Elbow radiographic anatomy: Measurement techniques and normative data

Background: An increase in elbow pathology in adolescents has paralleled an increase in sports participation. Evaluation and classification of these injuries is challenging because of limited information regarding normal anatomy. The purpose of this study was to evaluate normal radiographic anatomy in adolescents to establish parameters for diagnosing abnormal development. Established and new measurements were evaluated for reliability and variance based on age and sex. Methods: Three orthopaedic surgeons independently, and in a standardized fashion, evaluated the normal anteroposterior and lateral elbow radiographs of 178 adolescent and young adult subjects. Fourteen measurements were performed including radial neck-shaft angle, articular surface angle, articular surface morphologic assessment (subjective and objective evaluation of the patterns of ridges and sulci), among others. We performed a statistical analysis by age and sex for each measure and assessed for inter- and intraobserver reliability. Results: The distal humerus articular surface was relatively flat in adolescence and became more contoured with age, as objectively demonstrated by increasing depth of the trochlear and trochleocapitellar sulci, and decreasing trochlear notch angle. Overall measurements were similar between males and females, with an increased carrying angle in females. There were several statistically significant differences based on age and sex; but these were small and unlikely to be clinically significant. Inter and intraobserver reliability were variable; some commonly utilized tools had poor reliability. Conclusion: Most commonly utilized radiographic measures were consistent between sexes, across the adolescent age group, and between adolescents and young adults. Several commonly used assessment tools show poor reliability.