Parsonage-Turner syndrome (PTS) is an underdiagnosed condition that presents with debilitating symptoms in affected patients, with reported incidence rates varying between 1.64 and 3 per 100,000 individuals. Clinical presentation often includes acute shoulder pain associated with neurological deficits that do not follow a regular diagnostic pattern. The cause of this disease is not fully understood, but it is generally triggered by an upper respiratory infection a few weeks prior to presentation. Other associated risk factors include genetic predisposition, vaccines, and surgical intervention. Diagnosis often relies on clinical investigation, holistic physical exam, and appropriate diagnostic studies. Treatment is often conservative, in the form of physical rehabilitation and pain management to avoid muscular atrophy. The condition generally resolves over time, with a recovery rate of 65% at 10 months and a favorable prognosis for most cases. However, recurrences are noted, especially in patients with a genetic predisposition to the condition (75% in the hereditary form vs. 26% in the general form). Future research should explore the pathophysiological processes behind this disease to extrapolate strategies that can achieve an earlier diagnosis and more effective treatment.

Shoulder pain and shoulder surgery are increasingly prevalent and encompass a broad spectrum of pathologies, including rotator cuff disease, glenohumeral osteoarthritis, and shoulder instability. Growing evidence suggests that gender-related factors influence disease presentation, patient-reported outcomes, and postoperative recovery; however, these effects remain inconsistently reported across the literature. This current concepts review synthesizes available evidence on the influence of gender on pre-operative characteristics, non-operative management, and postoperative outcomes following common shoulder procedures, including rotator cuff repair, anatomic and reverse shoulder arthroplasty, and surgical stabilization for instability. A comprehensive literature search of PubMed, the Cochrane Library, and Google Scholar was performed for studies published through October 2025, with outcomes assessed using validated instruments such as the Western Ontario Rotator Cuff Index, American Shoulder and Elbow Surgeons score, Constant-Murley score, Simple Shoulder Test, Visual Analog Scale, and Shoulder Pain and Disability Index. Across shoulder pathologies, female patients consistently demonstrated worse pre-operative functional scores, higher pain levels, and greater perceived disability despite similar structural disease severity. Postoperatively, both genders experienced meaningful clinical improvement; however, females often reported higher early postoperative pain and lower absolute functional outcomes, particularly following shoulder arthroplasty for glenohumeral osteoarthritis and surgical treatment of multidirectional instability. In contrast, outcomes following rotator cuff repair and anterior instability stabilization were largely comparable between genders. Recognition of these gender-related differences is essential for individualized patient counseling, expectation setting, and optimization of management strategies, and highlights the need for future studies with robust gender-disaggregated analyses.

Introduction Acromioclavicular (AC) joint separation is a common injury that results from direct or indirect trauma to the shoulder. The purpose of this study was to explore the incidence, demographic variations, and injury mechanisms of AC joint separations in the United States from 2004 to 2023. Methods The National Electronic Injury Surveillance System database was queried to identify all patients who visited participating emergency departments between 2004 and 2023 and were diagnosed with an AC joint separation. Examined variables included age, sex, year, and injury mechanisms. National injury estimates were calculated using sample weights. Annual incidence rates were calculated using U.S. Census population estimates. Results A total of 4163 AC joint separations were recorded, representing an estimated 196,983 injuries. The overall incidence rate was 3.1 per 100,000 person-years. The highest incidence of AC joint separations was among patients aged 10 to 30 years (47.6%), and the majority of patients were male (83.9%). Sports-related injuries had a significantly greater incidence rate compared to transportation-related and fall-related injuries (p < 0.001). The most common injury mechanisms involved bicycles (15.9%), football (10.5%), stairs/steps (6.0%), and snowboarding (5.8%). Conclusion The incidence of AC joint separations has increased over the past two decades, with the majority caused by sports-related and transportation-related injuries. Level of Evidence: III

