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With the rising prevalence of shoulder arthroplasty, the incidence of revision shoulder arthroplasty is also increasing. The complexity of these revision procedures poses significant challenges, with bone loss being a critical factor impacting treatment outcomes. Addressing substantial humeral bone defects is crucial for ensuring implant stability and functionality. A comprehensive literature review was conducted using PubMed, Medline, and Google Scholar to identify existing classification systems for proximal humeral bone loss in the context of revision shoulder arthroplasty. The study assessed the advantages and limitations of these classifications, using this information to propose a new diagnostic and therapeutic algorithm. Several classification systems for proximal humeral bone loss were identified. McLendon et al. classify proximal humeral bone loss based on a 5-cm bone loss threshold and suggest an allograft prosthesis composite for losses exceeding this limit. Boileau's system stratifies bone loss into four types based on the extent of loss, with specific recommendations for each category. The PHAROS classification provides a detailed anatomical assessment but lacks quantitative precision. The proposed PHBL-SCORe system offers a novel algorithm incorporating preoperative radiographic measurements to determine the percentage of bone loss and guide treatment options. Proximal humeral bone loss presents significant challenges in revision shoulder arthroplasty, necessitating precise preoperative planning and classification to guide surgical intervention. Existing classification systems provide valuable frameworks but often rely on average population values, neglecting individual anatomical variations. The proposed PHBL-SCORe system offers a patient-specific approach, improving the accuracy of bone loss assessment and optimizing treatment strategies. Implementing this classification in clinical practice could enhance surgical outcomes and reduce complications associated with rRSA (revision Reverse Shoulder arthroplasty). Further studies are required to validate this algorithm and explore its long-term efficacy in diverse patient populations.

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INTRODUCTION: In reverse shoulder arthroplasty (RSA) new designs enable greater amounts of lateralization to prevent instability and scapular notching and increase range of motion, however, excessive lateralization leads to stress upon the acromion that can result in scapular spine fatigue fractures. Aim of this study was to gender- and size-specifically assess the influence of glenosphere size and different humeral designs on lateralization, distalization, and bony impingement-free range of motion (ROM) in patients undergoing RSA. METHODS: Computed tomography scans from 30 osteoarthritic patients (f:15, m:15) and 20 cuff tear arthropathy patients (f:10, m:10) were used to virtually simulate RSA implantation. The efficacy of an inlay Grammont-type system vs. an onlay lateralizing system combined with different glenosphere sizes (36 mm vs. 42 mm) in achieving ROM, lateralization, and distalization was evaluated. Moreover, gender and patient's constitution were correlated to humeral size by radiologically measuring the best-fit circle of the humeral head. RESULTS: A different amount of relative lateralization was achieved in both genders using large glenospheres and onlay designs. Latter yielded a higher ROM in all planes for men and women with a 42 mm glenosphere; with the 36 mm glenosphere, an increased ROM was observed only in men. The 155° inlay design led to joint medialization only in men, whereas all designs led to lateralization in women. When adjusting the absolute amount of lateralization to humerus' size (or patient's height), regardless of implant type, women received greater relative lateralization using 36 mm glenosphere (inlay: 1%; onlay 12%) than men with 42 mm glenosphere (inlay: -3%; onlay: 8%). CONCLUSION: The relative lateralization achieved using onlay design is much higher in women than men. Small glenospheres yield greater relative lateralization in women compared to large glenospheres in men. Humeral lateralization using onlay designs should be used cautiously in women, as they lead to great relative lateralization increasing stress onto the acromion. LEVEL OF EVIDENCE: Basic Science Study, Computer Modeling.

