Prosthetic design of reverse shoulder arthroplasty contributes to scapular notching and instability

Figure 3 The prosthesis-scapular neck angle (PSNA) is the angle subtended by the intersection of line AB and line BC. Point C is located 1 cm medial to the junction of the glenosphere and the most inferior and lateral bone of the inferior glenoid rim or scapular neck. The peg-glenoid rim distance (PGRD) is the distance between points B and D. PGRD: Peg-glenoid rim distance; PSNA: Prosthesis-scapular neck angle. Reprinted with permission from Simovitch et al[16], Figure 4A.