BACKGROUND:Submission techniques are a major part of mixed martial arts (MMA) and can result in a wide range of injuries to different parts of the body. Knowledge of the patterns of these submissions is lacking in literature. The aim of this study was to provide a comprehensive analysis of the submissions performed during MMA bouts in the Ultimate Fighting Championship (UFC). METHODS:All UFC pay-per-view (PPV) events from UFC 1-294 were screened via the official UFC website. Results of match scorecards, event characteristics, year, number of submission finishes, number of male and female fights per event, UFC fighter characteristics, gender, weight division, anatomical location of submission, type and round of submission, were recorded. Submission rates were assessed between different subgroups. An independent t-test, ANOVA test and Joinpoint regression analysis were used to explore relationships between different variables, with P value less than 0.05 deemed significant. RESULTS:A total of 293 PPV events were included from 1993 to 2023, comprising a total of 3123 professional fights, 272 of which occurred prior to the implementation of the unified rules of MMA. Overall, 618 fights ended in submission, comprising an overall submission rate of 19.8%. No significant difference was found between submission rates of male and female fighters(P=0.853). Submission rates were found to significantly decrease across the years from the first PPV(P<0.001). The head was the most commonly targeted anatomical location of all submissions (74.3%, P<0.001). Choking submissions were significantly more common than non-choking submissions (65.5% vs. 34.5%, P<0.001), with the rear naked choke being the most utilized submission maneuver (32.7%). Among male fighters, a higher number of submission finishes occurred in intermediate weight divisions compared to lighter and heavier weight divisions. CONCLUSIONS:The submission rate in the UFC is around 20%. While submission rates are decreasing, our study found that the head was most targeted, the majority were choking submissions, and intermediate weight divisions recorded a higher number of submission finishes. Future studies should work on addressing the sequelae of submission procedures on the health and safety of fighters.

BACKGROUND:Rotator cuff repair (RCR) is a frequently performed outpatient orthopaedic surgery, with substantial financial implications for health-care systems. Time-driven activity-based costing (TDABC) is a method for nuanced cost analysis and is a valuable tool for strategic health-care decision-making. The aim of this study was to apply the TDABC methodology to RCR procedures to identify specific avenues to optimize cost-efficiency within the health-care system in 2 critical areas: (1) the reduction of variability in the episode duration, and (2) the standardization of suture anchor acquisition costs. METHODS:Using a multicenter, retrospective design, this study incorporates data from all patients who underwent an RCR surgical procedure at 1 of 4 academic tertiary health systems across the United States. Data were extracted from Avant-Garde Health's Care Measurement platform and were analyzed utilizing TDABC methodology. Cost analysis was performed using 2 primary metrics: the opportunity costs arising from a possible reduction in episode duration variability, and the potential monetary savings achievable through the standardization of suture anchor costs. RESULTS:In this study, 921 RCR cases performed at 4 institutions had a mean episode duration cost of $4,094 ± $1,850. There was a significant threefold cost variability between the 10th percentile ($2,282) and the 90th percentile ($6,833) (p < 0.01). The mean episode duration was registered at 7.1 hours. The largest variability in the episode duration was time spent in the post-acute care unit and the ward after the surgical procedure. By reducing the episode duration variability, it was estimated that up to 640 care-hours could be saved annually at a single hospital. Likewise, standardizing suture anchor acquisition costs could generate direct savings totaling $217,440 across the hospitals. CONCLUSIONS:This multicenter study offers valuable insights into RCR cost as a function of care pathways and suture anchor cost. It outlines avenues for achieving cost-savings and operational efficiency. These findings can serve as a foundational basis for developing health-economics models. LEVEL OF EVIDENCE:Economic and Decision Analysis Level III. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:Allograft prosthetic composite (APC) and megaprosthesis (MP) have both been used to reconstruct the proximal humerus after its resection due to primary or secondary tumors. However, varied results have been reported in the literature with no consensus on which reconstruction has better overall outcomes. METHODS:PubMed, Cochrane, and Google Scholar (pages 1-20) were queried through September 2024. The compared outcomes consisted of adverse events, patient-reported outcomes measures, and range of motion. Ten studies and 400 patients were included, with 115 in the APC group and 285 in the MP group. RESULTS:The APC group had a higher rate of reoperations (odds ratio, 2.50; 95% CI, 1.40-4.45; P=0.002) than did the MP group over an average follow-up of 7.0 years. However, better postoperative flexion (mean difference, 10.11; 95% CI, 5.33-14.90; P<0.001) and Musculoskeletal Tumor Society scores (mean difference, 3.73; 95% CI, 1.37- 6.08; P=0.002) were seen in the APC group. CONCLUSIONS:The present study shows a lower rate of revision with the use of MP but better functional outcomes and forward flexion with APC as the surgical option for proximal humerus reconstruction. Level of evidence: III.

