Osteology of the coronoid process with clinical correlation to coronoid fractures in terrible triad injuries

Background: Terrible triad complex elbow fracture-dislocations are represented by elbow dislocations associated with fractures of the coronoid and radial head. Published literature has focused on classifying coronoid fractures by their radiographic morphology on plain x-ray images and computed tomography imaging. No study has specifically related native coronoid osteology to in situ fracture morphology. We identified 3 distinct bony regions of the coronoid, (medial, intermediate, and lateral ridges) with correlation to common fracture patterns associated with terrible triad injuries. Methods: Coronoid osteology in 8 fresh frozen cadaveric elbows was examined, and three distinct ridges were identified and dimensions measured. Results: The measurements were compared with retrospective intraoperative measurements taken of coronoid fracture fragments being stabilized during terrible triad injury repair. Conclusion: Classification of native coronoid process anatomy into functional ridges (medial, intermediate, lateral) may improve our understanding of coronoid fracture patterns in unstable terrible triad injuries. Level of evidence: Basic Science, Anatomic Study, Cadaver and In Vivo. (C) 2013 Journal of Shoulder and Elbow Surgery Board of Trustees.