Step 2- Effect of lateral vs. anterolateral acromioplasty

In a second step lateral and anterolateral acromioplasty of 5mm and 10mm were simulated on the 3 segmented scapulae using Blender 2.78 (Fig. ​(Fig.3).3). Starting position was defined by the preoperative radiographs as well as the preoperative CSA of the unaltered scapula as measured on a true anteroposterior radiograph according to Moor et al. [10]. Each scapula was then rotated in steps of ±10° from -40° (extension) to +40° (flexion). The CSA was measured in every position as the angle between CAP, inferior glenoid rim and superior glenoid rim.

Axial view of the p1 scapula schematically depicting the area of the acromion (green), which is surgically removed during anterolateral (left) and lateral (right) acromioplasty

To increase the validity of the study five additional scapulae (p4-p8) were included. Segmentation of the scapulae from MRI Dicom data, simulation of acromioplasty and CSA measurement were performed identically as described above.

Written informed consent was obtained from all eight patients and Ethic Committee Approval was obtained (KEK Nr.: ZH2016-000826).