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Correct identification of the center point of the glenoid surface guides glenoid component placement. It is unknown whether the center point on the glenoid surface corresponds to the center of the glenoid vault at the medial extent of the glenoid prosthesis. We reviewed 20 consecutive computed tomography scans obtained preoperatively in patients with primary osteoarthritis. A glenoid center point was chosen on the glenoid surface and then projected back into the glenoid vault along the scapular axis and perpendicular to glenoid inclination. The difference from the projection of the glenoid surface center point to the center point at a 1.5-cm depth into the glenoid vault was then measured. The mean deviation of the glenoid center point at a depth of 1.5 cm from the center point at the glenoid articular surface was 1.7 mm anterior and 3.9 mm inferior. The most common deviation of the center point of the glenoid vault at the projected medial limit of the glenoid prosthesis was slightly anterior and inferior to the center point on the glenoid surface. Identifying the center of the glenoid surface coupled with alignment of the glenoid prosthesis in neutral version and anatomic inclination provides a reliable means to guide placement of glenoid components. [ABSTRACT FROM AUTHOR]

Background: Stemless humeral components are being clinically investigated for reverse shoulder arthroplasty (RSA) procedures. There is, however, a paucity of basic science literature on the surgical parameters that influence the success of these procedures. Therefore, this cadaveric biomechanical study evaluated the neck shaft angle (NSA) of implantation on the survivability and performance of stemless RSA humeral components during cyclical loading., Methods: Twelve paired cadaveric humeri were implanted with stemless RSA humeral components at NSAs of 135° and 145°. Implant-bone motion at the periphery of the implant was measured with 3 optical machine vision USB3 cameras outfitted with c-mount premium lenses and quantified with ProAnalyst software. A custom 3-dimensional loading apparatus was used to cyclically apply 3 loading directions representative of physiological states at 5 progressively increasing loading magnitudes. Stemless 135° and 145° implants were compared based on the maximum implant-bone relative distraction detected, as well as the survivorship of the implants throughout the loading protocol., Results: Primary fixation and implant biomechanical survivorship were substantially better in the 145° NSA implants. The 135° NSA implants elicited significantly higher implant-bone distractions during cyclical loading ( P  = .001), and implant survivorship was considerably lower in the 135° NSA specimens when compared to the 145° NSA specimens (135° NSA: 0%, 145° NSA: 50%) ( P  < .001)., Conclusion: NSA is a modifiable parameter that influences time-zero implant stability, as well as the early survivorship of the stemless RSA humeral components tested in this study. NSA resections of 145° appear to promote better stability than those utilizing 135° NSAs during early postoperative eccentric loads. Further studies are required to assess if other stemless reversed humeral implant designs have improved time-zero fixation at higher NSAs., (© 2024 The Author(s).)

Background: The Latarjet procedure is an effective shoulder stabilizing surgery, however, the procedure results in an alteration of anatomy that may result in shoulder and elbow weakness. Thus, the purpose of this study was to assess post-operative shoulder and elbow strength after the Latarjet procedure. We hypothesized that shoulder and elbow strength are not affected after the procedure., Methods: The study group consisted of patients that had undergone the arthroscopic Latarjet procedure. An isokinetic dynamometer was used to evaluate the strength of bilateral shoulder internal rotation, elbow flexion, forearm supination using peak torque (N/m), as well as grip strength (kilograms). Shoulder range of motion and the potential effects of hand dominance were further analysed., Results: Nineteen patients with a mean age of 29 years and an average follow up of 47 months were included. Shoulder internal rotation strength, elbow flexion and forearm supination strength and grip strength were not significantly different when compared to the non-operative side ( p  > 0.13). The range of shoulder external rotation was significantly reduced ( p  < 0.001) on the Latarjet side., Conclusion: The results from this study demonstrate no statistically significant differences in the strength of shoulder internal rotation, elbow flexion, forearm supination or grip strength despite the surgical alterations to the subscapularis and conjoint tendon., Competing Interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2023.)

Introduction: Despite technological advancements in recent years, glenoid component loosening remains a common complication after anatomical total shoulder arthroplasty (ATSA) and is one of the main causes of revision surgery. Increasing emphasis is placed on the prevention of glenoid component failure. Previous studies have successfully predicted range of motion, patient-reported outcomes and short-term complications after ATSA using machine learning methods, but an accurate predictive model for (glenoid component) revision is currently lacking. This study aims to use a large international database to accurately predict aseptic loosening of the glenoid component after ATSA using machine learning algorithms., Methods and Analysis: For this multicentre, retrospective study, individual patient data will be compiled from previously published studies reporting revision of ATSA. A systematic literature search will be performed in Medline (PubMed) identifying all studies reporting outcomes of ATSA. Authors will be contacted and invited to participate in the Machine Learning Consortium by sharing their anonymised databases. All databases reporting revisions after ATSA will be included, and individual patients with a follow-up less than 2 years or a fracture as the indication for ATSA will be excluded. First, features (predictive variables) will be identified using a random forest feature selection. The resulting features from the compiled database will be used to train various machine learning algorithms (stochastic gradient boosting, random forest, support vector machine, neural network and elastic-net penalised logistic regression). The developed and validated algorithms will be evaluated across discrimination (c-statistic), calibration, the Brier score and the decision curve analysis. The best-performing algorithm will be used to create an open-access online prediction tool., Ethics and Dissemination: Data will be collected adhering to the WHO regulation on data sharing. An Institutional Review Board review is not applicable. The study results will be published in a peer-reviewed journal., Competing Interests: Competing interests: LL received consultancy fees from Depuy Stryker and royalties from Depuy-Synthes. TL received consultancy fees from Depuy Mitek and Stryker. GAB received consultancy fees from Depuy-Synthes and Stryker. The remaining authors certify that they have received no funding and have no commercial associations that might pose a conflict of interest in connection with the submitted article., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The reverse shoulder arthroplasty conceived by Paul Grammont in 1985 has gradually gained popularity as a treatment for multiple shoulder diseases. Unlike previous reverse shoulder prosthesis characterized by unsatisfactory results and a high glenoid implant failure rate, the Grammont design has immediately shown good clinical outcomes. This semi constrained prosthesis solved the issues of the very first designs by medializing and distalizing the center of rotation with an increased stability of the replacement of the component. The indication was initially limited to cuff tear arthropathy (CTA). It has then been expanded to irreparable massive cuff tears and displaced humeral head fractures. The most frequent problems of this design are a limited postoperative external rotation and scapular notching. Different modifications to the original Grammont design have been proposed with the aim of decreasing the risk of failure and complications and improving the clinical outcomes. Both the position and version/inclination of the glenosphere and the humeral configuration (e.g. neck shaft angle) influence the RSA outcomes. A lateralized glenoid (whether with bone or metal) and a 135° Inlay system configuration leads to a moment arm which is the closest to the native shoulder. Clinical research will focus on implant designs reducing bone adaptations and revision rate, strategies to prevent more effectively infections. Furthermore, there is still room for improvement in terms of better postoperative internal and external rotations and clinical outcomes after RSA implanted for humeral fracture and revision shoulder arthroplasty., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Preoperative traditional software planning (TSP) is a method used to assist surgeons with implant selection and glenoid guide-pin insertion in shoulder arthroplasty. Mixed-Reality (MR) is a new technology that uses digital holograms of the preoperative plan and guide-pin trajectory projected into the operative field. The purpose of this study was to compare TSP to MR in a simulated surgical environment involving insertion of guide-pins into models of severely deformed glenoids., Methods: Eight surgeons inserted guide-pins into eight randomized three-dimensional-printed severely eroded glenoid models in a simulated surgical environment using either TSP or MR. In total, 128 glenoid models were used and statistically compared. The outcomes compared between techniques included procedural time, difference in guide-pin start point, difference in version and inclination, and surgeon confidence via a confidence rating scale., Results: When comparing traditional preoperative software planning to MR visualization as techniques to assist surgeons in glenoid guide pin insertion, there were no statistically significant differences in terms of mean procedure time (P=0.634), glenoid start-point (TSP = 2.2 ± 0.2 mm , MR = 2.1 ± 0.1 mm; P=0.760), guide-pin orientation (P=0.586), or confidence rating score (P=0.850)., Conclusions: The results demonstrate that there were no significant differences between traditional preoperative software planning and MR visualization for guide-pin placement into models of eroded glenoids. A perceived benefit of MR is the real-time intraoperative visibility of the surgical plan and the patient's anatomy; however, this did not translate into decreased procedural time or improved guide-pin position. Level of evidence: Basic Science Study; Biomechanics.

Postoperative periprosthetic humeral shaft fractures represent a growing and difficult complication to treat given the aging patient population and associated bone loss. Determining the best treatment option is multifactorial, including patient characteristics, fracture pattern, remaining bone stock, and implant stability. Possible treatment options include nonoperative management with bracing or surgical intervention. Nonoperative treatment has been shown to have higher nonunion rates, thus should only be selected for a specific patient population with minimally displaced fractures or those that are unfit for surgery. Surgical management is recommended with prosthetic loosening, fracture nonunion, or failure of nonoperative treatment. Surgical options include open reduction and internal fixation, revision arthroplasty, or hybrid fixation. Careful evaluation, decision making, and planning is required in the treatment of these fractures., (Copyright © 2023 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Orthopaedic Trauma Association.)

