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Background: Reports have demonstrated that reverse shoulder arthroplasty restores overhead elevation but fails to restore active external rotation. The teres minor muscle-tendon unit contributes to active external rotation, and its deficiency may impair the clinical outcome. It was therefore the purpose of this study to evaluate the influence of fatty infiltration of the teres minor muscle on the clinical outcome after reverse total shoulder replacement.Methods: Forty-two shoulders in forty-two patients (average age, seventy-one years) with painful cuff tear arthropathy or an irreparable rotator cuff deficiency with pseudoparesis were treated with a reverse Delta-III shoulder arthroplasty and followed clinically for a minimum of twenty-four months. Preoperatively, fatty infiltration of the teres minor was assessed, according to the grading system of Goutallier et al., with use of magnetic resonance imaging. The effect of teres minor fatty infiltration on the subjective and objective outcomes of the reverse shoulder arthroplasty was evaluated.Results: The thirty shoulders with stage-0, 1, or 2 fatty infiltration of the teres minor muscle (group 1) had a significantly better ultimate Constant score, a significantly better subjective shoulder value, and significantly greater preoperative-to-postoperative improvement than the twelve shoulders with stage-3 or 4 fatty infiltration (group 2). In group 1 the relative Constant score increased by an average of 41% and the subjective shoulder value increased by an average of 44%, whereas in group 2 the respective increases were 32% (p = 0.033) and 25% (p = 0.018). Group 1 had an average increase of 6.2 points in the score for extremity positioning, whereas group 2 gained only 5.3 points (p = 0.033). Group 1 had a net gain of 9 degrees of external rotation with the arm at the side compared with an average net loss of 7 degrees in group 2 (p < 0.001).Conclusions: Stage-3 or 4 fatty infiltration of the teres minor compromises the clinical outcome of reverse shoulder arthroplasty for the treatment of irreparable rotator cuff tears. [ABSTRACT FROM AUTHOR]

Background: The reverse Delta III shoulder prosthesis can relieve pain and restore function in patients with cuff tear arthropathy. The most frequently reported radiographic complication is inferior scapular notching. The purpose of the present study was to evaluate the clinical relevance of notching and to determine the anatomic and radiographic parameters that predispose to its occurrence.Methods: Seventy-seven consecutive shoulders in seventy-six patients with an irreparable rotator cuff deficiency were managed with a reverse Delta III shoulder arthroplasty and were followed clinically and radiographically for a minimum of twenty-four months. The effects of cranial-caudal glenoid component positioning and the prosthesis-scapular neck angle on the development of inferior scapular notching and clinical outcome were assessed.Results: All shoulders that had development of notching did so in the first fourteen months. Of the seventy-seven shoulders that were studied, thirty-four (44%) had inferior scapular notching, twenty-three (30%) had posterior notching, and six (8%) had anterior notching. Osteophytes along the inferior part of the scapula occurred in twenty-one (27%) of the seventy-seven shoulders. The angle between the glenosphere and the scapular neck (r = 0.667) as well as the craniocaudal position of the glenosphere (r = 0.654) were highly correlated with inferior notching (p < 0.001). A notching index was calculated with use of the height of implantation of the glenosphere and the postoperative prosthesis-scapular neck angle. This allowed prediction of the occurrence of notching with a sensitivity of 91% and specificity of 88%. The height of implantation of the glenosphere had approximately an eight times greater influence on inferior notching than the prosthesis-scapular neck angle did. Inferior scapular notching was associated with a significantly poorer clinical outcome.Conclusions: Inferior scapular notching after reverse total shoulder arthroplasty adversely affects the intermediate-term clinical outcome. It can be prevented by optimal positioning of the glenoid component. [ABSTRACT FROM AUTHOR]

Background: Recent studies have suggested that tenotomy and repair of the subscapularis tendon carried out for anterior approaches to the shoulder can be followed by failure of the tendon repair and by changes resulting in permanent loss of subscapularis function. We hypothesized that release of the subscapularis with use of a superficial osteotomy of the lesser tuberosity followed by repair of the two opposing bone surfaces would lead to consistent bone-to-bone healing, which would be possible to monitor radiographically, and would lead to satisfactory clinical and structural outcomes.Methods: Thirty-nine shoulders in thirty-six consecutive patients who, at an average age of fifty-seven years, had undergone total shoulder replacement through an anterior approach involving an osteotomy of the lesser tuberosity were evaluated at an average of thirty-nine months. Assessment included a standardized interview and physical examination, scoring according to the system described by Constant and Murley, and imaging with conventional radiography and computed tomography to assess healing of the osteotomy site and changes in the subscapularis.Results: The osteotomized tuberosity fragment healed in an anatomical position in all shoulders, and no cuff tendon ruptures were observed. At the time of follow-up, thirty-three (89%) of thirty-seven shoulders evaluated with a belly-press test had a negative result and twenty-seven (75%) of thirty-six shoulders evaluated with a lift-off test had an unequivocally normal result. Fatty infiltration of the subscapularis muscle increased after the operation (p < 0.0001) and was at least stage two in eleven (32%) of thirty-four shoulders. The fatty infiltration had progressed by one stage in eight (24%) of the thirty-four shoulders, by two stages in five shoulders (15%), and by three stages in two shoulders (6%).Conclusions: Osteotomy of the lesser tuberosity provides an easy anterior approach for total shoulder replacement and is followed by consistent bone-to-bone healing, which can be monitored, and good subscapularis function. In the presence of documented anatomical healing of the osteotomy site, postoperative fatty infiltration of the subscapularis muscle remains unexplained and needs to be investigated further as it is associated with a poorer clinical outcome. [ABSTRACT FROM AUTHOR]

Background: Recent studies have suggested that tenotomy and repair of the subscapularis tendon carried out for anterior approaches to the shoulder can be followed by failure of the tendon repair and by changes resulting in permanent loss of subscapularis function. We hypothesized that release of the subscapularis with use of a superficial osteotomy of the lesser tuberosity followed by repair of the two opposing bone surfaces would lead to consistent bone-to-bone healing, which would be possible to monitor radiographically, and would lead to satisfactory clinical and structural outcomes.Methods: Thirty-nine shoulders in thirty-six consecutive patients who, at an average age of fifty-seven years, had undergone total shoulder replacement through an anterior approach involving an osteotomy of the lesser tuberosity were evaluated at an average of thirty-nine months. Assessment included a standardized interview and physical examination, scoring according to the system described by Constant and Murley, and imaging with conventional radiography and computed tomography to assess healing of the osteotomy site and changes in the subscapularis.Results: The osteotomized tuberosity fragment healed in an anatomical position in all shoulders, and no cuff tendon ruptures were observed. At the time of follow-up, thirty-three (89%) of thirty-seven shoulders evaluated with a belly-press test had a negative result and twenty-seven (75%) of thirty-six shoulders evaluated with a lift-off test had an unequivocally normal result. Fatty infiltration of the subscapularis muscle increased after the operation (p < 0.0001) and was at least stage two in eleven (32%) of thirty-four shoulders. The fatty infiltration had progressed by one stage in eight (24%) of the thirty-four shoulders, by two stages in five shoulders (15%), and by three stages in two shoulders (6%).Conclusions: Osteotomy of the lesser tuberosity provides an easy anterior approach for total shoulder replacement and is followed by consistent bone-to-bone healing, which can be monitored, and good subscapularis function. In the presence of documented anatomical healing of the osteotomy site, postoperative fatty infiltration of the subscapularis muscle remains unexplained and needs to be investigated further as it is associated with a poorer clinical outcome. [ABSTRACT FROM AUTHOR]

Abstract Background Retraction, atrophy and fatty infiltration are signs subsequent to chronic rotator cuff tendon tears. They are associated with an increased pennation angle and a shortening of the muscle fibers in series. These deleterious changes of the muscular architecture are not reversible with current repair techniques and are the main factors for failed rotator cuff tendon repair. Whereas fast stretching of the retracted musculotendinous unit results in proliferation of non-contractile fibrous tissue, slow stretching may lead to muscle regeneration in terms of sarcomerogenesis. To slowly stretch the retracted musculotendinous unit in a sheep model, two here described tensioning devices have been developed and mounted on the scapular spine of the sheep using an expandable threaded rod, which has been interposed between the retracted tendon end and the original insertion site at the humeral head. Traction is transmitted in line with the musculotendinous unit by sutures knotted on the expandable threaded rod. The threaded rod of the tensioner is driven within the body through a rotating axis, which enters the body on the opposite side. The tendon end, which was previously released (16 weeks prior) from its insertion site with a bone chip, was elongated with a velocity of 1 mm/day. Results After several steps of technical improvements, the tensioner proved to be capable of actively stretching the retracted and degenerated muscle back to the original length and to withstand the external forces acting on it. Conclusion This technical report describes the experimental technique for continuous elongation of the musculotendinous unit and reversion of the length of chronically shortened muscle.

