The effect of adjusting the baseplate size to the glenoid on primary fixation stability in reverse total shoulder arthroplasty: A finite element analysis

The effect of adjusting the baseplate size to the glenoid on primary fixation stability in reverse total shoulder arthroplasty: A finite element analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The effect of adjusting the baseplate size to the glenoid on primary fixation stability in reverse total shoulder arthroplasty: A finite element analysis Soung-Yon Kim, Soo-Won Chae This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7738651/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Jan, 2026 Read the published version in Journal of Orthopaedic Surgery and Research → Version 1 posted 12 You are reading this latest preprint version Abstract Background The optimal baseplate size for reverse shoulder arthroplasty in patients with varying glenoid dimensions remains controversial. In this study, we comparatively evaluated the biomechanical effects of adjusting the baseplate size to different glenoid dimensions on primary fixation stability and analyzed the structural relationship between the baseplate and glenoid when adjusting the baseplate size to the glenoid size in reverse total shoulder arthroplasty. Methods We evaluated the primary fixation stability and structural relationship of the glenoid components with two different baseplate sizes (25- vs. 29-mm diameter) with a circular design in different glenoid sizes (i.e., small vs. large) using finite element analysis. Three-dimensional finite element models were constructed from 14 cadaveric scapulae and glenoid components with 25- and 29-mm baseplates. The relative micromotion of the bone–baseplate interface, distribution of bone stress under the baseplate and around the screws, contact surface area between the bone and baseplate back surface, contact surface area between the bone and screws, and length of the supporting bone stock (LSBS) for screws were analyzed. Results Compared with the 29-mm baseplate, the 25-mm baseplate improved the primary fixation stability of the glenoid component in the small glenoid via the biomechanical effect of increased contact surface area of the anterior and posterior screws with the bone and increased LSBS of the anterior and posterior screws. In the large glenoid, baseplate size did not significantly affect the primary fixation stability of the glenoid component. Conclusions In the small glenoid, adjusting the baseplate size using a small baseplate matching the anatomical size improves primary fixation stability of the glenoid component. Optimizing bone-screw contact and LSBS is critical for baseplate stability in the small glenoid. However, in the large glenoid with sufficient bone stock, adjusting the baseplate size to the glenoid does not affect the primary fixation stability. Baseplate size selection can be more flexible in the large glenoid without compromising primary fixation stability. Reverse total shoulder arthroplasty Adjusting the size Baseplate Glenoid Biomechanical effect Primary fixation stability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Background The indications for reverse total shoulder arthroplasty (RTSA) have expanded to include various pathologic shoulder conditions; therefore, its use has markedly increased worldwide [ 1 – 5 ]. However, baseplate fixation failure and glenoid component loosening are common complications of RTSA [ 6 , 7 ] and remain a concern [ 8 – 11 ]. Various baseplate designs have been developed to improve the fixation stability and longevity of the glenoid component by altering various parameters, such as the baseplate profile, baseplate size, center of rotation, baseplate central fixation, configurations of the baseplate back surface, and peripheral screw diameter, number, and type [ 12 – 16 ]. Different baseplate sizes are required that correspond with ethnic variations in patients’ bone size [ 17 – 19 ]. Optimizing the size of the baseplate is one factor for design improvement to enhance the stable fixation of the glenoid component. Among Asian populations, particularly female patients with a short stature, the regular 29-mm baseplate is too large for insertion [ 18 , 19 ], and screw fixation into the glenoid is difficult because of insufficient bone stock [ 16 ]. These issues raise concerns regarding insufficient fixation stability of the baseplate and glenoid component loosening and have led to a recent increase in applying the smaller 25-mm baseplate, particularly in Asian populations. However, the biomechanical effects of adjusting the size of the baseplate to different glenoid dimensions on the primary fixation stability of the glenoid component in RTSA