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Purpose: Radiographic measurements have gained wide acceptance in anticipating the risk of inappropriate glenoid component positioning in reverse shoulder arthroplasty (RSA). This study aims to investigate whether the RSA angle overcorrects the base plate inclination, tilting it inferiorly, compared to the base plate correction angle (BCA), which provides neutral inclination and lateralization. Methods: One hundred normal anteroposterior shoulder radiographs were evaluated to determine the average values of the RSA angle, BCA, base plate orientation angle (BOA), and the base plate shoulder angle (BSA), which represents the amount of overcorrection accomplished via the RSA angle beyond the BCA's scope. The interobserver reliability among two independent testers was assessed by the intraclass correlation coefficient. A t-test was applied to compare the mean values of the BCA and RSA angle. Results: The mean BOA and BCA values were 118° ± 5.7° and 17° ± 4.6°, respectively. The RSA angle value was 23° ± 6°. Compared to the BCA, the RSA angle overcorrected the base plate inclination by 15° ± 5° (BSA). The Student's t-test showed a statistically significant difference between the values of the BCA and RSA angle (p-value = 0.000). The interobserver reliability was excellent for all angle measurements among two independent testers. Conclusion: The RSA angle and the BOA/BCA are reliable radiographic measurements to determine the inclination of the inferior glenoid segment prior to RSA. However, surgeons need to consider the inherent inferior inclination associated with positioning the base plate according to the RSA angle (15° ± 5°). [ABSTRACT FROM AUTHOR]

Aims: Optimal glenoid positioning in reverse shoulder arthroplasty (RSA) is crucial to provide impingement-free range of motion (ROM). Lateralization and inclination correction are not yet systematically used. Using planning software, we simulated the most used glenoid implant positions. The primary goal was to determine the configuration that delivers the best theoretical impingement-free ROM. Methods: With the use of a 3D planning software (Blueprint) for RSA, 41 shoulders in 41 consecutive patients (17 males and 24 females; means age 73 years (SD 7)) undergoing RSA were planned. For the same anteroposterior positioning and retroversion of the glenoid implant, four different glenoid baseplate configurations were used on each shoulder to compare ROM: 1) no correction of the RSA angle and no lateralization (C-L-); 2) correction of the RSA angle with medialization by inferior reaming (C+M+); 3) correction of the RSA angle without lateralization by superior compensation (C+L-); and 4) correction of the RSA angle and additional lateralization (C+L+). The same humeral inlay implant and positioning were used on the humeral side for the four different glenoid configurations with a 3 mm symmetric 135° inclined polyethylene liner. Results: The configuration with lateralization and correction of the RSA angle (C+L+) led to better ROM in flexion, extension, adduction, and external rotation (p ≤ 0.001). Only internal rotation was not significantly different between groups (p = 0.388). The configuration where correction of the inclination was done by medialization (C+M+) led to the worst ROM in adduction, extension, abduction, flexion, and external rotation of the shoulder. Conclusion: Our software study shows that, when using a 135° inlay reversed humeral implant, correcting glenoid inclination (RSA angle 0°) and lateralizing the glenoid component by using an angled bony or metallic augment of 8 to 10 mm provides optimal impingement-free ROM. Cite this article: Bone Jt Open 2024;5(10):851–857.

Radiographic evaluation of the implant configuration after reverse shoulder arthroplasty (RSA) is time-consuming and subject to interobserver disagreement. The final configuration is a combination of implant features and surgical execution. Artificial intelligence (AI) algorithms have been shown to perform accurate and efficient analysis of images. The purpose of this study was to develop an AI algorithm to automatically measure glenosphere inclination, humeral component inclination, and the lateralization and distalization shoulder angles (DSAs) on postoperative anteroposterior radiographs after RSA. The Digital Imaging and Communications in Medicine files corresponding to postoperative anteroposterior radiographs obtained after implantation of 143 RSAs were retrieved and used in this study. Four angles were analyzed: (1) glenoid inclination angle (GIA, between the central fixation feature of the glenoid and the floor of the supraspinatus fossa), (2) humeral alignment angle (HAA, between the long axis of the humeral shaft and a perpendicular to the metallic bearing of the prosthesis), (3) DSA, and (4) lateralization shoulder angle (LSA). A UNet segmentation model was trained to segment bony and implant elements using manually segmented training (n = 89) and validation (n = 22) images. Then, an image-processing–based pipeline was developed to measure all 4 angles using AI-segmented images. Measures performed by 3 physician observers and the AI algorithm were then completed in 32 additional images. The agreements among human observers and between observers and the AI algorithm were evaluated using intraclass correlation coefficients (ICCs) and absolute differences in degree. The ICCs (95% confidence interval) for manual measurements of LSA, DSA, GIA, and HAA were 0.79 (0.55, 0.90), 0.90 (0.80, 0.95), 0.96 (0.93, 0.98), and 0.99 (0.97, 0.99), respectively. The AI algorithm measured the 32 images in the test set in less than 2 minutes. The agreement between observers and the AI algorithm was lowest when measuring the LSA for observer 2, with an ICC of 0.77 (0.52, 0.89), and an absolute difference in degrees (median [interquartile range]) of 5 (4). Better agreements were found between the AI measurements and the average manual measurements: absolute differences in degree for LSA, DSA, GIA, and HAA were 3 (5), 2 (3), 2 (2), and 2 (1), respectively; ICCs for LSA, DSA, GIA, and HAA were 0.89 (0.79, 0.95), 0.96 (0.93, 0.98), 0.85 (0.68, 0.93), and 0.98 (0.95, 0.99), respectively. The AI algorithm developed in this study can automatically measure the GIA, HAA, LSA, and DSA on postoperative anteroposterior radiographs obtained after implantation on RSA. [ABSTRACT FROM AUTHOR]

Glenoid placement is critical for successful outcomes in total shoulder arthroplasty (TSA). Preoperative templating with three-dimensional imaging has improved implant positioning, but deviations from the planned inclination and version still occur. Mixed-Reality (MR) is a novel technology that allows surgeons intra-operative access to three-dimensional imaging and templates, capable of overlaying the surgical field to help guide component positioning. The purpose of this study was to compare the execution of preoperative templates using MR vs.standard instruments (SIs). Retrospective review of 97 total shoulder arthroplasties (18 anatomic, 79 reverse) from a single high-volume shoulder surgeon between January 2021 and February 2023, including only primary diagnoses of osteoarthritis, rotator cuff arthropathy, or a massive irreparable rotator cuff tear. To be included, patients needed a templated preoperative plan and then a postoperative computed tomography scan. Allocation to MR vs. SI was based on availability of the MR headset, industry technical personnel, and the templated preoperative plan loaded into the software, but preoperative or intraoperative patient factors did not contribute to the allocation decision. Postoperative inclination and version were measured by two independent, blinded physicians and compared to the preoperative template. From these measurements, we calculated the mean difference, standard deviation (SD), and variance to compare MR and SI. Comparing 25 MR to 72 SI cases, MR significantly improved both inclination (P <.001) and version (P <.001). Specifically, MR improved the mean difference from preoperative templates (by 1.9° inclination, 2.4° version), narrowed the SD (by 1.7° inclination, 1.8° version), and decreased the variance (11.7-3.0 inclination, 14.9-4.3 version). A scatterplot of the data demonstrates a concentration of MR cases within 5° of plan relative to SI cases typically within 10° of plan. There was no difference in operative time. MR improved the accuracy and precision of glenoid positioning. Although it is unlikely that 2° makes a detectable clinical difference, our results demonstrate the potential ability for technology like MR to narrow the bell curve and decrease the outliers in glenoid placement. This will be particularly relevant as MR and other similar technologies continue to evolve into more effective methods in guiding surgical execution. [ABSTRACT FROM AUTHOR]

The most common joint to dislocate is the glenohumeral joint, resulting in chronic pain and limited function. The role of the capsuloligamentous structures and muscle balance in contributing to shoulder stability has been well documented in the literature but the case is not the same for the bony anatomy of the glenoid. There is limited data on the contribution of glenoid osteometry in increasing the risk of anterior shoulder dislocation. This study sought to find out the association between anterior glenohumeral instability and glenoid anteversion/inclination. A retrospective, case-control study was carried out. The study was carried out at the Departments of Radiology and Imaging at two university hospitals. Shoulder Magnetic Resonance Imaging (MRI) scans for 45 patients aged between 18 to 45 years with recurrent anterior shoulder instability were used in the study and compared with a control consisting of shoulder MRIs of 45 patients with other shoulder pathologies but having no incidences of dislocation. A structured data collection tool was used to collect the data. Data was analyzed using Statistical Package for the Social Sciences (SPSS) version 26. The mean age for all the participants was 32.0 (SD 9.0) years. The mean age for the cases was 29.0 (SD 8.7) years, while for the controls was 34.6 (SD 8.5) years. The glenoid was anteverted in 40% and 35.6% of cases and controls respectively (p = 1.00) and retroverted in 60% and 64.4% of cases and controls respectively (p =0.666). Most of the glenoids were superiorly inclined (91.1% and 93.3% for cases and controls respectively. The differences in the glenoid version and inclination between the cases and controls were not statistically significant (p = 0.288 and p = 0.489 for the glenoid version and inclination respectively. Glenoid version and inclination are not significantly increased in patients with anterior shoulder instability compared to unmatched controls. [ABSTRACT FROM AUTHOR]