Background: Navigated augmented reality (AR) through a head-mounted display (HMD) has led to accurate glenoid component placement in reverse shoulder arthroplasty (RSA) in an in-vitro setting. The purpose of this study is to evaluate the deviation between planned, intraoperative, and postoperative inclination, retroversion, entry point, and depth of the glenoid component placement during RSA, assisted by navigated AR through an HMD, in a surgical setting., Methods: A prospective, multicenter study was conducted. All consecutive patients undergoing RSA in 2 institutions, between August 2021 and January 2023, were considered potentially eligible for inclusion in the study. Inclusion criteria were as follows: age >18 years, surgery assisted by AR through an HMD, and postoperative computed tomography (CT) scans at 6 weeks. All participants agreed to participate in the study and informed consent was provided in all cases. Preoperative CT scans were undertaken for all cases and used for 3-dimensional (3D) planning. Intraoperatively, glenoid preparation and component placement were assisted by a navigated AR system through an HMD in all patients. Intraoperative parameters were recorded by the system. A postoperative CT scan was undertaken at 6 weeks, and 3D reconstruction was performed to obtain postoperative parameters. The deviation between planned, intraoperative, and postoperative inclination, retroversion, entry point, and depth of the glenoid component placement was calculated. Outliers were defined as >5° for inclination and retroversion and >5 mm for entry point., Results: Seventeen patients (9 females, 12 right shoulders) with a mean age of 72.8 ± 9.1 years (range, 47.0-82.0) met inclusion criteria. The mean deviation between intra- and postoperative measurements was 1.5° ± 1.0° (range, 0.0°-3.0°) for inclination, 2.8° ± 1.5° (range, 1.0°-4.5°) for retroversion, 1.8 ± 1.0 mm (range, 0.7-3.0 mm) for entry point, and 1.9 ± 1.9 mm (range, 0.0-4.5 mm) for depth. The mean deviation between planned and postoperative values was 2.5° ± 3.2° (range, 0.0°-11.0°) for inclination, 3.4° ± 4.6° (range, 0.0°-18.0°) for retroversion, 2.0 ± 2.5 mm (range, 0.0°-9.7°) for entry point, and 1.3 ± 1.6 mm (range, 1.3-4.5 mm) for depth. There were no outliers between intra- and postoperative values and there were 3 outliers between planned and postoperative values. The mean time (minutes : seconds) for the tracker unit placement and the scapula registration was 03:02 (range, 01:48 to 04:26) and 08:16 (range, 02:09 to 17:58), respectively., Conclusion: The use of a navigated AR system through an HMD in RSA led to low deviations between planned, intraoperative, and postoperative parameters for glenoid component placement., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Scapular morphological attributes show promise as prognostic indicators of retear following rotator cuff repair. Current evaluation techniques using single-slice magnetic-resonance imaging (MRI) are, however, prone to error, while more accurate computed tomography (CT)-based three-dimensional techniques, are limited by cost and radiation exposure. In this study we propose deep learning-based methods that enable automatic scapular morphological analysis from diagnostic MRI despite the anisotropic resolution and reduced field of view, compared to CT. A deep learning-based segmentation network was trained with paired CT derived scapula segmentations. An algorithm to fuse multi-plane segmentations was developed to generated high-resolution 3D models of the scapula on which morphological landmark- and axes were predicted using a second deep learning network for morphological analysis. Using the proposed methods, the critical shoulder angle, glenoid inclination and version were measured from MRI with accuracies of -1.3 ± 1.7 degrees, 1.3 ± 2.1 degree, and - 1.4 ± 3.4 degrees respectively, compared to CT. Inter-class correlation between MRI and CT derived metrics were substantial for the glenoid version and almost perfect for the other metrics. This study demonstrates how deep learning can overcome reduced resolution, bone border contrast and field of view, to enable 3D scapular morphology analysis on MRI., Competing Interests: Declarations. Competing interests: The authors declare no competing interests. Alexandra Oswald: The author’s work is funded by the Innosuise Grant 35656.1 IP-LS “Computer Assisted Planning for Rotator Cuff Repair” which includes partial funding by Synthes GmbH. J. Tomas Rojas: The author, their immediate family, and any research foundation with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article. Alexandre Lädermann: This author is a paid consultant for Arthrex, Stryker, Medacta, and Enovis. He received royalties from Stryker and Medacta. He is the (co-)founder of FORE, Med4Cast, and BeeMed. He owns stock options in Medacta and Follow Health. He is on the board of the French Arthroscopic Society. Matthias A. Zumstein: This author reports grants from Medacta and non-financial support from Angiocrine Biosciences, outside the submitted work. Kate Gerber: The author’s work is funded by the Innosuise Grant 35656.1 IP-LS “Computer Assisted Planning for Rotator Cuff Repair” which includes partial funding by Synthes GmbH., (© 2025. The Author(s).)

The ARCR&#95;Pred study was initiated to document and predict the safety and effectiveness of arthroscopic rotator cuff repair (ARCR) in a representative Swiss patient cohort. In the present manuscript, we aimed to describe the overall and baseline characteristics of the study, report on functional outcome data and explore case-mix adjustment and differences between public and private hospitals. Between June 2020 and November 2021, primary ARCR patients were prospectively enrolled in a multicenter cohort across 18 Swiss and one German orthopedic center. Baseline characteristics, including sociodemographic and diagnostic variables, were reported. Clinical scores and patient-reported outcome measures were assessed up to 24-month follow-up. After screening 2350 individuals, 973 patients with ARCR were included. Follow-up rates reached 99%, 95%, 89% and 88% at 6 weeks, 6, 12, and 24 months, respectively. While the proportion of massive tears was higher in the study population (44% vs. 20%, Std. Diff. = 0.56), there were no other major differences in key characteristics between enrolled and non-enrolled patients or in patients lost to follow-up. Functional scores improved over time, with positive changes rates ranging from 83% to 92% at 6-month, reaching 91% to 97% at 12- and 24-month follow-up. In linear mixed models, used to estimate the associations between baseline factors, hospital type and standardized 0-100 scores, marginal effects for time ranged from 20 to 30, 28 to 39 and 34 to 41 points at the 6-, 12- and 24-month follow-up, respectively. Except at the 12-month follow-up, where marginal effects for the interaction terms ranged from -5 to -4 points in the standardized scores, there were no consistent outcome differences between public and private hospitals. Increasing number of years of education was consistently associated with better scores, greater feelings of depression and anxiety, smoking and ASA group III-IV were consistently associated with worse scores. Tear severity showed a consistent negative association solely for the Constant-Score. The ARCR&#95;Pred study shows high potential for generalizability to the population of patients undergoing an ARCR in Switzerland. Further analyses are needed to establish relevant clinimetrics for the Swiss population and to compare outcomes for surgical techniques, surgeon experiences profiles and post-operative management., Competing Interests: All authors declare that they have no competing interests., (Copyright: © 2025 Stojanov et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Numerous physical diagnostic shoulder tests have been established to determine the presence of rotator cuff tears and to identify the affected muscles. However, reported sensitivities and specificities of these tests vary strongly. The aim of this study was to identify diagnostic postures that are biomechanically most sensitive in identifying rotator cuff lesions and compensation mechanisms., Methods: A musculoskeletal modeling study investigating muscle activity in healthy shoulders as well as in shoulders with anterior, superior, and posterosuperior rotator cuff tear patterns, was conducted. Muscle moment arms and muscle synergism for the Lift-off and Bear Hug tests, Jobe and Full-can tests, and Infraspinatus and Hornblower tests were compared for healthy and pathological models., Results: In a healthy model the Lift-off test showed significantly higher subscapularis activity compared to the Bear Hug test (P < .001). Teres minor and infraspinatus activity were threefold and twofold higher, in the Hornblower than the Infraspinatus test, respectively. In superior tests, supraspinatus activity was more than twofold lower than lateral deltoid activity and synergistic activity increase was smallest (Δ 1%-3% in deltoid). Activity increase was highest in posterosuperior tests for the teres minor with 66.4% activity increase in the Infraspinatus test (P < .001) and 81.3% increase in the Hornblower test (P < .001)., Conclusions: The Lift-off test was significantly more sensitive in detecting subscapularis tears and the Hornblower test was more effective in assessing teres minor integrity in posterosuperior tears. Both, Jobe and Full-can tests demonstrated low biomechanical sensitivity in the detection of superior rotator cuff tears., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Tear size and shape are known to prognosticate the efficacy of surgical rotator cuff (RC) repair however, current manual measurements on magnetic resonance images (MRI), exhibit high interobserver variabilities and exclude three-dimensional (3D) morphological information. This study aimed to develop algorithms for automatic 3D analyses of posterosuperior full-thickness RC tear to enable efficient and precise tear evaluation and 3D tear visualization., Methods: - A deep-learning network for automatic segmentation of the tear region in coronal and sagittal multicenter MRI was trained with manually segmented (consensus of 3 experts) pd- and T2 weighted MRI of shoulders with full-thickness posterosuperior tears (n=200). Algorithms for automatic measurement of tendon retraction, tear width, tear area and automatic Patte classification, considering 3D morphology of the shoulder were implemented and evaluated against manual segmentation (n= 59). Automatic Patte classification was calculated using automatic segmented humerus and scapula on T1-weighted MRI of the same shoulders., Results: - Tears were automatically segmented, enabling 3D visualization of the tear, with mean Dice coefficient of 0.58 ± 0.21 compared to an interobserver variability of 0.46 ± 0.21. The mean absolute error of automatic tendon retraction and tear width measurements (4.98 ± 4.49 mm and 3.88 ± 3.18 mm) were lower than the interobserver variabilities (5.42 ± 7.09 mm and 5.92 ± 1.02 mm). The correlations of all measurements performed on automatic tear segmentations compared to those on consensus segmentations were higher than the interobserver correlation. Automatic Patte classification achieved a Cohen's kappa value of 0.62, compared to the interobserver variability of 0.56. Retraction calculated using standard linear measures underestimated the tear size relative to measurements considering the curved shape of the humeral head, especially for larger tears., Conclusion: - Even on highly heterogeneous data, the proposed algorithms showed the feasibility to successfully automate tear size analysis and to enable automatic 3D visualization of the tear situation. The presented algorithms standardize cross-center tear analyses and enable the calculation of additional metrics, potentially improving the predictive power of image-based tear measurements for the outcome of surgical treatments, thus aiding in RC tear diagnosis, treatment decision and planning., (Copyright © 2024. Published by Elsevier Inc.)