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BACKGROUND AND PURPOSE: We aimed to report the survival of different reverse shoulder arthroplasty (RSA) designs and brands, and factors associated with revision. The secondary aim was to evaluate the reasons for revision. METHODS: We included 4,696 inlay and 798 onlay RSAs reported to the Norwegian Arthroplasty Register (NAR) 2007-2022. Kaplan-Meier estimates of survivorship and Cox models adjusted for age, sex, diagnosis, implant design, humeral fixation, and previous surgery were investigated to assess revision risks. The reasons for revision were compared using competing risk analysis. RESULTS: Overall, the 10-year survival rate was 94% (confidence interval [CI] 93-95). At 5 years all brands exceeded 90%. Compared with Delta Xtend (n = 3,865), Aequalis Ascend Flex (HR 2.8, CI 1.7-4.6), Aequalis Reversed II (HR 2.2, CI 1.2-4.2), SMR (HR 2.5, CI 1.3-4.7), and Promos (HR 2.2, CI 1.0-4.9) had increased risk of revision. Onlay and inlay RSAs had similar risk of revision (HR 1.2, CI 0.8-1.8). Instability and deep infection were the most frequent revision causes. Male sex (HR 2.3, CI 1.7-3.1), fracture sequelae (HR 3.1, CI 2.1-5.0), and fractures operated on with uncemented humeral stems had increased risk of revision (HR 3.5, CI 1.6-7.3). CONCLUSION: We found similar risk of revision with inlay and onlay designs. Some prosthesis brands had a higher rate of revision than the most common implant, but numbers were low.

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BACKGROUND Reverse shoulder arthroplasty (RSA) is an accepted treatment that provides reproducible results in the treatment of rotator cuff deficiency and proximal humerus fractures. This single-center study aimed to evaluate the outcomes from reverse shoulder arthroplasty for rotator cuff insufficiency and proximal humerus fractures in 22 patients from a single center. MATERIAL AND METHODS Twenty-two patients were included in the study. The median age of the patients was 66 years (Range: 58-95). Proximal humerus fractures were diagnosed using X-ray and CT, while rotator cuff tears were diagnosed using MRI. For the assessment of joint function, the Constant-Murley score, the American Shoulder and Elbow Surgeons (ASES), and the Disabilities of Arm, Shoulder, and Hand (DASH) scores were used as patient-reported outcome measures. Kaplan-Meier analysis was conducted to evaluate implant survival. RESULTS The mean follow-up duration was 4.05±1.2 years. Significant improvements were observed: ASES Score: Increased from 35.8±2.8 to 81.3±5.4 (p<0.001). VAS Pain Score: Decreased from 7.3±1 to 2.9±0.9 (p<0.001). DASH Score: Improved from 66.3±4.3 to 32.5±3.6 (p<0.001). Constant-Murley Score: Increased from 48.3±3.5 to 74.6±7.7 (p<0.001). Kaplan-Meier analysis estimated implant survival at 6.7 years (95% CI, 6.3-7.2). CONCLUSIONS When performed with appropriate indications, RSA yields positive results, as seen in the literature and our study. Interscalene block anesthesia, advancements in implant technology, and adherence to surgical procedures can reduce RSA complications and ensure its safe application.

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Reverse total shoulder arthroplasty (RSA) was historically reserved for the elderly, low-demand patient with rotator cuff arthropathy (RCA) or as a salvage procedure after failed primary arthroplasty. Surgeon expertise and the advancement of implant design has allowed RSA to now become commonplace not only for RCA but also for glenohumeral osteoarthritis. RSA provides a robust glenoid baseplate fixation, which allows for easier and more reliable bone grafting or augmentation when needed. For patients with severe glenoid bone loss, RSA has been shown to have superior or equivalent patient-reported outcomes and shoulder range of motion when compared with total shoulder arthroplasty.