Background: Superior inclination of the base plate in reverse shoulder arthroplasty (RSA) is underestimated and may lead to major setbacks in terms of functional outcomes due to the altered biomechanics. Joint instability, scapular notching, and loosening of the glenoid component are considered the most serious sequelae. Therefore, a thorough preoperative radiological assessment of the affected shoulder joint and customized design of the prosthesis according to the glenoid morphology are decisive and directly correlated to the outcome. In this article, we propose a simple radiographic technique to assess the inclination of the glenoid preoperatively, which identifies the need for intraoperative correction. Materials and Methods: One hundred inconspicuous shoulder radiographs were included in the control group (CG) to define the normal ranges of the base plate orientation angle (BOA) and the base plate correction angle (BCA). Further, both angles were measured on 2-dimensional (2D) computed tomography scans of patients with proximal humerus fractures as well as radiographs, 2D and 3-dimensional (3D) computed tomography scans of patients with cuff tear arthropathy who underwent RSA between 2018 and 2021. The interobserver reliability among three independent testers was evaluated by calculating the intraclass correlation coefficient. In cuff tear arthropathy cases, the BOA and BCA measurements on different imaging modalities were compared using the Wilcoxon test. Possible variations of both angles' values based on glenoid erosion types, according to the Favard classification, were also investigated. Results: Regardless of the imaging modality used, the interobserver reliability was excellent among three independent observers. In the CG, the mean BOA and BCA values were 118° ± 6° and 17° ± 5°, respectively. The mean corrected BOA values of the CG and fracture group were 136° ± 5° and 140° ± 5°, respectively. In contrast to the BCA values, the BOA measurements on radiographs showed a statistically significant difference compared to those obtained on 2D- and 3D scans in the cuff arthropathy group. Further, both angles’ values varied according to the extent and location of the glenoid erosion. The lowest mean BOA and highest mean BCA values were observed in cases with Favard glenoid type E3. Conclusions: The BOA and the BCA are reliable tools proposed to aid in precisely positioning the glenoid component in RSA in the preoperative setting. Whereas, the BOA determines the inclination of the inferior glenoid segment, the BCA represents the extent of correction required to obtain a neutral inclination of the base plate. Glenoid type E3 of the Favard classification with superior wear is particularly susceptible to base plate superior tilt.

Background: Two surgical techniques were compared : Standard BIO-RSA, performed with a glenoid eccentric reaming along with a cylindric bone graft augmentation vs. the Angled BIO-RSA, performed with a glenoid concentric reaming and a defect correction with an angled bone graft. Methods: Patients undergoing RSA from January 2016 to April 2019, with one of the two techniques being performed, were retrospectively reviewed. Glenoids were classified according to Favard. Clinical (Constant-Murley, VAS and ROM) and radiographic (superior tilt correction) data were collected pre-operatively and at 12 months post-operatively. Results: 141 shoulders were included. Angled BIO-RSA group showed statistically significant better outcomes in terms of forward flexion (149.9° Vs 139.3°) and abduction (136.4° Vs 126.7°). The use of an Angled BIO-RSA showed a statistically significant better superior tilt correction (1.252° Vs 4.09°). Angled BIO-RSA, leads to a better inclination correction and a mean postoperative tilt value inferior to 5° in E1 and E3 differently from standard BIO-RSA. Discussion: Both techniques were able to correct glenoid superior inclination with excellent postoperative short-term results. However, angled BIO-RSA technique appears to be more effective in ensuring a correct inclination of the prosthetic glenoid component with better clinical outcomes. [ABSTRACT FROM AUTHOR]

Background: Posterior humeral head (HH) subluxation after anatomic total shoulder arthroplasty (aTSA) is associated with worse outcomes, but it is unclear how corrective glenoid reaming correlates with HH alignment and whether HH alignment changes over time. Therefore, it was aimed to analyze the relationship between HH alignment and the scapula following aTSA to identify anatomic and surgical factors that contribute to realignment of the HH, glenoid loosening, and clinical outcomes. Methods: Three-dimensional scapulohumeral alignment was assessed on three-dimensionally reconstructed computed tomography scans of 23 patients: preoperative (T0), 2 years post-aTSA (T1), and ≥5 years post-aTSA (T2). Anterior-posterior (AP), superior-inferior (SI), and medial-lateral offset measures of the HH center to the scapula were referenced to the HH diameter (scapulohumeral subluxation index). Glenoid version and inclination were measured at T0 and T1. Central peg osteolysis, rotator cuff fatty infiltration, and vault perforation were assessed on two-dimensional computed tomography. Relative Constant Score at T2 measured clinical outcome. Results: Glenoid correction correlated strongly with AP and SI position of the HH (r = 0.733 and r = 0.797, respectively). Each degree of retroversion correction resulted in 0.9% AP scapulohumeral subluxation index offset change toward anterior. Each degree of inclination correction to superior resulted in a 1.0% offset change toward superior. A gradual postoperative proximal (mean difference [MD], −3%; P = .019), anterior (MD, 2%; P = .025), and medial (MD, 3 mm; P

Computational musculoskeletal modeling represents a valuable approach to examining biological systems in physical anthropology. Probabilistic modeling builds on computational musculoskeletal models by associating mathematical distributions of specific musculoskeletal features within known ranges of biological variability with functional outcomes. The purpose of this study was to determine if overlap in rotator cuff muscle force predictions would occur between species during the performance of an evolutionarily relevant horizontal bimanual arm suspension task. This necessitated creating novel probabilistic models of the human and chimpanzee glenohumeral joint through augmentation of previously published deterministic models. Glenohumeral musculoskeletal features of anthropological interest were probabilistically modeled to produce distributions of predicted human and chimpanzee rotator cuff muscle force that were representative of the specific anatomical manipulations. Musculoskeletal features modeled probabilistically included rotator cuff origins and deltoid insertion, glenoid inclination, and joint stability. Predicted human rotator cuff muscle force distributions were mostly limited to alternating between infraspinatus and teres minor, with both 100% and 0% muscle force predicted for both muscles. The chimpanzee model predicted low‐to‐moderate muscle force across all rotator cuff muscles. Rotator cuff muscle force predictions were most sensitive to changes of muscle origins and insertions. Results indicate that functional rotator cuff overlap is unlikely between chimpanzees and humans without greater modifications of the glenohumeral musculoskeletal phenotypes. The results also highlight the low efficacy of the human upper extremity in overhead, weight‐bearing tasks, and propensity for rotator cuff injury. [ABSTRACT FROM AUTHOR]

Background: Glenoid defects can be addressed traditionally by asymmetric reaming or by bone-preserving correction to a more lateral joint line by bone or metal augmented baseplates in reverse shoulder arthroplasties. While there is more evidence in literature regarding the outcome and complications of Bony Increased Offset Reversed Shoulder Arthroplasty (BIO-RSA), there is minimal reported experience with the outcome after metal glenoid augments. The aim of this study was to determine whether a metal augment can correct the glenoid deformity in an anatomic manner. Methods: Glenoid morphology and deformity were determined in 50 patients with Walch type B1, B2, D and Favard type E0–E3 glenoid defects using preoperative radiographic and computed tomography (CT) analysis. All patients received a preoperative planning CT with 3D planning, and measurements of glenoid inclination (in 3 planes proximal, middle, distal), reversed shoulder arthroplasty angle (RSA) and glenoid version were obtained. All patients had a pathologic inclination in the coronal or frontal planes of > 10°. Above the threshold of 10° pathological glenoid version or inclination metal hemi-augments of 10°, 20°, or 30° were used which allow an individual 360° augment positioning according to the patient glenoid deformity. Results: The mean preoperative numbers of the glenoid version demonstrate that most glenoids were in retroversion and superior inclination. In total 2410° wedges, 1820° wedges and 8 30° wedges were used. In the majority of cases, the wedge was positioned posteriorly and/or cranially between 10:00 and 12:00 o'clock, which allows a correction in a 3D manner of the glenoid inclination and version. The mean RSA angle could be corrected from 22.76 ± 6.06 to 0.19° ± 2.7 (p < 0.0001). The highest retroversion of the glenoid is evidenced in the proximal section and it could be corrected from − 23.32° ± 4.56 to − 6.74° ± 7.75 (p < 0.0001) and in the middle section from − 18.93° ± 3.35 to − 7.66° ± 5.28 (p < 0.0001). A mean sphere bone overhang distance (SBOD) of 5.70 ± 2.04 mm was found in order to avoid or minimize relevant scapular notching. Conclusion: By using a new 360° metal-augmented baseplate, the preoperative pathological inclination and retroversion can be corrected without medialization of the joint line. Future clinical results will show whether this bone-preserving procedure improves also the clinical outcomes as compared to asymmetric medialized reaming or wedged BIO-RSA. Level of evidence: Level IV, Case series. [ABSTRACT FROM AUTHOR]

Introduction: Excessive version and inclination of the glenoid component during total shoulder arthroplasty can lead to glenohumeral instability, early loosening, and even failure. The orientation and position of the central pin determine the version and inclination of the glenoid component. The purpose of this study was to compare the differences in centerline position and orientation obtained using "3D preoperative planning based on the best-fit method for glenoid elements" and the surgeon's manipulation. Materials and methods: Twenty-nine CT images of glenohumeral osteoarthritis of the shoulder were reconstructed into a 3D model, and a 3D printer was used to create an in vitro model for the surgeon to drill the center pin. The 3D shoulder model was also used for 3D preoperative planning (3DPP) using the best-fit method for glenoid elements. The in vitro model was scanned and the version, inclination and center position were measured to compare with the 3DPP results. Results: The respective mean inclinations (versions) of the surgeon and 3DPP were −2.63° ± 6.60 (2.87° ± 5.97) and −1.96° ± 4.24 (−3.21° ± 4.00), respectively. There was no significant difference in the inclination and version of the surgeon and 3DPP. For surgeons, the probability of the inclination and version being greater than 10° was 13.8% (4/29) and 10.3% (3/29), respectively. Compared to the 3DPP results, the surgeon's center position was shifted down an average of 1.63 mm. There was a significant difference in the center position of the surgeon and 3DPP (p < 0.05). Conclusion: The central pin drilled by surgeons using general instruments was significantly lower than those defined using 3D preoperative planning and standard central definitions. 3D preoperative planning prevents the version and inclination of the centerline from exceeding safe values (± 10°). [ABSTRACT FROM AUTHOR]

