Coronoid fracture

The coronoid process is the bony projection at the front of the proximal ulna. It is the primary anterior buttress preventing posterior elbow dislocation, and is where the anterior capsule and the anterior bundle of the MCL attach. Isolated coronoid fractures are uncommon; they most often occur as part of complex elbow dislocations (terrible triad, Monteggia equivalent) or with radial head fractures. The Regan-Morrey classification describes severity (tips, anteromedial facet, basal).

Elbow pain after trauma, typically in the context of a dislocation injury. X-rays and CT characterize the fracture size and displacement. CT is essential for anteromedial coronoid fractures, which are difficult to visualize on plain X-rays.

Larger coronoid fractures associated with elbow instability — particularly anteromedial facet fractures and those in the context of terrible triad — require fixation.

External patient-education references and related OSI pages for additional background:

• Britannica — Bone disease (fractures)
• Britannica — Joint (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language