Analysis of radial head and coronoid process fractures in terrible triad of elbow.

PURPOSE

To describe the morphological characteristics of radial head and coronoid fractures and evaluate the relationship of two fracture patterns in terrible triad.

METHODS

Distributions of all types of radial head and coronoid fractures according to the Mason, Regan-Morrey, and O'Driscoll classifications were firstly described by reviewing radiographs and computed tomography scans in 92 consecutive terrible triads. Then, distributions of all combinations of radial head and coronoid fractures were reported. Correlation analysis between severity of radial head and coronoid fractures was finally performed.

RESULTS

In radial head fractures, Mason 2 accounted for 68%, Mason 3 accounted for 32%, and no Mason 1 was found. In coronoid fractures, there were 29 type 1, 44 type 2, and 19 type 3 in Regan-Morrey classification and 72 type 1, one type 2, and 19 type 3 in O'Driscoll classification. There were 28 M2R2, 23 M2R1, 16 M3R2, 12 M2R3, seven M3R3, and six M3R1 in combined Mason and Regan-Morrey type. There were 53 M2O1, 19 M3O1, 10 M3O3, nine M2O3, and one M2O2 in combined Mason and O'Driscoll type. A weak correlation was found between radial head and coronoid fractures.

CONCLUSIONS

In terrible triad injuries, the most common type of radial head fracture is Mason 2, while the most common type of coronoid fracture is Regan-Morrey type 2 or O'Driscoll type 1. In combinations of two fracture patterns, M2R2 or M2O1 is the most common. Severity of radial head fractures is weakly correlated with coronoid fractures.