Drag here to reorder.
  • Case 2: trough line sign
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.