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BackgroundThe appropriate amount of cementation at the time of reverse total shoulder arthroplasty with significant proximal bone loss or resection is unknown. Extensive cementation of a humeral prosthesis makes eventual revision arthroplasty more challenging, increasing the risk of periprosthetic fracture. We analyzed the degree of subsidence and torque tolerance of humeral components undergoing standard cementation technique vs. our reduced polymethyl methacrylate (PMMA) protocol. Reduced cementation may provide sufficient biomechanical stability to resist physiologically relevant loads, while still permitting a clinically attainable torque for debonding the prosthesis.MethodsA total of 12 cadaveric humeri (6 matched pairs) underwent resection of 5 cm of bone distal to the greater tuberosity. Each pair of humeri underwent standard humeral arthroplasty preparation followed by either cementation using a 1.5-cm PMMA sphere at a location 3 cm inferior to the porous coating or standard full stem cementation. A 6-degree-of-freedom robot was used to perform all testing. Each humeral sample underwent 200 cycles of abduction, adduction, and forward elevation while being subjected to a physiologic compression force. Next, the samples were fixed in place and subjected to an increasing torque until implant-cement separation or failure occurred. Paired t tests were used to compare mean implant subsidence vs. a predetermined 5-mm threshold, as well as removal torque in matched samples.ResultsFully and partially cemented implants subsided 0.49 mm (95% CI 0.23-0.76 mm) and 1.85 mm (95% CI 0.41-3.29 mm), respectively, which were significantly less than the predetermined 5-mm threshold (P

Objective: The objective of this study was to evaluate clinical and radiological outcomes of a short stem reverse shoulder prosthesis with metaphyseal fixation specifically in older patients. Methods: All patients, older than 70 years, submitted to a Reverse Shoulder Arthroplasty (RSA) using a cementless onlay short stem (Aequalis Ascend™ Flex Convertible Shoulder System (Stryker®)) from January 2017 to December 2021, with a minimum follow-up of 2 years, were included. Postoperative radiographs were assessed for stem loosening, subsidence, and varus-valgus tilt. Range of motion, visual analogue scale for pain, constant score, complication rate and revision rate were also analysed. Results: A total of 34 patients with a mean age of 75 years (range 71–83 years) were submitted to a cementless onlay short stem RSA with a Bone Increased Off-Set (BIO-RSA) construct. The mean follow-up period was 61 months (range 54–87). Significant improvements (p < 0.001) were observed for the constant score and range of motion from the preoperative state to final follow-up. One case exhibited a significant varus deviation (> 5˚) during the follow-up period. No case of stem loosening was identified. There was only one case of complication because of post-traumatic dislocation, but the stem didn't need revision. Conclusion: Short stem RSA, even in patients older than 70 years, can yield a stable fixation with a good clinical and radiological outcome at short-medium term follow-up. Level of Evidence: Level III; Retrospective Study [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to obtain the morphological and morphometric variations of the glenoid cavity of the scapula in the population of Bihar and compare it to that of the study done in different races by the previous author. Method: A total of 120 dry adult human scapulae of unknown age and sex in which 60 belong to the right side and 60 belonging to the left side were obtained from the Department of Anatomy and forensic medicine of Indira Gandhi Institute of Medical Sciences, Patna and also from other medical colleges of Bihar. Results: The most common shape of the glenoid cavity recorded in this study was pearshaped followed by inverted comma-shaped. The least common shape was oval. The mean scapular length was observed as 137.11±8.72 mm, the mean breadth of scapula was 98.73±10.92 mm, the mean supero-inferior glenoid diameter was 36.34±3.91 mm, the mean anteroposterior glenoid diameter was 24.95±4.58 mm and mean glenoid cavity index was 68.82±10.33. Conclusion: Morphological and morphometric analysis of the glenoid cavity of the scapula is very important during designing and fitting of glenoid components in total shoulder arthroplasty and its associated shoulder pathology. [ABSTRACT FROM AUTHOR]

Background: Fishing is a popular recreational activity that stresses the shoulder. With the expanding prevalence of reverse total shoulder arthroplasty (rTSA), it is important to better understand return to fishing. Methods: A retrospective chart review from the electronic medical record was performed on patients undergoing primary rTSA by the designated surgeon with a minimum 6 month follow up. Demographic and surgical variables included age, sex, side of surgery and need for revision.Return to fishing metrics included casting distance and reason to not return to sport. Satisfaction and pain scores were also recorded. Results: Nineteen patients self-identified as participating in fishing before undergoing rTSA. Fifteen patients (79 %) were male and mean age was 68.47 years ( ± 9.95 years). 15 participants (79 %) indicated that they were able to return to fishing after their rTSA with a mean age of 67.07 years ( ± 10.64 years). Of those who returned to sport, 14 participants (93 %) indicated that their pain was better than it was before rTSA. Average VAS pain score of the return to sport group was 1.67 ( ± 2.79, range 0–7). Postoperative casting distance was the same in 10 patients (67 %). The most common reason for not returning to fishing was issues with pain and function. Conclusion: rTSA could allow for return to fishing with similar functional status. Switching casting technique and grip may help improve return to sport. Implant considerations may improve stability and ROM which may help further augment return to fishing.

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Abstract Background The incidence of Total Shoulder Arthroplasty (TSA) and Reverse Total Shoulder Arthroplasty (RTSA) is constantly increasing. As a result, the interest in post-surgical rehabilitation has grown, since it is crucial in order to achieve full recovery and successful outcomes. The first aim of this study is to investigate the Italian physiotherapists (PTs) clinical practice in the management of patients with TSA and RTSA and to compare it with the best evidence available in the literature. The second purpose of this study is to assess any existing difference between the survey answers and the different sample subgroups. Materials and methods This cross-sectional observation study was designed following the CHERRIES checklist and the STROBE guidelines. A 4-sections survey with a total of 30 questions was developed for investigating post-surgery rehabilitation management in patient with TSA and RTSA. The survey was sent to Italian PTs from December 2020 until February 2021. Results Six-hundred and seven PTs completed the survey regarding both TSA and RTSA; 43.5% of participants (n = 264/607) stated that TSA is more likely to dislocate during abduction and external rotation. Regarding reverse prosthesis, 53.5% (n = 325/607) affirmed RTSA is more likely to dislocate during internal rotation, adduction and extension. In order to recover passive Range of Motion (pROM), 62.1% (n = 377/607) of participants reported that they gain anterior flexion, abduction, internal rotation, external rotation up to 30°, with full pROM in all directions granted at 6–12 weeks. Regarding the active ROM (aROM), 44.2% (n = 268/607) of participants stated that they use active-assisted procedures within a range under 90° of elevation and abduction at 3–4 weeks and higher than 90° at 6–12 weeks, with full recovery at a 3-month mark. Sixty-five point seven percent of the sample (n = 399/607) declared that, during the rehabilitation of patients with TSA, they tend to focus on strengthening the scapular and rotator cuff muscles, deltoid, biceps and triceps. Conversely, 68.0% (n = 413/607) of participants stated that, for the rehabilitation of patients with RTSA, they preferably focus on strengthening the periscapular and deltoid muscles. Finally, 33.1% (n = 201/607) of participants indicated the instability of the glenoid prosthetic component as the most frequent complication in patients with TSA, while 42.5% (n = 258/607) of PTs identified scapular neck erosion as the most frequent post-RTSA surgery complication. Conclusions The clinical practice of Italian PTs effectively reflects the indications of the literature as far as the strengthening of the main muscle groups and the prevention of movements, which may result in a dislocation, are concerned. Some differences emerged in the clinical practice of Italian PTs, regarding the restoration of active and passive movement, the starting and progression of muscle strengthening and the return to sport (RTS). These differences are actually quite representative of the current knowledge in post-surgical rehabilitation for shoulder prosthesis in the rehabilitation field. Level of evidence V

Background: Periprosthetic joint infection (PJI) after shoulder arthroplasty remains a significant complication. This study aimed to explore the epidemiology and risk factors of shoulder PJI in patients aged 60 and younger, analyze treatment options, and evaluate outcomes after 1-year follow-up. Methods: In this retrospective multicentric observational study, data from 1404 shoulders in patients under 60 who underwent primary shoulder arthroplasty were analyzed. Patients with PJI and at least 1-year follow-up after infection treatment were included. Results: The study identified 55 shoulders with PJI, resulting in a 2.35% infection rate after primary shoulder arthroplasty in the young population. Male gender and reverse shoulder arthroplasty were risk factors for infection, while previous surgeries did not significantly contribute. The most common causative agents were Cutibacterium acnes and Staphylococcus epidermidis. Open washout had a 52.9% success rate for acute infections, while one-stage and two-stage revisions achieved infection control rates of 91.3% and 85.7%, respectively. Resection arthroplasty had an 81.8% success rate but poorer functional outcomes. Conclusions: PJI following shoulder arthroplasty in young patients is a significant concern. Preoperative planning should be carefully considered to minimize infection risk. Treatment options such as open washout and one-stage and two-stage revisions offer effective infection control and improved functional outcomes. Resection arthroplasty should be reserved for complex cases where reimplantation is not a viable option. [ABSTRACT FROM AUTHOR]