have not been completely elucidated. No comparative study has substantiated the usefulness of a small baseplate versus other baseplate sizes—relative to glenoid dimensions—in terms of the fixation stability of the glenoid component. The aim of this study was to evaluate the biomechanical effects of adjusting the baseplate size to different glenoid dimensions on the primary fixation stability of the glenoid component and to analyze the structural relationship between the baseplate and glenoid when adjusting the baseplate size to the glenoid size in RTSA. We hypothesized that (1) the effect of adjusting the baseplate size to the glenoid size on primary fixation stability would vary depending on the size and (2) adjusting the baseplate size to the glenoid size would have different findings regarding the structural relationship between the baseplate and glenoid, which would be related to the primary fixation stability of the glenoid component. Materials and methods FE modeling Fourteen fresh-frozen cadaveric scapulae (from 7 female and 7 male donors; average age 62.9 years) with no obvious bony deformity or degenerative arthritis were scanned with computed tomography (CT). The cadavers utilized in this research were donated to Catholic University (Seoul, Republic of Korea) in compliance with Korean legal requirements. Catholic University of Korea's Institutional Review Board (IRB) holds certification from the Association for the Accreditation of Human Research Protection Programs. Since this cadaver study does not involve identification or use of personal information from individuals, IRB approval was not necessary under the institution's review policies. The CT images (Siemens Somatom Drive by Siemens, Erlangen, Germany; 1-mm thick; 0.24-mm pixel dimension) were imported into Mimics software (Materialise, Leuven, Belgium) to generate 3D point cloud data for the scapulae. CT image threshold values were used to differentiate and identify the boundaries of cortical bone and cancellous bone. The 3D point cloud data of the glenoid component (AequalisReversed Shoulder prosthesis; Tornier, Inc., Edina, MN, USA), consisting of 25- and 29-mm baseplates and a 36-mm glenosphere, were generated using 3D laser scanning (3D Scanner Freedom UHD; DOF Inc., Seoul, Korea; 5-megapixel resolution; <10-µm accuracy). The 3D point cloud data of each scapula and glenoid component were converted into a nonuniform rational B-spline surface (NURBS 3D models) using reverse engineering software (Rapidform 3D Systems, Inc., Rock Hill, SC, USA). The reference axis of the scapula and geometric measurements of the glenoid length and width were computed using SolidWorks software 2011 (SolidWorks Corporation, Concord, MA, USA). The reference axis of the scapula was determined using orthogonal coordinates (that is, x , y , and z ). These coordinates were defined by the most dorsal aspect of the inferior angle of the scapula, the intersection of the scapular spine and medial border, and the center of the glenoid surface, respectively [20]. Glenoid length was defined as the maximum superior–inferior dimension of the glenoid rim. Glenoid width was defined as the maximum anterior–posterior dimension of the glenoid rim orthogonal to the superior–inferior dimension. The 3D models of the glenoid component were virtually implanted into 3D models of the scapulae, based on the manufacturer’s instructions. The baseplate was positioned inferiorly so that the inferior margin of the baseplate was aligned with the inferior margin of the glenoid rim and rotated 11° anteriorly toward the coracoid base for maximal screw fixation [21]. Glenoid reaming and baseplate implantation were performed with a tilt of 0°. The screw insertion angles for baseplate fixation were applied equally in all models. The anterior screw was inserted toward the middle of the baseplate at an angle of 7° inferiorly and 4° posteriorly. The posterior screw was inserted toward the middle of the baseplate at an angle of 7° superiorly and 4° anteriorly. The superior screw was positioned toward the coracoid base at an angle of 30° superiorly and 7° anteriorly. The inferior screw was positioned into the scapular pillar at an angle of 30° inferiorly and 15° anteriorly. Each glenoid component with a 25-mm or 29-mm baseplate was implanted into a small or large glenoid. Therefore, four groups of seven FE models were generated, based on the baseplate and glenoid sizes. The FE models of the scapulae and glenoid components were constructed using HyperMesh software (ver. 11.0, Altair Engineering, Troy, MI, USA) using 10-node linear tetrahedral elements (C3D10M). A mesh convergence test was performed by varying the number of elements. The number of elements was