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Background: This study evaluated national trends in cemented and uncemented reverse shoulder arthroplasty (RSA) for proximal humerus fractures using a comprehensive national surgical database. This study aimed to compare RSA used in the treatment of proximal humerus fractures with the literature and to determine the country's trend. Methods: A cross-sectional study was conducted using the health records of individuals aged ≥ 18 years who underwent RSA for proximal humerus fractures between 2016 and 2022. Patients were divided into cemented and uncemented groups, and demographic data (age, sex), duration of hospital stay, transfusions, revisions, mortality, and Charlson Comorbidity Index (CCI) scores were analyzed. Results: A total of 618 cemented RSA and 1,364 uncemented RSA procedures were reviewed. Patients who underwent cemented RSA were significantly older than those who had uncemented RSA (p = 0.002). Transfusion rates were higher in the cemented RSA group (p = 0.006). The frequency of revision surgery was 6.1%. Younger age and male sex were associated with revision (p < 0.001). CCI scores were higher among transfused patients than non-transfused patients (p < 0.001). The incidence of cemented RSA was 11.7% and 49% in 2016 and 2022, respectively. Differences were found among hospital types and geographical regions. Conclusions: While cemented RSA has been gaining attention and increased application in recent years for proximal humerus fractures, uncemented RSA still predominates. The choice between these 2 methods is largely influenced by regional and hospital-level factors. The type of RSA and high CCI scores were found to have no significant impact on the risk of surgical revision.

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PURPOSE: The purpose of this study was to evaluate clinical outcomes after tendon transfers in the setting of reverse total shoulder arthroplasty (RTSA). METHODS: PubMed and Embase were searched according to Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines to find primary clinical studies of any type of tendon transfer in the setting of RTSA. RESULTS: Overall, 17 studies (level of evidence [LOE] I: 1, LOE II: 0, LOE III: 3, LOE IV: 13) met inclusion criteria, with 300 shoulders. Most patients were female (56.7%), with an average age of 68.7 years (range 19 to 89) and a mean follow-up of 46.2 months (range 6 to 174). 11 studies reported outcomes after combined latissimus dorsi and teres major transfer (LDTM) while eight studies reported on latissimus dorsi transfer only (LD). Improvements in commonly reported subjective and functional outcome measures were as follows: external rotation +32° (LDTM) and +30° (LD), flexion +65° (LDTM) and +59° (LD), Visual Analog Score -5.4 (LDTM) and -4.5 (LD), subjective shoulder value +43.8% (LDTM) and +46.3% (LD), and overall Constant score +33.8 (LDTM) and +38.7 (LD). The overall complication rate was 11.3%, including tendon transfer ruptures (0.7%), instability (3.0%), infection (2.0%), and nerve injury (0.3%). The all-cause repeat operation rate was 7.3%, most commonly for arthroplasty revision (5.3%). Subgroup analysis revealed that lateralized implants with tendon transfer resulted in markedly greater improvements in Constant score, flexion, ER1, and ER2 while medialized implants with tendon transfer had markedly greater improvements in Visual Analog Score, subjective shoulder value, and abduction. CONCLUSION: Patients undergoing tendon transfer of either combined LDTM or latissimus dorsi alone in the setting of RTSA have markedly improved subjective and functional outcomes. A moderate incidence of complications (11.3%) was noted in this patient population.

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BACKGROUND AND PURPOSE: There is controversy regarding the results of stemmed and stemless total shoulder arthroplasty (TSA) used for osteoarthritis. Therefore, we aimed to compare revision rates of stemmed and stemless TSA and to examine the impact of metal-backed glenoid components. METHODS: We included all patients reported to the Danish Shoulder Arthroplasty Register from January 1, 2012 to December 31, 2022 with an anatomical TSA used for osteoarthritis. Primary outcome was revision (removal or exchange of components) for any reason. RESULTS: 3,338 arthroplasties were included. The hazard ratio for revision of stemless TSA adjusted for age and sex was 1.83 (95% confidence interval [CI] 1.21-2.78) with stemmed TSA as reference. When excluding all arthroplasties with a metal-backed glenoid component, the adjusted hazard ratio for revision of stemless TSA was 1.37 (CI 0.85-2.20). For the Eclipse stemless TSA system, the adjusted hazard ratio for revision of a metal-backed glenoid component was 8.75 (CI 2.40-31.9) with stemless Eclipse with an all-polyethylene glenoid component as reference. CONCLUSION: We showed that the risk of revision of stemless TSAs was increased and that it was related to their combination with metal-backed glenoid components.

