Observer Variability in Assessing Articular Surface Displacement in Acetabular Fractures Using a Standardized Measurement Technique

The objective of this study was to determine the inter- and intraobserver reliability of plain
films as compared with CT scans in quantitatively measuring articular displacement in acetabular fractures utilizing a standardized measurement technique. Three independent reviewers compared the standardized measurement technique to direct measurement of the articular displacement. Weighted kappa statistics were performed to assess the inter- and intraobserver agreement. The standardized method of measurement showed slightly better inter- (0.24) and intraobserver (0.36) reliability for measuring articular displacement, as compared to direct measurement (0.12 and 0.22). Measurements using CT scans showed higher inter- (0.3) and intraobserver (0.43) reliability, when compared to plain radiographs (0.27 and 0.36). Measurements performed on fracture patterns which did not include a posterior wall component had higher inter- (0.41) and intraobserver (0.44) reliability, when compared to patterns with posterior wall fractures (0.12 and 0.22). Based on these results, it was concluded that the use of the standardized method of measurement, as described by Borrelli et al., was not superior to direct measurement of articular displacement. (Journal of Surgical Orthopaedic Advances 18(1):9–12, 2009)