Introduction: The effectiveness of rotator cuff tear repair surgery is influenced by multiple patient-related, pathology-centred and technical factors, which is thought to contribute to the reported retear rates between 17% and 94%. Adequate patient selection is thought to be essential in reaching satisfactory results. However, no clear consensus has been reached on which factors are most predictive of successful surgery. A clinical decision tool that encompassed all aspects is still to be made. Artificial intelligence (AI) and machine learning algorithms use complex self-learning models that can be used to make patient-specific decision-making tools. The aim of this study is to develop and train an algorithm that can be used as an online available clinical prediction tool, to predict the risk of retear in patients undergoing rotator cuff repair., Methods and Analysis: This is a retrospective, multicentre, cohort study using pooled individual patient data from multiple studies of patients who have undergone rotator cuff repair and were evaluated by advanced imaging for healing at a minimum of 6 months after surgery. This study consists of two parts. Part one: collecting all potential factors that might influence retear risks from retrospective multicentre data, aiming to include more than 1000 patients worldwide. Part two: combining all influencing factors into a model that can clinically be used as a prediction tool using machine learning., Ethics and Dissemination: For safe multicentre data exchange and analysis, our Machine Learning Consortium adheres to the WHO regulation 'Policy on Use and Sharing of Data Collected by WHO in Member States Outside the Context of Public Health Emergencies'. The study results will be disseminated through publication in a peer-reviewed journal. Institutional Review Board approval does not apply to the current study protocol., Competing Interests: Competing interests: AL is a paid consultant for Arthrex, Medacta and Stryker. He receives royalties from Stryker. He is the founder of BeeMed, Med4Cast and FORE. He owns stock options from Medacta. LL is a consultant for Depuy Stryker, received royalties from Depuy. TL is consultant for Depuy Mitek and Stryker. GAB received consultancy fees from Depuy-Synthes and Research Funds from SECEC, Vivalto Santé. The remaining authors certify that neither he or she has funding or commercial associations that might pose a conflict of interest in connection with the submitted article., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Finite element analysis has suggested that stemless implants may theoretically decrease stress shielding. The purpose of this study was to assess the radiographic proximal humeral bone adaptations seen following stemless anatomic total shoulder arthroplasty., Methods: A retrospective review of 152 prospectively followed stemless total shoulder arthroplasty utilizing a single implant design was performed. Anteroposterior and lateral radiographs were reviewed at standard time points. Stress shielding was graded as mild, moderate, and severe. The effect of stress shielding on clinical and functional outcomes was assessed. Also, the influence of subscapularis management on the occurrence of stress shielding was determined., Results: At 2 years postoperatively, stress shielding was noted in 61 (41%) shoulders. A total of 11 (7%) shoulders demonstrated severe stress shielding with 6 occurring along the medial calcar. There was one instance of greater tuberosity resorption. At the final follow-up, no humeral implants were radiographically loose or migrated. There was no statistically significant difference in clinical and functional outcomes between shoulders with and without stress shielding. Patients undergoing a lesser tuberosity osteotomy had lower rates of stress shielding, which was statistically significant ( p  = 0.021)., Discussion: Stress shielding does occur at higher rates than anticipated following stemless total shoulder arthroplasty, but was not associated with implant migration or failure at 2 years follow-up., Level of Evidence: IV, Case series., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2021.)

Background: In a simple isolated capitellar/trochlear fracture without extensive posterior comminution, arthroscopic reduction and internal fixation (ARIF) can provide an alternative option to open reduction internal fixation. The purpose of this retrospective case series was to report on the technique and outcomes of arthroscopic reduction and internal fixation of capitellar/trochlear fractures., Methods: All patients that underwent ARIF at a single upper extremity referral centre in the last twenty years were reviewed. Patient demographics, preoperative, intraoperative, and postoperative records were obtained through chart review and telephone followup., Results: Ten cases of ARIF were identified over a twenty year period performed by two surgeons. The average age of patients was 37 years (17-63 years), with nine females and one male. With an average followup of eight years, nine of ten patients had a mean range of motion from 0 to 142 degrees. Their average MEPI and PREE score were 93 ± 7 and 8 ± 14, respectively. Four patients had focal cartilage collapse with three that required a reoperation. There were no infections, nonunions, or arthroscopy related complications., Conclusion: ARIF offers an alternative to ORIF for capitellar/trochlear fractures producing good results while providing better visualization of the fracture reduction and minimizing soft tissue dissection., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2021.)

Purpose: This study aimed to assess the accuracy and reproducibility of four common segmentation techniques measuring subchondral bone cyst volume in clinical-CT scans of glenohumeral OA patients., Methods: Ten humeral head osteotomies collected from cystic OA patients, having undergone total shoulder arthroplasty, were scanned within a micro-CT scanner, and corresponding preoperative clinical-CT scans were gathered. Cyst volumes were measured manually in micro-CT and served as a reference standard (n = 13). Respective cyst volumes were measured on the clinical-CT scans by two independent graders using four segmentation techniques: Qualitative, Edge Detection, Region Growing, and Thresholding. Cyst volume measured in micro-CT was compared to the different clinical-CT techniques using linear regression and Bland-Altman analysis. Reproducibility of each technique was assessed using intraclass correlation coefficient (ICC)., Results: Each technique outputted lower volumes on average than the reference standard (-0.24 to -3.99 mm 3 ). All linear regression slopes and intercepts were not significantly different than 1 and 0, respectively (p < 0.05). Cyst volumes measured using Qualitative and Edge Detection techniques had the highest overall agreement with reference micro-CT volumes (mean discrepancy: 0.24, 0.92 mm 3 ). These techniques showed good to excellent reproducibility between graders., Conclusions: Qualitative and Edge Detection techniques were found to accurately and reproducibly measure subchondral cyst volume in clinical-CT. These findings provide evidence that clinical-CT may accurately gauge glenohumeral cystic presence, which may be useful for disease monitoring and preoperative planning., Level of Evidence: Retrospective cohort Level 3 study., (© 2023. The Author(s).)

Introduction: Shoulder instability is a common injury, with a reported incidence of 23.9 per 100 000 person-years. There is still an ongoing debate on the most effective treatment strategy. Non-operative treatment has recurrence rates of up to 60%, whereas operative treatments such as the Bankart repair and bone block procedures show lower recurrence rates (16% and 2%, respectively) but higher complication rates (<2% and up to 30%, respectively). Methods to determine risk of recurrence have been developed; however, patient-specific decision-making tools are still lacking. Artificial intelligence and machine learning algorithms use self-learning complex models that can be used to make patient-specific decision-making tools. The aim of the current study is to develop and train a machine learning algorithm to create a prediction model to be used in clinical practice-as an online prediction tool-to estimate recurrence rates following a Bankart repair., Methods and Analysis: This is a multicentre retrospective cohort study. Patients with traumatic anterior shoulder dislocations that were treated with an arthroscopic Bankart repair without remplissage will be included. This study includes two parts. Part 1, collecting all potential factors influencing the recurrence rate following an arthroscopic Bankart repair in patients using multicentre data, aiming to include data from >1000 patients worldwide. Part 2, the multicentre data will be re-evaluated (and where applicable complemented) using machine learning algorithms to predict outcomes. Recurrence will be the primary outcome measure., Ethics and Dissemination: For safe multicentre data exchange and analysis, our Machine Learning Consortium adhered to the WHO regulation 'Policy on Use and Sharing of Data Collected by WHO in Member States Outside the Context of Public Health Emergencies'. The study results will be disseminated through publication in a peer-reviewed journal. No Institutional Review Board is required for this study., Competing Interests: Competing interests: GSA reports as ‘financial activities outside the submitted work’ to be a consultant for ConMed Linvatec. LL is a consultant for Depuy Stryker, received royalties from Depuy. TL is consultant for Depuy Mitek and Stryker. GAB received consultancy fees from Depuy-Synthes and Research Funds from SECEC, Vivalto Santé. The remaining authors certify that neither he or she has funding or commercial associations that might pose a conflict of interest in connection with the submitted article., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Implant manufacturers typically offer several sizes of a humeral stem for shoulder arthroplasty so that time zero fixation can be achieved with the optimal size. Stem size can be templated preoperatively but is definitively determined intraoperatively. The purpose of this study was to determine if preoperatively acquired parameters, including patient demographics and imaging, could be used to reliably predict intraoperative humeral stem size., Methods: A cohort of 290 patients that underwent shoulder arthroplasty (116 anatomic and 174 reverse) was analyzed to create a regression formula to predict intraoperative stem size. The initial cohort was separated into train and test groups (randomly selected 80% and 20%, respectively). Patient demographics, anatomical measurements, and statistical shape model parameters determined from a preoperative shoulder arthroplasty planning software program were used for multilinear regression. The implant used for all cases was a short-stemmed metaphyseal-fit prosthesis., Results: Metaphyseal bone density, humeral statistical shape model parameters, and humeral intramedullary canal diameter were identified as highly predictive of intraoperative final humeral prosthesis size. On the train group, a coefficient of determination R 2 of 0.63 was obtained for the multilinear regression equation combining these parameters. When analyzing the cohort for the prediction of stem size in the test group, 95% were within plus or minus one size of that used during surgery., Conclusion: Preoperative criteria such as humeral geometry and proximal humeral bone density can be combined in a single multilinear equation to predict intraoperative humeral stem size within one size variation. Embedding the surgeon's decision-making process into an automated algorithm potentially allows this process to be applied across the surgical community. Predicting intraoperative decisions such as humeral stem size also has potential implications for the management of implant stocks for both manufacturers and health-care facilities., (© 2022 The Author(s).)

