Interobserver and intraobserver variations in radial head fracture classification-assessment of two classification systems

Objective: The aim of this study was to evaluate the intra- and interobserver variation of two classification systems for radial head fractures (Mason and Charalambous classifications) using plain radiographs.

Material and methods: Five observers classified 30 radial head fractures as per the two classifications using anteroposterior and lateral elbow radiographs. Assessments were done on two occasions, at least 6 weeks apart.

Results: The interobserver and intraobserver variation of the Mason classification showed fair (mean kappa = 0.33) and moderate agreement (mean kappa = 0.43) respectively. The interobserver and intraobserver variation of the Charalambous classification showed moderate agreement for both (mean kappa = 0.42 and 0.49 respectively). A greater proportion of radial head fractures could be classified using the Charalambous classification compared with the Mason classification (P < 0.001). With the Charalambous classification, the inter-observer variation was better when assessing fracture morphology (4 morphology groups) versus fracture displacement (2 displaced/un-displaced groups) (p = 0.010).

Conclusions: The Mason and Charalambous classifications for radial head fractures confer similar reliability when using plain radiographs, but the latter allows a greater proportion of fractures to be classified. Raters may agree more on fracture morphology as compared to fracture displacement. Our findings also demonstrate the limitations of using plain radiographs in classifying radial head fractures for clinical or research purposes, and suggest that evaluation with more sensitive modalities such as Computed Tomography may be preferable.