Abstract Background The purpose of this study was to define the features of scapular morphology that are associated with changes in the critical shoulder angle (CSA) by developing the best predictive model for the CSA based on multiple potential explanatory variables, using a completely 3D assessment. Methods 3D meshes were created from CT DICOMs using InVesalius (Vers 3.1.1, RTI [Renato Archer Information Technology Centre], Brazil) and Meshmixer (3.4.35, Autodesk Inc., San Rafael, CA). The analysis included 17 potential angular, weighted linear and area measurements. The correlation of the explanatory variables with the CSA was investigated with the Pearson’s correlation coefficient. Using multivariable linear regression, the approach for predictive model-building was leave-one-out cross-validation and best subset selection. Results Fifty-three meshes were analysed. Glenoid inclination (GI) and coronal plane angulation of the acromion (CPAA) [Pearson’s r: 0.535; -0.502] correlated best with CSA. The best model (adjusted R-squared value 0.67) for CSA prediction contained 10 explanatory variables including glenoid, scapular spine and acromial factors. CPAA and GI were the most important based on their distribution, estimate of coefficients and loss in predictive power if removed. Conclusions The relationship between scapular morphology and CSA is more complex than the concept of it being dictated solely by GI and acromial horizontal offset and includes glenoid, scapular spine and acromial factors of which CPAA and GI are most important. A further investigation in a closely defined cohort with rotator cuff tears is required before drawing any clinical conclusions about the role of surgical modification of scapular morphology. Level of evidence Level 4 retrospective observational cohort study with no comparison group.

The positioning of the glTenoid component in RSA ( Reverse Shoulder Arthroplasty) is one of the factors determining implant survival and postoperative outcomes. Therefore, accurate determination of the glenoid version and inclination in RSA is essential for the surgeon - preoperatively to plan his work and postoperatively - to assess the outcome. Excessive retroversion and superior inclination are prerequisites for unsatisfactory results and are associated with a high frequency of revisions. The glenoid inclination is often described as the angle between the glenoid fossa line and the suprascapular reference line. The study included a 2-year follow-up of patients with reverse shoulder arthroplasty in the Department of Orthopedics. The analysis is based on pre / postoperative CT and three-dimensional reconstruction using Medi Cad software. A comparative analysis was made with the results obtained by X-ray examination. The results showed a high incidence of superior inclination of native glenoid fossae. The obtained ß-inclination angle averaged 13.8 °, and the difference in this radiographically measured parameter was 7.3 °. CT analysis preoperatively significantly improves the position of the glenoid component and avoids the superior inclination of the baseplate of the prosthesis.

Abstract Objective Anatomical parameters and pathologies that can affect the critical shoulder angle (CSA) are subjects of discussion. To date, we do not know if the CSA value changes in the different decades of life in a population characterized by the same ethnicity, nor if there are differences related to gender or side. This study hypothesizes that age and gender may affect the CSA. Methods Patients older than 15 years old affected by a shoulder trauma and who were discharged with a diagnosis of shoulder contusion were enrolled. A true AP view of the shoulder was obtained as well as data regarding age and gender of all participants. The CSA was measured by three authors, and interoperator reliability was assessed. Eight subcategories, according to decades of life, were considered. Finally, the studied population was divided into three subcategories according to CSA values ( 0.05). Linear regression analysis showed a CSA increase by 0.04° every year. The mean CSA in subjects aged between 15 and 19 years was significantly lower than all the other groups, except for patients older than 80 years. No significant differences were found between CSA subcategories, gender, or side. Conclusions In the general population, the mean CSA value was 33.6°. No significant differences were found regarding the mean CSA value according to gender or side. A significant positive linear correlation between CSA and age was detected. In each decade of life, the CSA value, which is genetically determined, shows a large variability. Level of evidence: IV.

Optimal implant placement in reverse total shoulder arthroplasty (rTSA) remains controversial. Specifically, the optimal glenoid inclination is unknown. Therefore, a cadaveric shoulder simulator with 3-dimentional human motion specific to rTSA was used to study joint contact and muscle forces as a function of glenoid component inclination. Eight human cadaver shoulders were tested before and after rTSA implantation. Scapular plane abduction kinematics from control subjects and those with rTSA drove a cadaveric shoulder simulator with 3-dimentional scapulothoracic and glenohumeral motion. Glenoid inclination varied from −20° to +20°. Outputs included compression, superior-inferior (S/I) shear, and anterior-posterior shear forces from a 6° of freedom load cell in the joint, and deltoid and rotator cuff muscle forces. Data were evaluated with statistical parametric mapping and t -tests. Inferior glenoid inclination (−) reduced S/I shear by up to 125% relative to superior inclination, with similar compression to the neutral condition (0°). Superior inclinations (+) increased the S/I shear force by approximately the same magnitude, yet decreased compression by 25% in the most superior inclination (+20°). There were few differences in deltoid or rotator cuff forces due to inclination. Only the middle deltoid decreased by approximately 7% for the most inferior inclination (−20°). Compared with native shoulders, the neutral (0°) rTSA inclination showed reduced forces of 30%-75% in the anterior deltoid and a trend toward decreased forces in the middle deltoid. Force demands on the rotator cuff varied as a function of elevation, with a trend toward increased forces in rTSA at peak glenohumeral elevation. Inferior inclination reduces superior shear forces, without influencing compression. Superior inclination increased S/I shear, while decreasing compression, which may be a source of component loosening and joint instability after rTSA. Inferior inclination of the rTSA glenoid may reduce the likelihood of glenoid loosening by reducing the magnitude of cyclic shear and compressive loading during arm elevation activities, although this may be altered by specific-subject body habitus and motion. These factors are especially important in revision rTSA or glenoid bone grafting where there is already a 3-fold increase in glenoid baseplate loosening vs. primary rTSA. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to define the features of scapular morphology that are associated with changes in the critical shoulder angle (CSA) by developing the best predictive model for the CSA based on multiple potential explanatory variables, using a completely 3D assessment. Methods: 3D meshes were created from CT DICOMs using InVesalius (Vers 3.1.1, RTI [Renato Archer Information Technology Centre], Brazil) and Meshmixer (3.4.35, Autodesk Inc., San Rafael, CA). The analysis included 17 potential angular, weighted linear and area measurements. The correlation of the explanatory variables with the CSA was investigated with the Pearson's correlation coefficient. Using multivariable linear regression, the approach for predictive model-building was leave-one-out cross-validation and best subset selection. Results: Fifty-three meshes were analysed. Glenoid inclination (GI) and coronal plane angulation of the acromion (CPAA) [Pearson's r: 0.535; -0.502] correlated best with CSA. The best model (adjusted R-squared value 0.67) for CSA prediction contained 10 explanatory variables including glenoid, scapular spine and acromial factors. CPAA and GI were the most important based on their distribution, estimate of coefficients and loss in predictive power if removed. Conclusions: The relationship between scapular morphology and CSA is more complex than the concept of it being dictated solely by GI and acromial horizontal offset and includes glenoid, scapular spine and acromial factors of which CPAA and GI are most important. A further investigation in a closely defined cohort with rotator cuff tears is required before drawing any clinical conclusions about the role of surgical modification of scapular morphology. Level of evidence: Level 4 retrospective observational cohort study with no comparison group. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the variation in measured glenoid inclination measurements between each of the most used methods for measuring the scapular transverse axis with computed tomography (CT) scans, and to investigate the underlying causes that explain the differences. Methods: The glenoid center, trigonum and supraspinatus fossa were identified manually by four expert shoulder surgeons on 82 scapulae CT-scans. The transverse axis was generated either from the identified landmarks (Glenoid-Trigonum line (GT-line), Best-Fit Line Fossa (BFLF)) or by an automatic software (Y-axis). An assessment of the interobserver reliability was performed. We compared the measured glenoid inclination when modifying the transverse axis to assess its impact. Results: Glenoid inclination remained stable between 6.3 and 8.5°. The variations occurred significantly when changing the method that determined the transverse axis with a mean biase from −1.7 (BFLF vs. Y-axis) to 0.6 (BFLF vs. GT-line). The Y-axis method showed higher stability to the inclination variation (p = 0.030). 9% of cases presented more than 5° of discrepancies between the methods. The manual methods presented a lower ICC (BFLF = 0.96, GT-line = 0.87) with the widest dispersion. Conclusion: Methods that determine the scapular transverse axis could have a critical impact on the measurement of the glenoid inclination. Despite an overall good concordance, around 10% of cases may provide high discrepancies (≥5°) between the methods with a possible impact on surgeon clinical choice. Trigonum should be used with caution as its anatomy is highly variable and more than two single points provide a better interrater concordance. The Y-axis is the most stable referential for the glenoid inclination. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to determine the relationships between glenoid inclination (GI), acromial index (AI), critical shoulder angle (CSA), superior inclination (SI), and symptomatic degenerative full-thickness supraspinatus tears (SSTs). Materials and Methods: Patients who were diagnosed with SSTs (n=39) between 2015 and 2017 were assessed retrospectively. Controls were matched to age, gender, and side. Measured GI, AI, CSA, and SI values were compared between the SSTs and control groups (n=39). The mean age for the SSTs group was 52.74±5.49 years, and the mean age for the control group was 51.15±5.22 years. Results: The mean GI for the SSTs group was 19.97°±5.62°, and it was 13.72°±6.55° for the control group (p<0.001). The mean AI was 0.7±0.08 and 0.67±0.07 in the SSTs and control groups, respectively (p=0.035). The mean CSA for the SSTs group was 35.05°±4.09° and it was 33.06°±3.42° for the control group (p=0.022). The mean SI was 25.13°±5.71° and 25.91°±5.81° in the SSTs and control groups, respectively (p=0.552). For a cut-off value of GI ≥17.35°, sensitivity was 79.54%, and specificity was 79.51% (p=0.001). For a cut-off value of AI ≥0.67, sensitivity was 61.54% and specificity was 56.4% (p=0.031). For a cut-off value of CSA ≥33.45°, sensitivity was 64.12%, and specificity was 64.54% (p=0.014). Conclusion: Higher measurement values of glenoid inclination, acromial index, and critical shoulder angle were associated with symptomatic degenerative full-thickness supraspinatus tears, and no correlation was found with superior inclination measurement. The glenoid inclination measurement had the highest sensitivity and specificity in predicting symptomatic degenerative full-thickness supraspinatus tears. [ABSTRACT FROM AUTHOR]