Background: Hybrid glenoid components in total shoulder arthroplasty (TSA) utilize both polyethylene and metal components to provide short-term stability and long-term biologic fixation through bone ingrowth., Questions/purpose: We sought to systematically review the literature for studies that assessed outcomes of TSA performed using hybrid glenoid components., Methods: PubMed, Medline, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Embase were searched systematically for articles measuring clinical and patient-reported outcomes and rates of complication and revision following TSA using a hybrid glenoid component., Results: Seven studies with 593 shoulders were included in this review. The mean age of patients was 65 ± 1 years, and 46% of the population was male. Mean follow-up was 50 months (4.2 years). The overall complication rate was 7% and rate of revision was 2.5%; glenoid radiolucency was present in 33% of shoulders at mean follow-up of 50 months. Mean improvements in forward elevation, external rotation, internal rotation score, and abduction were 49°, 28°, 2 points, and 42°, respectively. Mean improvements in Constant, American Shoulder and Elbow Surgeons (ASES), and University of California, Los Angeles (UCLA) scores were 36 points, 52 points, and 17 points, respectively., Conclusion: Our review found that TSA using hybrid glenoid components results in low rates of complication and revision at early follow-up. Long-term studies are warranted to understand more fully the role of hybrid glenoid components in TSA., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: George S. Athwal, MD, FRCSC, reports he is a consultant and product developer with royalty contracts for Wright Medical Technologies, Exactech, and Conmed Linvatec, outside the submitted work. The other authors declared no potential conflicts of interest., (© The Author(s) 2021.)

Background: The purpose of this biomechanical simulator study was primarily to compare latissimus dorsi to lower trapezius tendon transfers for active external rotation and the pectoralis major transfer for internal rotation after reverse shoulder arthroplasty. Secondarily, the role of humeral component lateralization on transfer function was assessed., Methods: Eight rotator cuff deficient cadavers underwent reverse shoulder arthroplasty with an adjustable lateralization humeral component. Latissimus dorsi and lower trapezius transfers were compared for active external rotation restoration and pectoralis major transfer for internal rotation restoration. Internal rotation/external rotation torques were measured for each lateralization at varying abduction and internal rotation/external rotation ranges-of-motion., Results: The lower trapezius transfer generated, on average, 1.6 ± 0.2 nm more torque than the latissimus dorsi transfer (p < 0.001). The internal rotation/external rotation torques of all tendon transfers decreased as abduction increased (p < 0.01). At 0° elevation, reverse shoulder arthroplasty humeral component lateralization had a significant positive effect on tendon transfer torque at 60° internal rotation and external rotation (p < 0.01)., Discussion: Both the lower trapezius and the latissimus dorsi tendon transfers were effective in restoring active external rotation after reverse shoulder arthroplasty; however, the lower trapezius generated significantly more torque. Additionally, the pectoralis major transfer was effective in restoring active internal rotation. All tendon transfers were optimized with greater humeral component lateralization., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© 2020 The British Elbow & Shoulder Society.)

Indications for Reverse Shoulder Arthroplasty (RSA) have been extended over the last 25 years, and RSA has become the most frequently implanted shoulder arthroplasty worldwide. The initial Grammont design with medialization of the joint center of rotation (JCOR), placement of the JCOR at the bone-implant interface, distalization and semi-constrained configuration has been associated with drawbacks such as reduced rotation and range of motion (ROM), notching, instability and loss of shoulder contour. This review summarizes new strategies to overcome these drawbacks and analyzes the use of glenoid-sided, humeral-sided or global bipolar lateralization, which are applied differently by surgeons and current implant manufacturers. Advantages and drawbacks are discussed. There is evidence that lateralization addresses the initial drawbacks of the Grammont design, improving stability, rates of notching, ROM and shoulder contour, but the ideal extent of lateralization of the glenoid and humerus remains unclear, as well as the maximal acceptable joint reaction force after reduction. Overstuffing and spine of scapula fractures are potential risks. CT-based 3D planning as well as artificial intelligence will help surgeons with planning and execution of appropriate lateralization in RSA. Long-term follow-up of lateralization with new implant designs and implantation strategies is needed.

Background: The use of stemless humeral implants for shoulder arthroplasty is becoming increasingly widespread. However, little is known about the difference in clinical, functional, and radiographic outcomes of stemless shoulder arthroplasty between men and women. Men and women do have reported differences in size, strength, and bone quality. As such, the purpose of this study was to evaluate sex-related differences in outcomes when using stemless humeral implants., Methods: A retrospective review of 227 patients (men = 143 and women = 84) undergoing stemless shoulder arthroplasty was compared for sex-related differences. Clinical, functional, and radiographic outcomes were compared, including American Shoulder and Elbow Surgeons (ASES) scores, visual analog scale pain scores, range of motion, radiolucencies, operative data, implant data, and complications. Statistical analysis included descriptive statistics, t-tests, chi-square tests, and logistic regression., Results: Preoperatively, men had a statistically significant greater range of motion of forward elevation ( P  < .01), external rotation (ER) at adduction ( P  = .04), ER at 90° abduction ( P  = .03), and baseline ASES scores ( P  < .01). At 2 years, there were no differences between men and women in ASES score ( P  = .12), visual analog scale pain score ( P  = .74), active ER ( P  = .98), implant migration, or radiolucencies ( P  > .99). Mean operating time was 9 minutes longer in male patients ( P  < .01). There was no significant difference in surgical complications, including dislocation, fracture, infection, or loosening. The three-year revision-free survival was 98.8% for women and 97.9% for men., Conclusion: Patient sex is not predictive of postoperative functional outcomes after stemless shoulder arthroplasty. The operative time was significantly shorter in female patients, and there was no significant difference in surgical complications between men and women., (© 2021 The Author(s).)

Background: The COVID-19 pandemic has interrupted orthopaedic training structures for both surgeons and trainees. The concept of skill decay must be considered during inactivity of elective practice. The purpose of this study was to provide an evidence-based curriculum in association with immersive virtual reality (iVR) to prevent skill decay during periods of training cessation and beyond., Methods: A review of pertinent literature for orthopaedic surgical skill decay was performed. Early experience by faculty instructors and residency and fellowship program directors was gathered from multiple institutions with experience in virtual training methods including iVR. A proposed curriculum for cognitive and manual skill acquisition during COVID-19 was produced from qualitative narrative group opinion., Results: Skill decay can occur on the order of days to months and is dependent on the initial skill level. A novel curriculum for structured continuing medical education during and after periods of surgical disruption including e-learning, virtual meetings, and iVR simulators was produced from expert opinion and based on competency-based curriculum standards., Conclusion: Skill decay mitigation strategies should use best available evidence technologies and course structures that satisfy advanced learning concepts. The virtual curriculum including iVR simulators may provide cost-effective solutions to training., (Copyright © 2021 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Orthopaedic Surgeons.)

Background: Scapular spine insufficiency fractures following reverse shoulder arthroplasty are poorly understood. There exists limited literature regarding the role of reverse shoulder arthroplasty lateralization on scapular spine strains and fractures. The purpose of this cadaveric biomechanical simulator study was to evaluate the role of glenoid lateralization on scapular spine strain., Methods: Eight cadaveric shoulders were tested using an in-vitro simulator. A custom modular reverse shoulder arthroplasty was implanted that allowed for in-situ glenoid lateralization adjustment. Scapular spine strain was measured by strain gauges placed in clinically relevant Levy zones along the scapular spine. All specimens were tested in loaded forward elevation and abduction., Results: Glenoid lateralization from 0 to 5 mm caused negligible changes in scapular spine strains. Lateralization from 5 to 10 mm, however, caused significant increases in strain at 0° forward elevation in all strain gauges (p < 0.026). Strains measured in Levy zone 2 were significantly higher than all other locations (p < 0.039). Additionally, forward elevation resulted in significantly higher strain values than abduction (p = 0.001)., Conclusions: Glenoid lateralization is an important parameter in reverse shoulder arthroplasty; however, our results demonstrate higher degrees of lateralization may place higher strains on the scapular spine. An understanding of reverse shoulder arthroplasty lateralization and scapular spine strains is important to optimize parameters and to mitigate negative effects., Level of Evidence: Basic Sciences Study, Cadaveric Model, Biomechanics., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© 2020 The British Elbow & Shoulder Society.)