Background: The incidence of Total Shoulder Arthroplasty (TSA) and Reverse Total Shoulder Arthroplasty (RTSA) is constantly increasing. As a result, the interest in post-surgical rehabilitation has grown, since it is crucial in order to achieve full recovery and successful outcomes. The first aim of this study is to investigate the Italian physiotherapists (PTs) clinical practice in the management of patients with TSA and RTSA and to compare it with the best evidence available in the literature. The second purpose of this study is to assess any existing difference between the survey answers and the different sample subgroups. Materials and methods: This cross-sectional observation study was designed following the CHERRIES checklist and the STROBE guidelines. A 4-sections survey with a total of 30 questions was developed for investigating post-surgery rehabilitation management in patient with TSA and RTSA. The survey was sent to Italian PTs from December 2020 until February 2021. Results: Six-hundred and seven PTs completed the survey regarding both TSA and RTSA; 43.5% of participants (n = 264/607) stated that TSA is more likely to dislocate during abduction and external rotation. Regarding reverse prosthesis, 53.5% (n = 325/607) affirmed RTSA is more likely to dislocate during internal rotation, adduction and extension. In order to recover passive Range of Motion (pROM), 62.1% (n = 377/607) of participants reported that they gain anterior flexion, abduction, internal rotation, external rotation up to 30°, with full pROM in all directions granted at 6–12 weeks. Regarding the active ROM (aROM), 44.2% (n = 268/607) of participants stated that they use active-assisted procedures within a range under 90° of elevation and abduction at 3–4 weeks and higher than 90° at 6–12 weeks, with full recovery at a 3-month mark. Sixty-five point seven percent of the sample (n = 399/607) declared that, during the rehabilitation of patients with TSA, they tend to focus on strengthening the scapular and rotator cuff muscles, deltoid, biceps and triceps. Conversely, 68.0% (n = 413/607) of participants stated that, for the rehabilitation of patients with RTSA, they preferably focus on strengthening the periscapular and deltoid muscles. Finally, 33.1% (n = 201/607) of participants indicated the instability of the glenoid prosthetic component as the most frequent complication in patients with TSA, while 42.5% (n = 258/607) of PTs identified scapular neck erosion as the most frequent post-RTSA surgery complication. Conclusions: The clinical practice of Italian PTs effectively reflects the indications of the literature as far as the strengthening of the main muscle groups and the prevention of movements, which may result in a dislocation, are concerned. Some differences emerged in the clinical practice of Italian PTs, regarding the restoration of active and passive movement, the starting and progression of muscle strengthening and the return to sport (RTS). These differences are actually quite representative of the current knowledge in post-surgical rehabilitation for shoulder prosthesis in the rehabilitation field. Level of evidence: V [ABSTRACT FROM AUTHOR]

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Abstract Objective The present study aimed to evaluate the clinical outcomes of reverse shoulder arthroplasty to treat several conditions. Methods Retrospective, longitudinal study analyzing the Constant and University of California at Los Angeles (UCLA) scores and range of motion of patients undergoing reverse shoulder arthroplasty. Results In total, 28 patients were analyzed, with a mean age of 75.6 years old. The mean duration of follow-up was 45 months. Overall, there was a significant variation (p< 0.0001) between the preoperative (10.2 points) and the postoperative UCLA scores (29.6 points), corresponding to a relative increase of approximately 200%. In addition, the mean Constant score was 67.8, and the complication rate was 17.8%. As for functional outcomes per etiology, fracture sequelae cases presented the best mean elevation (165°), Constant score (79 points), postoperative UCLA score (32.5 points), and absolute delta UCLA score increase (22 points), but with no statistical significance. However, cases operated for fracture sequelae showed significantly higher elevation (p= 0.027) and Constant score (p= 0.047) compared to rotator cuff arthropathy cases. In addition, the lowest mean postoperative Constant and UCLA scores were observed for the following etiologies: primary arthrosis, acute fracture, and arthroplasty revision. Conclusion Reverse shoulder arthroplasty showed satisfactory functional outcomes and may be a treatment option not only for rotator cuff arthropathy but for several other conditions.

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Copyright of Die Orthopädie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: The employment of reverse shoulder arthroplasty for dislocated proximal humerus fractures of elderly patients becomes increasingly relevant. The standard inclination angle of the humeral component was 155°. Lately, there is a trend towards smaller inclination angles of 145° or 135°. Additionally, there has been an increased focus on the lateralization of the glenosphere. This retrospective comparative study evaluates clinical and radiological results of patients treated for proximal humerus fractures by reverse shoulder arthroplasty with different inclination angles of the humeral component, which was either 135° or 155°. Additionally, a different lateral offset of the glenosphere, which was either 0 mm or 4 mm, was used. Methods: For this retrospective comparative analysis, 58 out of 66 patients treated by reverse total shoulder arthroplasty for proximal humerus fractures were included. The minimum follow-up was 24 months. Thirty (m = 3, f = 27; mean age 78 years; mean FU 35 months, range 24–58 months) were treated with a standard 155° humeral component and a glenosphere without lateral offset (group A), while 28 patients (m = 2, f = 26; mean age 79 years; mean FU 30 months, range 24–46 months) were treated with a 135° humeral component and a glenosphere with a 4 mm lateral offset (group B). We determined range of motion, Constant score, and the American Shoulder and Elbow Surgeons Shoulder score as clinical outcomes and evaluated tuberosity healing as well as scapula notching. Results: Neither forward flexion (A = 128°, B = 121°; p = 0.710) nor abduction (A = 111°, B = 106°; p = 0.327) revealed differences between the groups. The mean Constant Score rated 63 in group A, while it was 61 in group B (p = 0.350). There were no differences of the ASES Score between the groups (A = 74, B = 72; p = 0.270). There was an increased risk for scapula notching in group A (47%) in comparison to group B (4%, p = 0.001). Healing of the greater tuberosity was achieved in 57% of group A and in 75% of group B (p = 0.142). The healing rate of the lesser tuberosity measured 33% in group A and 71% in group B (p = 0.004). Conclusions: Both inclination angles of the humeral component are feasible options for the treatment of proximal humerus fractures in elderly patients. Neither the inclination angle nor the lateral offset of the glenosphere seem to have a relevant influence on the clinical outcome. The healing rate of the lesser tuberosity was higher in implants with a decreased neck-shaft angle. There is an increased risk for scapula notching, if a higher inclination angle of the humeral component is chosen. Level of evidence: III. Retrospective comparative study. [ABSTRACT FROM AUTHOR]

Copyright of Obere Extremitat is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Periprosthetic joint infection (PJI) after shoulder arthroplasty remains a significant complication. This study aimed to explore the epidemiology and risk factors of shoulder PJI in patients aged 60 and younger, analyze treatment options, and evaluate outcomes after 1-year follow-up. Methods: In this retrospective multicentric observational study, data from 1404 shoulders in patients under 60 who underwent primary shoulder arthroplasty were analyzed. Patients with PJI and at least 1-year follow-up after infection treatment were included. Results: The study identified 55 shoulders with PJI, resulting in a 2.35% infection rate after primary shoulder arthroplasty in the young population. Male gender and reverse shoulder arthroplasty were risk factors for infection, while previous surgeries did not significantly contribute. The most common causative agents were Cutibacterium acnes and Staphylococcus epidermidis. Open washout had a 52.9% success rate for acute infections, while one-stage and two-stage revisions achieved infection control rates of 91.3% and 85.7%, respectively. Resection arthroplasty had an 81.8% success rate but poorer functional outcomes. Conclusions: PJI following shoulder arthroplasty in young patients is a significant concern. Preoperative planning should be carefully considered to minimize infection risk. Treatment options such as open washout and one-stage and two-stage revisions offer effective infection control and improved functional outcomes. Resection arthroplasty should be reserved for complex cases where reimplantation is not a viable option.