Background:This study reviews interventional clinical trials to evaluate the efficacy and evolution of current therapeutic strategies for shoulder instability. Methods:ClinicalTrials.gov was queried using key search terms for interventional clinical trials targeting shoulder instability. Data extracted included phase, status, duration, country, population size, age groups, study design, enrollment models, interventions, and outcomes. Publication rate was calculated by the ratio of published articles to total number of included trials. Results:Forty-five interventional trials investigating shoulder instability were included. Most trials did not have a defined phase. Most trials (>90 %) began post-2010 with an average duration of 37 months. Europe/UK/Russia led in trial numbers (55.6 %). Primary endpoints focused on shoulder function and mobility, with the Western-Ontario-Shoulder-Instability-Index being the most common outcome measure. Interventions included surgical procedures (46.7 %), physical therapy (37.8 %), behavioral therapy (4.4 %), and other modalities (11.1 %). Nine trials produced 14 publications, resulting in a publication rate of 25.9 %. Published results varied, including comparisons of treatment efficacy, such as heavy versus light strengthening programs, and outcomes for surgical and non-surgical interventions. Conclusion:Interventional trials on shoulder instability are limited, mostly originating from Europe and North America. Low publication rates and lack of blinding highlight areas for improvement. Publishing results is essential for continuous development and outcome improvement.

Background: Augmenting subscapularis peel repairs with the long head of the biceps tendon (LHBT) may provide increased strength to the repaired construct. We aimed to report on the early outcomes of anatomic total shoulder arthroplasty (aTSA) in patients whose subscapularis peel repairs were augmented with LHBT autografts. Methods: All patients who underwent aTSA with augmentation of subscapularis peel repair using LHBT were reviewed. Patients were included if they had a minimum 1-year follow-up. Preoperative demographics and intraoperative information were recorded. Primary outcomes were American Shoulder and Elbow Surgeon (ASES) scores and visual analog scale (VAS) pain scores, which were assessed at 3, 6, and 12 months, as well as changes in range of motion values. Results: Sixteen patients with a mean age of 63.3 years and a mean follow-up of 12.4 months were included in the study. Six patients were female and 10 were male. Average LHBT length was 7.3 cm (range, 6.5-9.0 cm). Two patients were converted to reverse shoulder arthroplasty (12.5%). For the remaining 14 patients, there were statistically significant improvements exceeding the minimal clinically important difference in both ASES (34.1-92.1, P<0.001) and VAS (6.3-0.9, P<0.001) scores. Patients exhibited a mean improvement of 47.7 degrees in forward elevation (P<0.001), 30.8 degrees in abduction (P<0.001), 21.4 degrees in external rotation (P<0.001), and a 3-level improvement for internal rotation. Conclusions: At 1-year minimum follow-up, patients who underwent aTSA with augmentation of the subscapularis peel repair with the LHBT demonstrated favorable outcomes. Level of evidence: IV.

BACKGROUND:The introduction of patient-specific instrumentation (PSI) in total shoulder arthroplasty (TSA) has improved implant positioning accuracy. However, whether PSI yields additional clinical benefit compared to standard instrumentation (SI) in the setting of primary TSA (anatomic and reverse) remains unclear. METHODS:PubMed, Cochrane, Embase, and Google Scholar were queried through August 2024. Inclusion criteria consisted of studies that compared PSI to SI in TSA (anatomic and reverse). Key outcomes analyzed included adverse events, patient-reported outcomes, and discrepancies between planned and achieved implant positioning. RESULTS:Five retrospective studies, three randomized controlled trials, and one prospective study met the inclusion criteria. There was no difference in complications (odds ratio [OR], 1.00; 95% CI, 0.16 to 6.10; P=1.00), reoperation (OR, 1.35; 95% CI, 0.37 to 4.91; P=0.65), American Shoulder and Elbow Surgeons score (mean difference [MD], 1.61; 95% CI, -4.08 to 7.30; P=0.58), Constant-Murley Score (MD, 3.06; 95% CI, -3.68 to 9.81; P=0.37), version error (MD, -0.76; 95% CI, -2.51 to 0.99; P=0.40), and inclination error (MD, -2.89; 95% CI, -5.82 to 0.05; P=0.05) between the two groups. CONCLUSIONS:This study found no significant differences in patient-reported outcomes, complication rates, or implant positioning accuracy between PSI and SI in primary TSA. Future randomized controlled trials comparing these two types of instrumentation would be useful to assess whether a benefit exists for PSI in the setting of primary TSA. Level of evidence: III.

