Agreement of olecranon fractures before and after the exposure to four classification systems.

Background: Although classification systems of olecranon fractures are important to help choose the best treatment and to predict prognosis, their degree of observer agreement is poorly investigated. The objective of this study was to investigate the intraobserver and interobserver reliability of currently used classification systems for olecranon fractures. Our hypothesis is that the Colton classification presents an acceptable agreement because it is simpler to use; on the other hand, considering the AO classification's complexity, we expect it to reach a lower level of agreement.