Does bony increased-offset reverse shoulder arthroplasty decrease scapular notching?

Background: The purpose of this cohort study was to compare scapular notching rates, range of motion, and functional outcomes between patients who underwent a standard Grammont-style reverse shoulder arthroplasty (RSA) and patients who underwent bony increased-offset reverse shoulder arthroplasty (BIO-RSA) at a minimum of 2 years' follow-up. We hypothesized that the BIO-RSA cohort would have lower notching rates and improved rotational range of motion; however, validated outcome scores between cohorts would be no different. Methods: A comparative cohort study was designed after a sample size calculation. A total of 40 patients were studied with 20 in each cohort (RSA vs BIO-RSA). All patients underwent an interview and physical examination. Outcomes included range of motion; shoulder strength; Disabilities of the Arm, Shoulder and Hand (DASH) score; American Shoulder and Elbow Surgeons score; Simple Shoulder Test score; Constant score; and Global Rating of Change scale score. Radiographs were obtained for all patients and examined for scapular notching. Results: When we compared demographic characteristics between the standard RSA and BIO-RSA cohorts, including age, sex, and follow-up duration, there were no significant differences between groups (P > .05). In addition, there were no significant differences between cohorts when we compared forward elevation (P=.418); external rotation (P =.999); internal rotation (P=.071); strength (P >.376); Disabilities of the Arm, Shoulder and Hand score (P=.229); American Shoulder and Elbow Surgeons score (P=.579); Simple Shoulder Test score (P=.522); Constant score (P=.917); or Global Rating of Change scale score (P=.167). The frequency of scapular notching, however, was significantly higher (P=.022) in the RSA cohort than in the BIO-RSA cohort: 75% versus 40%. Conclusions: Although the scapular notching rate was significantly higher in the standard RSA group, no other outcome measures were statistically different, including range of motion, strength, and validated outcome scores. (C) 2015 Journal of Shoulder and Elbow Surgery Board of Trustees.