Background: Tendon transfers are established techniques to regain external rotation mobility in patients with an irreparable, posterosuperior massive rotator cuff tear (MRCT). Posterosuperior MRCT with intact teres minor (type D MRCT) can lead to excessive teres minor loading to maintain external rotation. We hypothesize that tendon transfers are effective in relieving teres minor loading in type D MRCTs. Our aim was to biomechanically assess muscle synergism with latissimus dorsi (LD transfer) and lower trapezius (LT transfer) tendon transfer during external rotation at different abduction heights., Methods: Using musculoskeletal modeling, we analyzed and compared the moment arm, muscle torque, and muscle activity between a healthy and type D MRCT pathologic model with and without the LD- or LT transfer at infraspinatus and teres minor insertion sites. Output measures were analyzed during external rotation at different abduction angles and 10-50 N resistance against external rotation. We assessed its impact on teres minor loading in a type D MRCT. Morphologic variations were parameterized using the critical shoulder angle and the acromiohumeral distance to address variations among patients., Results: Both transfer types reduced teres minor torque and activity significantly, reaching physiological state at 40 N external resistance (P < .001), with insertion to infraspinatus site being more effective than teres minor site (P < .001). External rotation moment arms of LD transfer were larger than LT transfer at 90° abduction (25.1 ± 0.8 mm vs. 21.2 ± 0.6 mm, P < .001) and vice versa at 0° abduction (17.4 ± 0.5 mm vs. 24.0 ± 0.2 mm, P < .001). Although the healthy infraspinatus was the main external rotator in all abduction angles (50%-70% torque), a type D MRCT resulted in a 70%-90% increase of teres minor torque and an up to 7-fold increase in its activity leading to excessive loadings beyond 10 N resistance against external rotation. Varying the critical shoulder angle and the acromiohumeral distance led to minor variations in muscle moment arm and muscle activity., Conclusion: We identified biomechanical efficacy of both tendon transfers in type D MRCT regarding teres minor load relief and superior performance of the transfers at the infraspinatus insertion site., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The role of anatomic factors in rotator cuff (RC) pathology or in the development of shoulder osteoarthritis (OA) is not yet well understood or recognized. While 2-dimensional imaging and measurements are easy to capture and interpret, three-dimensional (3D) methods provide a more thorough description and analysis of the scapula's complex shape. The purpose of this study is to investigate whether scapular anatomy is associated with RC tears or glenohumeral OA using 3D statistical shape modelling., Methods: A total of 126 computed tomography scans of complete scapulae were captured from 3 cohorts: RC pathology, OA, and control (C). The RC cohort included patients with posterosuperior RC tears, the OA cohort included patients with glenohumeral OA, and the C cohort included patients without shoulder pathology, imaged for other purposes. The RC and OA cohorts each included 55 patients matched by age and gender, while the C cohort included 16 patients, without a specific matching. A full segmentation of each scapula was manually created and 3D surfaces were reconstructed for input to a statistical shape modelling analysis. Statistical shape modelling-based correspondence particles were analyzed using principal component analysis and linear discriminant analysis. Various landmarks were manually identified on each scapula. From these landmarks, 3D measurements of glenoid version and inclination, critical shoulder angle, acromial angle, among others, were obtained. Measurements were compared between the 3 cohorts using analysis of variance or Student's T-test, as appropriate., Results: There were no statistically significant differences in mean age (RC: 57 ± 9, OA: 58 ± 8, and C: 61 ± 7 years) or gender proportion (males: RC: 51%, OA: 51%, and C: 75%) between the 3 cohorts. A total of 13 principal component analysis modes captured significant shape variation (83.3% of overall variation) of the scapula. The linear discriminant analysis was significantly different between OA and both RC and C (RC: 1.0 ± 1.4, OA: -1.0 ± 1.9, and C: 1.4 ± 1.2). Compared to C, the OA cohort had smaller critical shoulder angle (24.9 ± 6.1° vs. 32.4 ± 4.3°; P < .001), larger acromion angle (65.4 ± 9.3° vs. 57.4 ± 9.5°; P = .019), among other parameters. Compared to RC, the OA cohort also had less distance between coracoid and acromion (47.2 ± 5.8° vs. 44.2 ± 6.4°; P = .026), as well as similar morphologic differences as to the C cohort. There were no significant differences between RC and C cohort., Conclusions: Principal component analysis and linear discriminant analysis applied to manually segmented scapulae revealed statistically significant differences in scapular morphology between OA and control scapulae (a more superior and more horizontal acromion with a lower critical shoulder angle), but only minimal differences between RC and control scapulae (except a more anterior anterolateral corner of the acromion)., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Abstract: Paget-Schroetter syndrome describes a primary thrombosis of the subclavian vein induced by effort. In most cases, the clinical presentation includes painful swelling, discoloration, and visible collateral circulation in the arm. Paget-Schroetter syndrome is treated with anticoagulation, rest, and physical therapy. In certain cases, invasive treatment such as thrombolysis and decompression surgery (first rib resection) may be necessary. We present the case of a 28-year-old healthy male patient with effort-induced deep vein thrombosis of the upper extremity after posterior shoulder subluxation. Anticoagulation, rest, and physical therapy were used to treat the patient, who became asymptomatic and was able to resume normal activities without restriction. To our knowledge, this is the first case of effort-induced upper extremity deep vein thrombosis after posterior shoulder subluxation. Paget-Schroetter syndrome is rare diagnosis that requires vigilance during musculoskeletal assessment for shoulder pain and swelling. The early detection, radiological confirmation, and prompt initiation of treatment are essential to successful management of Paget-Schroetter syndrome. The impact of associated posterior shoulder subluxation remains unclear., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: Osteoarthritis (OA) and rotator cuff tear (RCT) pathologies have distinct scapular morphologies that impact disease progression. Previous studies examined the correlation between scapular morphology and glenohumeral joint biomechanics through critical shoulder angle (CSA) variations. In abduction, higher CSAs, common in RCT patients, increase vertical shear force and rotator cuff activation, while lower CSAs, common in OA patients, are associated with higher compressive force. However, the impact of the complete patient-specific scapular morphology remains unexplored due to challenges in establishing personalized models. Methods: CT data of 48 OA patients and 55 RCT patients were collected. An automated pipeline customized the AnyBody™ model with patient-specific scapular morphology and glenohumeral joint geometry. Biomechanical simulations calculated glenohumeral joint forces and instability ratios (shear-to-compressive forces). Moment arms and torques of rotator cuff and deltoid muscles were analyzed for each patient-specific geometry. Results and discussion: This study confirms the increased instability ratio on the glenohumeral joint in RCT patients during abduction (mean maximum is 32.80% higher than that in OA), while OA patients exhibit a higher vertical instability ratio in flexion (mean maximum is 24.53% higher than that in RCT) due to the increased inferior vertical shear force. This study further shows lower total joint force in OA patients than that in RCT patients (mean maximum total force for the RCT group is 11.86% greater than that for the OA group), attributed to mechanically advantageous muscle moment arms. The findings highlight the significant impact of the glenohumeral joint center positioning on muscle moment arms and the total force generated. We propose that the RCT pathomechanism is related to force magnitude, while the OA pathomechanism is associated with the shear-to-compressive loading ratio. Overall, this research contributes to the understanding of the impact of the complete 3D scapular morphology of the individual on shoulder biomechanics., Competing Interests: The authors declare the following financial interests/personal relationships that may be considered potential competing interests: AL is a paid consultant for Arthrex, Stryker, Medacta, and Enovis. He received royalties from Stryker and Medacta. He is the (co-)founder of FORE, Med4Cast, and BeeMed. He owns stock options in Medacta and Follow Health. He is on the board of the French Arthroscopic Society. MZ received grants from Medacta and non-financial support from Angiocrine Bioscience, outside the submitted work. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Oswald, Menze, Hess, Jacxsens, Rojas, Lädermann, Schär, Ferguson, Zumstein and Gerber.)