determined via a convergence study that calculated the relative micromotion of the bone–baseplate interface and maximum bone stress around the inferior screw. The values of relative micromotion and maximum bone stress would be constant when the total number of elements was greater than approximately 200,000. The variance among consecutively converged models was <2.2%. Therefore, an element number greater than 200,000 was considered reasonable. The average total number of elements in the resulting meshes was 260,861. Material properties and boundary conditions The scapular and glenoid components were modeled using linear elastic properties. The scapula was modeled using the material properties of cortical and cancellous bones (Young’s modulus of 10 GPa and 1 GPa, and Poisson’s ratio of 0.3 and 0.4, respectively) [22]. The glenoid component was modeled using the material properties of cobalt–chrome (CoCr; glenosphere) and titanium-aluminum-vanadium alloy (Ti6Al4V8; baseplate and screws) (Young’s modulus 230 GPa and 117 GPa, respectively, and Poisson’s ratio of 0.3 for both) [23-25]. The contact condition between the baseplate and glenosphere was tied to the assumption that the baseplate and glenosphere are completely tightened and function as one unit. All screws were modeled as cylinders and rigidly bonded to the baseplate. The interface between the screw and bone was modeled as the frictional contact with a friction coefficient of 0.98 [26]. A friction coefficient of 0.74 was applied to the contact surface between the bone and baseplate back surface [23-25]. Fixed boundary conditions were applied to the medial border of the scapula to prevent movement. FE analysis Abaqus 6.10 (Dassault Systemes, Waltham, MA, USA) was used to simulate 30°, 60°, and 90° glenohumeral abduction in the scapular plane, which represents a common arc of motion in daily activities [27]. Single axial loads of 750 N at 30°, 60°, and 90° abduction angles were applied to the center of the glenosphere, such that they were parallel to the long axis of the humeral shaft (Fig. 1) [28]. We measured the relative micromotion of the bone–baseplate interface at the upper portion of the baseplate (measuring point 1), upper portion of the baseplate post (measuring point 2), lower portion of the baseplate post (measuring point 3), and lower portion of the baseplate (measuring point 4) along the axis connecting the superior and inferior screw holes of the baseplate (Fig. 2). The von Mises stress of the bone under the baseplate and around the screws was calculated at 2-mm intervals along a reference line from the node of the maximum bone stress to the baseplate screw entrance hole, parallel to the screw/post axis. The contact surface area between the bone and baseplate back surface, contact surface area between the bone and screws, and the LSBS for screws from the glenoid margin to the point of screw penetration were also measured (Fig. 3). All statistical analyses were performed using SPSS version 25.0 (IBM Corp., Armonk, NY, USA). Differences between two groups were evaluated with the Wilcoxon rank-sum test and all data are presented as the mean ± the standard deviation. Reported p-values were two-tailed and p-values <0.05 were considered statistically significant. Results Glenoid measurement The mean length and width of the small glenoid group were 31.8 ± 1.0 mm and 21.9 ± 0.6 mm, respectively. The mean length and width of the large glenoid group were 36.9 ± 1.8 mm and 27.5 ± 0.7 mm, respectively. The glenoid length and width were significantly different between the small and large glenoid groups (both: p = 0.006). Relative micromotion of the bone–baseplate interface Relative micromotion of the bone–baseplate interface increased from measuring point 1 to measuring point 4. A greater relative micromotion occurred during the loading condition at measuring point 4. In the small glenoid group, relative micromotion at measuring points 2, 3, and 4 at 30° abduction was significantly greater with the 29-mm baseplate than with the 25-mm baseplate (measuring point 2, p = 0.0012; measuring point 3, p = 0.0006; and measuring point 4, p = 0.0006). Relative micromotion at measuring points 2, 3, and 4 at 60° abduction in the small glenoid group was also significantly greater with the 29-mm baseplate than with the 25-mm baseplate (measuring point 2, p = 0.0070; measuring point 3, p = 0.0006; and measuring point 4, p = 0.0006). No significant difference was observed in the relative micromotion at any measuring point at 90° abduction between the 25- and 29-mm baseplates (p > 0.05) (Fig. 4a). In the large glenoid group, values of the relative micromotion for any measuring points at 30°, 60°, and 90° abductions were greater