As its indications expand, reverse total shoulder arthroplasty (rTSA) utilization continues to increase. Though relatively uncommon, instability following rTSA can be associated with significant morbidity and need for subsequent revision and treatment. This case control study aims to characterize factors leading to instability after rTSA, especially in those with no previous shoulder surgery. 194 rTSAs performed within the study period with appropriate operative indications and follow-up were included. Risk factors used in analysis included age, gender, BMI, ASA class, Charlson comorbidity index (CCI), glenosphere, tray, and liner size. Data was analyzed using a hierarchical binary logistical regression to create a predictive model for instability. Seven patients sustained a post-operative dislocation. Mean time to dislocation was 60.4 weeks. Five required open reduction with placement of either a larger humeral tray or polyethylene spacer. One required open reduction with osteophyte removal, and one was converted to a resection arthroplasty. Dislocators were more likely to have a larger BMI (p = 0.002), higher ASA classification (p = 0.09), and larger liner size (p = 0.01). This study demonstrates a large series of patients successfully treated with rTSA. Dislocations were an uncommon complication, but were clearly associated with higher patient BMI, ASA classification, and increased liner size. [ABSTRACT FROM AUTHOR]

Introduction: There are a variety of baseplate options when performing reverse total shoulder arthroplasty (RTSA). Currently, there is no consensus on the optimal glenoid baseplate. The hypothesis of this study was that the use of lateralized baseplates would improve patient-determined outcomes and postoperative range of motion after RTSA compared with standard baseplates without increasing the risk of complications., Methods: Patients undergoing RTSA were stratified into a standard baseplate group (SBG) and a lateralized baseplate group (LBG). The LBG included 3 mm lateralization, 6 mm lateralization, and full-wedge augmentation (8 mm lateralization). The Western Ontario Osteoarthritis Score, American Shoulder and Elbow Surgeons score, Single Assessment Numeric Evaluation (SANE), and Simple Shoulder Test (SST) were recorded at baseline, 1 year, and 2 years. Range of motion was recorded at baseline and 1 year. Differences in complications between groups were recorded., Results: The LBG included 187 patients, and the SBG included 51 patients. No difference was observed in any patient-determined outcome score at 1-year follow-up. At 2 years, there were greater Western Ontario Osteoarthritis Score (84 ± 16 versus 74 ± 19; P = 0.01), American Shoulder and Elbow Surgeons score (81 ± 15 versus 70 ± 20; P = 0.001), SST (8.0 ± 2.4 versus 6.6 ± 2.6; P = 0.007), and SANE (82 ± 17 versus 68 ± 25; P = 0.0005). The improvement in SST (5.0 ± 2.7 versus 3.3 ± 3.6; P = 0.02) and SANE (54 ± 26 versus 37 ± 30; P = 0.004) at 2 years compared with baseline was greater in the LBG compared with the SBG. No difference was observed in any range-of-motion metric between groups. Total complications were similar between groups ( P = 0.91). Scapular notching was more prevalent in the SBG (7.8% versus 1.6%; P = 0.01)., Conclusion: The LBG had better patient-determined outcome scores compared with the SBG at 2-year follow-up with a similar rate of overall complications but a lower rate of scapular notching. Range of motion was not improved by the use of a lateralized baseplate compared with a standard baseplate., Competing Interests: Keith Baumgarten has disclosures that may be considered as a potential conflict of interest (Stryker/Wright Medical, Miach). Neither Carson Max nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article., (Copyright © 2024 by the American Academy of Orthopaedic Surgeons.)

Aims: The survival of humeral hemiarthroplasties in patients with relatively intact glenoid cartilage could theoretically be extended by minimizing the associated postoperative glenoid erosion. Ceramic has gained attention as an alternative to metal as a material for hemiarthroplasties because of its superior tribological properties. The aim of this study was to assess the in vitro wear performance of ceramic and metal humeral hemiarthroplasties on natural glenoids., Methods: Intact right cadaveric shoulders from donors aged between 50 and 65 years were assigned to a ceramic group (n = 8, four male cadavers) and a metal group (n = 9, four male cadavers). A dedicated shoulder wear simulator was used to simulate daily activity by replicating the relevant joint motion and loading profiles. During testing, the joint was kept lubricated with diluted calf serum at room temperature. Each test of wear was performed for 500,000 cycles at 1.2 Hz. At intervals of 125,000 cycles, micro-CT scans of each glenoid were taken to characterize and quantify glenoid wear by calculating the change in the thickness of its articular cartilage., Results: At the completion of the wear test, the total thickness of the cartilage had significantly decreased in both the ceramic and metal groups, by 27% (p = 0.019) and 29% (p = 0.008), respectively. However, the differences between the two were not significant (p = 0.606) and the patterns of wear in the specimens were unpredictable. No significant correlation was found between cartilage wear and various factors, including age, sex, the size of the humeral head, joint mismatch, the thickness of the native cartilage, and the surface roughness (all p > 0.05)., Conclusion: Although ceramic has better tribological properties than metal, we did not find evidence that its use in hemiarthroplasty of the shoulder in patients with healthy cartilage is a better alternative than conventional metal humeral heads., Competing Interests: H. Mahmud reports funding from the Brunei UBD Chancellor’s PhD Scholarship, related to this study. D. Wang reports research consulting fees from Imperial College London, related to this study. C. H. Heinrichs and U. N. Hansen report the provision of implants by orthopaedic manufacturer Mathys Ltd Bettlach, related to this study. A. A. Amis and R. Emery report an institutional grant (paid to Imperial College London) from the Wellcome Trust to fund the project to build the shoulder wear simulator, related to this study., (© 2024 Mahmud et al.)

Aims: We sought to compare functional outcomes and survival between non-smokers, former smokers, and current smokers who underwent anatomical total shoulder arthroplasty (aTSA) in a large cohort of patients., Methods: A retrospective review of a prospectively collected shoulder arthroplasty database was performed between August 1991 and September 2020 to identify patients who underwent primary aTSA. Patients were excluded for preoperative diagnoses of fracture, infection, or oncological disease. Three cohorts were created based on smoking status: non-smokers, former smokers, and current smokers. Outcome scores (American Shoulder and Elbow Surgeons (ASES), Constant-Murley score, Shoulder Pain and Disability Index (SPADI), Simple Shoulder Test (SST), University of California, Los Angeles activity scale (UCLA)), range of motion (external rotation (ER), forward elevation (FE), internal rotation, abduction), and shoulder strength (ER, FE) evaluated at two- to four-year follow-up were compared between cohorts. Evaluation of revision-free survival was performed using the Kaplan-Meier method to final follow-up., Results: We included 428 primary aTSAs with a mean follow-up of 2.4 years (SD 0.6). Our cohort consisted of 251 non-smokers, 138 former smokers who quit a mean 21 years (SD 14) prior to surgery (25 pack-years (SD 22)), and 39 current smokers (23 pack-years (SD 20)). At two- to four-year follow-up, former smokers had less favourable SPADI, SST, and FE strength compared to non-smokers, and current smokers had less favourable SPADI, SST, ASES score, UCLA score, Constant-Murley score, FE, abduction, and ER strength compared to non-smokers. Non-smokers exhibited higher revision-free survival rates at two, five, eight, and ten years postoperatively compared to former smokers and current smokers, who had similar rates., Conclusion: Our study suggests that smoking has a negative effect on aTSA functional outcomes that may persist even after quitting., Competing Interests: K. A. Hao reports consulting fees from LinkBio, unrelated to this study. B. S. Schoch reports royalties or licenses and consulting fees from Responsive Arthroscopy, Inomed, and Exactech, all of which are unrelated to this study. K. W. Farmer reports consulting fees from Arthrex and Exactech, unrelated to this study. T. W. Wright reports royalties or licenses from Exactech and Wolters Kluwer Health, unrelated to this study. J. J. King reports consulting fees from Exactech and LinkBio, unrelated to this study., (© 2024 The British Editorial Society of Bone & Joint Surgery.)