Iterative evolutions in arthroscopic rotator cuff repair aim to improve its biomechanical and biological properties. This technical note describes an arthroscopic rotator cuff repair technique that combines the advantages of a modified Mason-Allen suture technique with the advantages of an arthroscopic transosseous-equivalent construct. Two alternatives for creating this construct are described. The Mason-Allen stitch is easy to perform, is cost-effective, and increases tissue security without tendon strangulation. The arthroscopic transosseous-equivalent construct increases footprint contact pressure and coverage, aiding healing of the repaired rotator cuff., (© 2024 The Authors.)

Background: Navigated augmented reality (AR) through a head-mounted display (HMD) may lead to accurate glenoid component placement in reverse shoulder arthroplasty (RSA). The purpose of this study is to evaluate the deviation between planned, intra- and postoperative inclination, retroversion, entry point, depth, and rotation of the glenoid component placement assisted by a navigated AR through HMD during RSA., Methods: Both shoulders of 6 fresh frozen human cadavers, free from fractures or other bony pathologies, were used. Preoperative computed tomography (CT) scans were used for the 3-dimensional (3D) planning. The glenoid component placement was assisted using a navigated AR system through an HMD in all specimens. Intraoperative inclination, retroversion, depth, and rotation were measured by the system. A postoperative CT scan was performed. The pre- and postoperative 3D CT scan reconstructions were superimposed to calculate the deviation between planned and postoperative inclination, retroversion, entry point, depth, and rotation of the glenoid component placement. Additionally, a comparison between intra- and postoperative values was calculated. Outliers were defined as >10° inclination, >10° retroversion, >3 mm entry point., Results: The registration algorithm of the scapulae prior to the procedure was correctly completed for all cases. The deviations between planned and postoperative values were 1.0° ± 0.7° for inclination, 1.8° ± 1.3° for retroversion, 1.1 ± 0.4 mm for entry point, 0.7 ± 0.6 mm for depth, and 1.7° ± 1.6° for rotation. The deviation between intra- and postoperative values were 0.9° ± 0.8° for inclination, 1.2° ± 1.1° for retroversion, 0.6 ± 0.5 mm for depth, and 0.3° ± 0.2° for rotation. There were no outliers between planned and postoperative parameters., Conclusion: In this study, the use of a navigated AR system through an HMD for RSA led to low deviation between planned and postoperative values and between intra- and postoperative parameters., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Choosing the optimal treatment for massive rotator cuff tears (MRCTs) still poses a surgical problem. In MRCTs with good muscle quality, but short tendon length, nonaugmented repairs lead to high failure rates of up to 90%. The aim of the study was to evaluate midterm clinical and radiologic outcomes of massive rotator cuff tears with good muscle quality, but short tendon length, which were repaired with synthetic patch augmentation., Methods: A retrospective study of patients who underwent arthroscopic or open rotator cuff repairs with patch augmentation between 2016 and 2019 was performed. We included patients older than 18 years, who presented with an MRCT confirmed by an magnetic resonance imaging (MRI) arthrogram showing good muscle quality (Goutallier ≤ II) and short tendon length (length <15 mm). Constant-Murley score (CS), Subjective Shoulder Value (SSV), and range of motion (ROM) were compared pre- and postoperatively. We excluded patients older than 75 years or with presence of rotator cuff arthropathy Hamada stage ≥2a. Patients were followed up for 2 years minimum. Clinical failures were defined by reoperation, forward flexion <120° or a relative CS < 70. Structural integrity of the repair was assessed using an MRI scan. Comparison between different variables and outcomes was performed using Wilcoxon-Mann-Whitney and χ 2 tests., Results: Fifteen patients (mean age 57 years, 13 [86.7%] male, 9 [60%] right shoulders) were reevaluated with a mean follow-up of 43.8 months (27-55 months). There was a significant improvement in the absolute CS (from 33 to 81 points, P = .03), the relative CS (from 41% to 88%, P = .04), the SSV (from 31% to 93%, P = .007), and forward flexion (from 111° to 163°, P = .004) but not in external rotation (from 37° to 38°, P = .5). There were 3 clinical failures (1 atraumatic, 2 traumatic) with reoperations (2 reverse total shoulder arthroplasties and 1 refixation). Structurally, there were 3 Sugaya grade 4 and 5 Sugaya grade 5 reruptures resulting in a retear rate of 53%. The presence of a complete or partial rerupture was not associated with inferior outcomes compared with intact cuff repairs. There were no correlations between the grade of retraction, muscle quality, or rotator cuff tear configuration and rerupture or functional outcomes., Conclusion: Patch augmented cuff repair leads to a significant improvement of functional and structural outcomes. Partial reruptures were not associated with inferior functional outcomes. Prospective randomized trials are needed to confirm the results found in our study., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.)

Shoulder stiffness is a frequent complication after proximal humeral fractures treated with or without surgery. Shoulder stiffness is associated with high rates of absence from work and a significant financial burden for the healthcare system. Secondary stiffness is characterized by additional extracapsular adhesions, including subacromial, subcoracoid, and subdeltoid spaces, usually derived from post-fracture or post-surgical extraarticular hematomas. Several secondary causes may coexist with capsular and extracapsular adhesions decreasing the shoulder motion, such as malunion, nonunion, metalwork failure, infection, and osteoarthritis, among others. Conservative treatment, usually prescribed for primary shoulder stiffness, has shown unfavorable results in secondary stiffness, and surgical intervention may be required. Surgical interventions need to be patient-specific. Usually, open or arthroscopic fibro-arthrolysis and subacromial release are performed, together with plate removal and biceps tenotomy/tenodesis. In severe osteoarthritis, shoulder replacement may be indicated. Ruling out infection is recommended in every case.

Chronic traumatic anterior shoulder instability can be defined as recurrent trauma-associated shoulder instability requiring the assessment of three anatomic lesions: a capsuloligamentous and/or labral lesion; anterior glenoid bone loss and a Hill-Sachs lesion. Surgical treatment is generally indicated. It remains controversial how risk factors should be evaluated to decide between a soft-tissue, free bone-block or Latarjet-type procedure. Patient risk factors for recurrence are age; hyperlaxity; competitive, contact and overhead sports. Trauma-related factors are soft tissue lesions and most importantly bone loss with implications for treatment. Different treatment options are discussed and compared for complications, return to sports parameters, short- and long-term outcomes and osteoarthritis. Arthroscopic Bankart and open Latarjet procedures have a serious learning curve. Osteoarthritis is associated with the number of previous dislocations as well as surgical techniques. Latarjet-type procedures have the lowest rate of dislocation recurrence and if performed correctly, do not seem to increase the risk of osteoarthritis.

Three-dimensional (3D)-image-based anatomical analysis of rotator cuff tear patients has been proposed as a way to improve repair prognosis analysis to reduce the incidence of postoperative retear. However, for application in clinics, an efficient and robust method for the segmentation of anatomy from MRI is required. We present the use of a deep learning network for automatic segmentation of the humerus, scapula, and rotator cuff muscles with integrated automatic result verification. Trained on N = 111 and tested on N = 60 diagnostic T1-weighted MRI of 76 rotator cuff tear patients acquired from 19 centers, a nnU-Net segmented the anatomy with an average Dice coefficient of 0.91 ± 0.06. For the automatic identification of inaccurate segmentations during the inference procedure, the nnU-Net framework was adapted to allow for the estimation of label-specific network uncertainty directly from its subnetworks. The average Dice coefficient of segmentation results from the subnetworks identified labels requiring segmentation correction with an average sensitivity of 1.0 and a specificity of 0.94. The presented automatic methods facilitate the use of 3D diagnosis in clinical routine by eliminating the need for time-consuming manual segmentation and slice-by-slice segmentation verification.

