Session VI - Upper Extremity

*Coronoid Fracture Patterns

David C. Ring, MD; Massachusetts General Hospital, Boston, Massachusetts, USA (a-AO Foundation)

Purpose: Fractures of the coronoid have been classified on the basis of size alone. With greater experience in treating coronoid fractures, it has become clear to me that the overall injury pattern and specific fragment characteristics may also be important.

Methods: A single surgeon repaired 41 coronoid fractures in 40 patients with fracture-dislocation of the elbow over a 3-year period. Each coronoid fracture was characterized on the basis of operative exposure according to the overall pattern of injury, the pattern of coronoid fragmentation, the size of the fracture fragments, and associated ligament injuries.

Results: The coronoid fracture was associated with an olecranon fracture-dislocation in 22 patients, an elbow dislocation and radial head fracture (terrible triad) in 16 patients, and a posteromedial varus rotational instability pattern in 3 patients. Among patients with olecranon fracture-dislocations, 6 had anterior and 16 had posterior displacement of the forearm. Twenty of the fractures associated with an olecranon fracture involved more than 50% of the coronoid height, and 2 were smaller fractures involving the anteromedial facet and tip of the coronoid process. Among the 20 large coronoid fractures, 9 were large single fragments, 8 had three fragments (anteromedial facet, central, and lesser sigmoid notch), 1 had a single sagittal split, and 2 had more than 3 fragments. Seven patients with posterior olecranon fracture-dislocations had lateral collateral ligament injury, and one with an anterior dislocation had injury to both the medial and lateral collateral ligaments. All 16 patients with terrible triad injuries had small (less than 50%) coronoid fractures and lateral collateral ligament injury. There was a transverse fracture of the tip in 15 patients (14 simple, 1 comminuted) and a fracture of the anteromedial facet and the tip in 1. The three patients with posteromedial varus rotational instability injuries had fracture of the anteromedial facet of the coronoid, fracture of the tip of the coronoid, and fracture of the sublime tubercle. All three had injury to the lateral collateral ligament.

Conclusions: Fractures of the coronoid associated with olecranon fracture-dislocations, terrible triad injuries, and posteromedial varus rotational instability injuries have distinct injury patterns. Small fractures can involve the tip (terrible triad injuries) or the anteromedial facet (all posteromedial varus rotational instability and a few terrible triad and olecranon fracture-dislocations). Large fractures (olecranon fracture-dislocations) can vary substantially. Anticipation and recognition of these patterns can help guide treatment. In particular, anteromedial facet fractures may require a separate medial exposure and internal fixation, and very comminuted large fractures may require hinged external fixation.

* If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options and e-consultant or employee.