Background: Walch B2 glenoids can present a challenge to shoulder arthroplasty surgeons. Short-term studies have demonstrated that corrective reaming to 10° of retroversion in anatomic total shoulder arthroplasty (aTSA) can result in good outcomes; however, there is little data reporting the long-term outcomes in this cohort. B2 glenoids treated with high-side reaming present a theoretical risk of early glenoid component failure as one may ream into the subchondral bone. This study aimed to demonstrate that (1) B2 glenoids treated with corrective reaming have durable results and (2) offer similar results to Walch A1/2 in long-term follow-up., Methods: Patients who underwent aTSA by a single surgeon (E.L.F.) were identified from a shoulder arthroplasty registry. Inclusion criteria included Walch A1, A2, or B2 glenoid; a diagnosis of primary shoulder osteoarthritis; and a minimum radiographic and clinical follow-up of 5 years. Forty-three patients with B2 glenoids were compared to a cohort of 42 patients with A1 or A2 glenoids. Preoperative computed tomography (CT) and radiographs were used to assess deformity, glenoid version, and posterior subluxation of the humeral head. Postoperatively, patients were assessed with radiographs and patient-reported outcome measures including American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score, Simple Shoulder Test (SST) score, and visual analog scale (VAS)., Results: Eighty-five shoulders (82 patients, 42 B2 and 43 A1/A2 glenoids) with an average follow-up of 9.4 years were included. In the B2 cohort, the average retroversion was 21.1° and posterior subluxation was 69.4% compared with 10.6° (P < .001) and 57.5% (P < .001), respectively, in the A1 or A2 cohort. The cohort demographics were similar except for male sex (B2 69.8% vs. A1 or A2 37.2%, P = .008). There was no difference between the cohorts in their improvement in ASES (P = .807), SST (P = .586), and VAS (P = .930) scores. There was no difference in lateral humeral offset (P = .889) or acromial humeral interval (P = .468) between initial postoperative and final follow-up visits. Survivorship for B2 glenoids was 97.6%, 94.1%, and 73.3% at 5, 10, and 15 years, respectively, compared with 97.6%, 91.9%, and 83.5% in type A glenoids. The revision rate was similar between the 2 groups (P = .432). Lazarus score (P = .682) and rates of humeral radiolucency (P = .366) and humeral osteolysis (P = .194) were similar between the 2 cohorts at final follow-up., Conclusion: Asymmetric reaming of patients with B2 glenoids is a reliable method of glenoid preparation with excellent mid- to long-term clinical results, patient-reported outcomes, and low revision rates similar to their A1 and A2 counterparts., (Published by Elsevier Inc.)

Background: This study aims to accelerate revision surgery and treatment using X-ray imaging and deep learning to identify shoulder implant manufacturers in advance., Methods: A feature engineering approach based on principal component analysis and a k-means algorithm was used to cluster shoulder implant data. In addition, a pre-trained DenseNet201 combined with a capsule network (DenseNet201-Caps) shoulder implant classification model was proposed., Results: DenseNet201-Caps was the most effective classification model on the clustered dataset with an accuracy of 94.25% and an F1 score of 96.30%. Notably, clustering the dataset in advance improved the accuracy and the Caps implementations successfully enhanced the performance of all convolutional neural network models. The analysed results indicate that DenseNet201-Caps struggled to distinguish between the Cofield and Depuy manufacturers. Hence, a multistage classification approach was developed with an improved accuracy of 96.55% achieved., Conclusions: The DenseNet201-Caps method enables the accurate identification of shoulder implant manufacturers., (© 2024 John Wiley & Sons Ltd.)

Background: Superior augment use may help avoid superior tilt while minimizing removal of inferior glenoid bone. Therefore, our goal was to compare superior augments vs. no-augment baseplates in reverse shoulder arthroplasty (RSA) for patients with rotator cuff dysfunction and no significant superior glenoid erosion., Methods: A multicenter retrospective analysis of 145 patients who underwent RSA with intraoperative navigation (Equinoxe GPS; Exactech) and 3-year follow-up (mean 32 months' follow-up, range 20-61 months) who had preoperative superior inclination less than 10° and retroversion less than 15°. Patient demographics, radiographic measurements, surgical characteristics, patient-reported outcomes at preoperative and postoperative visit closest to 3 years, and adverse events at final follow-up were obtained. Operative time, planned inclination, and planned version of the baseplate were obtained. χ 2 test was used to compare categorical variables, and Student t test was used to compare the augment and no-augment cohorts., Results: The study population consisted of 54 superior augment patients and 91 no-augment patients. The augment cohort had lower body mass index (27.2 vs. 29.4, P = .023) and higher native superior inclination (5.9° vs. 1.4°, P < .001). No difference between the augment and no-augment cohorts was found regarding age (P = .643), gender (P = .314), medical comorbidities (P > .05), surgical indication (P = .082), and native glenoid version (P = .564). The augment cohort had higher internal rotation score (4.6 vs. 3.9, P = .023), and all remaining range of motion (ROM) and patient-reported outcomes (PROs) preoperatively were not significantly different. At final follow-up, active ROM in all planes was not different between the cohorts. Regarding PROs, the postoperative Shoulder Arthroplasty Smart score was significantly higher (78.0 vs. 73.6, P = .042), and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score trended toward higher (83.6 vs. 77.5, P = .063) in the augment cohort. The augment cohort had a significantly lower proportion of patients who planned to have superior baseplate tilt (1.9% vs. 14.3%, P = .012) and had greater mean inclination correction (6.3° vs. 1.3°, P < .001), compared with the no-augment cohort. Adverse events were rare, and there was no significant difference found between the augment and no-augment cohorts (5.6% vs. 3.3%, P = .509)., Discussion: Superior augmented baseplate in RSA with minimal superior glenoid erosion is associated with similar ROM and adverse events with somewhat improved postoperative PROs compared with nonaugmented baseplates at the 3-year follow-up. Additionally, superior augments resulted in a greater proportion of baseplates planned to avoid superior tilt, and trended toward shorter operative times. Further investigation of long-term glenoid baseplate loosening is imperative to fully understand the cost-effectiveness of superior augments in the setting of minimal glenoid deformity., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The purpose of this study was to evaluate the influence of humeral position of the Affinis Short implant in stemless anatomic total shoulder arthroplasties (STSAs) on clinical and radiologic results and mid- to long-term survival in the treatment of primary osteoarthritis (OA) of the shoulder., Methods: Eighty patients treated with a stemless shoulder arthroplasty for OA of the shoulder were evaluated with a mean follow-up of 92 ± 14 months (range 69-116 months) by the Constant Score (CS), Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH), and active range of motion (ROM). Radiographic assessment for bone adaptations and humeral implant position was performed by plain radiographs. Comparison of the pre- and postoperative centers of rotation (CORs) was used to assess the restoration of the geometry of the humeral head. The appraisal of proper humeral component positioning was correlated with the functional outcomes. A Kaplan-Meier analysis was performed to investigate the influence of humeral implant position compared to survival time. Complications were noted., Results: The ROM (P < .001), CS (P < .001), and DASH scores (P < .001) showed significant improvements after surgery for the entire series. The COR restoration was anatomic in 75% (n = 60) of all implants and in 25% (n = 20) nonanatomic implants (pre- and postoperative COR deviation of 2.7 ± 1.8 mm vs. 5.1 ± 3.2 mm, P = .0380). The humeral component position did not affect the functional outcome whereas the 10-year unadjusted cumulative survival rate for the anatomic group was significantly higher in comparison with the nonanatomic group (96.7% vs. 75%, P = .002). The radiologic evaluation revealed minor periprosthetic bone adaptions in various forms without clinical significance or further intervention. No revision was necessary because of a failed fixation of the stemless humeral component., Conclusions: Regarding the treatment of primary OA of the shoulder, STSA shows excellent long-term survival and clinical outcomes. In particular, STSA implants are able to restore the geometry of the humeral head. Nonanatomic reconstruction may influence the survival over the long term in different pathways. Further studies are necessary to elucidate the effect of humeral component position in STSA on function, pain, and implant survival rates., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Optimal glenosphere positioning in a lateralized reverse shoulder arthroplasty (RSA) to maximize functional outcomes has yet to be clearly defined. Center of rotation (COR) measurements have largely relied on anteroposterior radiographs, which allow assessment of lateralization and inferior position, but ignore scapular Y radiographs, which may provide an assessment of the posterior and inferior position relative to the acromion. The purpose of this study was to evaluate the COR in the sagittal plane and assess the effect of glenosphere positioning with functional outcomes using a 135° inlay stem with a lateralized glenoid., Methods: A retrospective review was performed on a prospectively maintained multicenter database on patients who underwent primary RSA from 2015 to 2021 with a 135° inlay stem. The COR was measured on minimum 2-year postoperative sagittal plain radiographs using a best-fit circle fit method. A best-fit circle was made on the glenosphere and the center was marked. From there, 4 measurements were made: (1) center to the inner cortex of the coracoid, (2) center to the inner cortex of the anterior acromion, (3) center to the inner cortex of the middle acromion, and (4) center to the inner cortex of the posterior acromion. Regression analysis was performed to evaluate any association between the position of the COR relative to bony landmarks with functional outcomes., Results: A total of 136 RSAs met the study criteria. There was no relation with any of the distances with outcome scores (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, visual analog scale). In regard to range of motion (ROM), each distance had an effect on at least 1 parameter. The COR to coracoid distance had the broadest association with ROM, with improvements in forward flexion (FF), external rotation (ER0), and internal rotation with the arm at 90° (IR90) (P < .001, P = .031, and P < .001, respectively). The COR to coracoid distance was also the only distance to affect the final FF and IR90. For every 1-mm increase in this distance, there was a 1.8° increase in FF and 1.5° increase in IR90 (β = 1.78, 95% confidence interval [CI] 0.85-2.72, P < .001, and β = 1.53, 95% CI 0.65-2.41, P < .001; respectively)., Conclusion: Evaluation of the COR following RSA in the sagittal plane suggests that a posteroinferior glenosphere position may improve ROM when using a 135° inlay humeral component and a lateralized glenoid., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

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., (© 2024. The Author(s).)