Background: The purpose of this study was to develop novel three-dimensional (3D) measures of bone density from computed tomography (CT) scans and to compare them with validated two-dimensional (2D) radiographic assessments of bone density. Patient demographic data were also analyzed to see if there were any predictors of bone density (age, sex, etiology)., Methods: The study group consisted of 290 consecutive patients undergoing primary shoulder arthroplasty surgery (total anatomic, reverse, and hemiarthroplasty). All underwent preoperative CT imaging. Three 3D CT measurements (metaphysis cancellous, metaphysis cortical, and proximal diaphysis) were developed and automated into software. The developed 3D measurements were compared with validated 2D measures (Tingart and Gianotti Index). Patient demographic data were correlated with these measurements. The difference between the size of the final sounder and of the final stem was calculated as Delta., Results: There was moderately strong correlation between Tingart and Gianotti measures (0.674, P  < .001), as well as between 3D metaphysis cancellous measurements and Tingart (0.645, P  < .001). Decreased bone density was highly correlated with female sex. Tingart (area under the curve [AUC]: 0.87, 95% confidence interval [CI]: 0.82-0.91) and 3D metaphysis cancellous (AUC: 0.78, 95% CI: 0.72-0.84) had the highest correlation. These were significantly more than other measures of bone density ( P  < .01). Decreased bone density measured with Tingart also had moderate correlation with advanced age (AUC: 0.67, 95% CI: 0.6-0.73), but less so for etiology (AUC: 0.62, 95% CI: 0.55-0.69). The 3D metaphysis cancellous measure had lower correlation with age (AUC: 0.59, 95% CI: 0.52-0.66) and etiology (AUC: 0.59, 95% CI: 0.52-0.65). The highest correlation with Delta (the difference between the final sounder and the stem size) was with the 3D metaphysis cancellous measure (AUC: 0.67, 95% CI: 0.59-0.73), followed by Tingart (AUC: 0.647, 95% CI: 0.57-0.671). A multiple regression model to predict Delta demonstrated the stronger prediction using 3D metaphysis cancellous (analysis of variance F-ratio of 42.6, P  < .001) than Tingart (35.9, P  < .001)., Conclusion: This study demonstrates that automated measures of bone density can be obtained from 3D CT scans. Of the three novel 3D measurements of bone density, the humeral metaphysis cancellous measurement was most correlated to the known 2D measures and most correlated to the intraoperative assessment of bone density (delta)., (© 2021 The Author(s).)

Background: Acromial fractures are a substantial complication following reverse shoulder arthroplasty, reported to affect up to 7% of patients. Previous studies have shown that implant placement affects acromial stress during elevation of the arm in the scaption plane. The purpose of this study was to investigate the results of arm loading and variation in plane of elevation on acromial stresses., Methods: Nine elevation angles (0°-120°), in three planes of elevation (abduction (0°), scaption (30°), and forward elevation (60°)), and three hand loads (0, 2.5, 5 kg) were investigated. Finite element models were generated using computed tomography data from 10 cadaveric shoulders (age 68 ± 19 yrs) to determine acromial stress distributions. Models were created for a lateralized glenosphere (0, 5, 10 mm), inferiorized glenosphere (0, 2.5, 5 mm), and humeral offset (-5, 0, 5 mm)., Results: For all planes of elevation (0°, 30°, 60°) and hand loads (0, 2.5, 5 kg) investigated, glenoid lateralization consistently increased acromial stress, glenoid inferiorization consistently decreased acromial stress, and humeral offset proved to be insignificant in altering acromial stress. Abduction resulted in significantly higher peak acromial stresses (p = 0.002) as compared to scaption and forward elevation., Conclusions: In addition to implant position and design, patient activity, such as plane of elevation and hand loads, has substantial effects on acromial stresses., Level of Evidence: Basic science study., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: George S. Athwal is a consultant for Wright Medical and Exactech. No company was involved with this study., (© 2020 The British Elbow & Shoulder Society.)

Background: The humeral head osteotomy during shoulder arthroplasty influences humeral component height, version and possibly neck-shaft angle. These parameters all potentially influence outcomes of anatomic and reverse shoulder replacement to a variable degree. Patient-specific guides and navigation have been studied and utilized clinically for glenoid component placement. Little, however, has been done to evaluate these techniques for humeral head osteotomies. The purpose of this study, therefore, was to evaluate the use of patient-specific guides and surgical navigation for executing a planned humeral head osteotomy., Methods: The DICOM images of 10 shoulder computed tomography scans (5 normal and 5 osteoarthritic) were used to print 3D polylactic models of the humerus. Each model was duplicated, such that there were 2 identical groups of 10 models. After preoperative planning of a humeral head osteotomy, Group 1 underwent osteotomy via a patient-specific guide, while group 2 underwent a real time navigated osteotomy with an optically tracked sagittal saw. The cut height (millimeters), version (degrees) and neck-shaft angle (degrees) were recorded and statistically compared between groups., Results: There were no statistically significant differences between patient-specific guides and navigation for osteotomy cut height ( P  = .45) and humeral version ( P  = .059). Navigation, however, resulted in significantly less neck-shaft angle error than the patient specific guides ( P  = .023). Subgroup analysis of the osteoarthritic cases showed statistical significance for navigation resulting in less version error than the patient specific guides ( P  = .048)., Conclusion: No significant differences were found between patient specific guides and navigation for recreation of the preoperatively planned humeral head cut height and version. Neck-shaft angle, however, had significantly less deviation from the preoperative plan when conducted with navigation., (© 2021 The Author(s).)

Background: Stem size is an important element for successful time zero primary fixation of a press-fit humeral stem in shoulder arthroplasty. Little basic science research, however, has been conducted on the effects of implant thickness and canal fill on load transfer, contact, and stress shielding. The purpose of this finite element study was to determine the effects of varying stem thickness on bone contact, bone stresses, and bone resorption owing to stress shielding., Methods: Three generic short-stem implant models were developed and varied based on cross-sectional thickness (thinner - 8 mm, medium - 12 mm, thicker - 16 mm). Using a finite element model, three outcome measures were determined (1) the amount of bone-to-implant contact, (2) changes in cortical and trabecular bone stresses from the intact state, and (3) changes in cortical and trabecular strain energy densities which can predict bone remodeling or stress shielding., Results: Increasing the size of the humeral stem had no significant effects on bone-to-implant contact during loading ( P  > .07). The thinner implant with the lowest canal fill ratio produced significantly lower changes in stress from the intact state in both cortical and trabecular bone ( P  < .002). In addition, the thinner implant resulted in a substantially lower volume of bone predicted to stress shield and resorb when compared with the medium and thicker stems., Discussion: The results demonstrate that thinner implants and lower canal fill may be beneficial over thicker sizes, provided equal initial fixation can be achieved. The thinner implant has a greater degree of load sharing and increases the mechanical load placed on surrounding bone, reducing the risk of stress shielding and bone resorption., (© 2021 The Authors.)

Aims: The aim of this study was to describe a quantitative 3D CT method to measure rotator cuff muscle volume, atrophy, and balance in healthy controls and in three pathological shoulder cohorts., Methods: In all, 102 CT scans were included in the analysis: 46 healthy, 21 cuff tear arthropathy (CTA), 18 irreparable rotator cuff tear (IRCT), and 17 primary osteoarthritis (OA). The four rotator cuff muscles were manually segmented and their volume, including intramuscular fat, was calculated. The normalized volume (NV) of each muscle was calculated by dividing muscle volume to the patient's scapular bone volume. Muscle volume and percentage of muscle atrophy were compared between muscles and between cohorts., Results: Rotator cuff muscle volume was significantly decreased in patients with OA, CTA, and IRCT compared to healthy patients (p < 0.0001). Atrophy was comparable for all muscles between CTA, IRCT, and OA patients, except for the supraspinatus, which was significantly more atrophied in CTA and IRCT (p = 0.002). In healthy shoulders, the anterior cuff represented 45% of the entire cuff, while the posterior cuff represented 40%. A similar partition between anterior and posterior cuff was also found in both CTA and IRCT patients. However, in OA patients, the relative volume of the anterior (42%) and posterior cuff (45%) were similar., Conclusion: This study shows that rotator cuff muscle volume is significantly decreased in patients with OA, CTA, or IRCT compared to healthy patients, but that only minimal differences can be observed between the different pathological groups. This suggests that the influence of rotator cuff muscle volume and atrophy (including intramuscular fat) as an independent factor of outcome may be overestimated. Cite this article: Bone Jt Open  2021;2(7):552-561.

