Statistical shape modeling-based reconstruction eliminates the need for full scapular computed tomography scan data in preoperative total shoulder arthroplasty planning

Abstract

BackgroundPreoperative total shoulder arthroplasty (TSA) planning tools use a three-dimensional (3D) model of the full scapula based on computed tomography (CT) images with a scan length covering the complete scapula with a given radiation exposure for patients. The aim of this study is to investigate whether full scapular models can be reconstructed from partial CT data. MethodsIn this retrospective cohort study, bone models representing 5 scan lengths with decreasing levels of scapular coverage (level 1-5) were created. All the models were reconstructed with a validated statistical shape model (SSM) allowing automatic 3D measurements of glenoid version, inclination, scapular offset, and center point position. Radiation exposure between 2 patient groups (group 1 = corresponding to L1, group 2 = complete scapula) was compared. ResultsIn terms of inclination and version, we found a mean absolute difference between the complete model and the different partial scan models of 0.5° (SD 0.4°). The maximum difference was 3° for inclination and 2° for version. For scapular offset and center point position, the mean difference was 0 mm (max 1 mm). The mean radiation exposure was 4 mSv (SD 2 mSv) for group 1 and 13 mSv (SD 6 mSv) for group 2 (P = .009). ConclusionAn SSM-based reconstruction technique can accurately reconstruct complete scapular bone models based on partial CT scan data. Incorporation of an SSM-based reconstruction technique in software tools for preoperative TSA planning would lead to decreased radiation exposure (9 mSv) for patients without influencing its accuracy.