Terrible Triad Injury

The "terrible triad" is one of the most serious elbow injuries. It is three injuries that happen together: an elbow dislocation (the joint pops out), a fracture of the small bony hook on the front of the ulna that helps lock the elbow in place (the coronoid), and a fracture of the disc-shaped top of the smaller forearm bone (see radial head fracture for more on that piece). Together, these injuries knock out the supports that hold the elbow in place: the bony stops, the ligaments on both sides, and the front of the joint lining. Without surgery to repair each injured part, the elbow simply slips out of place again.

A high-energy elbow injury with an obvious deformity makes the dislocation easy to identify. After your provider puts the joint back into place, a CT scan is obtained: it maps both fractures in 3D so the surgical team can plan exactly which structures need fixing and in what order. Your provider also carefully checks the pulses at your wrist and the sensation in your hand before and after the reduction, since the nerves and arteries running through the elbow can be caught up in this type of injury.

The dislocated elbow goes back into place first; the imaging that follows is used to plan the reconstruction.

Every terrible triad injury needs surgery; there's no non-operative path that ends in a stable, working elbow. The reconstruction usually addresses all three components in one operation: fixing or replacing the radial head, repairing or pinning the coronoid fracture, and reattaching the torn outer ligament (and sometimes the inner one too).

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

• AAOS OrthoInfo, patient education library
• OSI glossary, orthopedic terminology in plain language