Background: Scapular notching is a common complication of reverse total shoulder arthroplasty (RTSA). Although the notching rate has reduced significantly thanks to modifications to the surgical technique and humeral and glenoid components, uncontrollable polyethylene (PE)-induced osteolysis can still occur. In contrast to conventional-bearing (CB-RTSA), inverted-bearing RTSA (IB-RTSA) systems, with PE glenospheres and metal or ceramic humeral liners, avoid PE abrasion through scapulohumeral contact. If present, the resulting notch has a different size and configuration than with CB-RTSA. Thus, a modified notching classification seems reasonable. Even in CB-RTSA, the early stages of notching show a different configuration than implied by the established Nerot-Sirveaux classification; therefore, a modification of the classification system is recommended., Methods: In a prospective multicentre study, 250 cases underwent IB-RTSA. Of these, 39 died, and 28 were lost to follow-up for other reasons, leaving 183 shoulders for the final follow-up examination at a mean of 120.7 months (range 84.1-172.4 months). In the CB-RTSA group, we retrospectively evaluated radiographs of 59 consecutive patients with a follow-up ranging from 2 to 7 years. We analysed the appearance, evolution over time, and location of bone loss on the scapular neck according to the modified Nerot-Sirveaux classification., Results: In IB-RTSA, notching resulted in a new morphological configuration: In contrast to the Nerot-Sirveaux classification, notching began far from the baseplate as an impression or abrasion of the humeral component in the inferior scapular rim. Due to simultaneous mechanical ablation, the defect gradually enlarged, but usually did not contact the baseplate or extend beyond the inferior peg. No signs of PE-induced osteolysis were found. The notching rate reached 19% after 2 years and approached 36% after 10 years. Most shoulders had grade 0 notching (64%), followed by grade 1 (29%); extensive erosion (grade 4) was not observed. In the CB-RTSA group, a small bony impression or erosion without signs of PE-induced osteolysis was observed medial to the scapular neck, without contact with the metaglene in the early phase, which was similar to the impression of the humeral component in IB-RTSA. The notching rate was 86% for CB-RTSA., Conclusions: A new classification was developed for IB-RTSA, which corresponds to the pathophysiological processes and is compatible with the existing Nerot-Sirveaux classification. Bone erosion in CB-RTSA is not adequately represented by the established classification in the early stages. For this reason, a supplement to the existing classification is presented., Level of Evidence: Level 4, Case Series, Treatment Study., (© 2024. The Author(s).)

Introduction: The older generation of high thickness metal-backed glenoid prostheses had a high failure rate. The goal of our study was to analyze the medium-term clinical and radiological results of a technically modified generation of metal backed glenoids with 35% decrease in thickness., Methods: Thirty-nine patients (43 shoulders) with a mean age of 66.5 years at surgery were examined from two to ten years (mean 71.2 months) using the Constant-Score, Subjective Shoulder Value and X-ray in a.p. and axial view. Indication for surgery included patients with glenoid types B1, B2, or B3 and/or posterior subluxation but intact rotator cuff, or patients who did not want a reverse prosthesis and had high functional demands. Inclusion criteria comprised participation in a clinical and radiological follow-up examination, along with a minimum follow-up duration of 24 months. Additionally, in all cases, the Constant Score and the Subjective Shoulder Value (PROM) had to be determined. Exclusion criteria were an incomplete dataset, implantation of a different prosthesis type, and failure to meet the minimum follow-up time., Results: The absolute Constant Score (CS) improved significantly (p < 0.0001) from 43 ± 13 (range: 20-69) points before to 80 ± 13 (range: 46-98) points after surgery. The only preoperative negative influencing factor on the result was the glenoid protrusion according to Lévigne (p = 0.0150). No significant differences in functional outcomes were found between glenoid types A2, B1, B2 and B3. Radiolucent lines at the interface were observed in a total of four patients (13%). Radiological signs of glenoid osteolysis were seen in six patients (20%). Humeral upward migration was observed in four patients (13%) and posterior shoulder joint decentering occurred in one patient (3%). Implant-specific complications occurred in three cases (7%). Due to a massive rotator cuff tear, two cases (4.7%) had to be converted to a reversed implant, with the primary metal component remaining in place. If the implant-specific and rotator cuff-associated complications are summarized, the rate is 11.7%. All components that required conversion to an reverse implant have so far remained free of complications., Conclusion: Favorable clinical results can be achieved, especially in patients with an eccentric glenoid type. Severe preoperative glenoid erosion (Walch A2, B2, B3) does not appear to have any influence on postoperative functional results. The complication and revision rates are significantly better than in previous studies with conventional metal-backed glenoid components. Conversion of the anatomical glenoid component to a reverse system was always possible and good clinical results were achieved., Competing Interests: Declarations Ethics approval and consent to participate This study was approved by the Institutional Review Board of the Ludwig-Maximilians-University Munich, Germany (Project No. 23-0155). All data for the study were collected on the basis of a normal standardized clinical investigation. All patients provided written consent for the use of their anonymous data. Financial interests Peter Habermeyer has received patent royalties from Arthrex Inc. Patric Raiss is a paid Consultant for Arthrex Inc. Jeremy Rapaport and Petra Magosch declare they have no financial interests. Conflict of interest Peter Habermeyer receives patent royalties from Arthrex Inc. Jeremy Rapaport and his immediate family, and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article. Patric Raiss is a paid Consultant for Arthrex Inc. Petra Magosch and her immediate family, and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: The radiographic evaluation of novel cementless anatomic polyethylene (PE) glenoid components featuring a titanium-coated back is still unclear. This study explores potential radiolucent lines (RLL) between the radiopaque titanium layer and sclerotic convex reamed bone in an intermodal comparison analysis with computed tomography (CT) scans., Materials and Methods: Eight RM pressfit vitamys glenoids (Mathys ® ) were implanted into cadaveric scapulae. In the CT scans, glenoids were quantified by evaluating ideal complete bony support (NO GAP) and gap between bone and titanium coating (GAP). X-rays were in perfect 0-degree projection and tilted in ± 10° and ± 20° mediolateral (ml) and craniocaudal (cc) directions. Radiographs evaluated were graded as NO RLL, RLL (gap > 1 mm) or DL (double line, gap < 1 mm) in an intermodal comparison of CT and X-ray findings., Results: The inter-rater (Cohen's = 0.643) and intra-rater reliability (Cohen's = 0.714) were good. The overall evaluation showed a significant agreement between (NO) RLL on X-ray and (NO) GAP on CT (p < 0.001). The - 10-degree ml projection showed good agreement between CT and X-ray (Cohen's = 0.628). Adequate agreement was shown at 0 degrees (Cohen's = 0.386), + 10 degrees ml (Cohen's = 0.338), and + 20 degrees cc (Cohen's = 0.327). Compared to the scenario DL = NO RLL, the true a.p. view showed better sensitivity when the DL is classified as RLL. Conversely, the true a.p. view demonstrated both better specificity and significant agreement between the X-ray and CT findings in scenario when DL = No RLL., Conclusion: Standard true a. p. projections are reliable in ruling out gaps when no RLL or DL is visible and the detection of RLL shows high intermodal agreement. Varying agreement across tilting angles emphasizes the importance of a comprehensive approach in evaluating bone support and CT is indispensable for a scientifically reliable assessment., Level of Evidence: Level III Treatment Study., Competing Interests: Declarations Competing interests The authors declare that they have no conflict of interest., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Reverse shoulder arthroplasty (RSA) is a well-recognized treatment for many shoulder conditions, including rotator cuff arthropathy, primary glenohumeral joint arthritis, and rheumatoid arthritis, and can be used in both trauma and revision settings. Over the past 10 years, its popularity in New Zealand has been increasing, with a 6%-7% annual growth rate during this period. Stemless RSA designs have the following proposed advantages: They can preserve humeral bone stock, they can limit periprosthetic fractures, and they can be indicated in patients with abnormal diaphyseal humeral anatomy. To date, only 1 study has evaluated the outcomes of the Lima SMR Stemless implant. We present our data with an aim to report how the stemless reverse arthroplasty compares to a conventional stemmed implant., Methods: We performed a retrospective review of a consecutive series of patients treated at a single institution between 2015 and 2020. The endpoint was defined as final follow-up at a minimum of 2 years. Patients were excluded from the final analysis if they underwent revision. Thirty-three patients were identified as having undergone stemless RSA. Thirty patients had patient-reported outcome measures and radiographs at a minimum of 2 years' follow-up. Three patients had undergone revision within 2 years. The same sample size of stemmed RSAs (n = 33) was selected for comparison., Results: A total of 60 patients were included in the final analysis, of whom 30 underwent stemless RSA and 30 underwent stemmed RSA. The demographic characteristics of the 2 groups were comparable except age at operation, which showed a statistically significant difference (P = .001): 77 years (stemmed) vs. 65 years (stemless). The mean Oxford Shoulder Score was 40.1 in the stemless group vs. 40 in the stemmed group. The mean American Shoulder and Elbow Surgeons score was 72.9 in the stemless group vs. 79 in the stemmed group. Patient-reported outcome measures, pain scores, and satisfaction ratings were not statistically significantly different between the 2 groups. In terms of radiographic data, subsidence was observed in 2 patients in the stemless RSA group but the patients had no clinical symptoms. Also in the stemless RSA group, 1 patient had an acromial stress fracture and 1 patient had a superficial wound infection successfully treated with oral antibiotics. In terms of revisions in the stemless RSA group, 1 patient underwent revision owing to chronic infection, 1 underwent revision as a result of a periprosthetic fracture after a fall, and 1 underwent revision for gross instability., Conclusions: The early results of sRSA are promising, and the stemless implant shows similar outcomes to a conventional stemmed implant., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Purpose: The aim of the present systematic review is to collect all the available evidence regarding the clinical and radiological results of revision to reverse shoulder arthroplasty (RSA) of modular anatomic shoulder prostheses (TSA) using a convertible metal-backed glenoid (MBG)., Methods: This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Studies investigating revision of TSA to RSA utilizing a convertible MBG and reporting clinical and radiological outcomes were identified., Results: A total of five studies on the use of convertible modular glenoid component in the setting of TSA revision to RSA were finally included in the present systematic review. A total of 60 procedures were reported. Mean operative times was 65 min. Intraoperative complications included 3 cases of glenoid loosening. Only one case of dislocation was reported as postoperative complication. At mean follow-up of 32.3 months post-revision, no glenoid loosening was reported, VAS score decreased from 7.7 to 1.5, Constant Score increased from 24.8 to 57.6., Conclusions: Revision to RSA after failed TSA using a convertible modular glenoid component was associated with a low rate of intraoperative and postoperative complications, low surgical time and led to good results in term of pain relieve and functional outcomes. Given the complexity and risk associated with revision of anatomic shoulder prosthesis having a convertible glenoid may help to simplify the procedure and improve clinical results., (© 2024. The Author(s) under exclusive licence to SICOT aisbl.)

