INTRODUCTION: Optimizing patient outcomes in reverse total shoulder arthroplasty remains a subject of ongoing research. Newly described radiographic angles allow the determination of the glenoid and humeral component contributions to lateralization and distalization, which might play a role in patient outcomes. Thus, this study aims to explore the effect of radiographically measured glenoid versus humeral lateralization and distalization on patient reported outcomes and reoperation. METHODS: 217 consecutive patients who underwent rTSA from November 2016 to August 2022 were retrospectively reviewed. Pre-operative and final follow-up subjective shoulder value (SSV), visual analogue scale for pain (VAS), and American Shoulder and Elbow Surgeons Score (ASES), and unplanned reoperations were recorded. Preoperative and postoperative Lateralization Shoulder Angle (LSA) and Distalization Shoulder Angle (DSA) were also recorded. Postoperative Glenoid Lateralization Angle (GLA), Humeral Lateralization Angle (HLA), modified Distalization Shoulder Angle (mDSA), Glenoid Distalization Angle (GDA), and Humeral Distalization Angle (HDA). Correlations between different pairings of radiographic angular measurements were calculated along with correlations between individual radiographic measurements and each patient reported outcome measure. RESULTS: Greater positive change from preoperative to postoperative LSA and smaller postoperative DSA were significantly correlated with improved SSV in both univariable and multivariable analysis. A larger decrease from preoperative to postoperative LSA was associated with higher odds of reporting VAS > 0 on univariable analysis at follow up. Otherwise, there were no associations between radiographic measurements and postoperative outcome scores. The strongest correlation for postoperative lateralization measurements was between LSA and HLA (r = +0.83) and for postoperative distalization measurements was between mDSA and GDA (r = +0.72). Greater postoperative LSA and HLA values had higher odds of reoperation (post LSA OR = 1.11; p = 0.011, post HLA OR = 1.10; p = 0.047). CONCLUSIONS: Greater positive change from preoperative to postoperative LSA was associated with improved subjective-shoulder value scores. Lower global distalization was associated with greater subjective-shoulder value scores. While global lateralization may be beneficial in moderation along with limiting global distalization, the independent effects of glenoid or humeral-sided lateralization or distalization measured radiographically may have a lesser impact on patient reported outcomes.
Kirkham et al. (Thu,) studied this question.