Although typically favorable in outcome, anatomic total shoulder arthroplasty (aTSA) can require long-term revision. The most common cause for revision is glenoid loosening, which may result from eccentric cyclic forces and joint translations. "Rocking" of the glenoid component may be exacerbated by the joint geometry, such as glenoid inclination and version. Restoration of premorbid glenoid inclination may be preferable, although laboratory and computational models indicate that both superior inclination and inferior inclination have benefits. This discrepancy may arise because previous studies were limited by a lack of physiological conditions to test inclination. Therefore, a cadaveric shoulder simulator with 3-dimensional human motion was used to study joint contact and muscle forces with isolated changes in glenoid inclination. Eight human cadaveric shoulders were tested before and after aTSA. Scapular-plane abduction kinematics from human subjects were used to drive a cadaveric shoulder simulator with 3-dimensional scapulothoracic and glenohumeral motion. Glenoid inclination was varied from −10° to +20°, whereas compressive, superior-inferior shear, and anterior-posterior shear forces were collected with a 6- df load cell during motion. Outputs also included muscle forces of the deltoid and rotator cuff. Data were evaluated with statistical parametric mapping repeated-measures analysis of variance and t tests. Inferior glenoid inclination (−10°) reduced both compressive and superior-inferior shear forces vs. neutral 0° inclination by up to 40%, and even more when compared with superior inclination (P <.001). Superior inclinations (+10° and +20°) tended to increase deltoid and rotator cuff forces vs. neutral 0° inclination or inferior inclination, on the order of 20%-40% (P ≤.045). All force metrics except anterior-posterior shear were lowest for inferior inclination. Most aTSA muscle forces for neutral 0° inclination were not significantly different from native shoulders and decreased 45% and 15% in the posterior deltoid and supraspinatus, respectively (P ≤.003). Joint translations were similar to prior reports in aTSA patients and did not differ between any inclinations or compared with native shoulders. Joint reaction forces were similar to those observed in human subjects with instrumented aTSA implants, providing confidence in the relative magnitude of our results. Inferior inclination reduces overall forces in the shoulder. Superior inclinations increase the muscle effort required for the shoulder to achieve similar motion, thus increasing the forces exerted on the glenoid component. These results suggest that a preference toward aTSA glenoid components in inferior inclination may reduce the likelihood of glenoid loosening by reducing excessive muscle and joint contact forces. [ABSTRACT FROM AUTHOR]

The critical shoulder angle (CSA) is a surrogate marker of the coronal plane morphology of the scapula. CSA differences between scapulae could be due to differences in glenoid inclination (GI) or the location of the most lateral part of the acromion relative to the inferior glenoid, or both. An understanding of the hierarchy of the scapular morphological changes associated with glenohumeral osteoarthritis (GHOA) and rotator cuff (RC) tears would allow accurate biomechanical modeling. A prospective observational case control study was undertaken in which the GI, "nonglenoid"-CSA, acromial vertical offset index, acromial horizontal offset index, acromial horizontal-vertical offset index, and coronal plane angulation of the acromion (CPAA-m) were measured on high-quality radiographs to compare coronal plane scapular anatomy in: (1) patients with asymptomatic atraumatic full-thickness RC tears, (2) patients with symptomatic primary GHOA, and (3) a control group with no RC tear or GHOA treated for glenohumeral instability or symptomatic labral pathology. Intraobserver reliability of the measurements was performed. In the GHOA group, the GI was lower (less superiorly inclined) than the RC tear group (difference between the means: −4.8°, 95% confidence interval [CI] [−8.8°, −0.9°], P =.014) and the control group (difference between the means: −7.9°, 95% CI [−11.8°, −3.9°], P =.000); there was no difference in the acromial measurements. In the RC tear group, the nonglenoid-CSA was higher (difference between the means: 7.7°, 95% CI [3.0°, 12.3°], P =.001), the acromial vertical offset index was lower (difference between the means: −0.13, 95% CI [−0.24, −0.01], P =.026), and the acromial horizontal-vertical offset index was higher (difference between the means: 0.15, 95% CI [0.01, 0.28], P =.030) than the control group; there was no difference in the acromial horizontal offset index or the GI. The CPAA-m was lower (greater coronal plane downslope of the acromion) in both GHOA (difference between the means: −9.6°, 95% CI [−18.6°, −0.5°], P =.036) and RC tears (difference between the means: −9.9°, 95% CI [−19.0°, −0.9°], P =.029) compared with the control group. The intraclass correlation coefficients for intraobserver reliability demonstrated excellent reliability for the measurements (all >0.900). Scapulae associated with GHOA have lower GI, but no spatial differences in the location of the lateral acromion compared with a normal population. Scapulae associated with RC tears have a lower vertical offset of the lateral acromion, but no difference in horizontal offset or GI compared with a normal population. The downslope of the acromion in the coronal plane is greater (lower CPAA-m) in both RC tears and GHOA than the normal population. [ABSTRACT FROM AUTHOR]

Background This study was performed to compare glenoid version and inclination measured using two-dimensional (2D) images from computed tomography (CT) scans or three-dimensional (3D) reconstructed bone models. Methods Thirty patients who had undergone conventional CT scans were included. Two orthopedic surgeons measured glenoid version and inclination three times on 2D images from CT scans (2D measurement), and two other orthopedic surgeons performed the same measurements using 3D reconstructed bone models (3D measurement). The 3D-reconstructed bone models were acquired and measured with Mimics and 3-Matics (Materialise). Results Mean glenoid version and inclination in 2D measurements were –1.705º and 9.08º, respectively, while those in 3D measurements were 2.635º and 7.23º. The intra-observer reliability in 2D measurements was 0.605 and 0.698, respectively, while that in 3D measurements was 0.883 and 0.892. The inter-observer reliability in 2D measurements was 0.456 and 0.374, respectively, while that in 3D measurements was 0.853 and 0.845. Conclusions The difference between 2D and 3D measurements is not due to differences in image data but to the use of different tools. However, more consistent results were obtained in 3D measurement. Therefore, 3D measurement can be a good alternative for measuring glenoid version and inclination.

Background: Avoiding inclination of the glenoid baseplate in reverse shoulder arthroplasty often requires considerable glenoid reaming. It is proposed that the use of a metal wedged baseplate in all patients can achieve neutral inclination with reduced glenoid reaming., Materials and Methods: A prospective clinical single-centre study with minimum two-year follow-up was carried out. Glenoid deformity was classified on CT and surgery planned using BluePrint TM . The Tornier Perform ® Reversed Wedged Augmented Glenoid was used in all cases. Clinical outcome scores and radiographs were assessed., Results: Seventy-three patients, mean age 76.6 years. Twenty-eight demonstrated no glenoid deformity and 19 demonstrated marked retroversion. Seventy completed two-year follow-up. Mean pain scores fell from 6 to 0.7. All Patient Reported Outcome Meaures (PROMS) were significantly improved. Active elevation increased by 62° and external rotation by 28.7° ( p  < 0.001). In patients with no glenoid wear (E0/A1), correction of inferior inclination was achievable with a 15° full-wedge baseplate in all cases, reducing the reaming depth by 4.4 mm ( p  < 0.001). In patients with severe glenoid wear, a 35° half wedge baseplate was often necessary to correct the deformity. The most common complications were stress reactions/fractures., Conclusion: A metal wedged baseplate can achieve neutral inclination in all patients, minimising bone reaming and preserving lateralisation with good two-year outcomes., Level of Evidence: IV (case series with no comparison group)., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: SB has a paid consultancy agreement with Stryker and Mathys Inc. HC has a paid consultancy agreement for Mathys Inc., (© The Author(s) 2024.)

We sought to assess the reliability of 4 different shoulder arthroplasty 3-dimensional preoperative planning programs. Comparison was also made to manual measurements conducted by 2 fellowship-trained musculoskeletal radiologists. We hypothesized that there would be significant variation in measurements of glenoid anatomy affected by glenoid deformity. A retrospective review of computed tomography (CT) scans of patients undergoing shoulder arthroplasty was undertaken. A total of 76 computed tomographies were analyzed for glenoid version and inclination by 4 templating software systems (VIP, Blueprint, TrueSight, ExactechGPS). Inter-rater reliability was assessed via intra-class correlation coefficient (ICC). For those shoulders with glenohumeral arthritis (58/76), ICC was also calculated when sub-grouping by modified Walch classification. Lin's concordance correlation coefficient was calculated for each system with 2 musculoskeletal-trained radiologists' measurements. Measurements of glenoid version and inclination differed between at least 2 programs by 5º-10º in 75% and 92% of glenoids respectively, and by >10º in 18% and 45% respectively. ICC was excellent for version but only moderate for inclination. ICC was highest among Walch A glenoids for both version (near excellent) and inclination (good), and lowest among Walch D for version (near poor) and Walch B for inclination (moderate). When measuring version, VIP had the highest concordance with manual measurement; Blueprint had the lowest. For inclination Blueprint had the highest concordance; ExactechGPS had the lowest. Despite overall high reliability for measures of glenoid version between 4 frequently utilized shoulder arthroplasty templating softwares, this reliability is significantly affected by glenoid deformity. The programs were overall less reliable when measuring inclination, and a similar trend of decreasing reliability with increasing glenoid deformity emerged that was not statistically significant. Concordance with manual measurement is also variable. Further research is needed to understand how this variability should be accounted for during shoulder arthroplasty preoperative planning. Level III; Retrospective Comparative Study [ABSTRACT FROM AUTHOR]

