Optimal Screw Placement for Reverse Total Shoulder Arthroplasty

The reverse design of the total shoulder arthroplasty has been utilized for elderly patients with severely degenerated glenohumoral joints that are rotator cuff deficient. One of the most common causes of failure in shoulder arthroplasty involves loosening or catastrophic failure of the glenoid component. Such problems can be related to suboptimal fixation due to bone loss from fractures, severe degenerative changes and from previous failed arthroplasty surgery [1]. This emphasizes the need to secure the glenoid component with sound screw purchase beyond the glenoid vault. However, such fixation can often be tenuous as scapula bone quality is heterogeneous with a wide variation across short distances [2, 3]. Moreover, it can be difficult to identify regions with the best bone stock intraoperatively. This often requires multiple passes with the drill, which leads to further bone loss and potential decreased screw purchase. Thus, it is important for the surgeon to have a firm understanding of scapular anatomy with potential screw trajectories in mind.