Figure 2: (a) Measurement of prosthesis-scapular neck angle (PSNA) and peg-glenoid rim distance (PGRD). The distance from A to B is the PGRD, and the angle AB to BC is the PSNA. (b) Measurement of base plate distance. Positive numbers denote placement of the glenoid baseplate above the inferior rim of the glenoid, negative numbers denote placement below the inferior rim of the glenoid