Background: Clinical significance, as opposed to statistical significance, has increasingly been utilized to evaluate outcomes after total shoulder arthroplasty (TSA). The purpose of this study was to identify thresholds of the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) for TSA outcome metrics and determine if these thresholds are influenced by prosthesis type (anatomic or reverse TSA), sex, or preoperative diagnosis., Methods: A prospectively collected international multicenter database inclusive of 38 surgeons was queried for patients receiving a primary aTSA or rTSA between 2003 and 2021. Prospectively, outcome metrics including ASES, shoulder function score (SFS), SST, UCLA, Constant, VAS Pain, shoulder arthroplasty smart (SAS) score, forward flexion, abduction, external rotation, and internal rotation was recorded preoperatively and at each follow-up. A patient satisfaction question was administered at each follow-up. Anchor-based MCID, SCB, and PASS were calculated as defined previously overall and according to implant type, preoperative diagnosis, and sex. The percentage of patients achieving thresholds was also quantified., Results: A total of 5851 total shoulder arthroplasties (TSAs) including aTSA (n = 2236) and rTSA (n = 3615) were included in the study cohort. The following were identified as MCID thresholds for the overall (aTSA + rTSA irrespective of diagnosis or sex) cohort: VAS Pain (-1.5), SFS (1.2), SST (2.1), Constant (7.2), ASES (13.9), UCLA (8.2), SPADI (-21.5), and SAS (7.3), Abduction (13°), Forward elevation (16°), External rotation (4°), Internal rotation score (0.2). SCB thresholds for the overall cohort were: VAS Pain (-3.3), SFS (2.9), SST 3.8), Constant (18.9), ASES (33.1), UCLA (12.3), SPADI (-44.7), and SAS (18.2), Abduction (30°), Forward elevation (31°), External rotation (12°), Internal rotation score (0.9). PASS thresholds for the overall cohort were: VAS Pain (0.8), SFS (7.3), SST (9.2), Constant (64.2), ASES (79.5), UCLA (29.5), SPADI (24.7), and SAS (72.5), Abduction (104°), Forward elevation (130°), External rotation (30°), Internal rotation score (3.2). MCID, SCB, and PASS thresholds varied depending on preoperative diagnosis and sex., Conclusion: MCID, SCB, and PASS thresholds vary depending on implant type, preoperative diagnosis, and sex. A comprehensive understanding of these differences as well as identification of clinically relevant thresholds for legacy and novel metrics is essential to assist surgeons in evaluating their patient's outcomes, interpreting the literature, and counseling their patients preoperatively regarding expectations for improvement. Given that PASS thresholds are fragile and vary greatly depending on cohort variability, caution should be exercised in conflating them across different studies., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Introduction: Similar to the management of periprosthetic joint infections of the lower limb, one-stage revision in total shoulder arthroplasty (TSA) infections is an option that has been highlighted in scientific publications since the early 2010s. However, there are only a few studies which validate this treatment and determine its scope of application in relation to two-stage treatment., Hypothesis: Single-stage revision for infected TSA is a reliable treatment allowing good infection control and satisfactory functional results., Methods: This single-center retrospective series of 34 consecutive patients operated on between 2014 and 2020 for a one-stage prosthetic revision was evaluated at a minimum of 2 years of follow-up. All of the patients included underwent revision shoulder arthroplasty during this period with the diagnosis of infection confirmed by microbiological analysis of surgical samples. Patients who did not benefit from a bipolar revision were excluded. All patients were followed at least 2 years after the intervention. Clinically suspected recurrence of infection was confirmed by a periprosthetic sample under radiographic guidance. Functional clinical outcomes as well as mechanical complications were also reported., Results: The average follow-up was 40.4 months (24-102±21.6). A septic recurrence was observed in three patients (8.8%). A mechanical complication was present in four patients (14.7%), and three (11.8%) required at least one surgical revision. The mean Constant-Murley score at the last follow-up was 49 (42-57±21.83)., Discussion: Single-stage revision for shoulder periprosthetic joint infection results in a success rate of 91.2% with satisfactory functional results after more than 2 years of follow-up., Level of Evidence: IV; retrospective study., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Background: The design of reverse shoulder arthroplasty (RSA) implants has evolved significantly over the past 50 years. Today there are many options available that differ in design of the glenoid and humeral components, fixation methods, sizes, and modularity. With respect to the humeral component, the literature has generally focused on the differences between inlay and onlay designs and the potential impact on outcomes. However, inlay and onlay design represents only one factor of many., Methods: It is our hypothesis that separating onlay and inlay designs into 2 distinct entities is an oversimplification as there can be a wide overlap of the 2 designs, depending on surgical technique and the implant selected. As such, the differences between inlay and onlay designs should be measured in absolute terms-meaning combined distalization and lateralization., Results: By reviewing the many factors that can contribute to the glenosphere-humerus relationship, the role of inlay and onlay humeral designs as an important distinguishing feature is shown to be limited. Preliminary studies suggest that the amount of distalization and lateralization of the construct may be the most accurate method of describing the differences in the constructs., Conclusions: Inlay and onlay humeral component design represents only one factor of many that may impact outcomes. A more accurate method of defining specific design and technique factors in RSA is the degree of lateralization and distalization., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Porous metallic prosthesis components can now be manufactured using additive manufacturing techniques, and may prove beneficial for promoting bony ingrowth, for accommodating drug delivery systems, and for reducing stress shielding. Using finite element modeling techniques, 36 scenarios (three porous stems, three bone densities, and four held arm positions) were analysed to assess the viability of porous humeral stems for use in total shoulder arthroplasty, and their resulting mechanobiological impact on the surrounding humerus bone. All three porous stems were predicted to experience stresses below the yield strength of Ti6Al4V (880 MPa) and to be capable of withstanding more than 10 million cycles of each loading scenario before failure. There was an indication that within an 80 mm region of the proximal humerus, there would be a reduction in bone resorption as stem porosity increased. Overall, this study shows promise that these porous structures are mechanically viable for incorporation into permanent shoulder prostheses to combat orthopedic infections., (© 2024 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

