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Baumann's Angle

Summary:

  • Baumann's angle is used for assessing supracondylar fractures (distal fracture of the humerus).  
  • The angle is determined by drawing a line straight down through the middle of the humeral shaft and then through the trochlea and then drawing a line that is perpendicular to the humeral shaft line. Then a line is made parallel, but running through the lateral condylar physis. 
  • The angle between the humeral shaft line and the parallel line to the lateral condylar physis should be about 70 - 75 degrees.

Baumann's Angle

    Baumann's Angle X-Ray Image




    How to Measure

    Baumann's angle is one of several radiographic methods used when assessing for the presence of a supracondylar fracture on an AP radiograph (x-ray).  It can be formed by:

    • Drawing a line straight down through the middle of the humeral shaft and then through the trochlea and then drawing a line that is perpendicular to the humeral shaft line.
    • Then a line is made parallel, but running through the lateral condylar physis. 
    Clinical Application
    • The angle between the humeral shaft line and the parallel line to the lateral condylar physis should be about 70-75 degrees.  Anything greater than this is concerning for fracture with displacement. 
    • It should be compared to the other (non-inured elbow) as a comparison and a difference of more than 5 degrees suggests a coronal plane deformity.
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    References
      1. Williamson DM et al. Normal characteristics of the Baumann (humerocapitellar) angle: an aid in assessment of supracondylar fractures. J Pediatr Orthop 1992;12(5):636-9.  PubMed
      Editors & Reviewers

      Editors:  Anthony J. Busti, MD, PharmD, FNLA, FAHA
      Last Updated:  June 2015