Perioperative deltoid pathologies in the setting of reverse shoulder arthroplasty: a narrative review.

Background and Objective: The reverse total shoulder arthroplasty (RSA) is a widely used innovative procedure for managing shoulder pathologies like severe rotator cuff arthropathy, osteoarthritis with significant glenoid deformity, or proximal humerus fractures. RSA prosthesis designs utilize the deltoid muscle to bypass the role of the rotator cuff, and to generate most of the force required for shoulder elevation. As such, preoperative deltoid insufficiency or injury, as well as any intraoperative or postoperative complications involving the deltoid, can significantly impact patient outcomes, rehabilitation, and recovery following RSA. The aim of our review is to highlight the critical role of the deltoid muscle in RSA and discuss the different perioperative challenges that may impact its function and the overall success of the procedure. Methods: The PubMed/MEDLINE database was screened for studies describing or reporting peri-operative deltoid or axillary nerve pathologies in the setting of RSA, from database inception until August of 2023. Articles were excluded if animals subjects were involved, or if they were written in the non-English language. Relevant search terms were used, and additional articles were retrieved from the reference lists of included articles. Key Content and Findings: Ensuring the health and integrity of the deltoid muscle is essential for obtaining successful RSA outcomes. At the preoperative stage, deltoid insults can occur due to imbalances in glenohumeral musculature, pre-existing axillary nerve injury and subsequent deltoid atrophy, and concurrent viral infections. Remaining vigilant regarding diagnosis is important at this stage, as surgical treatment should be delayed until symptomatic resolution occurs. Intraoperatively, deltoid injuries can occur due to significant retraction, dissection, or iatrogenic fractures or nerve injuries. Conducting periodic intraoperative axillary nerve assessments and utilizing intraoperative nerve monitoring allow surgeons to potentially intervene in order to help minimize nerve damage. Postoperatively, pathologies can occur due to deltoid fatigue or acromial stress fractures. At that stage, educating patients about potential setbacks is important to set appropriate expectations and minimize injury risk. Conclusions: Considering the importance of the deltoid in achieving proper RSA outcomes, significant attention should be garnered towards its integrity and health throughout the perioperative process.