Objective: Anatomical parameters and pathologies that can affect the critical shoulder angle (CSA) are subjects of discussion. To date, we do not know if the CSA value changes in the different decades of life in a population characterized by the same ethnicity, nor if there are differences related to gender or side. This study hypothesizes that age and gender may affect the CSA.Methods: Patients older than 15 years old affected by a shoulder trauma and who were discharged with a diagnosis of shoulder contusion were enrolled. A true AP view of the shoulder was obtained as well as data regarding age and gender of all participants. The CSA was measured by three authors, and interoperator reliability was assessed. Eight subcategories, according to decades of life, were considered. Finally, the studied population was divided into three subcategories according to CSA values (< 30°; 30-35°; ≥ 35°).Results: The initial sample comprised 3587 shoulder X-rays. The interobserver reproducibility was high, with an intraclass correlation coefficient of 0.865 (95% CI 0.793-0.915). Two thousand eight hundred seventy-three radiograms were excluded. The studied group comprised 714 patients [431 females, 283 males; mean age (SD): 47.2 (20.9) years, range: 11-93 years]. The mean CSA was 33.6° (range: 24-50°; SD: 3.9°). The mean CSA values in females and males were 33.7°and 33.5°, respectively. The mean CSA values of the right and left shoulders were 33.3° and 33.9°, respectively (p > 0.05). Linear regression analysis showed a CSA increase by 0.04° every year. The mean CSA in subjects aged between 15 and 19 years was significantly lower than all the other groups, except for patients older than 80 years. No significant differences were found between CSA subcategories, gender, or side.Conclusions: In the general population, the mean CSA value was 33.6°. No significant differences were found regarding the mean CSA value according to gender or side. A significant positive linear correlation between CSA and age was detected. In each decade of life, the CSA value, which is genetically determined, shows a large variability.Level Of Evidence: IV. [ABSTRACT FROM AUTHOR]

Abstract Background There are no published studies of the influence of geometry of the scapula on the postoperative recovery of rotator cuff injuries. Our aim was to explore the relationship between the critical shoulder angle (CSA), acromion index (AI), glenoid inclination (GI), and postoperative repair outcomes in shoulder joints after arthroscopic supraspinatus tendon repair. Methods Sixty two patients suffering a supraspinatus tear were analyzed retrospectively following failure of conservative treatment and subsequent shoulder arthroscopy in our hospital. Standard anterior and posterior X-rays of the injured shoulder had been performed prior to surgery, with follow ups for at least 2 years (24–43 months). Magnetic resonance imaging (MRI) was performed 2 years after surgery to assess repair of the supraspinatus tendon. Patients were divided into either the intact or re-tear group, according to the MRI results. In addition, assessments using the Constant Shoulder Score (CSS), the American Shoulder and Elbow Surgeon (ASES) Shoulder Assessment Form, the University of California at Los Angeles (UCLA) score and visual analog scale (VAS) score were performed to establish shoulder function at the 2-year evaluation for each patient. Results The mean CSA of all patients was 35.79° ± 3.59°, mean AI was 0.72 ± 0.05, and mean GI was 15.87° ± 3.62°. The CSA, AI, and GI in the intact group were statistically significantly different than the re-tear group (p 0.05). Conclusions The geometry of the scapula had no significant effect on the recovery of postoperative function of patients with rotator cuff injury, but the value of the CSA, AI, and GI affected the risk of rotator cuff re-tear.

While retroversion of the glenoid in anatomic total shoulder arthroplasty (TSA) has been increasingly studied, the effect of glenoid inclination on clinical outcomes has received less attention. The goal of this study was to examine the influence of pre- and postoperative inclination on clinical outcomes after anatomic TSA. Patients undergoing primary anatomic TSA with minimum 2-year outcomes were included from a multicenter prospectively maintained database of shoulder arthroplasties from 2015 to 2017. Preoperative and postoperative radiographs were independently evaluated to assess native glenoid inclination and postoperative prosthetic glenoid inclination using the previously described TSA angle. A receiver-operator characteristic (ROC) curve analysis was performed to determine if a significant threshold existed for preoperative inclination, postoperative inclination, or amount of inclination correction. A linear regression analysis assessing the correlation between each of these measurements and the postoperative Constant score was performed. For final analysis, means and standard deviations of the Constant scores for patients above and below the calculated inclination thresholds for each group were compared using SPSS. Seventy-two anatomic TSAs with minimum 2-year follow-up were included. ROC analysis determined a significant threshold of 10 degrees of postoperative inclination for prediction of the 2 year postoperative Constant score (AUC = 0.682), P =.010. This finding was additionally supported in the linear regression analysis, where postoperative inclination was significantly associated with the postoperative Constant score (P =.046). Patients below the postoperative inclination threshold of 10 degrees had significantly improved Constant scores compared to those above the threshold (mean 65.3, P =.005; Table 2). Two degrees of inclination correction was predictive of the 2 year postoperative Constant score (AUC = 0.754; P <.001; sensitivity 68%, specificity 74%). Inclination correction was significantly associated with postoperative Constant score (P = 0.003). Patients above the inclination correction threshold of 2 degrees had significantly improved Constant scores (mean 75.4) compared to those below the threshold (mean 65.9, P =.003). When appropriately corrected, preoperative inclination over 10 degrees does not appear to significantly influence postoperative outcome of anatomic TSA. There is a significant association between postoperative inclination and 2 year Constant scores. Inclination correction is particularly associated with postoperative Constant score. These results encourage the need for future studies with detailed analysis as to how to best predict and correct inclination to produce favorable and durable outcomes after anatomic TSA. Level III; Retrospective Comparative Study [ABSTRACT FROM AUTHOR]

The relationship of numerous implant design and positioning-related variables with range of motion and clinical outcomes have been investigated for reverse shoulder arthroplasty (RSA). While glenosphere inclination has been investigated with regards to implant fixation and scapular notching, little research has been done on the association between glenosphere inclination and clinical outcomes. Therefore, the primary objective of this study was to investigate the relationship between preoperative glenoid inclination, postoperative glenosphere inclination and inclination change (∆INC) from pre- to postoperative on clinical outcomes after RSA. A multicenter retrospective study was conducted of RSAs with minimum 2-year clinical follow-up. All included patients had the same RSA prosthesis. Preoperative, postoperative, and ∆INC from pre-to postoperatively were measured for each patient. The primary study outcome was the minimum 2-year ASES score. Secondary outcomes were active range of motion, Constant-Murley score and Western Ontario Ostearthritis Shoulder (WOOS) score at a minimum of 2 years postoperatively. Receiver-operator characteristic curve analyses were performed to determine if any significant thresholds in inclination existed. Univariate analyses were performed with ANOVA to compare subgroup means. Finally, a multivariate logistic regression was performed to examine each inclination variable as a predictor of clinical outcome while controlling for patient and implant-related variables. Eighty seven patients were included in the study. The mean age was 70 years and 53% of patients were male. The examiners had excellent reliability determined by intraclass correlation coefficients for all 3 measurements. There was no apparent correlation between preoperative inclination, postoperative inclination or ∆INC with minimum 2-year ASES scores. This was confirmed in the receiver-operator characteristic analyses, where no significant thresholds were found for each of the 3 assessed measurements (P >.05 for all analyses). A subgroup analysis comparing patients with low preoperative inclination (<10°) and patients with high preoperative inclination (>10°) stratified by the ∆INC demonstrated no significant association with inclination (P >.05 for all comparisons). In the multivariate regression analysis, inclination had no significant association with the minimum 2-year ASES scores. For the studied implant system, preoperative inclination, postoperative inclination and ∆INC did not have a significant association with postoperative clinical outcomes after RSA. Level III; Retrospective Comparison Study [ABSTRACT FROM AUTHOR]

Background: Shoulder unlike any other joint has a wide range of mobility and is important in day to day activities. Different ethnic groups vary in skeletal anatomy and anthropometry. Most of our knowledge on the shoulder—anatomy, surgical technique and prosthesis designs is based on western literature. There are few studies on the Indian population. Our aim is to study the anthropometry of glenoid based on 3D CT scan of the shoulder. Our objectives are to calculate glenoid height, width, version, inclination, analyse the data for differences between male and female, compare data with similar studies in India and other countries and study the impact on shoulder arthroplasty implant size. Materials and methods: 100 CT scans (male/female—50/50) of the Indian population are studied from our database. Glenoid measurements are calculated and analyzed. Results: The mean value of glenoid height is 32.9 ± 3.2 mm (27.6–41.7 mm), width 23.4 ± 2.62 mm (19.1–30.9 mm), version 0.07 ± 5.38° (− 11° to + 10.85°) and inclination 6.68 ± 5.49° (− 9.91° to + 20.75°). In our study glenoid is retroverted, superiorly inclined and height is more than width. The height and width are less than French and Americans but slightly more than the Japanese population. Conclusion: There are significant differences in Indian glenoid measurements compared to other countries. Even the smallest size of shoulder arthroplasty glenoid component currently available in India is larger than the mean glenoid size of our study. As shoulder replacement surgeries are rising in India, we may have to bring changes in the implant design and surgical technique to suit our population. [ABSTRACT FROM AUTHOR]