Background: PARP-1 (poly[ADP-ribose]) was shown to influence the inflammatory response after rotator cuff tear, leading to fibrosis, muscular atrophy, and fatty infiltration in mouse rotator cuff degeneration. So far, it is not known how PARP-1 influences enthesis healing after rotator cuff tear repair., Hypothesis/purpose: This study aimed to examine the feasibility of oral PARP-1 inhibition and investigate its influence on rat supraspinatus enthesis and muscle healing after rotator cuff repair. The hypothesis was that oral PARP-1 inhibition would improve enthesis healing after acute rotator cuff repair in a rat model., Study Design: Controlled laboratory study., Methods: In 24 Sprague-Dawley rats, the supraspinatus tendon was sharply detached and immediately repaired with a single transosseous suture. The rats were randomly allocated into 2 groups, with the rats in the inhibitor group receiving veliparib with a target dose of 12.5 mg/kg/d via drinking water during the postoperative recovery period. The animals were sacrificed 8 weeks after surgery. For the analysis, macroscopic, biomechanical, and histologic methods were used., Results: Oral veliparib was safe for the rats, with no adverse effects observed. In total, the inhibitor group had a significantly better histologic grading of the enthesis with less scar tissue formation. The macroscopic cross-sectional area of the supraspinatus muscles was 10.5% higher ( P = .034) in the inhibitor group, which was in agreement with an 8.7% higher microscopic muscle fiber diameter on histologic sections ( P < .0001). There were no statistically significant differences in the biomechanical properties between the groups., Conclusion: This study is the first to investigate the influence of PARP-1 inhibition on healing enthesis. On the basis of these findings, we conclude that oral veliparib, which was previously shown to inhibit PARP-1 effectively, is safe to apply and has beneficial effects on morphologic enthesis healing and muscle fiber size., Clinical Relevance: Modulating the inflammatory response through PARP-1 inhibition during the postoperative healing period is a promising approach to improve enthesis healing and reduce rotator cuff retearing. With substances already approved by the Food and Drug Administration, PARP-1 inhibition bears high potential for future translation into clinical application.

Background: Patient-specific instrumentation (PSI) may potentially improve humeral osteotomy in shoulder arthroplasty. The purpose of this study was to compare the deviation between planned and postosteotomy humeral inclination, retrotorsion, and height in shoulder arthroplasty, using PSI vs. standard cutting guides (SCG)., Methods: Twenty fresh-frozen cadaveric specimens were allocated to undergo humeral osteotomy using either PSI or SCG, such that the 2 groups have similar age, gender, and side. Preosteotomy computed tomography (CT) scan was performed and used for the 3-dimensional (3D) planning. The osteotomy procedure was performed using a PSI designed for each specimen or an SCG depending on the group. A postosteotomy CT scan was performed. The preosteotomy and postosteotomy 3D CT scan reconstructions were superimposed to calculate the deviation between planned and postosteotomy inclination, retrotorsion, and height. Outliers were defined as cases with 1 or more of the following deviations: >5° inclination, >10° retrotorsion, and >3 mm height. The deviation and outliers in inclination, retrotorsion, and height were compared between the 2 groups., Results: The deviations between planned and postosteotomy parameters were similar among the PSI and SCG groups for inclination (P = .260), whereas they were significantly greater in the SCG group for retrotorsion (P < .001) and height (P = .003). There were 8 outliers in the SCG group, compared with only 1 outlier in the PSI group (P = .005). Most outliers in the SCG group were due to deviation >10° in retrotorsion., Conclusion: After 3D planning, PSI had less deviation between planned and postosteotomy humeral retrotorsion and height, relative to SCG., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Component positioning is a key factor for avoiding complications and improving functional outcomes in reverse shoulder arthroplasty. Preoperative planning can improve component positioning. However, translating the preoperative plan into the surgical procedure can be challenging. This is particularly the case for the glenoid component positioning in severe deformity or limited visualization of the scapula. Different computational-assisted techniques have been developed to aid implementation of the preoperative plan into the surgical procedure. Navigated augmented reality (AR) refers to the real world augmented with virtual real-time information about the position and orientation of instruments and components. This information can be presented through a head-mounted display (HMD), which enables the user to visualize the virtual information directly overlaid onto the real world. Navigated AR systems through HMD have been validated for shoulder arthroplasty using phantoms and cadavers. This article details a step-by-step guide use of a navigated AR system through HMD, in the placement of the glenoid bony-augmented component., (© 2022 The Authors.)

Introduction: 8-10% of all Ulnar styloid fractures (USF) accompanying distal radius fractures are addressed surgically. The surgical fixation has to counteract forces of translation and rotation acting on the distal radioulnar joint (DRUJ). The different technics used were never compared biomechanically. Our study aims to compare the effects of different techniques of USF fixation on the forearm rotation and the dorsal-palmar (DP)-translation of the DRUJ., Material and Methods: 9 forearm specimens were mounted on a custom testing system. Load was applied for Pronosupination and DP-translation with the forearm placed in neutral position, pronation and supination. The positional change of the DRUJ was measured using a MicroScribe. Six different, sequential conditions were tested in the same specimen: intact, USF and 4 repair techniques (2 K-wire, tension band wiring (TBW), headless compression screw, suture anchor)., Results: The USF significantly increased DP-translation and pronosupination compared to the intact condition. The DP-translation in neutral was reduced significantly with all four techniques compared to the USF condition. TBW and suture anchor also showed a significant difference to the K-wire fixation. In supination only the TBW and suture anchor significantly decreased DP-Translation. The rotational stability of the DRUJ was only restored by the K-wire fixation and the TBW., Conclusions: All four USF repair techniques partially restored translational stability; however, only K-wire fixation and TBW techniques restored rotational stability. TBW was biomechanically superior to the other techniques as it restored translational stability and rotational stability., Competing Interests: Declaration of Competing Interest The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2021. Published by Elsevier Ltd.)

Orthoregeneration is defined as a solution for orthopaedic conditions that harnesses the benefits of biology to improve healing, reduce pain, improve function, and optimally, provide an environment for tissue regeneration. Options include drugs, surgical intervention, scaffolds, biologics as a product of cells, and physical and electro-magnetic stimuli. The goal of regenerative medicine is to enhance the healing of tissue after musculoskeletal injuries as both isolated treatment and adjunct to surgical management, using novel therapies to improve recovery and outcomes. Various orthopaedic biologics (orthobiologics) have been investigated for the treatment of pathology involving the shoulder including the rotator cuff tendons, glenohumeral articular cartilage, glenoid labrum, the joint capsule, and bone. Promising and established treatment modalities include hyaluronic acid (HA); platelet-rich plasma (PRP) and platelet rich concentrates (PRC); bone marrow aspirate (BMA) comprising mesenchymal stromal cells (MSCs alternatively termed medicinal signaling cells and frequently, misleadingly labelled "mesenchymal stem cells"); MSC harvested from adipose, umbilical, or placental sources; factors including vascular endothelial growth factors (VEGF), basic fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), transforming growth factor-beta (TGFβ), bone morphogenic protein (BMP), and matrix metalloproteinases (MMPs); prolotherapy; pulsed electromagnetic field therapy; microfracture and other marrow-stimulation techniques; biologic resurfacing using acellular dermal allografts, allograft Achilles tendons, allograft lateral menisci, fascia lata autografts, and porcine xenografts; osteochondral autograft or allograft); and autologous chondrocyte implantation (ACI). Studies involving hyaluronic acid, platelet rich plasma, and medicinal signaling cells of various origin tissues have shown mixed results to-date as isolated treatments and as surgical adjuncts. Despite varied results thus far, there is great potential for improved efficacy with refinement of current techniques and translation of burgeoning preclinical work. LEVEL OF EVIDENCE: Level V, expert opinion., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to evaluate the intermediate-term clinical and radiological outcomes for acute, unstable acromioclavicular joint (ACJ) injuries treated with the arthroscopically assisted BiPOD stabilisation technique., Methods: Twenty-three patients who sustained acute, unstable ACJ injuries were included in this prospective study. We recorded demographics, injury classification, time to surgery, clinical scores, radiological outcomes and complications; each patient completed a minimum of 2 years post-operative observation., Results: Mean follow-up was 26 months (range, 24-34). Clinical outcomes scores demonstrated good 2-year results: relative Constant score, 97.9/100; ACJ Index, 89.4/100; Subjective Shoulder Value, 92.4/100 and Taft = 11.1/12. Final C-C distance showed a mean of 0.7 mm (SD ± 1.8 mm) at 2 years. Complication rate was 9%., Conclusion: The BiPOD technique shows excellent, reliable intermediate-term results with a favourable complication rate compared to existing techniques; it provides a comprehensive surgical option for the stabilisation of acute ACJ injuries restoring both vertical and horizontal stability., (© 2021. The Author(s).)

Background: Olecranon osteotomies are frequently used to expose distal humeral intraarticular fractures. The step-cut olecranon osteotomy (SCOOT) is an augmented version of the oblique olecranon osteotomy, which has recently been evaluated biomechanically with tension band wiring (TBW) fixation. However, complications with TBW are common. In this study, we, therefore, compared the mean load to failure of TBW with compression screws for SCOOT fixation. We hypothesized a higher load to failure for the compression screw group., Methods: We performed a SCOOT on 36 Sawbones. Eighteen were fixed with TBW, and another 18 with two compression screws. The humeroulnar joint was simulated using an established test setup, which allows the application of triceps traction force through a tendon model to the ulna, while the humeroulnar joint is in a fixed position. Eight models of each fixation group were tested at 20°, and eight at 70° of flexion by isometrical loading until failure, which was defined as either a complete fracture or gap formation of more than 2 mm at the osteotomy site., Results: At 20° of flexion, mean load to failure was similar between the TBW group (1360 ± 238 N) and the compression screw group (1401 ± 261 N) ( P  = .88). Also, at 70° of flexion, the mean load to failure was similar between the TBW group (1398 ± 215 N) and the compression screw group (1614 ± 427 N) ( P  = .28)., Conclusions: SCOOTs fixed with TBW and compression screws showed similar loads to failure. A SCOOT fixed with compression screws might be a valuable alternative for surgeons when treating intraarticular distal humeral fractures. However, future in vivo studies are necessary to confirm our results in a clinical setting., (© 2021 The Authors.)

