Coronoid Fracture

The coronoid process is a small bony hook at the front of the upper end of your forearm bone (the ulna). It works like a doorstop — physically blocking the elbow from dislocating backward — and serves as an attachment point for ligaments that stabilize the joint. A coronoid fracture by itself is unusual; usually it shows up as part of a more complex elbow injury (a full elbow dislocation, a terrible triad injury that combines a coronoid fracture with damage to the radial head and ligaments, or a fractured radial head). Your surgeon will use the Regan-Morrey classification to grade severity — from a small chip off the tip to a large break through the base.

A coronoid fracture almost always happens as part of an elbow dislocation, so the symptoms overlap heavily with that injury. Your elbow swells rapidly, and you feel a deep ache at the front of the joint. Trying to straighten or bend the arm is painful and may feel mechanically blocked — as if something is caught inside the joint. Bruising typically spreads across the inner elbow and down the forearm within the first day or two.

If the elbow was dislocated and then put back into place, instability is the key concern: you may feel a clunk or sense that the elbow wants to slide back out when you try to extend it. Numbness or tingling along the ring and small fingers can occur if swelling compresses the ulnar nerve where it passes behind the inner elbow.

Elbow pain after a fall or impact — usually as part of a larger dislocation injury. X-rays and a CT scan together show the size of the fracture and how much it's shifted. The CT is essential for fractures involving the inner-front facet of the coronoid; those can be very hard to spot on plain X-rays alone.

Larger coronoid fractures that leave the elbow unstable — particularly anteromedial facet fractures and those that are part of a terrible triad injury — need surgical fixation to restore the doorstop and let the elbow heal stable.

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