Assessment of scapular morphology and surgical technique as predictors of notching in reverse shoulder arthroplasty.

There has been increased focus on understanding risk factors for scapular notching in reverse shoulder arthroplasty (RSA). We conducted a study to evaluate the scapular notching index and other factors associated with the occurrence of scapular notching. Ninety-one patients treated with primary RSA were followed for a minimum of 24 months. Patients' radiographic assessments were grouped by Nerot grade of scapular notching (group 1, grades 0 and 1; group 2, grades 2, 3, 4). Group mean differences were compared for preoperative scapular neck angle (SNA), prosthesis-scapular neck angle (PSNA), peg glenoid rim distance (PGRD), notching index, and clinical outcomes. There was no significant difference in mean (SD) notching index between group 1, 31.8 (4.4), and group 2, 33.1 (7.3), and there were no significant differences in SNA (102.8° vs 105.4°; P=.3), PSNA (125.8° vs 125.4°; P=.82), PGRD (15.4 vs 16.8 mm; P=.47), or clinical outcomes between the groups. Our results suggest that Grammont-style prostheses have a higher rate of notching regardless of optimal PGRD and variations in PSNA. Perhaps with certain scapular morphology, prosthetic design may be a more significant contributor to notching.