Background: Evoked potential monitoring is believed to prevent neurologic injury in various surgical settings; however, its clinical effect has not been scrutinized. It was hypothesized that an automated nerve monitor can minimize intraoperative nerve injury and thereby improve clinical outcomes in patients undergoing shoulder arthroplasty., Methods: A prospective, blinded, parallel group, superiority design, single-center, randomized controlled study was conducted. Study participants were equally randomized into either the automated nerve-monitored or the blinded monitored groups. The primary outcome was intraoperative nerve injury burden as assessed by the cumulative duration of nerve alerts. Secondary outcomes were neurologic deficits and functional scores of the operative arm, and the quality of life index (Euro Quality of life-5 domain-5 level score) at postoperative weeks 2, 6, and 12., Results: From September 2018 to July 2019, 213 patients were screened, of whom 200 were randomized. There was no statistically significant difference in the duration of nerve alerts between the automated nerve-monitored and control groups (median [25th, 75th interquartile range]: 1 [0, 18] and 5 [0, 26.5]; Hodges-Lehman difference [95% CI]: 0 [0 to 1] min; P = 0.526). There were no statistically significant differences in secondary outcomes between groups. However, in the ancillary analysis, there were reductions in neurologic deficits and improvements in quality of life index occurring in both groups over the course of the study period., Conclusions: Protection from nerve injury is a shared responsibility between surgeons and anesthesiologists. Although a progressive improvement of clinical outcomes were observed over the course of the study in both groups as a consequence of the real-time feedback provided by the automated nerve monitor, this trial did not demonstrate that automated nerve monitoring by itself changes important clinical outcomes compared with no monitoring., (Copyright © 2021, the American Society of Anesthesiologists. All Rights Reserved.)

Background: Several factors associated with B glenoid are also linked with obstetrical brachial plexus palsy (OBPP). The purpose of this observational study was to determine the incidence of OBPP risk factors in type B patients., Methods: A cohort of 154 patients (68% men, 187 shoulders) aged 63 ± 17 years with type B glenoids completed a questionnaire comprising history of perinatal characteristics related to OBPP. A literature review was performed following the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) to estimate the incidence of OBPP risk factors in the general population., Results: Twenty-seven patients (18%) reported one or more perinatal OBPP risk factors, including shoulder dystocia ( n = 4, 2.6%), macrosomia >4 kg ( n = 5, 3.2%), breech delivery ( n = 6, 3.9%), fetal distress ( n = 8, 5.2%), maternal diabetes ( n = 2, 1.3%), clavicular fracture ( n = 2, 1.3%), and forceps delivery ( n = 4, 2.6%). The comparison with the recent literature suggested that most perinatal OBPP risk factors were within the normal range, although the incidence of shoulder dystocia, forceps and vaginal breech deliveries exceeded the average rates., Conclusion: Perinatal factors related to OBPP did not occur in a higher frequency in patients with Walch type B OA compared to the general population, although some of them were in the high normal range.

Background: Bone quality influences humeral implant selection for shoulder arthroplasty. However, little is known about how well bone near the humeral resection represents more distal cancellous bone. This investigation aimed to quantify the correlations between the apparent density of sites near the humeral head resection plane and cancellous sites throughout the metaphysis., Methods: Using computed tomography data from 98 subjects, apparent bone density was quantified in 65 regions throughout the proximal humerus. Pearson's correlation coefficient was determined comparing the density between samples from the humeral resection and all supporting regions beneath the resection. Mean correlation coefficients were compared for (i) each sample region with all support regions, (ii) pooling all sample regions within a slice, and (iii) considering sample regions correlated with only the support regions in the same anatomic section., Results: Stronger correlations existed for bone sampled beneath the resection (0.33 ± 0.10≤ r ≤ 0.88 ± 0.10), instead of from the resected humeral head (0.22 ± 0.10≤ r ≤ 0.66 ± 0.14). None of sample region correlated strongly with all support regions; however, strong correlations existed when sample and support regions both came from the same anatomic section., Discussion: Assessments of cancellous bone quality in the proximal humerus should be made beneath the humeral resection not in the resected humeral head; and each anatomic quadrant should be assessed independently., (© 2021 The Author(s).)

Background: Surgical treatment of displaced olecranon fractures in the elderly has a high rate of complications, including wound breakdown and fixation failure. The purpose of this study was to assess the clinical, radiographic, and functional outcomes of nonsurgical management of displaced olecranon fractures in low-demand elderly and medically unwell patients., Methods: A retrospective review of 28 patients with displaced closed olecranon fractures was performed with an average follow-up of 11 months. The mean age at the time of injury was 79 ± 10 years. The average Charlson Comorbidity Index was 6.4 ± 2.6. Treatment modalities were at the discretion of the treating surgeon. A sling alone was used in 3 cases, an extension circumferential cast in 9, or a plaster or thermoplastic splint in 16. The mean period of immobilization was 5 ± 1 weeks. Outcomes included range of motion, ability to perform active overhead extension, as well as radiographic and functional outcomes., Results: At final follow-up, the mean elbow range of motion for the cohort was from 28° ± 21° extension to 127° ± 15° flexion. Active overhead elbow extension against gravity was noted or documented in 24 (86%) patients. Two patients (7%) were unable to perform active extension. No pain was noted in 18 elbows, severe pain was present in 1 elbow, and the remainder reported mild occasional pain. All olecranon fractures in this cohort were displaced on the initial lateral radiograph. The mean displacement was 11 ± 7 mm. Nonunion at final radiographic outcome was observed in 23 (82%) elbows. Two (7%) patients developed skin complications related to posteriorly placed splints; one of which was severe., Discussion: This study adds to the growing literature that supports nonoperative management of displaced olecranon fractures in elderly and medically unwell patients with low upper extremity demand. Patients can be counseled that they have a good chance of obtaining overhead extension, with minimal pain. Posteriorly based splints should not be used to minimize skin complications., (© 2021 The Authors.)

Background: Efforts during reverse total shoulder arthroplasty (RSA) have typically focused on maximizing ROM in elevation and external rotation and avoiding scapular notching. Improving internal rotation (IR) is often overlooked, despite its importance for functional outcomes in terms of patient self-care and hygiene. Although determinants of IR are multifactorial, it is unable to surpass limits of bony impingement of the implant. Identifying implant configurations that can reduce bony impingement in a computer model will help surgeons during preoperative planning and also direct implant design and clinical research going forward., Questions/purposes: In a CT-modeling study, we asked: What reverse total shoulder arthroplasty implant position improves the range of impingement free internal rotation without compromising other motions (external rotation and extension)?, Methods: CT images stored in a deidentified teaching database from 25 consecutive patients with Walch A1 glenoids underwent three-dimensional templating for RSA. Each template used the same implant and configuration, which consisted of an onlay humeral design and a 36-mm standard glenosphere. The resulting constructs were virtually taken through ROM until bony impingement was found. Variations were made in the RSA parameters of baseplate lateralization, glenosphere size, glenosphere overhang, humeral version, and humeral neck-shaft angle. Simulated ROM was repeated after each parameter was changed individually and then again after combining multiple changes into a single configuration. The impingement-free IR was calculated and compared between groups. We also evaluated the effect on other ROM including external rotation and extension to ensure that configurations with improvements in IR were not associated with losses in other areas., Results: Combining lateralization, inferiorization, varus neck-shaft angle, increased glenosphere size, and increased humeral anteversion resulted in a greater improvement in internal rotation than any single parameter change did (median baseline IR: 85° [interquartile range 73° to 90°]; combined changes: 119° [IQR 113° to 121°], median difference: 37° [IQR 32° to 43°]; p < 0.001)., Conclusion: Increased glenosphere overhang, varus neck-shaft angle, and humeral anteversion improved internal rotation in a computational model, while glenoid lateralization alone did not. Combining these techniques led to the greatest improvement in IR., Clinical Relevance: This computer model study showed that various implant changes including inferiorization, varus neck-shaft angle, increased glenosphere size, and increased humeral anteversion can be combined to increase impingement-free IR. Surgeons can employ these currently available implant configurations to improve IR when planning and performing RSA. These findings support the need for further clinical studies validating the effect of implant configuration on resultant IR., Competing Interests: Each author certifies that neither he, nor any member of his immediate family, has funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2020 by the Association of Bone and Joint Surgeons.)

Background : The Revised Short-Form McGill Pain Questionnaire Version-2 (SF-MPQ-2) is a multidimensional outcome measure designed to evaluate neuropathic and nonneuropathic pain. A recent systematic review found insufficient psychometric data with respect to musculoskeletal health conditions. Aims : The aim of this study was to describe the reproducibility (reliability and agreement) and internal consistency of the SF-MPQ-2 for use among patients with musculoskeletal shoulder pain. Methods : Eligible patients with shoulder pain from musculoskeletal (MSK) sources completed the SF-MPQ-2 at baseline ( n = 195), and a subset did so again after 3 to 7 days ( n = 48) if their response to the global rating of change scale remained unchanged. Cronbach's alpha (α) and intraclass correlation coefficient (ICC[2,1]) were calculated. Standard error of measurement (SEM), group and individual minimal detectable change (MDC90), and Bland-Altman plots were used to assess agreement. Results : Cronbach's α ranged from 0.83 to 0.95, suggesting very satisfactory internal consistency across the SF-MPQ-2 domains. Excellent ICC(2,1) scores were found in support of the total (0.95) and continuous (0.92) subscales; the remaining subscales displayed good ICC(2,1) scores (0.78-0.88). Bland-Altman analysis revealed no systematic bias between the test and retest scores (mean difference = 0.13 to 0.19). Though the best agreement coefficients were seen on the total scale (SEM = 0.5; MDC90 = 1.2, MDC90 group  = 0.3), they were acceptable for the SF-MPQ-2 subscales (SEM: range, 0.7-1; MDC90: range, 1.7-2.3; MDC90 group : range, 0.4-0.5). Conclusions : The SF-MPQ-2 provides good to excellent test-retest reliability for multidimensional pain assessment among patients with musculoskeletal shoulder pain conditions., Competing Interests: Samuel U. Jumbo has not declared any conflicts of interest. Joy C. MacDermid has not declared any conflicts of interest. Tara L. Packham has not declared any conflicts of interest. George S. Athwal has not declared any conflicts of interest. Kenneth J. Faber has not declared any conflicts of interest., (© 2020 The Author(s). Published with license by Taylor & Francis Group, LLC.)

