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

Figure 5 Illustration of measurement of the prosthesis-scapular neck angle and the prosthesis-scapular bone angle. A: The prosthesis-scapular neck angle is the angle between a line from superior to inferior along the glenoid baseplate and a line from the most inferior point of the baseplate’s prosthesis-bone interface to a point 1 cm medially along the inferior scapular neck; B: The prosthesis-scapular bone angle uses a point 6 cm medial along the scapular border to draw the second line. PSNA: Prosthesis-scapular neck angle; PSBA: Prosthesis-scapular bone angle. Reprinted with permission from Kempton et al[24], Figure 3.