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BACKGROUND: Reverse shoulder arthroplasty (RSA) offers promising functional outcomes for young patients, yet challenges persist in restoring internal rotation (IR). This study aimed to assess the restoration of IR after RSA in patients younger than 60 years of age and analyze the factors affecting IR recovery. METHODS: A retrospective multicenter study was conducted, examining the functional outcome of patients who underwent RSA, with a minimum follow-up period of 2 years. Two subgroups of patients who underwent primary RSA were analyzed separately with respect to active internal rotation with the elbow at the side (AIR1): "difficult AIR1" and "easy AIR1." RESULTS: The study included 136 patients (overall series) with a mean age of 51.6 years. The overall series showed statistically significant improvement in active range of motion (RoM), pain, and Constant scores, especially with active IR (p â€‹< â€‹0.01). According to etiology, statistically significant improvement (p â€‹< â€‹0.05) in active IR was observed for fracture sequelae, primary osteoarthritis, and rheumatoid arthritis, whereas no statistically significant improvement in IR was observed for tumor, revision, and cuff-tear arthropathy (p â€‹> â€‹0.05). In subgroup analysis, patients with easy AIR1 displayed a statistically significant lower body mass index and better Constant score mobility, as well as improved motion in forward elevation and active IR (p â€‹< â€‹0.05). No statistically significant associations were found between improved IR and prosthetic design or subscapularis repair. Scapular notch, lysis of the graft, and teres minor atrophy were significantly associated with better active IR (p â€‹< â€‹0.05). CONCLUSION: RSA improves active RoM, pain, and functional outcomes in patients aged under 60. However, the degree of improvement in IR may vary depending on several factors and the underlying etiologies. These insights are crucial for patient selection and counseling, guiding RSA optimization efforts. LEVEL OF EVIDENCE: IV.

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BACKGROUND: Reverse shoulder arthroplasty (RSA) is a frequently used therapy for complex proximal humeral fractures and posttraumatic disorders. The present study's purpose was to assess the clinical and radiological outcome of primary and secondary RSA, and to analyze the impact of refixation of the greater tuberosity (GT). PATIENTS AND METHODS: 28 patients with primary fracture RSA and 18 patients with RSA due to posttraumatic disorders were examined with a mean clinical follow-up of 2.5 ± 1.73 years. Operative details and radiographs were retrospectively reviewed. Additional analyses were performed for healed and non-healed GT in primary RSA. RESULTS: Patients with fracture RSA had higher Constant-Murley score (CMS) than secondary RSA without reaching significance (p = 0.104). No significant difference was present for the quality of life measured by the Short Form 36 (SF 36) and the range of motion. In primary RSA, 78.6% GT healed anatomically. Compared to non-healed GT, patients with healed GT had a significantly higher CMS (p = 0.011), external rotation (p = 0.026) and forward flexion (p = 0.083), whereas DASH score was lower without a significant difference (p = 0.268). SF 36 showed no significant difference. Patients with healed GT had a more neutral glenoid version (p = 0.009). CONCLUSION: Superior range of motion and clinical outcome scores were present for anatomically healed GT. Therefore, refixation of the tuberosities is recommended. Secondary RSA can result in inferior results compared to primary RSA, so patients need to be adequately informed.

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OBJECTIVE: To develop the'E-Bone', a comprehensive one-stop preoperative planning system for reverse total shoulder arthroplasty with improved accuracy and efficiency. METHODS: The nnU-net deep neural network was utilized for scapula segmentation to obtain precise scapula segmentation results. Based on the 3 key factors, namely bone density, upward and downward angle and nail length, the base was automatically positioned. The quantitative parameters required for surgical planning were calculated. A personalized guide plate was generated by combining glenoid morphology and base positioning information. The system interface was developed to modularize various functions for easy use, providing interactive operation and real-time display. RESULTS: Compared with the Mimics system, the'E-bone'preoperative planning system reduced complex manual adjustments during the planning process. The average planned nail length was longer than that of the Mimics system, and the planning time was reduced by 86%. The scapula segmentation accuracy of this system reached 99.93%, better than that of Mimics to achieve a higher precision. CONCLUSION: The"E-bone"system provides a one-stop, efficient, and accurate preoperative planning system for reverse shoulder replacement and potentially broader clinical applications.