» Medicare reimbursement: Physician payments have declined 29% since 2001, straining practice sustainability. Proposed legislation (H.R. 2474) could align payments with inflation, although concerns persist about its fiscal impact on Medicare.» Medicare advantage: These plans provide benefits such as cost caps and premium-free options for patients, but increase administrative burdens, delay care, and restrict provider networks for physicians.» Prior authorization: Intended to ensure appropriate care and control costs, prior authorization frequently delays treatment, raises administrative workloads, and contributes to physician burnout. Proposed reforms aim to balance efficiency and oversight.» Noncompete clauses: Advocates argue noncompete clauses protect healthcare investments, but critics highlight their role in limiting physician mobility, disrupting patient care, and reducing competition. Legal challenges to a federal ban add uncertainty.» Physician-owned hospitals: Supporters emphasize physician-owned hospitals' high-quality care and competitive benefits, whereas detractors warn of risks such as conflicts of interest, inequities in patient access, and strain on community hospitals.» Advancing nonopioid pain management: Nonopioid strategies reduce dependency risks and improve recovery but may require additional resources and upfront costs. Policies such as the Non-Opioids Prevent Addiction in the Nation Act aim to incentivize their use.

Purpose To evaluate the efficacy of isolated subacromial balloon spacer implantation in patients with massive irreparable rotator cuff tears (MIRCTs), as evidenced by changes in patient-reported outcomes and range-of-motion values. Methods A retrospective review of prospectively collected data was conducted for patients with MIRCTs who underwent subacromial balloon spacer implantation alone without any concomitant procedures, with a minimum 1-year follow-up. Patient demographics and preoperative magnetic resonance imaging findings were recorded. Outcomes included the American Shoulder and Elbow Surgeons (ASES) score, visual analog scale (VAS) pain score, active forward elevation, complications, and reoperations. Results A total of 34 patients (18 women, 16 men) were included. The mean age was 65.9 years, and the mean follow-up period was 15.9 months. On preoperative magnetic resonance imaging, the mean posterosuperior rotator cuff tear size was 3.57 cm, mean retraction size was 3.7 cm, 71% were Goutailler grade III/IV, and 94% had none or minimal osteoarthritis. There were no complications, and 2 patients (5.9%) underwent conversion to reverse shoulder arthroplasty. Significant improvements were observed in mean forward elevation (136.6 ° to 150.4 °, P = .009), ASES scores (39.5 to 76.1, P < .001), and VAS scores (6.1 to 2.1, P < .001) at final follow-up. At the final follow-up, 90.3% of patients reached the minimal clinically important difference for ASES scores, and 87.1% reached the minimal clinically important difference for VAS scores. Conclusions Isolated subacromial balloon spacer implantation is an effective treatment option for patients with MIRCTs, evident by the significant improvements in forward elevation and high rates of clinically meaningful ASES and VAS scores at a minimum 1-year follow-up. Level of Evidence Level IV, retrospective case series.

➢ Medical malpractice litigation in orthopaedic surgery remains a major challenge, as the field consistently ranks among the most frequently litigated specialties. Malpractice claims in orthopaedics often involve surgical errors, misdiagnoses, delayed treatment, and inadequate postoperative care, with substantial financial and emotional consequences for health-care providers. ➢ Malpractice risk varies by orthopaedic subspecialty, with adult reconstruction and spine surgeons facing the highest litigation rates, often due to nerve injuries, delayed or missed diagnoses, or postoperative complications. Although defense verdicts are the most common outcome, substantial settlements and plaintiff verdicts occur in cases involving irreversible damages, inadequate informed consent, or technical errors. ➢ Proactive risk management and legal preparedness can help to mitigate liability and protect physicians. Preventative strategies include clear, supportive communication to build patient trust, comprehensive documentation ensuring adherence to evidence-based guidelines, and diagnostic accuracy through use of objective tools.