Background: Kinematic changes of the scapulothoracic joint may influence the relative position of the glenoid fossa and, consequently, the glenohumeral joint. As the alignment of the scapula relative to the thorax differs between individuals, such variability may be another factor in the development of posterior head subluxation. The purpose of this study was to compare scapulothoracic alignment in pathologic type B shoulders with contralateral healthy shoulders., Methods: Seven adult volunteers with unilateral type B glenohumeral osteoarthritis (OA) underwent bilateral computed tomography (CT) scans of the shoulders and arms. A patient-specific, three-dimensional measurement technique that coupled medical imaging (i.e., CT) and optical motion capture was used., Results: The scapulothoracic distance at the trigonum was 75 ± 15 mm for pathologic shoulders and 78 ± 11 mm for healthy shoulders ( p = 0.583), while at the inferior angle, it was 102 ± 18 mm for pathologic shoulders and 108 ± 12 mm for healthy shoulders ( p = 0.466)., Conclusion: Scapula positioning at a resting position did not differ between pathologic and healthy shoulders. However, pathologic shoulders tended to be limited in maximal glenohumeral motion and exhibited greater anterior tilt of the scapula in internal rotation at 90 degrees, which may be adaptive to the restricted glenohumeral motion.

Background: The optimal insertion location of a latissimus dorsi tendon transfer to restore external rotation after reverse shoulder arthroplasty (RSA) is not well established. The aim of this biomechanical study was to determine the effect of tendon transfer location on external rotation torque, in conjunction with varying RSA humeral component lateralization. We hypothesized that proximal tendon transfers, along with increasing humeral lateralization, would maximize external rotation torque., Methods: Eight fresh-frozen cadaveric shoulders underwent RSA and were tested on an in vitro shoulder simulator. A latissimus dorsi tendon transfer was tested at three insertion locations (lateral greater tuberosity [Lat-GT]; teres minor footprint [Tm-FP]; lateral shaft [Lat-Shft]), and external rotation torque was measured. Additional test conditions included varying humeral component lateralization (-5, 0, +5, +10, +15 mm), abduction angle (0°, 45°, 90°), and internal/external rotation (-60°, -30°, 0°, 30°, 60°)., Results: The Lat-GT and Tm-FP insertions of the latissimus dorsi transfer both generated significantly greater torques ( P < .001) than the Lat-Shft. When comparing Lat-GT to Tm-FP, there were no significant differences ( P  = .362). At 60˚ of external rotation, RSA humeral component lateralization from -5 to +15 mm significantly increased the external rotation torque of Lat-GT by 67% ( P  = .035), Tm-FP by 43% ( P  = .001), and of Lat-Shft by 42% ( P  = .002)., Conclusion: Latissimus dorsi tendon transfer to the proximal lateral aspect of the greater tuberosity and to the insertion site of the teres minor generated significantly more external rotation torque than transfer to the lateral humeral shaft. In addition, the use of a humeral component with greater offset also substantially increases the torque generated by the tendon transfer., (© 2020 The Author(s).)

Importance: Video learning prior to surgery is common practice for trainees and surgeons, and immersive virtual reality (IVR) simulators are of increasing interest for surgical training. The training effectiveness of IVR compared with video training in complex skill acquisition should be studied., Objectives: To evaluate whether IVR improves learning effectiveness for surgical trainees and to validate a VR rating scale through correlation to real-world performance., Design, Setting, and Participants: This block randomized, intervention-controlled clinical trial included senior (ie, postgraduate year 4 and 5) orthopedic surgery residents from multiple institutions in Canada during a single training course. An intention-to-treat analysis was performed. Data were collected from January 30 to February 1, 2020., Intervention: An IVR training platform providing a case-based module for reverse shoulder arthroplasty (RSA) for advanced rotator cuff tear arthropathy. Participants were permitted to repeat the module indefinitely., Main Outcomes and Measures: The primary outcome measure was a validated performance metric for both the intervention and control groups (Objective Structured Assessment of Technical Skills [OSATS]). Secondary measures included transfer of training (ToT), transfer effectiveness ratio (TER), and cost-effectiveness (CER) ratios of IVR training compared with control. Additional secondary measures included IVR performance metrics measured on a novel rating scale compared with real-world performance., Results: A total of 18 senior surgical residents participated; 9 (50%) were randomized to the IVR group and 9 (50%) to the control group. Participant demographic characteristics were not different for age (mean [SD] age: IVR group, 31.1 [2.8] years; control group, 31.0 [2.7] years), gender (IVR group, 8 [89%] men; control group, 6 [67%] men), surgical experience (mean [SD] experience with RSA: IVR group, 3.3 [0.9]; control group, 3.2 [0.4]), or prior simulator use (had experience: IVR group 6 [67%]; control group, 4 [44%]). The IVR group completed training 387% faster considering a single repetition (mean [SD] time for IVR group: 4.1 [2.5] minutes; mean [SD] time for control group: 16.1 [2.6] minutes; difference, 12.0 minutes; 95% CI, 8.8-14.0 minutes; P < .001). The IVR group had significantly better mean (SD) OSATS scores than the control group (15.9 [2.5] vs 9.4 [3.2]; difference, 6.9; 95% CI, 3.3-9.7; P < .001). The IVR group also demonstrated higher mean (SD) verbal questioning scores (4.1 [1.0] vs 2.2 [1.7]; difference, 1.9; 95% CI, 0.1-3.3; P = .03). The IVR score (ie, Precision Score) had a strong correlation to real-world OSATS scores (r = 0.74) and final implant position (r = 0.73). The ToT was 59.4%, based on the OSATS score. The TER was 0.79, and the system was 34 times more cost-effective than control, based on CER., Conclusions and Relevance: In this study, surgical training with IVR demonstrated superior learning efficiency, knowledge, and skill transfer. The TER of 0.79 substituted for 47.4 minutes of operating room time when IVR was used for 60 minutes., Trial Registration: ClinicalTrials.gov Identifier: NCT04404010.

Background: Cuff tear arthropathy (CTA) is characterized by superior migration of the humeral head with superior erosion of the glenoid. Rarely, humeral head migration can be anteroinferior with associated anterior erosion of the glenoid, a pattern described by Favard as the type E4 glenoid. The purpose of this retrospective imaging study was to analyze the 2D and 3D characteristics of the E4 glenoid., Methods: A shoulder arthroplasty database of 258 cuff tear arthropathies was examined to identify patients with an E4 type deformity. This resulted in a study cohort of 15 females and 2 males with an average age of 75 years. All patients had radiographs and CT scans available for analysis. CT-scan DICOM (Digital Imaging and Communications in Medicine) data were uploaded to a validated three-dimensional (3D) imaging software. Muscle fatty infiltration, glenoid measurements (anteversion, inclination), and humeral head subluxation according to the scapular plane were determined., Results: The mean anteversion and inclination of the E4 cohort were 32° ± 14° and -5° ± 2, respectively. The mean anterior subluxation was 19% ± 16%. All cases had severe grade 3 or 4 fatty infiltration of the infraspinatus, whereas only 65% had grade 3 or 4 subscapularis fatty infiltration. A significant correlation existed between glenoid anteversion and humeral head subluxation ( p < 0.001), but no correlation was found with muscle fatty infiltration. The CT analysis demonstrated an acquired erosive biconcave morphology in 11 patients (65%) and monoconcavity in 6 patients (35%)., Conclusion: The E4 type glenoid deformity in cuff tear arthropathy is characterized by an anterior erosion and anteversion associated with anterior subluxation of the humeral head., Competing Interests: The authors declare no conflict of interest.