Despite advances in implant design and surgical technique, instability remains the most common early complication and reason for early revision after reverse shoulder arthroplasty (RSA). The purpose of this study is to evaluate the glenoid implant inclination, as measured by the β-angle, as an independent risk factor for instability after primary RSA. A retrospective case-control study was conducted matching cases with instability after primary RSA using a single implant to controls without instability. Controls were matched to age, sex, body mass index, and baseplate type (1:3 ratio of cases to controls). The preoperative, postoperative, and the change in pre- to postoperative glenoid inclination (β-angle) were compared between groups. Thirty-four cases (mean age, 66.2 years) were matched to 102 controls (mean age, 67.0 years). There was a wide range of postoperative (63° to 100°) and pre- to postoperative change (−16.5° to +30.5°) in β-angles collectively. There was no significant difference in the postoperative β-angle (mean, 80.8° vs. 82.7°, P =.19) or the change in β-angle (mean, +1.7° vs. +3.4°, P =.35) between cases and controls, respectively. Regression analysis demonstrated no increased odds of instability with the postoperative β-angle, odds ratio 0.965 (confidence interval [CI] = 0.916-1.02, P =.19). Likewise, for the preoperative to postoperative change in β-angle, there was no significantly increased odds of instability, odds ratio 0.978 (CI = 0.934-1.03, P =.35). Finally, there was no difference in risk of instability in patients whose implant positioning resulted in a net superior increase in inclination, relative risk 0.85 (95% CI = 0.46-1.56, P =.28). Neither the final prosthetic glenoid inclination nor the change in glenoid inclination, as measured by the β-angle, significantly influences the risk of prosthetic instability after primary RSA. [ABSTRACT FROM AUTHOR]

Background: Two techniques exist from which all 3D preoperative planning software for total shoulder arthroplasty are based. One technique is based on measurements constructed on the mid-glenoid and scapular landmarks (Landmark). The second is an automated system using a best-fit sphere technique (Automated). The purpose was to compare glenoid measurements from the two techniques against a control computed tomography-derived 3D printed scapula. Methods: Computed tomography scans of osteoarthritic shoulders of 20 patients undergoing primary total shoulder arthroplasty were analyzed with both 3D planning software techniques. Measurements from a 3D printed scapula (Scapula) from the true 3D computed tomography scan served as controls. Glenoid version and inclination measurements from each group were blinded and reviewed. Results: In 65% (Automated) and 45% (Landmark) of cases, either inclination or version varied by 5° or more versus 3D printed scapula. Significant variability in version differences compared to the scapula group existed (p = 0.007). Glenoid version from the Scapula = 13.0° ± 10.6°, Automated = 15.0° ± 13.9°, and Landmark = 12.2° ± 7.8°. Inclination from Scapula = 5.4° ± 7.9°, Automated = 6.1° ± 12.6°, and Landmark = 6.2° ± 9.1°. Discussion: A high percentage of cases showed discrepancies in glenoid inclination and version values from both techniques. Surgeons should be aware that regardless of software technique, there is variability compared to measurements from a control 3D computed tomography printed scapula. [ABSTRACT FROM AUTHOR]

Although the effect of 3-dimensional (3D) planning for total shoulder arthroplasty (TSA) on component positioning and patient outcomes has been increasingly studied, the effect of 3D planning on surgeon decision making has not been well studied. A retrospective review was performed of a database containing TSA cases for which the glenoid component was planned with a commercially available 3D computed tomography software program (Virtual Implant Positioning; Arthrex, Inc.) from 2016 to 2019. A total of 6483 cases planned by 417 surgeons were included. The glenoid version (V tech) and inclination (I tech) of the Virtual Implant Positioning technician plan as well as the surgeon's final plan for version (V surg) and inclination (I surg) were extracted. When the version and/or inclination of the surgeon plan matched that of the technician, that variable was defined as "accepted." The rates of acceptance of V tech and I tech were calculated and analyzed for association with implant type, native version and inclination, and running case count. A subgroup analysis of high-volume users (n > 30 cases) was analyzed to determine if any of the variables independently was associated with surgeon acceptance. There was a very high rate of matching of version (66%), inclination (72%), or both (55%) and a low rate (18%) where neither parameter of the glenoid plan matched that of the technician. In univariate analysis, as the case count and retroversion increased the rate of accepting of version dropped noticeably (70%-50% and 47%, respectively [ P <.0001]). The rate of accepting the plan for inclination did not vary much as case count changed. In the multivariate analysis, 23 of 56 high-volume surgeons had at least 1 independent factor associated with accepting the technician-planned glenoid version, and 5 surgeons had 2 independent factors. In the multivariate analysis of matching glenoid inclination, 27 of 56 high-volume surgeons had at least 1 independent factor associated with accepting the technician-planned glenoid version, and 9 surgeons had 2 or more independent factors. In a large database of TSAs with 3D-planned glenoids, there were high rates of cases with surgeon agreement with an initial plan provided by an industry technician: 66% in version, 72% in inclination, 55% for both version and inclination. Surgeon acceptance of the initial plan decreased as pathoanatomy increased and case count increased. Shoulder surgeons should be aware that an initial 3D preoperative plan provided by industry represents a potential source of cognitive bias in shoulder arthroplasty planning. [ABSTRACT FROM AUTHOR]

Preoperative planning software is widely available for most anatomic total shoulder arthroplasty (ATSA) systems. It can be most useful in determining implant selection and placement with advanced glenoid wear. The purpose of this study was to quantify inter- and intrasurgeon variability in preoperative planning of a series of ATSA cases. Forty-nine computed tomography scans were planned for ATSA by 9 fellowship-trained shoulder surgeons using the ExactechGPS platform (Exactech Inc., Gainesville, FL, USA). Each case was planned a second time between 4 and 12 weeks later. Variability within and between surgeons was measured for implant type, size, version and inclination correction, and implant face position. Interclass correlation coefficients, Pearson, and Light's kappa coefficients were used for statistical analysis. There was considerable variation in the frequency of augment use between surgeons and between rounds for the same surgeon. Thresholds for augment use also varied between surgeons. Interclass correlation coefficients for intersurgeon variability were 0.37 for version, 0.80 for inclination, 0.36 for implant type, and 0.36 for implant size. Pearson coefficients for intrasurgeon variability were 0.17 for version and 0.53 for inclination. Light's kappa coefficient for implant type was 0.64. This study demonstrates substantial inter- and intrasurgeon variability in preoperative planning of ATSA. Although the magnitude of differences in correction was small, surgeons differed significantly in the use of augments to achieve the resultant plan. Surgeons differed from each other on thresholds for augment use and maximum allowable residual retroversion. This suggests that there may a range of acceptable corrections for each shoulder rather than a single optimal plan. [ABSTRACT FROM AUTHOR]

Preoperative planning software is gaining utility in reverse total shoulder arthroplasty (RTSA), particularly when addressing pathologic glenoid wear. The purpose of this study was to quantify inter- and intrasurgeon variability in preoperative planning a series of RTSA cases to identify differences in how surgeons consider optimal implant placement. This may help identify opportunities to establish consensus when correlating plan differences with clinical data. A total of 49 computed tomography scans from actual RTSA cases were planned for RTSA by 9 fellowship-trained shoulder surgeons using the same platform (Exactech GPS, Exactech Inc., Gainesville, FL, USA). Each case was planned a second time 6-12 weeks later. Variability within and between surgeons was measured for implant selection, version correction, inclination correction, and implant face position. Interclass correlation coefficients, and Pearson and Light's kappa coefficient were used for statistical analysis. There was considerable variation in the frequency of augmented baseplate selection between surgeons and between rounds for the same surgeon. Thresholds for augment use also varied between surgeons. Interclass correlation coefficients for intersurgeon variability ranged from 0.43 for version, 0.42 for inclination, and 0.25 for baseplate type. Pearson coefficients for intrasurgeon variability were 0.34 for version and 0.30 for inclination. Light's kappa coefficient for baseplate type was 0.61. This study demonstrates substantial variability both between surgeons and between rounds for individual surgeons when planning RTSA. Although average differences between plans were relatively small, there were large differences in specific cases suggesting little consensus on optimal planning parameters and opportunities to establish guidelines based on glenoid pathoanatomy. The correlation of preoperative planning with clinical outcomes will help to establish such guidelines. [ABSTRACT FROM AUTHOR]

Glenoid lateralization has been shown to be the most imortant factor in maximizing passive range of motion and shoulder stability while preventing scapular impingement and notching. We aimed to evaluate mid- to long-term functional and radiologic outcomes after bony increased-offset–reverse shoulder arthroplasty (BIO-RSA) using a Grammont-style (medialized) humeral implant. The study included 143 consecutive shoulders (140 patients; mean age, 72 years) treated with a BIO-RSA for rotator cuff deficiency. A cylinder of autologous cancellous bone graft, harvested from the humeral head, was placed between the reamed glenoid surface and baseplate; fixation was achieved using a long central peg (25 mm) and 4 screws. A large baseplate (29 mm) with a small baseplate sphere (36 mm) was used in 77% of cases, and a Grammont-style (medialized) humeral implant with 155° of inclination was used in all cases. All patients underwent clinical and radiographic assessment at a minimum of 5 years after surgery; in addition, 86 cases (60%) underwent computed tomography scan assessment. At a mean follow-up of 75 months (range, 60-126 months), the survivorship of the BIO-RSA using revision as an endpoint was 96%. No cases of dislocation or humeral loosening were observed. Overall, 118 patients (83%) were either very satisfied (61%) or satisfied (22%). The adjusted Constant score improved from 40% ± 18% to 93% ± 23%, and the Subjective Shoulder Value improved from 31% ± 15% to 77% ± 18% (P <.001). The humeral bone graft incorporated completely in 96% of cases (137 of 143). Severe inferior scapular notching (grade 3 or 4) occurred in 18% (24 of 136). The risk of postoperative notching correlated to a lower body mass index (P <.05), superior glenosphere inclination (P =.02), and high or flush glenosphere positioning (P =.035). BIO-RSA is a safe and effective technique to lateralize the glenoid, providing consistent bone graft healing, excellent functional outcomes, a low revision rate, and a high rate of patient satisfaction. Thin patients (with a low body mass index) and glenosphere malposition (with persistent superior inclination and/or insufficient lowering of the baseplate and sphere) are associated with higher risk of scapular notching.Our data confirm the importance of implanting the baseplate with a neutral inclination (reverse shoulder arthroplasty angle < 5°) and with sufficient glenosphere inferior overhang (>5 mm) in preventing scapular notching. The use of a less medialized humeral implant (135° or 145° inclined) and smaller (25-mm) baseplate (when using a small, 36-mm sphere) should allow reduction in the incidence of scapular notching. [ABSTRACT FROM AUTHOR]

