Assessment of articular fragment displacement in acetabular fractures: a comparison between computerized tomography and plain radiographs / 中华创伤骨科杂志

ABSTRACT

Objectives To evaluate plain radiographs and computed tomography (CT) scans in respect of assessment of articular fragment displacements (step and gap) in displaced acetabular fractures. Methods A retrospective evaluation was done to analyze the CT scans and plain radiographs of 64 patients who had been treated for displaced acetabular fractures in our hospital from January 1998 to May 2003. Of them, 20 met the inclusion criteria. In a blind method, 3 independent reviewers measured step and gap deformities on plain radiographs and CT scans utilizing a standardized measurement technique. The sensitivity and specificity of plain radiographs in detecting step and gap displacements (2 mm and 4 mm) in comparison of those of CT scans were determined. Moreover, intraclass correlation coefficient and intraobserver reliability were also calculated. Results Compared with CT, plain radiographs showed poor sensitivity in detecting step deformity (sensitivity = 44.3%). As far as fracture type was concerned, plain radiographs were particularly poor at detecting step deformity in fractures involving a single column of the acetabulum (sensitivity = 0%). Excellent intraobserver and intraclass reliability existed among the 3 reviewers. Conclusions Compared with CT scans, plain radiographs are poorly sensitive in detection of step and gap deformities in patients with acetabular fractures, and particularly poor at detecting step deformities. Therefore, in treatment of displaced acetabular fractures, CT scans are essential and should not only be used together with plain radiographs in the preoperative evaluation but also be considered in the postoperative assessment of fracture reduction and predicting future outcomes.