with the 25-mm baseplate than with the 29-mm baseplate. However, no significant differences existed between the 25- and 29-mm baseplates (p > 0.05) (Fig. 4b). Stress distribution of the bone under the baseplate and around the screws The highest value for the maximum von Mises stress of the bone under the baseplate and around screws was typically around the inferior screw (Table 1). Concentration of the maximum bone stress around the inferior screw was more prominent in the small glenoid than in the large glenoid (Fig. 5). In the small glenoid group, the maximum bone stress at the inferior screw was significantly greater with the 29-mm baseplate than with the 25-mm baseplate at 30° and 60° abductions (p = 0.0006 and p = 0.0262, respectively). Maximum bone stress between the 25- and 29-mm baseplates at 90° abduction showed no significant difference (p > 0.05) (Fig. 6a). In the large glenoid group, the maximum bone stress between the 25- and 29-mm baseplates was not significantly different at 30°, 60°, and 90° abduction (p > 0.05) (Fig. 6b). Table 1 Maximum von Mises stress (MPa) of the bone around screws and the baseplate post Small glenoid Large glenoid 25-mm baseplate 29-mm baseplate p -value 25-mm baseplate 29-mm baseplate p- value At 30 ° abduction Anterior screw 17.3 ± 6.2 16.2 ± 5.5 0.6200 17.1 ± 3.4 18.6 ± 3.9 0.3176 Posterior screw 22.9 ± 8.3 29.1 ± 8.6 0.2086 12.5 ± 2.7 12.1 ± 2.0 0.7104 Superior screw 16.3 ± 4.4 17.6 ± 4.3 0.7104 16.0 ± 1.9 19.4 ± 4.1 0.0973 Inferior screw 45.2 ± 2.2 57.1 ± 7.2 0.0006 24.0 ± 2.9 23.3 ± 2.6 0.9015 Baseplate post 7.7 ± 1.5 6.2 ± 1.2 0.0728 7.3 ± 0.9 7.4 ± 0.8 0.7104 At 60° abduction Anterior screw 17.2 ± 4.2 15.6 ± 4.6 0.7104 11.7 ± 1.8 11.7 ± 3.1 0.7104 Posterior screw 16.2 ± 5.5 15.1 ± 6.9 0.9015 10.1 ± 1.6 10.2 ± 2.0 0.9272 Superior screw 11.9 ± 2.4 12.6 ± 4.8 0.9289 10.6 ± 3.1 10.6 ± 2.6 0.8048 Inferior screw 29.4 ± 5.2 37.3 ± 5.7 0.0262 17.9 ± 3.1 17.4 ± 5.0 0.6200 Baseplate post 6.4 ± 1.0 6.5 ± 1.5 0.9289 4.4 ± 1.4 5.5 ± 1.9 0.3176 At 90° abduction Anterior screw 6.7 ± 2.5 7.6 ± 3.0 0.4557 8.8 ± 2.2 7.8 ± 1.7 0.2220 Posterior screw 4.9 ± 1.8 6.4 ± 2.9 0.4557 8.5 ± 2.8 7.4 ± 2.6 0.4557 Superior screw 10.3 ± 2.1 9.7 ± 3.0 0.7104 10.3 ± 1.9 9.1 ± 2.6 0.6200 Inferior screw 13.1 ± 3.2 13.8 ± 2.5 0.8048 12.4 ± 0.8 12.1 ± 1.5 >0.999 Baseplate post 3.6 ± 0.6 3.7 ± 0.9 0.9015 4.4 ± 0.8 4.7 ± 0.7 0.5350 Contact surface area between the bone and the baseplate back surface The contact surface area between the bone and baseplate back surface was significantly greater with the 29-mm baseplate than with the 25-mm baseplate, regardless of glenoid size (small glenoid group: 278.8 ± 24.6 mm 2 and 240.9 ± 14.8 mm 2 , respectively, p = 0.007; large glenoid group: 348.9 ± 39.3 mm 2 and 255.5 ± 7.7 mm 2 , respectively, p = 0.0006). Contact surface area between the bone and the screws The contact surface area of the anterior and posterior screws with the bone was significantly greater with the 25-mm baseplate than with the 29-mm baseplate in the small glenoid group (p = 0.0262 and p = 0.0262, respectively). In the large glenoid group, no significant differences were observed in the contact surface area between the bone and screws between the 25- and 29-mm baseplates (p > 0.05) (Table 2). Table 2 Contact surface area (mm 2 ) between the bone and screws 25-mm baseplate 29-mm baseplate p-value Small glenoid Anterior screw 154.4 ± 21.2 127.5 ± 12.8 0.0262 Posterior screw 138.3 ± 16.2 113.6 ± 13.2 0.0262 Superior screw 271.3 ± 32.4 266.9 ± 30.7 0.4557 Inferior screw 435.3 ± 35.4 430.1 ± 30.2 0.8048 Large glenoid Anterior screw 193.8 ± 20.3 189.9 ± 17.0 >0.999 Posterior screw 153.2 ± 18.4 150.2 ± 16.5 0.8048 Superior screw 254.2 ± 29.3 249.8 ± 29.7 0.9015 Inferior screw 466.7 ± 10.1 466.2 ± 15.0 >0.999 LSBS for screws The LSBS for the anterior and posterior screws was significantly greater with the 25-mm baseplate than with the 29-mm baseplate in the small glenoid group (p = 0.0006, both). The LSBS for screws was not significantly different between the 25- and 29-mm baseplates in the large glenoid group (p > 0.05) (Table 3). Table 3 Length of the supporting bone stock (mm) for screws 25-mm baseplate 29-mm baseplate p-value Small glenoid Anterior screw 2.7 ± 0.6 1.6 ± 0.4 0.0006 Posterior screw 3.2 ± 0.7 2.0 ± 0.3 0.0006 Superior screw 6.2 ± 1.1 5.3 ± 1.0 0.1282 Inferior screw 2.2 ± 0.5 2.1 ± 0.4 0.9015 Large glenoid Anterior screw 3.3 ± 1.2 3.3 ± 1.0 >0.999 Posterior screw 3.3 ± 1.5 3.3 ± 1.3 0.9015 Superior screw 9.7 ± 1.3 8.8 ± 1.4 0.2086 Inferior screw 2.0 ± 0.4 2.0 ± 0.4 >0.999 Discussion Enhancing baseplate fixation to the glenoid is essential and continues to be a major focus. A concern is the optimal design of the baseplate in reverse shoulder