Scapular notching in reverse shoulder arthroplasty

The causes and consequences of scapular notching after reverse shoulder arthroplasty (RSA) were investigated in 326 consecutive patients (337 shoulders) undergoing RSA between 1991 and 2003. Patients underwent 269 (80%) primary RSAs and 68 revisions of unconstrained shoulder prosthesis. At last follow-up (average, 47 months; range, 24-120 months) 62% had scapular notching. Notching frequency and extension were correlated to the length of follow-up (P = .0005). Notching was more frequent in cuff tear arthropathy (P = .0004), grade 3 or 4 fatty infiltration of the infraspinatus (P = .01), and narrowed acromiohumeral distance (P < .0001). Glenoids preoperatively oriented superiorly were more at risk for notching (P = .006). More notching occurred when the RSA was implanted using an anterosuperior approach vs a deltopectoral approach (P < .0001). Notching was correlated with humeral radiolucencies in proximal zones (P < .0001) and with glenoid radiolucent lines (P < .0001). Positioning of the baseplate definitely influences scapular notching. High positioning of the baseplate and superior tilting must be avoided.