Background: Reverse shoulder arthroplasty continues to be utilized for the treatment of cuff tear arthropathy, glenohumeral degenerative joint disease, and irreparable rotator cuff tears. With advancement in component designs, glenoid retroversion and inclination are now correctable with augmented baseplates. However, quantifying bone loss and lateralization compared to standard baseplates has not been studied. The purpose of the current study is to determine the volume of bone reamed and net lateralization with a standardized baseplate vs. augmented baseplate when glenoid inclination was corrected to neutral., Methods: A series of 21 computed tomography scans of patients presenting for shoulder arthroplasty were chosen based on a range of increasing native positive inclination. Computed tomography scans were uploaded into segmentation software and processed. Four fellowship trained shoulder surgeons were then blinded from each other and virtually placed a neutral baseplate and an augmented baseplate for each specimen. Baseplate position was standardized. Additionally, baseplate backside seating of a minimum of 80% was also standardized and glenosphere (nonlateralized) size was selected to eliminate variation in baseplate contact and position. Glenoid inclination was corrected to a minimal of neutral in each specimen as well as glenoid retroversion corrected to <10 ° . Net lateralization from the center of the glenoid to the most lateral aspect of the baseplate was calculated in millimeters., Results: The mean glenoid retroversion was 8.1 ° and superior inclination was 10.6 ° for all specimens. Across all specimens and surgeons, use of a 10-degree augment resulted in similar baseplate backside seating area (219.2 mm 3 vs. 226.2 mm 3 , P  > .05). There was substantially lower volume of bone reamed in the augmented baseplate patients (619 mm 3 vs. 1102 mm 3 , P  < .001). Larger standard deviation seen in the augmented baseplate columns are attributed to differences in surgeon preference for percent backside seating, which was standardized at a minimum of 80%. Use of a 10-degree full wedge augment resulted in 2.4 mm additional glenoid lateralization than a neutral baseplate on average across all included scapulae., Conclusion: The current study demonstrates approximately 50% less bone removal and 2.4 mm of true lateralization with a 10-degree augmented baseplate when compared to standard baseplates., (© 2024 The Authors.)

Background: Preoperative planning software has been developed to measure glenoid version, glenoid inclination, and humeral head subluxation on computed tomography (CT) for shoulder arthroplasty. However, most studies analyzing the effect of glenoid positioning on outcome were done prior to the introduction of planning software. Thus, measurements obtained from the software can only be extrapolated to predict failure provided they are similar to classic measurements. The purpose of this study was to compare measurements obtained using classic manual measuring techniques and measurements generated from automated image analysis software. Methods: Ninety-five two-dimensional computed tomography scans of shoulders with primary glenohumeral osteoarthritis were measured for version according to Friedman method, inclination according to Maurer method, and subluxation according to Walch method. DICOM files were loaded into an image analysis software (Blueprint, Wright Medical) and the output was compared with values obtained manually using a paired sample t -test. Results: Average manual measurements included 13.8° version, 13.2° inclination, and 56.2% subluxation. Average image analysis software values included 17.4° version (3.5° difference, p < 0.0001), 9.2° inclination (3.9° difference, p < 0.001), and 74.2% for subluxation (18% difference, p < 0.0001). Conclusions: Glenoid version and inclination values from the software and manual measurement on two-dimensional computed tomography were relatively similar, within approximately 4°. However, subluxation measurements differed by approximately 20%. [ABSTRACT FROM AUTHOR]

Scapular anatomy, as measured by the acromial index (AI), critical shoulder angle (CSA), lateral acromial angle (LAA), and glenoid inclination (GI), has emerged as a possible contributor to the development of degenerative shoulder conditions such as rotator cuff tears and glenohumeral osteoarthritis. The purpose of this study was to investigate the published literature on influences of scapular morphology on the development of degenerative shoulder conditions. A systematic review of the Embase and PubMed databases was performed to identify published studies on the potential influence of scapular bony morphology on the development of degenerative rotator cuff tears and glenohumeral osteoarthritis. The studies were reviewed by 2 authors. The findings were summarized for various anatomic parameters. A meta-analysis was completed for parameters reported in more than 5 related publications. A total of 660 unique titles and 55 potentially relevant abstracts were reviewed with 30 published articles identified for inclusion. The AI, CSA, LAA, and GI were the most commonly reported bony measurements. Increased CSA and AI correlated with rotator cuff tears, whereas lower CSA appeared to be related to the presence of glenohumeral osteoarthritis. Decreased LAA correlated with degenerative rotator cuff tears. Five articles reported on the GI with mixed results on shoulder pathology. Degenerative rotator cuff tears appear to be significantly associated with the AI, CSA, and LAA. There does not appear to be a significant relationship between the included shoulder parameters and the development of osteoarthritis. [ABSTRACT FROM AUTHOR]

It remains unclear whether changes in scapular rotation influence the surgeon's ability to achieve resting radiographic neutral or inferior baseplate tilt at final follow-up. The purposes of this study were (1) to determine whether reverse total shoulder arthroplasty (RTSA) changes the resting scapular rotation, (2) to determine the association between glenoid inclination with respect to the scapula (β angle) and resting scapular rotation, and (3) to determine the β angle threshold that will most likely lead to resting radiographic neutral or inferior baseplate tilt relative to the thorax. This was a retrospective radiographic study. Patients with adequate-quality standing anteroposterior and Grashey radiographs obtained preoperatively and after primary RTSA at a minimum of 1 year were included. Glenoid inclination (β angle) was measured between the supraspinatus fossa and the glenoid. Resting scapular rotation was measured between the supraspinatus fossa and a vertical line. Baseplate tilt was then calculated as the angle between the glenoid and a vertical line. The study included 74 patients with a mean follow-up period of 3 years (range, 1-9 years). Scapular rotation changed 2° ± 12° (mean ± standard deviation) into upward rotation (P =.048). No association was found between the β angle and scapular rotation. In 71% of patients with a neutral or inferior baseplate tilt, a postoperative β angle greater than 85° was found. Resting radiographic scapular rotation changed 2° into upward rotation with RTSA and was not associated with the β angle. If the β angle is greater than 85°, resting radiographic baseplate tilt will most likely be inferior or neutral. [ABSTRACT FROM AUTHOR]

Avoiding superior inclination of the glenoid component in reverse shoulder arthroplasty (RSA) is crucial. We hypothesized that superior inclination was underestimated in RSA. Our purpose was to describe and assess a new measurement of inclination for the inferior portion of the glenoid (where the baseplate rests). The study included 47 shoulders with rotator cuff tear arthropathy (mean age, 76 years). The reverse shoulder arthroplasty angle (RSA angle), defined as the angle between the inferior part of the glenoid fossa and the perpendicular to the floor of the supraspinatus, was compared with the global glenoid inclination (β angle or total shoulder arthroplasty [TSA] angle). Measurements were made on plain anteroposterior radiographs and reformatted 2-dimensional (2D) computed tomography (CT) scans by 3 independent observers and compared with 3-dimensional (3D) software (Glenosys) measurements. The mean RSA angle was 25° ± 8° on plain radiographs, 20° ± 6° on reformatted 2D CT scans, and 21° ± 5° via 3D reconstruction software. The mean TSA angle was on average 10° ± 5° lower than the mean RSA angle (P <.001); this difference was observed regardless of the method of measurement (radiographs, 2D CT, or 3D CT) and type of glenoid erosion according to Favard. In Favard type E1 glenoids with central concentric erosion, the difference between the 2 angles was 12° ± 4° (P <.001). The same angle cannot be used to measure glenoid inclination in anatomic and reverse prostheses. The TSA (or β) angle underestimates the superior orientation of the reverse baseplate in RSA. The RSA angle (20° ± 5°) needs to be corrected to achieve neutral inclination of the baseplate (RSA angle = 0°). Surgeons should be aware that E1 glenoids (with central erosion) are at risk for baseplate superior tilt if the RSA angle is not corrected. [ABSTRACT FROM AUTHOR]

Background The objectives of this study were to determine whether glenoid inclination (1) could be measured accurately on magnetic resonance imaging (MRI) using computed tomography (CT) as a gold standard, (2) could be measured reliably on MRI, and (3) whether it differed between patients with rotator cuff tears and age-matched controls without evidence of rotator cuff tears or glenohumeral osteoarthritis. Methods In this comparative retrospective radiographic study, we measured glenoid inclination on T1 coronal MRI corrected into the plane of the scapula. We determined accuracy by comparison with CT and inter-rater reliability. We compared glenoid inclination between patients with full-thickness rotator cuff tears and patients aged >50 years without evidence of a rotator cuff tear or glenohumeral arthritis. An a priori power analysis determined adequate power to detect a 2° difference in glenoid inclination. Results (1) In a validation cohort of 37 patients with MRI and CT, the intraclass correlation coefficient was 0.877, with a mean difference of 0° (95% confidence interval, −1° to 1°). (2) For MRI inclination, the inter-rater intraclass correlation coefficient was 0.911. (3) Superior glenoid inclination was 2° higher (range, 1°-4°, P  < .001) in the rotator cuff tear group of 192 patients than in the control cohort of 107 patients. Conclusions Glenoid inclination can be accurately and reliably measured on MRI. Although superior glenoid inclination is statistically greater in those with rotator cuff tears than in patients of similar age without rotator cuff tears or glenohumeral arthritis, the difference is likely below clinical significance. [ABSTRACT FROM AUTHOR]