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BACKGROUND: Patient-specific aiming devices (PSAD) may improve precision and accuracy of glenoid component positioning in total shoulder arthroplasty, especially in degenerative glenoids. The aim of this study was to compare precision and accuracy of guide wire positioning into different glenoid models using a PSAD versus a standard guide. METHODS: Three experienced shoulder surgeons inserted 2.5 mm K-wires into polyurethane cast glenoid models of type Walch A, B and C (in total 180 models). Every surgeon placed guide wires into 10 glenoids of each type with a standard guide by DePuy Synthes in group (I) and with a PSAD in group (II). Deviation from planned version, inclination and entry point was measured, as well as investigation of a possible learning curve. RESULTS: Maximal deviation in version in B- and C-glenoids in (I) was 20.3° versus 4.8° in (II) (p < 0.001) and in inclination was 20.0° in (I) versus 3.7° in (II) (p < 0.001). For B-glenoid, more than 50% of the guide wires in (I) had a version deviation between 11.9° and 20.3° compared to ≤ 2.2° in (II) (p < 0.001). 50% of B- and C-glenoids in (I) showed a median inclination deviation of 4.6° (0.0°-20.0°; p < 0.001) versus 1.8° (0.0°-4.0°; p < 0.001) in (II). Deviation from the entry point was always less than 5.0 mm when using PSAD compared to a maximum of 7.7 mm with the standard guide and was most pronounced in type C (p < 0.001). CONCLUSION: PSAD enhance precision and accuracy of guide wire placement particularly for deformed B and C type glenoids compared to a standard guide in vitro. There was no learning curve for PSAD. However, findings of this study cannot be directly translated to the clinical reality and require further corroboration.

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BACKGROUND AND PURPOSE: International variation exists in the types of shoulder replacement used for treatment of specific diseases. Implant choice continues to evolve without high-quality evidence. Our aim was to evaluate trends in incidence rates of shoulder replacement and assess any recent changes in practice between countries by using registry data. METHODS: Patient characteristics, indication and year of surgery, type of replacement, and collection methods of patient-reported outcomes (PROMs) was extracted from 11 public joint registries. Meta-analyses examined use of reverse total shoulder replacement (RTSR) for osteoarthritis, cuff tear arthropathy, and acute fracture; use of anatomical total shoulder replacement (TSR) for osteoarthritis; and use of humeral hemiarthroplasty for fracture. RESULTS: The annual growth rate of shoulder replacements performed is 6-15% (2011-2019). The use of RTSR has almost doubled (93%). RTSR is now universally performed for cuff tear arthropathy (97.3%, 95% confidence interval [CI] 96.0-98.1). Its use for avascular necrosis, trauma, and inflammatory arthropathy is increasing. The use of RTSR was similar (43.1%, CI 30.0-57.2) versus TSR (44.7%, CI 31.1-59.1) for osteoarthritis. The types of PROMs used, collection time points, and response rates lack standardization. COVID-19 had a varying inter-registry impact on incidence rates. CONCLUSION: The incidence of shoulder replacements has grown. Use of RTSR has increased for all disease indications despite limited high-quality evidence driving this change in indications outside of cuff arthropathy. Consequently, less variation is observed in international practice. Existing differences now relate to use of newer implant types and methodology of PROMs collection, which prevents international comparison and outcome analysis.