Rotator cuff supraspinatus tendon injuries are common with high rates of anatomic failure after surgical repair. The purpose of the study was to define clinically relevant features of a mouse model of supraspinatus tendon injury to determine painful, functional, and structural outcomes; we further investigated two cell populations mediating healing using genetic lineage tracing after full detachment and repair of the supraspinatus tendon in mice. The pain was assessed using the mouse grimace scale and function by gait analysis and tensile testing. Histological and microCT analyses were used to determine enthesis/tendon and bone structure, respectively. Lineage tracing was carried out using inducible Cre lines for ScxCreERT2 (tendon cells) and αSMACreERT2 (myofibroblasts and mesenchymal progenitors). Mice only expressed pain transiently after surgery despite long-term impairment of functional and structural properties. Gait, tensile mechanical properties, and bone properties were significantly reduced after injury and repair. Lineage tracing showed relatively few Scx lin tendon cells while αSMA lin cells contributed strongly to scar formation. Despite surgical reattachment of healthy tendon, lineage tracing revealed poor preservation of supraspinatus tendon after acute injury and loss of tendon structure, suggesting that tendon degeneration is also a key impediment of successful rotator cuff repair. Scar formation after surgery is mediated largely by αSMA lin cells and results in permanently reduced functional and structural properties., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Background: Acromioclavicular joint (ACJ) injuries are common. Despite this, it remains unclear how best to assess, classify, and manage these cases. A simple, reliable, valid, and accurate radiographic parameter to measure ACJ displacement would allow improved consistency of diagnosis and subsequent treatment pathways., Purpose: To evaluate "the circles measurement" and associated "ABC classification" as a tool for assessing ACJ displacement and injury classification., Study Design: Descriptive laboratory study., Methods: The circles measurement is taken from a lateral Alexander radiograph of the shoulder. The measurement is the center-to-center distance between 2 circles drawn to define the lateral extent of the clavicle and the anteromedial extent of the acromion; it is independent of the displacement plane, judging total ACJ displacement in any direction rather than trying to quantify vertical and/or horizontal displacement. When utilized clinically, the circles measurement is a single measurement calculated as the difference between values recorded for the injured and uninjured sides. Validation of the circles measurement was performed using lateral Alexander radiographs (including ±20° projection error in all planes) and computed tomography of standardized ACJ injury simulations. We assessed inter- and intrarater reliability, convergent validity, and discriminant validity of the circles measurement and subsequently generated a classification of ACJ injury based on displacement., Results: Reliability and validity of the circles measurement was excellent throughout. Interrater reliability (ICC [intraclass correlation coefficient] [2,1], 95% CI; n = 78; 4 observers) was 0.976 (0.964-0.985). Intrarater reliability (ICC [2,1]; 95% CI; n = 78; 2 measures) was 0.998 (0.996-0.998). Convergent validity (Pearson correlation coefficient, r ) was 0.970 for ideal radiographs and 0.889 with ±20° projection error in all planes. Discriminant validity, with 1-way analysis of variance, showed a P value of <.0001 and effect size ( η 2 ) of 0.960, with the ability to distinguish between the previously defined stable (Rockwood IIIA) and unstable (Rockwood IIIB) injuries. The results permitted objective, statistically sound parameters for the proposed ABC classification system., Conclusion: The circles measurement is a simple, reliable, valid, accurate, and resilient parameter for assessing ACJ displacement and can be used in conjunction with the proposed ABC classification to define ACJ injuries more accurately and objectively than previously described., Clinical Relevance: This novel parameter has the potential to standardize the initial assessment and possibly the subsequent clinical management of ACJ injuries, in addition to providing a standardized measure for future research.

Purpose: Muscle fat content of the rotator cuff increases after a tear. In the healthy rotator cuff, the influence of age, body mass index (BMI) and critical shoulder angle (CSA) on muscle fat content is unknown. The primary aim was to correlate muscle fat content with age, BMI and CSA. The secondary aims were (1) to correlate muscle fat content in the entire muscle and slice Y (most lateral sagittal slice with scapular spine) and (2) assessed the reliability for CSA measurement in MRI., Methods: In 26 healthy shoulders (17 subjects), aged 40-65 years, BMI 20-35 kg/m 2 , Goutallier grade 0, Dixon MRI was applied. The CSA was > 35° in 14 shoulders and < 30° in 12 shoulders. Muscle fat content was calculated from Dixon MRI., Results: Infraspinatus muscle fat content correlates moderately with age (r = 0.553; p = 0.003) and BMI (r = 0.517; p = 0.007). Supraspinatus muscle fat content does not correlate with age (r = 0.363, p = 0.069) and BMI (r = 0.342, p = 0.087). No correlation between CSA and muscle fat content was found. Muscle fat content measurement in the entire muscle correlates strongly with measurement in slice Y (intraclass correlation coefficient supraspinatus muscle: 0.757; infraspinatus muscle: 0.794). CSA intermethod analysis between radiography and MR images shows very high reliability (intraclass correlation coefficient > 0.9) and no systematical deviation in Bland-Altman analysis., Conclusion: Muscle fat content in the healthy infraspinatus muscle does correlate with age and BMI, but not with the CSA. Muscle fat content measurement in the rotator cuff using Dixon MRI showed a high reliability between slice Y and the entire muscle., Level of Evidence: III.

Background: Multiple modifications of reverse total shoulder arthroplasty (RTSA) since the first Grammont design have developed to improve range of motion (ROM) and avoid notching. The effect of these changes in shoulder kinematics and the best compromise for ROM is still under debate. This computer simulation study evaluates the influence of humeral design, humeral neck-shaft angle (NSA), glenoid lateralization, and glenoid eccentricity on ROM of RTSA., Methods: We created a 3-dimensional computer model from computed tomography scans of 13 patients with primary osteoarthritis simulating implantation of a standardized reverse shoulder arthroplasty. We analyzed the effect of 4 different variables on impingement-free ROM: humeral design (inlay vs. semi-inlay vs. onlay), humeral NSA (135° vs. 145° vs. 155°), glenoid lateralization, and glenoid eccentricity on ROM., Results: The use of different humeral stem designs did not have a significant effect on total global ROM. Reducing NSA demonstrated a significant increase in adduction, and external and internal rotation in adduction, whereas a decrease in abduction and external rotation in abduction. Glenosphere lateralization was the most effective method for increasing total global ROM (P < .0001); however, extreme lateralization (+12 mm) did not show significant benefit compared with moderate lateralization (+4 mm). Glenosphere eccentricity increased only adduction and internal rotation in adduction., Conclusion: Only glenoid lateralization has a significant effect on increasing total global ROM in RTSA. The use of the semi-inlay 145° model combined with 4 mm lateralization and 2 mm inferior eccentricity represents the middle ground and the most universal approach in RTSA., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Understanding of the exact topography of the distal radioulnar ligaments insertions remains limited. An anatomical study was performed in 21 fresh frozen cadaveric wrists, where the superficial and deep ligaments were sequentially transected sharply at their ulnar insertions. The relationships between the distal radioulnar ligament footprints relative to the bony landmarks of the ulnar styloid were digitized. Our study demonstrated that in the coronal plane, the superficial distal radioulnar ligaments inserted at an average of 87% of the styloid height proximally to the styloid tip distally. The deep distal radioulnar ligaments inserted at an average of 81% of the styloid height distally to the fovea proximally. The superficial footprint had an area of 10.6 mm 2 on the ulnar styloid. The deep distal radioulnar ligaments attachment was asymmetric and generally had two separate footprints. This study adds important topographical knowledge about the footprint of the distal radioulnar ligaments and may contribute to understanding the consequences of ulnar styloid fractures and distal radioulnar ligaments lesions.

Purpose of Review: This review aims to describe the role of the latissimus dorsi transfer (LDT) for patients with irreparable posterosuperior rotator cuff tears (RCTs)., Recent Findings: Historically, the LDT has been performed as an open (double-incision) procedure for neurologically intact, relatively young patients with irreparable posterosuperior RCTs with disabling loss of active external rotation with or without impaired active elevation. The transferred tendon reconstitutes the posterior rotator cuff and force couple, respectively and thus has the potential to function effectively as an external rotator and humeral head depressor. Long-term results of the open technique have demonstrated in the majority of patients substantial and durable improvements in shoulder function and pain relief at the 10-year benchmark. With the advancements of arthroscopic surgery, the LDT was expanded to an arthroscopically assisted procedure with promising short-term results. In addition to adequate technical performance, the success of the procedure depends on preoperative factors, such as exclusion of glenohumeral osteoarthritis and acromial acetabularization; intact or reparable subscapularis tendon; intact (or hypertrophic) teres minor muscle; adequate preoperative activity of the latissimus dorsi; and normal or mild impairment of overhead function. The LDT (open or arthroscopically assisted) is a reliable treatment option for patients with massive, irreparable posterosuperior RCTs with disabling loss of active external rotation, with or without diminished overhead function and without advanced glenohumeral osteoarthritis. Precise patient selection is of tremendous importance in the success of the LDT.

