Ulnar fractures most commonly result from injury to the forearm.  Isolated ulnar diaphyseal fractures are known as “night stick” fractures as the injury may occur when the patient blocks overhead contact from a blunt object. Isolated ulnar diaphyseal fractures are notoriously slow healers and have a high rate of nonunion (up to 25% with closed treatment). Fractures of the proximal one-third of the ulna have the highest rate of nonunion. Isolated diaphyseal fractures with <50% of fracture opposition and 10 to 15 degrees of angulation are considered stable and can be treated conservatively. Nonoperative treatment includes a short arm cast or splint for 2 to 4 weeks. Early motion of the forearm has been shown to improve fracture union rates compared with a longer period of casting. The interosseous membrane and the distal radial-ulnar joint provide stability to the ulnar diaphyseal fracture during forearm rotation; this allows for immediate elbow motion.  Patients should be restricted from lifting with the arm until bridging callus is noted radiographically.1,2

Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).


  1. Pollock FH, Pankovich AM, Prieto JJ, Lorenz M. The isolated fracture of the ulnar shaft. Treatment without immobilization. J Bone Joint Surg Am. 1983;65(3):339-342.
  2. Wheeless CR. Ulna/ulnar shaft fracture. Wheeless’ Textbook of Orthopaedics website. http://www.wheelessonline.com/ortho/ulna_ulnar_shaft_fracture. Updated April 11, 2015. Accessed March 11, 2019.  
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