Background: Descriptions of glenoid deformities in glenohumeral osteoarthritis (GHOA) have focused on the axial plane. Less is known regarding arthritic glenoids with higher amounts of superior inclination and little evidence exists to guide management of inclination or combined version-inclination deformity when performing anatomic total shoulder arthroplasty (aTSA). We hypothesized that biplanar deformities (BD) would be present in a higher proportion of GHOA patients than previously appreciated, and these deformities would be difficult to adequately reconstruct with contemporary aTSA implants., Methods: A retrospective query was performed of GHOA patients indicated for TSA 2012-2017 with a computed tomography (CT) scan within three months of surgery. Images were uploaded to three-dimensional (3D) software for automated measurements. Glenoids with superior inclination ≥10°, and retroversion ≥20° were considered to have BD. Walch classification was determined, and C-type glenoids were excluded. Rotator-cuff muscle cross-sectional area (CSA) was measured and fatty infiltration was graded. Glenoids with BD were virtually planned for aTSA with correction to neutral inclination and version, then with 5° superior inclination and 10° retroversion., Results: Two-hundred and sixty-eight shoulders in 250 patients were included; average age was 65 years, 67% male. There were no differences in inclination between Walch types (P = .25). Twenty-nine shoulders with BD were identified (11%). These deformities were not associated with age (P = .47) or gender (P = .50) but were skewed towards Walch B-type, specifically B2 (P = .03). Acromial index and posterior humeral head subluxation were higher in BD patients (P = .04, P < .001, respectively). Biplanar deformities had similar cuff CSA compared to those without but were less frequently associated with fatty infiltration of the subscapularis (P = .05). When correcting to neutral version and inclination, 41% BD could not be reconstructed. Of those that could, 94% required augmented implants. When correcting to 5° superior inclination and 10° retroversion, 10% could not be reconstructed. Of those that could, 58% required augmented implants. With partial correction, augment use was predicted by retroversion >26° (P = .009). Inclination did not predict augment use (P = .90). Final implant position commonly involved unseating in the posterosuperior quadrant and cancellous exposure in the anteroinferior quadrant., Conclusions: This retrospective computed tomography (CT)-based study of 268 shoulders with GHOA found an 11% prevalence of BD. These deformities were commonly associated with Walch B2 wear patterns. Virtual aTSA planning showed a high failure rate (41%) when correcting to neutral version and inclination. Posteriorly augmented implants were frequently required, and often still involved unseating in the posterosuperior quadrant, increased cancellous exposure in the anteroinferior quadrant, and vault perforation., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Copyright of Obere Extremitat is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Rotator cuff tear is a common cause for shoulder pain and dysfunction. The morphology of scapular glenoid has always been an important research topic of degenerative rotator cuff tear. OBJECTIVE: To explore the relationship between glenoid version angle, scapular glenoid size and degenerative rotator cuff full-thickness tear. METHODS: In a matched case-control study, 36 patients with full-thickness rotator cuff tears diagnosed by MRI and shoulder arthroscopy in the Affiliated Hospital of Xuzhou Medical University from February 2020 to February 2021 were selected as the trial group. The 36 patients with non-shoulder diseases in the same period were selected as the control group according to the age, sex and number of the subjects. Chest CT was performed on admission in both groups. The glenoid version angle and anteroposterior diameter of scapular glenoid were measured by the same orthopedic surgeon on the chest CT, and the difference of the glenoid version angle between the two groups was statistically analyzed. RESULTS AND CONCLUSION: (1) The glenoid version angle: in the trial group (-3.5±4.6)°, compared with the control group (-1.9±3.9)°, there was a more obvious posterior inclination (P < 0.05). (2) In the trial group, the anteroposterior diameter of the scapular glenoid was (26.8±3.3) mm. In the control group, the anteroposterior diameter of the scapular glenoid was (27.2±3.6) mm (P > 0.05). (3) The shoulder joints of the control group were divided into left and right groups, and the results showed that the left scapular glenoid version angle was (-1.85±5.42)°, and the right scapular glenoid version angle was (-2.01±6.18)°. There was no significant difference between the two groups (P > 0.05). (4) When the patients were divided into groups according to sex, the results showed that there was a significant difference in the anteroposterior diameter of the scapular glenoid between males and females (P < 0.05). (5) It is concluded that there is no significant correlation between the size of the scapular glenoid (anteroposterior diameter) and the full-thickness tear of the rotator cuff, but results found the size characteristics of the scapular glenoid, the consistency of the left and right shoulders, and the significant differences between men and women. It is believed that it can provide guidance for the design of shoulder prosthesis in Chinese. There is a significant correlation between the glenoid version angle and the full-thickness rotator cuff tear. Excessive retroversion of the scapular glenoid may be a risk factor for degenerative full-thickness rotator cuff tear. Measuring the glenoid version angle is helpful for the diagnostic evaluation of full-thickness rotator cuff tear. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate if the C. acnes present at the end of a primary shoulder arthroplasty could be responsible for shoulder arthroplasty infection. Prospective study includes patients undergoing primary shoulder arthroplasty from January 2015 until December 2018. From all the patients included, 5 to 12 tissue samples were obtained and were specifically cultured to detect the presence of C. acnes. DNA was extracted from the C acnes isolated colonies and Whole Genome Sequencing (WGS) analysis was done. A cohort of 156 patients was finally included. In twenty-seven patients, the C. acnes was present at the end of the primary surgery. Two of these patients developed a C. acnes periprosthetic shoulder infection at 6 and 4 months after the primary surgery. WGS of C. acnes isolated colonies showed that all the revision-surgery isolates clustered near to the corresponding primary-surgery isolates compared to the other independent bacterial colonies. (99.89% of similarity). C. acnes present at the end of the primary surgery can be the cause of early or delayed periprosthetic joint infections in shoulder arthroplasty. [ABSTRACT FROM AUTHOR]

Shoulder pain is the main indication for prosthesis surgery; however, insufficient pain management “before” and “after” surgery makes the pain symptoms at risk of becoming chronic. In this article we will try to identify the approach to pain both in the acute phase and in the peri- and post-operative phase, suggesting pharmacological intervention that can ensure a better quality of life and a prompt recovery of joint function. [ABSTRACT FROM AUTHOR]

Copyright of Obere Extremitat is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

National shoulder arthroplasty registries are currently used to assess incidence, indication, type of prosthesis and revision, but they seem to lack sufficient information to lead to evidence based decision-making in shoulder surgery. There appears to be a large difference in registered parameters and outcome measurement per country. First we investigated whether existing registries have sufficient common datasets to enable pooling of data. Second, we determined whether known risk factors for prosthetic failure are being recorded. Through a non-systematic literature review studies on registries were analyzed for included parameters. Seven national registries were scrutinized for the data collected and these were classified according to categories of risk factors for failure: patient-, implant and surgeon related, and other parameters. This shows a large heterogeneity of registered parameters between countries. The majority of parameters shown to be relevant to outcome and failure of shoulder prostheses are not included in the studied registries. International agreement on parameters and outcome measurement for registries is paramount to enable pooling and comparison of data. If we intend to use the registries to provide us with evidence to improve prosthetic shoulder surgery, we need adjustment of the different parameters to be included. [ABSTRACT FROM AUTHOR]