Background: The critical shoulder angle (CSA) has been shown to be correlated with shoulder disease states. The biomechanical hypothesis to explain this correlation is that the CSA changes the shear and compressive forces on the shoulder. The objective of this study is to test this hypothesis by use of a validated computational shoulder model. Specifically, this study assesses the impact on glenohumeral biomechanics of modifying the CSA., Methods: An inverse dynamics 3-dimensional musculoskeletal model of the shoulder was used to quantify muscle forces and glenohumeral joint forces. The CSA was changed by altering the attachment point of the middle deltoid into a normal CSA (33°), a reduced CSA of 28°, and an increased CSA of 38°. Subject-specific kinematics of slow and fast speed abduction in the scapular plane and slow and fast forward flexion measured by a 3-dimensional motion capture system were used to quantify joint reaction shear and compressive forces., Results: Increasing the CSA results in increased superior-inferior forces (shearing forces; integrated over the range of motion; P < .05). Reducing CSA results in increased lateromedial (compressive) forces for both the maximum and integrated sum of the forces over the whole motion (P < .01)., Discussion/conclusion: Changes in the CSA modify glenohumeral joint biomechanics with increasing CSA producing higher shear forces that could contribute to rotator cuff overuse, whereas reducing the CSA results in higher compressive forces that contribute to joint wear., (Crown Copyright © 2020. Published by Elsevier Inc. All rights reserved.)

Background: Accurate classification and subsequent management of acromioclavicular (AC) joint injuries remains a contentious topic. The updated Rockwood classification acknowledges "stable IIIA" and "unstable IIIB" injuries, a watershed accepted by ISAKOS and important in guiding clinical management. Traditionally, the coracoclavicular distance is used to classify these injuries, despite well-documented limitations. This study aimed to evaluate displacement in AC joint injuries by measuring both coracoclavicular (CC) distance and the newly proposed acromial center line to dorsal clavicle (AC-DC) distance, in a cohort of patients, and correlate the results between the 2 measurements and relationship to Rockwood grade., Materials and Methods: Ninety consecutive cases of AC joint injury were evaluated radiographically for Rockwood classification, CC distance on anteroposterior radiographs, and AC-DC distance on Alexander view radiographs. Inter- and intraobserver reliability for each measurement was calculated as well as correlation between the 2 measurement types and the degree to which each measurement accurately represented the Rockwood classification., Results: Although both CC and AC-DC measurements showed very high inter- and intraobserver reliability, the CC distance systematically underestimated the degree of AC joint displacement when compared with the AC-DC measurement as the severity of injury increased, particularly in the presence of posterior horizontal displacement such as that seen in Rockwood IV injuries., Conclusion: The AC-DC measurement and use of the Alexander view provides the clinician with a more realistic appreciation of true AC joint displacement, especially in defining watershed cases (ie, IIIA/IIB/IV) and may better inform the decision-making process regarding management options and recommendations., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

Introduction: The purpose of this proof-of-concept study was to investigate the biomechanical performance of two surgical techniques, namely (1) the double Tight-Rope fixation with an additional acromioclavicular FiberTape fixation (DTRC) and (2) the fixation of the clavicle to the acromion and coracoid in a bipodal manner (Bipod) using a Poly-Tape and FiberTape. Both techniques intend to address vertical and horizontal instability after acromioclavicular dislocation. They were compared with the commonly used (3) double Tight-Rope (DTR) technique, which only stabilizes the clavicle to the coracoid., Materials and Methods: The acromioclavicular joint (ACJ) of 18 composite Sawbone shoulder specimens (6 per reconstruction group) were tested for posterosuperior elongation (70N cyclical load, 1500 cycles), load-to-failure and stiffness., Results: After 1500 cycles, the DTRC, Bipod and DTR group showed an elongation of 0.45 mm (SD 0.14 mm), 1.19 mm (SD 0.54 mm), and 0.46 mm (SD 0.15 mm), respectively. Although the elongation of the Bipod group was increased when compared to the other two groups (Bipod versus DTRC p = 0.008; Bipod versus DTR p = 0.006), the difference was less than 0.7 mm. The DTRC showed a higher load-to-failure of 656.1N (SD 58.1 N) compared to the Bipod [531.1 N (SD 108.2N) (p = 0.039)] and DTR group [522.8 N (SD 32.8 N) (p = 0.033)]., Conclusion: The DTRC and the DTR group resulted in similar low elongation, while the elongation in the Bipod technique was slightly higher. Even though this difference of 0.7 mm shows statistical significance, it most likely has no clinical relevance. When testing in posterosuperior direction, which is the clinically relevant load vector, an additional fixation of the clavicle to the acromion did not reduce elongation in this study. It is, furthermore, questionable if the benefit of an increased load-to-failure in combination with no improvement in elongation and stiffness as seen in the DTRC group outweighs the possible risks and increased costs coming with the DTRC refixation.

The use of reverse total shoulder arthroplasty (RSA) is becoming increasingly popular, but many biomechanical aspects are poorly understood. Particularly, the role and function of the subscapularis following RSA are unclear. Several clinical and biomechanical studies have analyzed its role in range of motion and stability. There is some evidence that the subscapularis is beneficial for stability but may reduce range of motion. This review provides an overview of the current literature, which suggests that the subscapularis may have a more important role in RSA than originally thought., 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) 2019.)

Rotator cuff supraspinatus tendon injuries are clinically challenging due to the high rates of failure after surgical repair. One key limitation to functional healing is the failure to regenerate the enthesis transition between tendon and bone, which heals by disorganized scar formation. Using two models of supraspinatus tendon injury in mouse (partial tear and full detachment/repair), the purpose of the study was to determine functional gait outcomes and identify the origin of the cells that mediate healing. Consistent with previous reports, enthesis injuries did not regenerate; partial tear resulted in a localized scar defect adjacent to intact enthesis, while full detachment with repair resulted in full disruption of enthesis alignment and massive scar formation between tendon and enthesis fibrocartilage. Although gait after partial tear injury was largely normal, gait was permanently impaired after full detachment/repair. Genetic lineage tracing of intrinsic tendon and cartilage/fibrocartilage cells (Scx CreERT2 and Sox9 CreERT2 , respectively), myofibroblasts (αSMA CreERT2 ), and Wnt-responsive stem cells (Axin2 CreERT2 ) failed to identify scar-forming cells in partial tear injury. Unmineralized enthesis fibrocartilage was strongly labeled by Sox9 CreERT2 while Axin2 CrERT2 labeled a subset of tendon cells away from the skeletal insertion site. In contrast to the partial tear model, Axin2 CreERT2 labeling showed considerable contribution of Axin2 lin cells to the scar after full detachment/repair. Clinical Significance: Clinically relevant models of rotator cuff tendon injuries in mouse enable the use of genetic tools; lineage tracing suggests that distinct mechanisms of healing are activated with full detachment/repair injuries versus partial tear. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3275-3284, 2018., (© 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Various procedures exist for patients with irreparable posterosuperior rotator cuff tears (IRCT). At present, no single surgical option has demonstrated clinical superiority.There is no panacea for treatment and patients must be aware, in cases of palliative or non-prosthetic options, of an alarming rate of structural failure (around 50%) in the short term.The current review does not support the initial use of complex and expensive techniques in the management of posterosuperior IRCT.Further prospective and comparative studies with large cohort populations and long-term follow-up are necessary to establish effectiveness of expensive or complicated procedures such as superior capsular reconstruction (SCR), subacromial spacers or biological augmentation as reliable and useful alternative treatments for IRCT. Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.180002., Competing Interests: ICMJE Conflict of interest statement: A. Lädermann declares consultancy for Arthrex, Medacta, DePuy Mitek, Wright; payment for manuscript preparation for Wright; travel/meeting expenses from Wright, activities outside the submitted work. G. Athwal declares consultancy for Wright, Exactech; royalties from Wright, Exactech; stocks/stock options from Wright, activities outside the submitted work. M. Scheibel declares consultancy for Arthrex, Storz, DJO, Medacta, Wright; royalties from Arthrex, Storz, activities outside the submitted work. M. Zumstein declares consultancy for Medacta; grants from Medacta, royalties from Medacta, activities outside the submitted work.

