Comparison of axillary lateral radiography with computed tomography in the preoperative characterization of glenohumeral wear patterns and the effects of body mass index on quality of imaging

Background: Preoperative imaging is important in planning glenoid component placement in shoulder arthroplasty. This study compared preoperative axillary lateral radiography with CT to determine which was more effective in characterization of glenoid erosion and subluxation and in measurement of glenoid version. We also sought to determine the effect of body mass index (BMI) on image quality. Methods: Eighty-eight patients who had shoulder arthroplasty for primary glenohumeral osteoarthritis were included. The Walch and Mayo classifications as well as glenoid version measurements were used. Kappa coefficients were obtained for interclass and intraclass reliabilities. Intraclass and interclass correlation coefficients were calculated for glenoid version measurements. Results: For glenoid erosion and subluxation, intraobserver and interobserver reliabilities indicated moderate (k=0.19-0.28) and fair agreement (k=0.41-0.50), respectively, which were similar for both imaging modalities and classifications. For glenoid version, interobserver reliability was good for both modalities, but intraobserver reliability showed substantial agreement for CT and only good agreement for radiographs (k=0.77, k=0.91, k=0.65-0.7, respectively). Increased BMI negatively affected image quality in both but more so on radiographs (P<0.0001). Conclusions: Both modalities had similar intraobserver and interobserver agreement; however, CT provided significantly more precise measurements of glenoid version regardless of classification used. A high BMI significantly affected the observers’ ability to judge classifications, especially on radiographs.