Apparently isolated partial articular fractures of the radial head: prevalence and reliability of radiographically diagnosed displacement.

The purpose of this study was to measure the prevalence and reliability of the radiographic diagnosis of displacement of apparently isolated partial articular radial head fractures and use these factors to assess treatment considerations. Among 119 radiographically visible partial fractures of the radial head not associated with other wrist, forearm, or elbow injury, 101 were classified as Mason type 1 (85%), 11 as borderline between Mason type 1 and Mason type 2 fractures (9%), and 7 as Mason type 2 fractures (6%) according to Broberg and Morrey's modification of the Mason classification. The intraobserver reliability of the classification of Mason type 1 and type 2 fractures was excellent (mean kappa, 0.85), but the interobserver reliability was only moderate (multirater kappa, 0.45). Because apparently isolated, stable partial fractures of the radial head are infrequently displaced and observers have moderate disagreement regarding the diagnosis of displacement, it is likely that displacement is overdiagnosed.