Background: Anatomic findings on MRI scans of the shoulder likely affect patients differently based on their physical demands and fitness levels. The natural history of these anatomic findings once professional overhead athletes retire remains unclear. A better understanding of what happens with these findings after retirement may influence how we manage shoulder problems in athletes., Purpose: (1) What is the natural history of MRI-observed findings in the throwing and nonthrowing shoulders of professional European handball players after retirement from the sport? What proportion of these individuals have diagnosable findings on MRI, and do these findings disappear after retirement? (2) Do clinical findings such as Constant and Murley score and shoulder ROM change after retirement in these professional overhead athletes?, Methods: The inception cohort of this series consisted of the entire Swiss National European handball team except the goalkeepers. These 30 professional players also played in the highest Swiss handball league in 2001. None of these players previously had shoulder surgery. During their career, they had a clinical assessment and bilateral shoulder MRI as part of an earlier study. We sought to evaluate the players who had retired and did not have a history of shoulder surgery, to evaluate the natural history of MRI-observed findings made in the initial study during their professional career. Of the 30 players, 10 were excluded (four continued to play professionally, four declined participation, and two had surgery after the initial study), leaving 20 (66%) for analysis at a mean of 6 years (SD, 3 years) after retirement. To gain a better understanding of the evolution of these MRI findings in the longer-term, we also evaluated 18 additional former professional European handball players who did not have any history of shoulder surgery, had all played in the highest Swiss league and for the National Team, and had terminated their career at a mean of 15 years (SD, 3 years) ago. All the subjects in both study groups (those at 6 and 15 years after retirement) underwent a detailed interview, standardized clinical examination including ROM measurements, collection of the Constant and Murley scores and the subjective shoulder value of both shoulders, and bilateral shoulder MRI. MRI findings (consisting of abnormalities and normal variations) were reported as radiographic diagnoses, independent of the potential that these findings could be considered normal variations in people in this age group., Results: At the initial MRI evaluation, the proportion of active professional European handballers with diagnosable MRI findings in the throwing shoulder was 19 of 20 (95%) and for the handballers with nonthrowing shoulders was 17 of 20 (85%), while 15 years after retirement, both shoulders of all subjects showed MRI findings. None of the rotator cuff tears progressed to full-thickness tears after retirement. In the throwing shoulders, we observed fewer individuals with ganglion cysts larger than 5 mm (initial followup: six of 20 [30%] versus 6 years after retirement: 0 of 20 (0%); odds ratio, 14.5; [95% CI, 0.7-283]; p = 0.044). The Constant and Murley score increased in the throwing shoulder from 93 points (SD, 6 points) at initial followup to 98 points (SD, 3 points) at a mean of 6 years after retirement (mean difference, 5 points; SD, 5 points; 95% CI, 2.5-7.4; p < 0.001), and to 97 points (SD, 3 points) at a mean of 15 years after retirement. However these differences are below the typically reported minimum clinically important difference for the Constant and Murley score, and so are unlikely to be clinically relevant. External rotation in 90° abduction remained increased in the throwing shoulder compared with the nonthrowing shoulder up to 15 years after retirement (initial followup: mean difference, 8°; p = 0.014; 15 years after retirement: mean difference, 4°; SD, 15; p = 0.026). Internal rotation remained decreased in the throwing compared with the nonthrowing shoulders (during the career: mean difference, 5° [SD, 10°], p = 0.036; 15 years after retirement: mean difference, 3° [SD, 4°], p = 0.021)., Conclusions: Our data suggest that findings of the throwing shoulder like partial rotator cuff tears, bony cysts and ganglions do not progress after retirement, and sometimes they resolve. Because of this and because many MRI changes correlate poorly with clinical symptoms, the indication for surgical treatment of these findings should be questioned very carefully., Level of Evidence: Level II, prognostic study.

With 12% of all injuries concerning the shoulder, acromioclavicular (AC) joint dislocations are a common injury especially in young and active patients. The Rockwood classification is widely accepted, which differentiates between six types depending on the degree of injury and the vertical dislocation. Because the classification does not adequately address the horizontal instability, its benefits are questionable and there is currently no consensus. For this reason, the classification and the therapy of these injuries are increasingly becoming the subject of scientific investigations. Whereas conservative treatment for type I and II injuries and operative treatment for type IV-VI injuries are widely accepted, there is still no agreement in treating type III lesions. The goal of this review article is to present the current evidence for the diagnostics, different classifications and therapeutic possibilities.

Purpose: The aim of this study was to identify the most accurate and reliable quantitative radiographic parameters for assessing vertical and horizontal instability in different Rockwood grades of acromioclavicular joint (ACJ) separations. Furthermore, the effect of projectional variation on these parameters was investigated in obtaining lateral Alexander view radiographs., Methods: A Sawbone model of a scapula with clavicle was mounted on a holding device, and acromioclavicular dislocations as per the Rockwood classification system were simulated with the addition of horizontal posterior displacement. Projectional variations for each injury type were performed by tilting/rotating the Sawbone construct in the coronal, sagittal or axial plane. Radiographic imaging in the form of an anterior-posterior Zanca view and a lateral Alexander view were taken for each injury type and each projectional variation. Five newly defined radiographic parameters for assessing horizontal and vertical displacement as well as commonly used coracoclavicular distance view were measured. Reliability, validity and the effect of projectional variation were investigated for these radiographic measurements., Results: All radiographic parameters showed excellent intra- and interobserver reliability. The validity was excellent for the acromial centre line to dorsal clavicle (AC-DC) in vertical displacement and for the glenoid centre line to posterior clavicle (GC-PC) in horizontal displacement, whilst the remaining measurements showed moderate validity. For AC-DC and GC-PC, convergent validity expressed strong correlation to the effective distance and discriminant validity demonstrated its ability to differentiate between various grades of ACJ dislocations. The effect of projectional variation increased with the degree of deviation and was maximal (3 mm) for AC-DC in 20° anteverted malpositioning and for GC-PC in 20° retroverted malpositioning., Conclusions: AC-DC and the GC-PC are two novel quantitative radiographic parameters of vertical and horizontal instability in ACJ dislocations that demonstrate excellent reliability and validity with reasonable inertness to malpositioning. The use of AC-DC for assessing vertical displacement and GC-PC for assessing horizontal displacement in a single Alexander view is recommended to guide the appropriate management of ACJ dislocations. A better appreciation of the degree of horizontal instability, especially in lower Rockwood grades (II, III) of ACJ dislocations, may improve management of these controversial injuries.

Background: This anatomic study investigated the distal humeral articular surface exposure achievable through a triceps-sparing oblique extra-articular osteotomy of the olecranon with a step-cut modification compared with the anconeus flap transolecranon apex distal chevron osteotomy. In addition, the bone contact surface areas of the osteotomized surfaces after transolecranon and extra-articular osteotomies were compared., Methods: Seven pairs of fresh adult cadaveric elbow joints were examined. Each of the right elbows underwent triceps-sparing extra-articular step-cut olecranon osteotomy (SCOOT) with an anconeus flap, and the left elbows underwent the anconeus flap transolecranon apex distal chevron osteotomies (CO). The articular surface exposed by each of the osteotomy techniques was then digitally analyzed using a 3-dimensional measurement system. The bone contact surface area of the osteotomized surfaces was also assessed., Results: The percentage of total joint exposed by the SCOOT group was less than the CO group (SCOOT: 64% ± 3% vs. CO: 73% ± 3%; P = .002). There was significantly greater bone contact surface area of the osteotomized surfaces in the SCOOT group compared with the CO group (SCOOT: 1172 ± 251 mm 2 vs. CO: 457 ± 133 mm 2 ; P = .002)., Conclusion: The triceps SCOOT procedure with an anconeus flap provides excellent distal humeral articular surface exposure with the added benefit of a substantially increased (2.6-times) bone contact surface area of the osteotomized surfaces., (Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Disturbed muscular architecture, atrophy, and fatty infiltration remain irreversible in chronic rotator cuff tears even after repair. Poly (adenosine 5'-diphosphate-ribose) polymerase 1 (PARP-1) is a key regulator of inflammation, apoptosis, muscle atrophy, muscle regeneration, and adipocyte development. We hypothesized that the absence of PARP-1 would lead to a reduction in damage to the muscle subsequent to combined tenotomy and neurectomy in a PARP-1 knockout (KO) mouse model., Methods: PARP-1 KO and wild-type C57BL/6 (WT group) mice were analyzed at 1, 6, and 12 weeks (total n = 84). In all mice, the supraspinatus and infraspinatus muscles of the left shoulder were detached and denervated. Macroscopic analysis, magnetic resonance imaging, gene expression analysis, immunohistochemistry, and histology were used to assess the differences in PARP-1 KO and WT mice., Results: The muscles in the PARP-1 KO group had significantly less retraction, atrophy, and fatty infiltration after 12 weeks than in the WT group. Gene expression of inflammatory, apoptotic, adipogenic, and muscular atrophy genes was significantly decreased in PARP-1 KO mice in the first 6 weeks., Discussion: Absence of PARP-1 leads to a reduction in muscular architectural damage, early inflammation, apoptosis, atrophy, and fatty infiltration after combined tenotomy and neurectomy of the rotator cuff muscle. Although the macroscopic reaction to injury is similar in the first 6 weeks, the ability of the muscles to regenerate was much greater in the PARP-1 KO group, leading to a near-normalization of the muscle after 12 weeks., (Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)