Background: The Walch type B pattern of glenohumeral osteoarthritis is characterized by posterior humeral head subluxation (PHHS). At present, it is unknown whether the percentage of subluxation measured on axillary radiographs is consistent with measurements on 2-dimensional (2D) axial or 3-dimensional (3D) volumetric computed tomography (CT). The purpose of this study was to evaluate PHHS across imaging modalities (radiographs, 2D CT, and 3D CT)., Methods: A cohort of 30 patients with Walch type B shoulders underwent radiography and standardized CT scans. The cohort comprised 10 type B1, 10 type B2, and 10 type B3 glenoids. PHHS was measured using the scapulohumeral subluxation method on axillary radiographs and 2D CT. On 3D CT, PHHS was measured volumetrically. PHHS was statistically compared between imaging modalities, with P ≤ .05 considered significant., Results: The mean PHHS value for the entire group was 69% ± 24% on radiographs, 65% ± 23% with 2D CT, and 74% ± 24% with 3D volumetric CT. PHHS as measured on complete axillary radiographs was not significantly different than that measured on 2D CT ( P  = .941). Additionally, PHHS on 3D volumetric CT was 9.5% greater than that on 2D CT ( P < .001). There were no significant differences in PHHS between the type B1, B2, and B3 groups with 2D or 3D CT measurement techniques ( P > .102)., Conclusion: Significant differences in PHHS were found between measurement techniques ( P < .035). A 9.5% difference in PHHS between 2D and 3D CT can be mostly accounted for by the linear (2D) vs. volumetric (3D) measurement techniques (a linear 80% PHHS value is mathematically equivalent to a volumetric PHHS value of 89.6%). Surgeons should be aware that subluxation values and therefore thresholds vary across different imaging modalities and measurement techniques., (© 2020 The Author(s).)

Background: The Latarjet and bone block procedures can be secured with screws or cortical buttons. The purpose of this biomechanical study was to compare quadruple buttons vs. double screws for fixation of anterior glenoid bone grafts., Methods: Twelve cadaveric scapulae (6 pairs) were denuded, resected, and potted. Pairs were randomized to quadruple-button or double-screw fixation after creation of a 15% anterior glenoid defect. The specimens underwent cyclic uniaxial compressive glenoid loading between 50 and 200 N for 1000 cycles at 1 Hz. Testing was repeated for conjoint tendon loads of 0 N (simulating a bone block procedure), 10 N, and 20 N (simulating a Latarjet procedure). Peak resultant relative coracoid graft displacement was optically tracked at 3 points (superior, central, and inferior) on the edge of the coracoid., Results: No significant differences were found between buttons and screws for bone block applications or with 10 N of conjoint tendon loading ( P ≥ .095). At 20 N of conjoint tendon loading, however, the screws were significantly more stable than the buttons ( P ≤ .023). During the initial 20-N conjoint load application, all 3 points displaced significantly more with the button reconstruction than with the screws ( P ≤ .01). Overall, mean displacements did not exceed 1 mm at any position on the coracoid, regardless of testing condition., Conclusions: The quadruple-button technique is comparable to screws when the coracoid is used as a bone block or when conjoint tendon loading is minimized. However, at higher conjoint tendon loads, the screws produced a more stable coracoid graft than the buttons., (Crown Copyright © 2020 Published by Elsevier Inc. on behalf of American Shoulder and Elbow Surgeons.)

Purpose of the Review: Reverse shoulder arthroplasty (RSA) is commonly considered as one of the options for surgical management of the functionally irreparable rotator cuff tear (FIRCT). This article reviews tips and tricks to optimize the outcome of RSA when performed specifically for this indication., Recent Findings: RSA has been reported to provide satisfactory outcomes in a large proportion of patients with FIRCTs. However, subjective satisfaction is lesser in patients with well-maintained preoperative motion as well as those with isolated loss of active external rotation. The popularity of implants that provide some degree of global lateralization continues to increase. Optimizing the outcome of RSA for FIRCTs requires a careful balance between minimizing perimeter impingement and enhancing the function of intact muscles, in particular the deltoid and any remaining rotator cuff. Controversy continues regarding the benefits and disadvantages of subscapularis repair at the time of RSA. Tendon and muscle transfers performed at the time of RSA have the potential to optimize the outcome in selected patients with profound weakness in external rotation or those with severe deltoid dysfunction. When RSA is considered for patients with a FIRCT without arthritis, careful attention to indications and technical pearls may contribute to optimize outcomes.

Background: A resorbable subacromial balloon has been developed to address humeral head migration following posterosuperior rotator cuff tears. The purpose of this experimental assessment was to quantify the effect of balloon augmentation on humeral head position., Methods: Eight cadaveric shoulders were subjected to 0°, 30°, 60° and 90° of abduction via a shoulder simulator. The deltoid was activated at 40N, then 80N. The subscapularis and infraspinatus with teres minor were then applied independently and together to create four muscle activation states for each deltoid load. The shoulder was tested intact, torn, then with the balloon. The centre of the humeral head was tracked using active optical markers., Results: When the rotator cuff was torn, the humeral head translated superior by 1.4 ± 1 mm overall (P = 0.009). Following balloon augment, the humeral head translated inferiorly by 2 ± 2 mm relative to the intact state (P = 0.042), and significantly more anterior than the intact (3 ± 2 mm; P = 0.005) state. Rotator cuff variation was only significantly different when the balloon was used, with the subscapularis translating the humeral head posteriorly (P = 0.006)., Discussion: The subacromial balloon inferiorized the humeral head compared to the torn state. Unexpected anterior humeral head translation was attributed to the posterosuperior balloon placement relative to the humeral head., (© 2019 The British Elbow & Shoulder Society.)

Virtual Reality (VR) in orthopedic surgery has significantly increased in popularity in the areas of preoperative planning, intraoperative usage, and for education and training; however, its utilization lags behind other surgical disciplines and industries. The use of VR in orthopedics is largely focused on education and is currently endorsed by North American and European training committees. The use of VR in shoulder and elbow surgery has varying levels of evidence, from I to IV, and typically involves educational randomized controlled trials. To date, however, the terms and definitions surrounding VR technology used in the literature are often redundant, confusing, or outdated. The purpose of this review, therefore, was to characterize previous uses of VR in shoulder and elbow surgery in preoperative, intraoperative, and educational domains including trauma and elective surgery. Secondary objectives were to provide recommendations for updated terminology of immersive VR (iVR) as well as provide a framework for standardized reporting of research surrounding iVR in shoulder and elbow surgery., (© 2020 The Authors.)

Background: Facioscapulohumeral muscular dystrophy (FSHD) is a rare condition associated with selective weakness of the muscles of the upper arm, face, and shoulder girdle, negatively affecting daily activities. Scapulothoracic arthrodesis may restore shoulder function and improve quality of life. The purpose of this review is to evaluate the outcomes and complications of scapulothoracic arthrodesis in FSHD patients., Methods: Medline, Pubmed, and Embase were systematically searched. Studies were included if they described scapulothoracic arthrodesis in FSHD with follow-up, and outcomes were adequately reported. Thirteen eligible articles reported the outcomes of 199 arthrodesis in 130 patients., Results: The mean gain of shoulder forward elevation and abduction were 45° (p < 0.05) and 40° (p < 0.05), respectively. There was an overall cosmetic satisfaction and improved performance of daily activities. There is limited and heterogeneous data on changes in pulmonary function, but such changes are clinically insignificant. The rate of complications was 41% of which 10% were serious, requiring an intervention or re-admission. The most common complications were hardware failure (8%), non-union (6%), and pneumothorax (5%)., Discussion: Scapulothoracic arthrodesis improved cosmesis, performance of daily activities and shoulder motion with no clinically significant loss of pulmonary function. The complication rate is high, and some are potentially serious., (© 2019 The British Elbow & Shoulder Society.)

Background: The shortened version of the Western Ontario Rotator Cuff Index (Short-WORC) is a patient reported outcome measure that evaluates quality of life (QoL) of patients with rotator cuff pathology. However, formal content validation of the full or Short-WORC has not been reported. This study aims to understand how 1) people interpret and calibrate responses to items on the Short-WORC and 2) compensatory strategies that might enhance function and thereby affect responses., Methods: This study uses cognitive interviewing, a qualitative methodology that focuses on the interpretation of questionnaire items. Patients with rotator cuff disorders (n = 10), clinicians (n = 6) and measurement researchers (n = 10) were interviewed using a talk aloud structured interview that evaluated each of the 7 items of the Short-WORC. All interviews were recorded and transcribed verbatim by one researcher (R.F). Analysis was done through an open coding scheme using a previously established framework., Results: Overall, the items on the Short-WORC were well received by participants. Through the interviews, the 6 themes of: Comprehension, Inadequate response definition, Reference Point, Relevance, Perspective Modifiers and Calibration Across Items emerged. The items of working above the shoulder (90%), compensating with the unaffected arm (88%) and lifting heavy objects (92%) were the most relevant to participants. Participants calibrated their scores on the items of sleeping and styling (19%) the most. Perspective modifiers of gender, influenced the calibrations of items of styling your hair (30%) and dressing or undressing (19%). Compensatory strategies of task-re allocation and using assistive devices/resources were frequently mentioned by participants. Overall, participants had minor comprehension issues, but found the 7- items of the Short-WORC to be relevant to QoL., Conclusions: Therefore, the findings demonstrate that the Short-WORC is not cognitively complex, but varies with patient perspectives. Overall, the Short-WORC provides evidence of demonstrating strong content validity when used for rotator cuff disorder patients.

