Results: All subjects completed the study through the primary outcome analysis. Mean pain after surgery was: interscalene = 1.9 (95% CI, 1.3 to 2.5), supraclavicular = 2.3 (1.7 to 2.9), suprascapular = 2.0 (1.4 to 2.6). The primary outcome, mean pain score difference of supraclavicular–interscalene was 0.4 (–0.4 to 1.2; P = 0.088 for noninferiority) and of suprascapular–interscalene was 0.1 (–0.7 to 0.9; P = 0.012 for noninferiority). Secondary outcomes showed similar opioid consumption with better preservation of vital capacity in the anterior suprascapular group (90% baseline [P < 0.001]) and the supraclavicular group (76% [P = 0.002]) when compared to the interscalene group (67%).
Conclusions: The anterior suprascapular block, but not the supraclavicular, provides noninferior analgesia compared to the interscalene approach for major arthroscopic shoulder surgery. Pulmonary function is best preserved with the anterior suprascapular nerve block.