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INTRODUCTION: Reverse total shoulder arthroplasty (RTSA) with structural bone graft has been described as a technique in addressing glenoid bony defects. Studies have demonstrated acceptable outcomes with structural autograft or allograft. However, most of these studies are relatively small and rarely evaluate bone graft incorporation with CT scan. The aim of this study was to assess clinical and radiographic outcomes and report graft incorporation assessed on CT scan after RTSA where structural bone autograft or allograft was used to reconstruct the glenoid. METHODS: From May 2011 through June 2016, 38 patients underwent RTSA with structural bone graft. Of these, 35 were available for a minimum 2-year follow-up and retrospectively enrolled. From July 2016 through February 2019, 32 patients undergoing RTSA with structural bone graft were prospectively enrolled. Preoperative and postoperative American Shoulder and Elbow Surgeons and visual analog scale (for pain) scores and radiographs were obtained. CT scan was obtained at least 1 year postoperatively. RESULTS: Thirty-five patients were enrolled retrospectively (52.2%) and 32 prospectively (47.8%). Autograft was used in 46 cases (68.7%) and allograft in 21 cases. The mean American Shoulder and Elbow Surgeons score improved from 33.1 (SD 18.5) to 78.2 (SD 22.4), with P < 0.0001. On postoperative radiographs, 63 cases (94.0%) showed stable RTSA constructs while four cases (6.0%) developed glenoid baseplate subsidence. Postoperative CT scan demonstrated complete graft incorporation in 45 cases (90.0%) while partial incorporation was noted in 4 cases (8.0%), and in 1 case (2.0%), there was no graft incorporation. No correlation was observed between baseplate subsidence and graft type (autograft versus allograft) or primary versus revision surgery. DISCUSSION: Reverse shoulder arthroplasty with structural bone autograft and allograft is reliable for glenoid augmentation in patients undergoing RTSA in both primary and revision settings. Bony incorporation of autograft and allograft as evaluated on CT scan is predictably high.

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Background: Postoperative radiographs may be performed on different timelines after shoulder arthroplasty. Radiographs obtained in the post-operative recovery unit (PACU) are often of poorer quality. The purpose of the current study was to explore and compare the quality of PACU radiographs and radiographs performed in the radiology suite on post-operative Day 1 (POD1), as well as determine their impact on changes in post-operative management. Methods: Our series included 50 consecutive anatomic total shoulder arthroplasties (TSA) for which post-operative radiographs were obtained in the PACU and 50 consecutive TSA for which post-operative radiographs were obtained in the radiology suite on POD 1. TSA radiographs were blinded and reviewed by 3 authors and graded on their quality using criteria described using previously published methods. The weighted kappa was used to describe the intra-rater agreement and inter-rater agreement between two raters. Results: There was no difference in age, sex, BMI, and comorbidities between cohorts. Intra-observer reliability was moderate to substantial with weighted kappa values of 0.65±0.07 (p<0.001), 0.58±0.09 (p<0.001), and 0.67±0.07 (p<0.001). Inter-observer reliability was moderate to substantial with weighted kappa values of 0.605±0.07 (p<0.001), 0.66±0.07 (p<0.001), and 0.65±0.08 (p<0.001). When assessing quality of radiographs, 30% of radiographs obtained in PACU were deemed quality while 57% of radiographs obtained in the radiology suite were deemed quality (p<0.001). Conclusion: Post-operative radiographs in the PACU do not alter patient management and are often inadequate to serve as baseline radiographs. Conversely, radiographs obtained in the radiology suite are of higher quality and can serve as a superior baseline radiograph. Level of Evidence: IV.