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 (β = 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 (β = 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., Competing Interests: Disclosure: No external funding was received for this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article ( http://links.lww.com/JBJS/I18 )., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Background: We aim to predict a clinical difference in the postoperative range of motion (RoM) between 2 reverse shoulder arthroplasty (RSA) stem designs (Inlay-155° and Onlay-145°) using preoperative planning software. We hypothesized that preoperative 3D planning could anticipate the differences in postoperative clinical RoM between 2 humeral stem designs and by keeping the same glenoid implant., Methods: Thirty-seven patients (14 men and 23 women, 76 ± 7 years) underwent a BIO-RSA (bony increased offset-RSA) with the use of preoperative planning and an intraoperative 3-dimensional-printed patient-specific guide for glenoid component implantation between January 2014 and September 2019 with a minimum follow-up of 2 years. Two types of humeral implants were used: Inlay with a 155° inclination (Inlay-155°) and Onlay with a 145°inclination (Onlay-145°). Glenoid implants remained unchanged. The postoperative RSA angle (inclination of the area in which the glenoid component of the RSA is implanted) and the lateralization shoulder angle were measured to confirm the good positioning of the glenoid implant and the global lateralization on postoperative X-rays. A correlation between simulated and clinical RoM was studied. Simulated and last follow-up active forward flexion (AFE), abduction, and external rotation (ER) were compared between the 2 types of implants., Results: No significant difference in RSA and lateralization shoulder angle was found between planned and postoperative radiological implants' position. Clinical RoM at the last follow-up was always significantly different from simulated preoperative RoM. A low-to-moderate but significant correlation existed for AFE, abduction, and ER (r = 0.45, r = 0.47, and r = 0.57, respectively; P < .01). AFE and abduction were systematically underestimated (126° ± 16° and 95° ± 13° simulated vs. 150° ± 24° and 114° ± 13° postoperatively; P < .001), whereas ER was systematically overestimated (50° ± 19° simulated vs. 36° ± 19° postoperatively; P < .001). Simulated abduction and ER highlighted a significant difference between Inlay-155° and Onlay-145° (12° ± 2°, P = .01, and 23° ± 3°, P < .001), and this was also retrieved clinically at the last follow-up (23° ± 2°, P = .02, and 22° ± 2°, P < .001)., Conclusions: This study is the first to evaluate the clinical relevance of predicted RoM for RSA preoperative planning. Motion that involves the scapulothoracic joint (AFE and abduction) is underestimated, while ER is overestimated. However, preoperative planning provides clinically relevant RoM prediction with a significant correlation between both and brings reliable data when comparing 2 different types of humeral implants (Inlay-155° and Onlay-145°) for abduction and ER. Thus, RoM simulation is a valuable tool to optimize implant selection and choose RSA implants to reach the optimal RoM., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The lateralization shoulder angle (LSA) and distalization shoulder angle (DSA) are used to reproducibly measure lateralization and distalization after reverse shoulder arthroplasty (RSA). However, LSA and DSA may not offer a precise measurement of humeral lateralization and distalization and this relationship has not been explored. The aim of this study was to evaluate the validity of these measurements and to propose new measurement methods to estimate implant lateralization and distalization., Methods: 3D models were constructed from computed tomography (CT) scans of 30 patients using a software platform. For each patient 24 different RSA modifications were created, resulting in 720 different RSA configurations. For each configuration LSA and DSA angles as well as lateralization and distalization distances were measured. Moreover, for each configuration two new measurements were done: the lateralization index (LI) and distalization index (DI). Correlations of the lateralization and distalization parameters were evaluated between measurements., Results: Weak correlations were founded between LSA and lateralization (r = 0.36, p < 0.01), whereas moderate correlations were observed between LI and lateralization (r = 0.72, p < 0.01). No significant correlations were found between DSA and distalization (r = 0.17, p = 0.113). In contrast, moderate correlations were identified between DI and distalization (r = 0.69, p < 0.01)., Conclusion: LI and DI are more reliable methods to estimate implant lateralization and distalization compared to angular radiographic measurements. However, the prognostic significance in predicting clinical outcomes after RSA remains unknown., (© 2024. The Author(s).)

Background: Allograft prosthetic composite (APC) reconstruction is performed after resection of proximal humerus tumors or failure of arthroplasty implants. There is limited literature on the postoperative outcomes of this technique. We sought to assess implant survival, failure rates, and postoperative functional outcomes after APC reconstruction of the proximal humerus., Methods: A systematic review of the PubMed and Embase databases was conducted. The study was registered on PROSPERO (ID: 448,663). The Strengthening of the Reporting of Observational Studies in Epidemiology checklist was used for quality assessment. Implant failure was determined using the Henderson classification for biological reconstruction. Functional outcome was primarily assessed using the Musculoskeletal Tumor Society score at last follow-up., Results: Twenty-five studies with a total of 488 patients were included. Mean follow-up in reporting studies ranged from 2.5 to 10 years. Five-year revision-free survival for implants ranged from 41% to 92%. Overall implant failure rate ranged from 9% to 54%, and reoperation rate ranged from 0% to 55%. Graft host nonunion (type 2) was the most common mode of failure, with rates ranging from 0% to 75%. The mean Musculoskeletal Tumor Society scores at last follow-up ranged from 57% to 90% across studies. A trend towards better functional outcomes was seen in patients having an APC with a reverse total shoulder arthroplasty (rTSA) compared with those with hemiarthroplasty., Conclusions: APCs show promise in proximal shoulder reconstruction, with heterogeneous functional outcomes that are noninferior to other reconstruction techniques. Graft host nonunion is a common mode of failure and remains a concern in this type of prosthesis. Future studies should compare rTSA-APCs and rTSA endoprostheses while controlling for potential confounders., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The utilization of short humeral stems in reverse total shoulder arthroplasty has gained attention in recent times. However, concerns regarding the risk of misalignment during implant insertion are associated with their use., Methods: Eight fresh-frozen cadaveric shoulders were prepared for dissection and biomechanical testing. A bespoke humeral implant was fabricated to facilitate assessment of neutral, varus, and valgus alignments using a single stem, and 10° was established as the maximum permissible angle for misalignments. Shift in humerus position and changes in deltoid length attributable to misalignments relative to the neutral position were evaluated using a Microscribe 3DLx system. The impingement-free range of motion, encompassing abduction, adduction, internal rotation, and external rotation (ER), was gauged using a digital goniometer. The capacity for abduction was evaluated at maximal abduction angles under successive loading on the middle deltoid. A specialized traction system coupled with a force transducer was employed to measure anterior dislocation forces., Results: Relative to the neutral alignment, valgus alignment resulted in a more distal (10.5 ± 2.4 mm) and medial (8.3 ± 2.2 mm) translation of the humeral component, whereas the varus alignment resulted in the humerus shifting more superiorly (11.2 ± 1.3 mm) and laterally (9.9 ± 0.9 mm) at 0° abduction. The valgus alignment exhibited the highest abduction angle than neutral alignment (86.2°, P < .001). Conversely, the varus alignment demonstrated significantly higher adduction (18.4 ± 7.4°, P < .001), internal rotation (68.9 ± 15.0°, P = .014), and ER (45.2 ± 10.5°, P = .002) at 0° abduction compared to the neutral alignments. Anterior dislocation forces were considerably lower (23.8 N) in the varus group compared to the neutral group at 0°ER (P = .047). Additionally, abduction capability was markedly higher in varus alignment at low deltoid loads than the neutral alignment (5N, P = .009; 7.5 N, P = .007)., Conclusions: The varus position enhances rotational range of motion (ROM) but increases instability, while the valgus position does not significantly impact ROM or instability compared to the neutral position., (Copyright © 2024. Published by Elsevier Inc.)

Background: Accurate and precise templating is paramount for anatomic total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (RSA) to enhance preoperative planning, streamline surgery, and improve implant positioning. We aimed to evaluate the predictive potential of readily available patient demographic data in TSA and RSA implant sizing, independent of implant design., Methods: A total of 578 consecutive, primary, noncemented shoulder arthroplasty cases were retrospectively reviewed. Demographic variables and implant characteristics were recorded. Multivariate linear regressions were conducted to predict implant sizes using patient demographic variables., Results: Linear models accurately predict TSA implant sizes within 2 millimeters of humerus stem sizes 75.3% of the time, head diameter 82.1%, head height 82.1%, and RSA glenosphere diameter 77.6% of the time. Linear models predict glenoid implant sizes accurately 68.2% and polyethylene thickness 76.6% of the time and within one size 100% and 95.7% of the time, respectively., Conclusion: Linear models accurately predict shoulder arthroplasty implant sizes from demographic data. No significant statistical differences were observed between linear models and machine learning algorithms, although the analysis was underpowered. Future sufficiently powered studies are required for more robust assessment of machine learning models in predicting primary shoulder arthroplasty implant sizes based on patient demographics., (Copyright © 2024 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Orthopaedic Surgeons.)