arthroplasty for ensuring initial fixation strength and sustaining longevity. Various baseplate design modifications in the shape (i.e., oval or circular), curvature of the surface in contact with the bone (i.e., flat or convex), central fixation type (i.e., central screw or post), and size (i.e., 25-, 29-, or 25 x 34-mm) have been proposed to improve fixation stability and decrease glenoid component loosening in RTSA [ 15 ]. However, fixation failure at the bone and baseplate interface remains a concern, especially in the presence of insufficient glenoid bone stock [ 12 ]. Fixing the regular-sized 29-mm baseplate onto a small glenoid, irrespective of the presence of glenoid wear, can be challenging because of insufficient bone stock [ 18 , 20 , 29 ]. Churchill et al. reported that the width and height of the female glenoid is 23.6 ± 1.5 mm and 32.6 ± 1.8 mm, respectively, and that the glenoid width and height are significantly larger in men than in women [ 30 ]. Clinical studies on RTSA that have assessed glenoid size report that the mean glenoid radius in Korean women aged over 60 years is 13.5 ± 1.7 mm [ 18 ], and the average glenoid in Japanese women of short stature is 23.9 mm wide and 34.2 mm long [ 19 ]. The implantation of a regular-sized 29-mm baseplate (14.5-mm radius) in the small glenoid of female patients with short stature is challenging, thus highlighting the necessity of a more appropriately sized baseplate for RTSA in this population. Therefore, the use of a small 25-mm baseplate has increased, particularly in Asian populations. Selecting an appropriately sized baseplate will likely minimize the risk of loosening and improve long-term RTSA outcomes. However, no comparative study has thoroughly evaluated the biomechanical effects of adjusting the size of the baseplate to different glenoid dimensions on the primary fixation stability of the glenoid component in RTSA. Furthermore, no comparative study has evaluated the structural relationship between the baseplate and glenoid when varying the baseplate size relative to the glenoid size. This relationship impacts the primary fixation stability of the glenoid component. In this study, we aimed to evaluate the biomechanical effects of adjusting the size of the baseplate to the glenoid size on the primary fixation stability in RTSA and to analyze the structural relationship between the baseplate and glenoid when adjusting the size of the baseplate up to the glenoid size. We investigated whether the primary fixation stability of the glenoid component differed between the regular-sized 29-mm and small-sized 25-mm baseplates when they were implanted into a small or large glenoid, and which structural relationship between the bone and baseplate was important for adjusting the baseplate size, based on the glenoid size, in RTSA. We used cadaveric scapulae to reflect the peculiar anatomical and morphological characteristics of the scapula and the glenoid and quantified the bone density of cortical and cancellous bone to better simulate in vivo conditions. In comparison with previous biomechanical or computer-assisted studies that have used a uniform cubical saw bone or polyurethane foam to assess the stability of the glenoid component, we believe that the use of cadaveric scapulae is more appropriate for investigating force transmission, stress distribution, and micromotion upon load application for the RTSA study [ 12 , 24 , 31 – 33 ]. We used FE analysis, which enables the repetitive application of consistent experimental conditions and a detailed evaluation of relative micromotion and bone stress compared to biomechanical studies. Our results revealed that the small-sized 25-mm baseplate provided improved primary fixation stability of the glenoid component, compared with the regular-sized 29-mm baseplate, when it was implanted into a small glenoid. The effect of adjusting the baseplate size to the glenoid dimensions was greater in small than in large glienoid. In small glenoids, the use of a 29-mm baseplate resulted in (1) greater relative micromotion of the bone–baseplate interface, (2) higher stress concentration at the inferior screw, (3) reduced bone-screw contact area at the anterior and posterior screws, and (4) decreased supporting bone stock length at the anterior and posterior screws. These findings suggested that oversizing the baseplate in small glenoids may compromise fixation stability and increase the risk of bone failure or loosening. However, in large glenoids, no significant differences were observed between 25- and 29-mm baseplates in terms of stress, contact surface area, or bone stock length, indicating that both sizes may provide comparable fixation stability. The present biomechanical