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BACKGROUND: Reverse shoulder arthroplasty is an established procedure for patients with rotator cuff tear arthropathy. However, the repair of the subscapularis tendon remains a controversial and frequently discussed topic. This prospective randomized study was conducted to evaluate the clinical benefit of the subscapularis repair after reverse shoulder arthroplasty. METHODS: Fifty patients (36 female and 14 male) were randomized and assigned to either the "repaired" (rep) or the "not repaired" (nrep) cohort. Intraoperatively, the subscapularis tendon was reattached in the rep cohort with 4 tendon-to-tendon sutures, whereas no repair was performed in the nrep cohort. The Constant-Murley Score (CS) and the range of motion were evaluated preoperatively as well as 12 and 36 months postoperatively. The Subjective Shoulder Value and the Lift-off test were performed 36 months postoperatively. The postoperative subscapularis integrity was assessed sonographically. RESULTS: Twelve months postoperatively the rep cohort presented better results in the CS (rep: 71 vs. nrep: 66, P = .037). The normalized CS was 80% in the rep cohort and 75% in the nrep cohort (P = .114). At our last follow-up after 36 months, we did not find significant differences between the rep cohort and the nrep cohort in the CS (rep: 76 vs. nrep: 75, P = .285) and normalized CS (rep: 91% vs. nrep: 91%, P = .388). Concerning internal rotation (in points), the rep cohort achieved better results than the nrep cohort (rep: 7.3 vs. nrep: 6.6, P = .040). Flexion (rep: 145° vs. nrep: 151°, P = .826), abduction (rep: 135° vs. nrep: 137°, P = .816), external rotation (rep: 34° vs. nrep: 37°, P = .817), and the Subjective Shoulder Value (rep: 81% vs. nrep: 77%, P = .398) presented no significant differences between the cohorts. The ultrasound examination after 36 months displayed an intact tendon in 70%. CONCLUSIONS: Although the subscapularis repair affects the postoperative internal rotation positively, there were no differences in midterm follow-up concerning the overall results after reverse total shoulder arthroplasty. Further, the external rotation is not affected by the repair of the subscapularis tendon.

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BACKGROUND: Optimizing the function of muscles that cross the glenohumeral articulation in reverse total shoulder arthroplasty (RTSA) is controversial. The current study used a geometric model of the shoulder to systematically examine surgical placement and implant-design parameters to determine which RTSA configuration most closely reproduces native muscle-tendon lengths of the deltoid and rotator cuff. METHODS: A geometric model of the glenohumeral joint was developed and adjusted to represent small, medium, and large shoulders. Muscle-tendon lengths were assessed for the anterior deltoid, middle deltoid, posterior deltoid, and supraspinatus from 0 to 90° of scaption; for the subscapularis from 0° to 60° of internal rotation (IR) and 0° to 60° of scaption; for the infraspinatus from 0° to 60° of external rotation (ER) and 0° to 60° of scaption; and for the teres minor from 0° to 60° of ER at 90° of scaption. RTSA designs were virtually implanted using the following parameters: (1) surgical placement with a centered or inferior glenosphere position and a humeral offset of 0, 5, or 10 mm relative to the anatomic neck plane, (2) implant design involving a glenosphere size of 30, 36, or 42 mm, glenosphere lateralization of 0, 5, or 10 mm, and humeral neck-shaft angle of 135°, 145°, or 155°. Thus, 486 RTSA-shoulder size combinations were analyzed. Linear regression assessed the strength of association between parameters and the change in each muscle-tendon length from the native length. RESULTS: The configuration that most closely restored anatomic muscle-tendon lengths in a small shoulder was a 30-mm glenosphere with a centered position, 5 mm of glenoid lateralization, 0 mm of humeral offset, and a 135° neck-shaft angle. For a medium shoulder, the corresponding combination was 36 mm, centered, 5 mm, 0 mm, and 135°. For a large shoulder, it was 30 mm, centered, 10 mm, 0 mm, and 135°. The most important implant-design parameter associated with restoration of native muscle-tendon lengths was the neck-shaft angle, with a 135° neck-shaft angle being favored (ß = 0.568 to 0.657, p < 0.001). The most important surgical parameter associated with restoration of native muscle-tendon lengths was humeral offset, with a humeral socket placed at the anatomic neck plane being favored (ß = 0.441 to 0.535, p < 0.001). CONCLUSIONS: A combination of a smaller, lateralized glenosphere, a humeral socket placed at the anatomic neck plane, and an anatomic 135° neck-shaft angle best restored native deltoid and rotator cuff muscle-tendon lengths in RTSA. CLINICAL RELEVANCE: This study of surgical and implant factors in RTSA highlighted optimal configurations for restoration of native muscle-tendon lengths of the deltoid and rotator cuff, which has direct implications for surgical technique and implant selection. Additionally, it demonstrated the most influential surgical and implant factors with respect to muscle-tendon lengths, which can be used to aid intraoperative decision-making.

