Intrarater and interrater reliability of the socket version marker in total hip replacement

The aim of this study was to evaluate the intraobserver and interobserver variability in determining the socket version using the wire marker. 100 anteroposterior pelvis radiographs of cemented primary total hip replacements were reviewed by two orthopaedic consultants and registrars, twice. Intrarater and interrater reliability were assessed using Cohen's kappa. Intrarater kappas for junior doctors were 0.78 and 0.80, 0.73 and 0.62 for Consultants. Interrater kappas were 0.60 between the two Consultants and 0.63 between the two Junior Doctors. The kappas between Consultant A and Junior Doctor A was 0.61, between Consultant A and Junior Doctor B was 0.59, between Consultant B and Junior Doctor A was 0.53 and between Consultant B and Junior Doctor B was 0.46. Intrarater reliability was substantial for the two junior doctors and the two consultants. Interrater reliability was moderate-to-substantial between the two consultants, between the two junior doctors and between each pair of junior doctors/consultants.