Background: Numerous fixed-stem implants exist for radial head arthroplasty; therefore, we conducted a systematic review to compare the safety and efficacy of different types of fixed-stem implants., Methods: We conducted a literature search, updated from a previous systematic review, to identify studies evaluating a fixed-stem radial head arthroplasty implant for any indication. We extracted data on revision rates, specific complications, and functional scores. We pooled results across studies using a random-effects method, using proportions for dichotomous data and mean values for functional scores. We analyzed outcomes by indication and specific implant., Results: We included 31 studies. Studies included patients with radial head fractures only, terrible-triad injuries, or Essex-Lopresti injuries or included a heterogeneous population. We identified 15 different fixed-stem implants. The results of our analysis revealed that patients with terrible-triad injuries may be at an increased risk of revision and instability and patients with Essex-Lopresti injuries may be at an increased risk of arthritis, capitellar erosion, and osteolysis. After removing these outliers and pooling the results by specific device, we observed variability across devices in the rates of revision, arthritis, capitellar erosion, instability, and osteolysis, as well as in functional scores., Conclusion: Differences were seen across different implants in revision rates, certain complications, and functional scores. This study highlighted that these devices should be evaluated within the context of the patient population under examination, as patients with Essex-Lopresti or terrible-triad injuries may demonstrate worse outcomes relative to those with a fracture only., (© 2019 The Author(s).)

Background: To evaluate the translations, cross-cultural adaptation procedures and measurement properties of the Western Ontario Rotator Cuff Index (WORC), when it is adapted for different cultures., Methods: A systematic review was performed, considering different cultural adaptions of the WORC accessible through MEDLINE, CINAHL, EMBASE and/or Google Scholar. Included were prospective cohort studies that used an adapted version of the WORC to measure QoL in patients with rotator cuff disorders. All studies were evaluated according to the current guidelines for cross-cultural adaptations and measurement properties., Results: The search retrieved 14 studies that met the inclusion criteria. According to the recommended guidelines for cross-cultural adaptations, 8 studies performed 100% of the steps, 2 studies performed 80% of the steps and 4 studies used previously translated measures. When evaluating the studies' psychometric properties based on the quality criteria, none of the studies reported all recommended measurement properties. All of the studies reported the measurement property of reliability, but none of the studies reported agreement. Internal consistency was fully reported by 15% of studies. Construct validity was reported by 43% of studies. Only one study reported 100% of the cross-cultural adaption guidelines and 83% of the quality criteria., Conclusions: Although the majority of studies demonstrated proper adaptation procedures, testing of the measurement properties were inadequate. It is recommended that the current adapted versions of the WORC undergo further testing before use in clinical practise, and researchers continue to adapt the WORC for different cultures as it proves to be an appropriate instrument for assessing rotator cuff pathology.

Background: Recently, a shorter version of the Western Ontario Rotator Cuff Index (Short-WORC) was created to reduce patient response burden. However, it has yet to be evaluated prospectively for reproducibility (reliability and agreement) and floor and ceiling effects., Methods: Patients (N = 162) with rotator cuff disorders completed the Short-WORC at baseline. From this cohort, 47 patients underwent measurement of test-retest reliability within 2 to 7 days. We used the Cronbach α to determine internal consistency and the intraclass correlation coefficient (ICC 2,1 ) to assess test-retest reliability. To evaluate parameters of agreement, the standard error of measurement, minimal detectable change (based on a 90% confidence interval), and Bland-Altman plots were used., Results: The Cronbach α was 0.82 at baseline, and the intraclass correlation coefficient (ICC 2,1 ) was 0.87. The agreement parameter was 8.4 for the standard error of measurement of agreement, and the limits of agreement fell within the range of -22.9 to 23.8. The Short-WORC is reliable over time and reflective of a patient's true score after an intervention., Conclusions: The Short-WORC demonstrated strong reproducibility parameters and can be used for patients with rotator cuff disorders. The Short-WORC indicated no systematic bias and was reflective of the true score of both individual patients and groups of patients at 2 time points., (© 2019 The Author(s).)

Background: The purpose of this multicenter, prospective study was to evaluate the efficacy and safety of a stemless total shoulder arthroplasty compared with a traditional stemmed control., Methods: Ninety-five shoulders were selected for participation in this Food and Drug Administration investigational device exemption clinical trial and underwent stemless total shoulder arthroplasty. Subjects returned for follow-up at 6 weeks, 6 months, 12 months, and 2 years postoperatively. Outcome measures included pain; range of motion; American Shoulder and Elbow Surgeons, Western Ontario Osteoarthritis of the Shoulder, and Short Form 12 scores; and radiographic review. Baseline data were compared with 2-year follow-up data to determine the rate of composite clinical success compared with the stemmed control., Results: All outcome assessments demonstrated significant improvements ( P ≤ .007). The mean American Shoulder and Elbow Surgeons score improved from 20 to 89 ( P < .0001), and the mean shoulder pain score decreased from 8.3 ± 1.6 to 0.7 ± 1.5 ( P < .0001). The mean Western Ontario Osteoarthritis of the Shoulder score decreased from 1443 ± 256 to 203 ± 267 ( P < .0001). On the Short Form 12, the mean physical health score increased from 33 ± 7 to 48 ± 9 ( P < .0001) and the mean mental health score increased from 50 ± 13 to 54 ± 8 ( P  = .007). Mean active forward elevation increased from 97° ± 27° to 143° ± 25° ( P < .0001), and mean active external rotation increased from 21° ± 16° to 53° ± 18° ( P < .0001). Kaplan-Meier analysis showed an implant survivorship rate of 98% at 2 years. The composite clinical success rate was 87% compared with 85% for the stemmed control., Conclusions: This study showed that a stemless rough-blasted humeral implant with metaphyseal bone fixation provides good clinical and radiographic outcomes and survivorship at 2 years, with outcomes comparable to a traditional stemmed implant., (© 2019 The Author(s).)

Objective: To assess the effectiveness of arthroscopic versus mini-open rotator cuff repair on function, pain and range of motion at 3-, 6- and 12-month follow ups., Design: Systematic review and meta-analysis of randomized controlled trials., Setting: Clinical setting., Participants: Patients 18 years and older with a rotator cuff tear., Intervention/comparison: Arthroscopic/mini-open rotator cuff repair surgery followed by post operative rehabilitation., Main Outcome Measures: Function and pain., Results: Six RCTs (n = 670) were included. The pooled results, demonstrated no significant difference between arthroscopic and mini open approach to rotator cuff repair on function (very low quality, 4 RCTs, 495 patients, SMD 0.00, 3-month; very low quality, 4 RCTs, 495 patients, SMD -0.01, 6-month; very low quality, 3 RCTs, 462 patients, SMD -0.09, 12-months). For pain, the pooled results, were not statistically different between groups (very low quality, 3 RCTs, 254 patients, MD -0.21, 3-month; very low quality, 3 RCTs, 254 patients, MD -0.03, 6-month; very low quality, 2 RCTs, 194 patients, MD -0.35, 12-months)., Conclusion: The effects of arthroscopic compared to mini-open rotator cuff repair, on function, pain and range of motion are too small to be clinically important at 3-, 6- and 12-month follow ups., Competing Interests: The authors have declared that no competing interests exist.

Objective: To assess the effectiveness of surgical vs conservative interventions on pain and function in patients with subacromial impingement syndrome., Design: Systematic review and meta-analysis of randomized controlled trials., Setting: Clinical setting., Participants: Patients 18 years and older with subacromial impingement syndrome., Intervention/comparison: Surgical intervention plus postoperative physiotherapy / placebo surgery plus physiotherapy or physiotherapy only., Main Outcome Measures: Pain and function., Results: 11 RCTs (n = 919) were included. The pooled results displayed no statistically or clinically different between surgery plus physiotherapy vs physiotherapy alone on pain levels at 3-, 6-months, 5- and 10 years follow up (moderate quality, 3 RCTs, 300 patients, WMD -0.39, 95% CI: -1.02 to 0.23, p = 0.22; moderate quality, 3 RCTs, 310 patients, WMD -0.36, 95% CI: -1.02 to 0.29, p = 0.27; low quality, 1 RCT, 109 patients, WMD -0.30, 95% CI: -1.54 to 0.94, p = 0.64; low quality, 1 RCT, 90 patients, WMD -1.00, 95% CI: -0.24 to 2.24, p = 0.11) respectively. Similarly, the pooled results were not statistically or clinically different between groups for function at 3-, 6-month and 1-year follow ups (very low quality, 2 RCTs, 184 patients, SMD 0.11, 95% CI: -0.57 to 0.79, p = 0.75; moderate quality, 3 RCTs, 310 patients, SMD 0.15, 95% CI: -0.14 to 0.43, p = 0.31; very low quality, 2 RCTs, 197 patients, SMD 0.11, 95% CI: -0.46 to 0.69, p = 0.70) respectively., Conclusion: The effects of surgery plus physiotherapy compared to physiotherapy alone on improving pain and function are too small to be clinically important at 3-, 6-months, 1-, 2-, 5- and ≥ 10-years follow up., Competing Interests: The authors have declared that no competing interests exist.