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BACKGROUND: Controversy exists regarding the ideal humeral component version to optimize humeral rotation and patient outcomes in reverse total shoulder arthroplasty (rTSA). METHODS: Patients undergoing primary rTSA for rotator cuff tear arthropathy, a massive rotator cuff tear, or primary osteoarthritis with a rotator cuff tear were randomized to placement of the humeral component in neutral version or 30° of retroversion. Shoulder active range of motion and strength and visual analog scale (VAS) pain, American Shoulder and Elbow Surgeons (ASES), and Patient-Reported Outcomes Measurement Information System Global 10 (PROMIS-10) scores were collected up to 2 years postoperatively. The goal of the study was to determine whether humeral external rotation and internal rotation are affected by humeral component version following rTSA at 2 years postoperatively. RESULTS: Sixty-six patients were included in the analysis. The median follow-up was 26 months for the neutral and 27 months for the 30° retroversion group. No differences between the groups were observed with respect to the primary diagnosis, sex, age, body mass index, or American Society of Anesthesiologists (ASA) class. The 2 groups did not differ significantly in terms of improvement at 2 years in active shoulder abduction (p = 0.969), forward elevation (p = 1.000), internal rotation measured as the highest spinal level reached (p = 1.000), internal rotation with the arm abducted 90° (p = 0.451), external rotation (p = 0.362), or muscle strength in forward elevation (p = 1.000), abduction (p = 1.000), external rotation (p = 0.617), or internal rotation (p = 1.000). The 2 groups did not differ significantly in terms of improvement in postoperative ASES (p = 1.000), PROMIS-10 physical (p = 1.000), or VAS pain scores (p = 0.718) at the time of final follow-up. In the neutral version group, 1 patient underwent revision for instability and 1 for stiffness. One acromial stress fracture occurred in the 30° humeral retroversion group. Scapular notching was observed in 7 (21.2%) of the patients in neutral version group and 5 (15.2%) of the patients in the 30° retroversion group (p = 0.750). CONCLUSIONS: Securing the humeral component at neutral version or 30° of retroversion in rTSA resulted in similar active shoulder external rotation, internal rotation, forward elevation, abduction, and strength measurements, complication rates, and VAS pain, PROMIS-10 physical, and ASES scores at 2 years postoperatively. LEVEL OF EVIDENCE: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

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BACKGROUND: The purpose of this study was to determine whether the addition of hydrogen peroxide to the preoperative skin preparation for primary total shoulder arthroplasty is associated with a difference in patient-reported outcomes, risk for postoperative infection, and risk for revision surgery at a minimum of 2-year follow-up. METHODS: This was a prospective, blinded, and controlled trial, which included a consecutive series of patients undergoing primary shoulder arthroplasty. The control group underwent standard sterile skin preparation using ethyl alcohol and ChloraPrep applicators, and the peroxide group had the same preparation with the addition of hydrogen peroxide between the alcohol and ChloraPrep applications. We then compared patient-reported outcome scores (American Shoulder and Elbow Surgeons Shoulder Score [ASES], simple shoulder test [SST], visual analog scale [VAS]), infections, and revision surgeries between the two groups at 2-year follow-up. RESULTS: Of the 61 patients included in the original study, 52 of 58 (85%) living patients agreed to participate in this study. No preoperative differences were observed between groups. No difference was observed in ASES, SST, or VAS scores at 2 years. More revision surgeries were done in the control group (7 versus 2, P = 0.268) and Cutibacterium acnes infections (2 versus 0, P = 0.168). CONCLUSION: The addition of hydrogen peroxide to the preoperative skin preparation before primary shoulder arthroplasty is safe, and additional research is warranted to investigate whether it may decrease the risk for revision surgery and postoperative C acnes infection. LEVEL OF EVIDENCE: III.

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