Background Glenoid deficiency and erosion (excessive retroversion/inclination) must be corrected in reverse shoulder arthroplasty (RSA) to avoid prosthetic notching or instability and to maximize function, range of motion, and prosthesis longevity. This study reports the results of RSA with an angled, autologous glenoid graft harvested from the humerus (angled BIO-RSA). Methods A trapezoidal bone graft, harvested from the humeral head and fixed with a long-post baseplate and screws, was used to compensate for residual glenoid bone loss/erosion. For simple to moderate (<25°) glenoid defects, standardized instrumentation combined with some eccentric reaming (<15°) was used to reconstruct the glenoid and obtain neutral implant alignment. For severe (>25°) and complex (multiplanar) glenoid bone defects, patient-specific grafts and guides were used after 3-dimensional planning. Patients were reviewed with minimum 2 years of follow-up. Mean follow-up was 36 months (range, 24-81 months). Preoperative and postoperative measurements of inclination and version were performed in the plane of the scapula on computed tomography images. Results The study included 54 patients (41 women, 13 men; mean 73 years old). Fifteen patients had combined vertical and horizontal glenoid bone deficiency. Among E2/E3 glenoids, inclination improved from 37° (range, 14° to 84°) to 10.2° (range −28° to 36°, P  < .001). Among B2/C glenoids, retroversion improved from −21° (range, −49° to 0°) to −10.6° (−32° to 4°, P  = .06). Complete radiographic incorporation of the graft occurred in 94% (51 of 54). Complications included infection in 1 and clinical aseptic baseplate loosening in 2. Mild notching occurred in 25% (13 of 51) of patients. Constant-Murley and Subjective Shoulder Value assessments increased from 31 to 68 and from 30% to 83%, respectively ( P  < .001). Conclusion Angled BIO-RSA predictably corrects glenoid deficiency, including severe (>25°) multiplanar deformity. Graft incorporation is predictable. Advantages of using an autograftharvested in situ include bone stock augmentation, lateralization, low donor-site morbidity, low relative cost, and flexibility needed to simultaneously correct posterior and superior glenoid defects. [ABSTRACT FROM AUTHOR]

Background Long-term results and complication rates in shoulder arthroplasty are related to implant positioning. Current literature reports increased precision in glenoid component positioning using 3-dimensional (3D) computed tomography (CT) planning tools. This study evaluated the accuracy of glenoid version and inclination measurements using 2D CT scans compared with a validated 3D software program and its influence on decision making on implant selection. Methods Preoperative CT scans were obtained from 50 patients undergoing total shoulder arthroplasty. Glenoid version and inclination measurements were performed in random order by 3 independent qualified orthopedic surgeons on reformatted 2D CT scans. Indication for anatomic or reverse shoulder arthroplasty was based on glenoid deformity and on rotator cuff conditions. Results were compared with those from a validated 3D computer software program, and the final decision was made according to the 3D planning. Results Mean preoperative glenoid retroversion on reformatted 2D CT scans was 11.9° ± 9.6° and mean superior inclination was 10.7° ± 8.6°. When the 3D software was used, glenoid retroversion averaged 15.1° ± 10.6° and superior inclination averaged 8.9° ± 9.9°. The 2D CT demonstrated good interobserver and intraobserver reliability for glenoid version and inclination. Decision on the choice of implant was adjusted in 7 patients after the 3D planning. Conclusions: Our findings show that measurements of glenoid version and inclination on reformatted 2D CT scans are less accurate compared with 3D measurements. A preoperative 3D planning software allows for improvement of virtual glenoid positioning and influences the decision making process. [ABSTRACT FROM AUTHOR]

Background Obstetric brachial plexus lesion (OBPL) frequently leads to glenohumeral dysplasia, and excessive retroversion of the glenoid is among the best known developmental disturbances. Most analyses of the glenoid are based on 2-dimensional (D) imaging and do not address glenoid inclination or provide information on the glenoid in the sagittal plane. We aim to describe the 3-D deformity of the glenoid in children with OBPL. Methods Preoperative computed tomography (CT) scans of the nonaffected and the affected scapula of 24 children (aged 5 to 12 years) with developmental disturbances after OBPL years were analyzed. The dimensions of the scapula and the deformation of the glenoid were visualized in 3-D. Results The retroversion of the glenoid fossa was greater in all affected shoulders, and 2-D measurements significantly overestimated retroversion compared with angles measured in 3-D. The inclination of the glenoid fossa was altered, and a distal bony edge loss was observed on 3-D reformations in the sagittal plane. The reliability of the measured angles was excellent, and the κ agreement for the description of the glenoid form was substantial. Furthermore, the dimensions of the scapula were significantly smaller on the affected shoulders. Conclusion OBPL is indeed a 3-D disorder. Our measurements revealed excessive retroversion of the glenoid fossa, and the reliability of the 3-D CT measurements was superior to their 2-D counterparts. 3-D CT reformations of the glenoid in the coronal and the sagittal plane added further to 3-D understanding of glenoid morphology in OBPL. These new findings legitimatize a 3-D CT-based description of the glenoid deformities connected with OPBL. [ABSTRACT FROM AUTHOR]

Background Posterior humeral subluxation is the main cause of failure of total shoulder arthroplasty. We aimed to compare humeral head subluxation in various reference planes and to search for a correlation with retroversion, inclination, and glenoid wear. Materials and methods We included 109 computed tomography scans of primary glenohumeral osteoarthritis and 97 of shoulder problems unrelated to shoulder osteoarthritis (controls); all computed tomography scans were reconstructed in the anatomic scapular plane and the glenoid hull plane that we defined. In both planes, we measured retroversion, inclination, glenohumeral offset (Walch index), and scapulohumeral offset. Results Retroversion in the scapular plane (Friedman method) was lower than that in the glenoid hull plane for controls and for arthritic shoulders. The threshold of scapulohumeral subluxation was 60% and 65% in the scapular plane and glenoid hull plane, respectively. The mean upward inclination was lower in the scapular plane (Churchill method) than in the glenoid hull plane (Maurer method). In the glenoid hull plane, 35% of type A2 glenoids showed glenohumeral offset greater than 75%, with mean retroversion of 25.6° ± 6° as compared with 7.5° ± 7.2° for the “centered” type A2 glenoids ( P  < .0001) and an upward inclination of –1.4° ± 8° and 6.3° ± 7° ( P  = .03), respectively. The correlation between retroversion and scapulohumeral offset was r  = 0.64 in the glenoid hull plane and r  = 0.59 in the scapular plane ( P  < .05). Conclusion Measurement in the glenoid hull plane may be more accurate than in the scapular plane. Thus, the glenoid hull method allows for better understanding type B3 of the modified Walch classification. [ABSTRACT FROM AUTHOR]

Background Computed tomography (CT) scans are often obtained before total shoulder arthroplasty to assess glenoid deformity. To allow correction of the slice axis into the plane of the scapula, these scans have typically required inclusion of the entirety of the scapula. The purpose of this study was to determine whether inclusion of the medial border and inferior angle is necessary for accurate measurement of scapular version, inclination, and humeral subluxation. Methods Fourteen CT scans in preoperative total shoulder arthroplasty patients with Walch B2 type glenoids underwent a standardized measurement protocol. Glenoid version, inclination, depth, and humeral subluxation were measured on 2-dimensional CT images corrected to the plane of the scapula. These measurements were then repeated in randomized, blinded fashion after subtracting 12.5%, 25%, and 50% of the scapula from the medial border and 12.5%, 25%, and 50% of the scapula from the inferior angle. Results Measurement of retroversion did not significantly differ between measurement of the full scapula and measurement of any of the incomplete scapulas, with the exception of the subtraction of 50% of the scapular width, which caused retroversion to be overestimated by 4.7° ( P  = .006) and led to inaccurate measurement of subluxation and glenoid depth. Conclusion If at least 8 cm of scapular width is imaged on a CT scan, accurate glenoid measurements can be made. Even if 50% of scapular height is not imaged, accurate measurements can be made. Failure to include the medial border or inferior angle does not preclude accurate glenoid measurement. [ABSTRACT FROM AUTHOR]

It is estimated that 5–30% of traumatic anterior shoulder dislocations are accompanied by greater tuberosity fracture (GTF), and the pathomechanism of these fractures is not yet clear. Our hypothesis is to examine the relationship between the scapula morphology and anterior shoulder dislocation (ASD) accompanying GTF. The patients were divided into two groups according to the accompanying GTF. 40 patients with isolated traumatic ASD and 31 patients with accompanying GTF were included in the study. Critical shoulder angle (CSA), glenoid inclination (GI), acromial index (AI) and greater tuberosity angle (GTA) values were measured in two sessions by two independent observers in the standard antero-posterior radiographs of the patients in both groups. The mean CSA was 40.82°±3.19° and 35.49°±2.19° in accompanying GTF group and the isolated ASD group, respectively. The mean CSA was significantly higher in accompanying GTF group than isolated ASD group(P <0.001). The GI was significantly higher in the isolated ASD than in accompanying GTF group (P = 0.001). The mean GI was 18.7°±6.85° and 10.45°±4.87° in accompanying GTF group and the isolated ASD, respectively. Cut-off value of CSA and GI was 38° (88.2% sensitivity,88.9% specificity) and 14.5° (70.6% sensitivity and 72.2% specificity), respectively. There was no significant difference regarding the mean GTA and AI values between GTF group and the isolated ASD group (P = 0.98, P = 0.63). Increased CSA and GI values are associated with traumatic anterior shoulder dislocation accompanied by greater tuberosity fracture. [ABSTRACT FROM AUTHOR]