Background: With the increased utilization of Total Shoulder Arthroplasty (TSA) in the outpatient setting, understanding the risk factors associated with complications and hospital readmissions becomes a more significant consideration. Prior developed assessment metrics in the literature either consisted of hard-to-implement tools or relied on postoperative data to guide decision-making. This study aimed to develop a preoperative risk assessment tool to help predict the risk of hospital readmission and other postoperative adverse outcomes. Methods: We retrospectively evaluated the 2019-2022(Q2) Medicare fee-for-service inpatient and outpatient claims data to identify primary anatomic or reserve TSAs and to predict postoperative adverse outcomes within 90 days postdischarge, including all-cause hospital readmissions, postoperative complications, emergency room visits, and mortality. We screened 108 candidate predictors, including demographics, social determinants of health, TSA indications, prior 12-month hospital, and skilled nursing home admissions, comorbidities measured by hierarchical conditional categories, and prior orthopedic device-related complications. We used two approaches to reduce the number of predictors based on 80% of the data: 1) the Least Absolute Shrinkage and Selection Operator logistic regression and 2) the machine-learning-based cross-validation approach, with the resulting predictor sets being assessed in the remaining 20% of the data. A scoring system was created based on the final regression models' coefficients, and score cutoff points were determined for low, medium, and high-risk patients. Results: A total of 208,634 TSA cases were included. There was a 6.8% hospital readmission rate with 11.2% of cases having at least one postoperative adverse outcome. Fifteen covariates were identified for predicting hospital readmission with the area under the curve of 0.70, and 16 were selected to predict any adverse postoperative outcome (area under the curve = 0.75). The Least Absolute Shrinkage and Selection Operator and machine learning approaches had similar performance. Advanced age and a history of fracture due to orthopedic devices are among the top predictors of hospital readmissions and other adverse outcomes. The score range for hospital readmission and an adverse postoperative outcome was 0 to 48 and 0 to 79, respectively. The cutoff points for the low, medium, and high-risk categories are 0-9, 10-14, >= 15 for hospital readmissions, and 0-11, 12-16, >= 17 for the composite outcome. Conclusion: Based on Medicare fee-for-service claims data, this study presents a preoperative risk stratification tool to assess hospital readmission or adverse surgical outcomes following TSA. Further investigation is warranted to validate these tools in a variety of diverse demographic settings and improve their predictive performance. Level of evidence: Level III; Retrospective Cohort Design Using Large Database; Prognosis Study (c) 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

As the incidence of reverse total shoulder arthroplasty (RSA) continues to increase with its expanding indications, a growing number of patients are being considered for bilateral RSA. This review aims to explore the functional outcomes of patients with bilateral RSA and examine the effect of risk factors and implant positioning on internal rotation. Multiple studies have reported favorable results in bilateral RSA patients, with significantly improved patient-reported and clinical outcomes bilaterally. Although challenges remain in achieving reliable improvements in internal rotation following RSA, several studies to date have demonstrated that bilateral RSA patients are able to retain independence in personal hygiene and activities of daily living, with difficulty experienced primarily only in extreme internal rotation tasks, such as washing the back or securing a bra. Nevertheless, compensatory strategies can enable patients to manage these limitations effectively. Patients who have undergone bilateral RSA demonstrate functional outcomes and perform internal rotation tasks at a level comparable to that of patients who have undergone bilateral anatomic total shoulder arthroplasty or a combination of total shoulder arthroplasty and RSA. Risk factors for internal rotation deficits after RSA include poor preoperative functional internal rotation, increased body mass index, preoperative opioid use, and preoperative diagnosis of a massive irreparable rotator cuff tear. Lateralization and inferior positioning of the glenoid component as well as humeral component retroversion can increase functional internal rotation, while repairing the subscapularis does not appear to offer any clinically significant benefit. Although some patient and surgical factors have been associated with internal rotation deficits after RSA, further investigation is necessary to better characterize the underlying causes of this issue.

Background/Objectives: The utility of artificial intelligence (AI) in medical education has recently garnered significant interest, with several studies exploring its applications across various educational domains; however, its role in orthopedic education, particularly in shoulder and elbow surgery, remains scarcely studied. This study aims to evaluate the performance of multiple AI models in answering shoulder- and elbow-related questions from the AAOS ResStudy question bank. Methods: A total of 50 shoulder- and elbow-related questions from the AAOS ResStudy question bank were selected for the study. Questions were categorized according to anatomical location, topic, concept, and difficulty. Each question, along with the possible multiple-choice answers, was provided to each chatbot. The performance of each chatbot was recorded and analyzed to identify significant differences between the chatbots’ performances across various categories. Results: The overall average performance of all chatbots was 60.4%. There were significant differences in the performances of different chatbots (p = 0.034): GPT-4o performed best, answering 74% of the questions correctly. AAOS members outperformed all chatbots, with an average accuracy of 79.4%. There were no significant differences in performance between shoulder and elbow questions (p = 0.931). Topic-wise, chatbots did worse on questions relating to “Adhesive Capsulitis” than those relating to “Instability” (p = 0.013), “Nerve Injuries” (p = 0.002), and “Arthroplasty” (p = 0.028). Concept-wise, the best performance was seen in “Diagnosis” (71.4%), but there were no significant differences in scores between different chatbots. Difficulty analysis revealed that chatbots performed significantly better on easy questions (68.5%) compared to moderate (45.4%; p = 0.04) and hard questions (40.0%; p = 0.012). Conclusions: AI chatbots show promise as supplementary tools in medical education and clinical decision-making, but their limitations necessitate cautious and complementary use alongside expert human judgment.

BACKGROUND:Hemiarthroplasty (HA) and anatomic total shoulder arthroplasty (aTSA) have been used to manage advanced stages of osteonecrosis of the shoulder. However, varied results have been reported in the literature with no consensus on which surgery yields better results. METHODS:PubMed, Cochrane, and Google Scholar (pages 1 to 20) were queried through August 2024. Inclusion criteria consisted of studies that compared the utility of HA with that of aTSA for the treatment of shoulder osteonecrosis. The compared outcomes consisted of adverse events (complications, and revision surgeries), patient-reported outcomes measures (American shoulder and elbow surgeons score), and range of motion, including forward flexion (FF), external rotation, and internal rotation (IR). RESULTS:Eight studies with a total of 504 patients met the above inclusion criteria. HA was shown to have a lower rate of complications (11.60% vs. 29.80%, odds ratio = 0.39, P < 0.001) and revision surgeries (7.70% vs. 17.60%, odds ratio = 0.33, P = 0.05) relative to aTSA at an average follow-up of 7.9 years. Better postoperative FF (mean difference = 19°; P < 0.001) and IR (standardized mean difference = 1°, P = 0.05) was seen in the HA group despite no observed difference at baseline. No difference was seen in external rotation (mean difference = 3°, P = 0.44) or American shoulder and elbow surgeons score (mean difference = 9.56, P = 0.17) between the two groups. CONCLUSION:This study supports HA and aTSA as viable surgical options for patients with shoulder osteonecrosis. In the currently available literature, HA had lower rates of complications and revision surgeries along with better observed postoperative FF and IR compared with aTSA. However, larger cohort studies and randomized controlled trials comparing these two procedures in patients with shoulder osteonecrosis are needed to establish clinical guidelines for this relatively rare pathology. LEVEL OF EVIDENCE:III.

Subscapularis dysfunction remains a devastating postoperative complication that negatively affects surgical outcomes following anatomic total shoulder arthroplasty (aTSA). This systematic review aims to determine the incidence of subscapularis failure following aTSA and evaluate the effectiveness of various surgical techniques and repair strategies. We conducted a comprehensive literature search following PRISMA guidelines across PubMed, Cochrane, and Embase databases up to August 21, 2023. Included studies explicitly described aTSA and related complications, excluding those that did not differentiate aTSA outcomes from other procedures or were reviews, case reports, or cadaveric studies. We extracted data on demographics, surgical approaches, subscapularis management techniques, repair strategies, and the subscapularis failure rates. This review included 56 studies published between 2010 and 2023, covering 6173 patients. The overall subscapularis failure rate was 3.7

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.