analysis demonstrated that baseplate size significantly influences screw fixation depending on the glenoid size. The bone contact surface area and the LSBS for the anterior and posterior screws were increased significantly when the 25-mm baseplate was inserted into a small glenoid, compared with that of the 29-mm baseplate inserted into a small glenoid. A small glenoid with insufficient bone stock for a regular-sized 29-mm baseplate decreased the bone contact surface area and LSBS for the anterior and posterior screws, resulting in a detrimental effect on primary fixation stability. In the large glenoid, adjusting the baseplate size to the glenoid did not significantly affect the primary stability of the glenoid component and no significant difference existed in the bone contact surface area and the LSBS for any screws between the 25- and 29-mm baseplates. A large glenoid with sufficient bone stock for both 25- and 29-mm baseplates was unaffected by the baseplate size in terms of primary fixation stability. Notably, the regular-sized 29-mm baseplate increased the contact surface area between the bone and baseplate back surface, regardless of the glenoid size. This finding suggested that the contact surface area of the screws with the bone and the LSBS for screws could be more important than the contact surface area between the bone and baseplate back surface for enhancing the primary fixation stability of the baseplate, especially when implanted in a small glenoid. Our findings support the findings of previous studies [ 16 , 23 , 33 – 35 ] reporting that optimal screw positioning and purchase are important for ensuring adequate baseplate stability and glenoid component fixation in RTSA. These results clinically highlight the importance of selecting an appropriately sized baseplate, based on glenoid morphology. In particular, for patients with small glenoids, a 25-mm baseplate may provide superior biomechanical advantages by reducing micromotion and stress concentration and optimizing screw engagement. By contrast, for large glenoids, surgeons may choose between 25- and 29-mm baseplates, based on other surgical considerations, without compromising fixation. To our knowledge, this is the first comparative study to assess the influence of baseplate size on the primary fixation stability of the glenoid component in association with the glenoid size, and to determine which biomechanical considerations are important for varying the baseplate size to improve the fixation stability. This study, however, had some limitations. First, we assessed the time-zero primary fixation stability and did not consider the long-term effects of osseointegration, wear, or loosening. Second, we used normal cadaveric shoulders without glenoid wear in our study. The stability of glenoid components may be affected differently, depending on the type of glenoid wear. Third, we did not consider the stabilizing effects of soft tissues, such as ligaments, joint capsule, or rotator cuff muscles, which may affect the RTSA biomechanics. Finally, we only evaluated baseplates with circular designs and limited this to the Aequalis Reversed baseplate (Tornier, Inc.). Conclusion The 25-mm baseplate inserted into a small glenoid improved the primary fixation stability of the glenoid component by the mechanical effect of increased contact surface area of the anterior and posterior screws with the bone, and increased LSBS for the anterior and posterior screws. Baseplate size did not significantly affect the primary stability of the glenoid component in a large glenoid with sufficient bone stock for both 25- and 29-mm baseplates. Our results suggest that ensuring the bone contact surface area and the LSBS for the anterior and posterior screws, rather than the contact surface area between the bone and the baseplate back surface, is an important consideration for adjusting the circular baseplate size, depending on glenoid size, to enhance the primary fixation stability of the glenoid component. For patients with small glenoids, adjusting the baseplate size using a smaller baseplate (e.g., 25-mm) matching the anatomical size is recommended to maintain optimal fixation stability of the glenoid component, whereas adjusting the baseplate size to the glenoid does not affect the primary fixation stability and baseplate size selection can be more flexible for patients with large glenoids. We believe that our findings could help provide information on the criteria for selecting the base plate size, based on the patient's glenoid size. Further studies are needed to determine whether baseplate size affects the fixation stability of the glenoid component differently, depending on the other baseplate design configurations (i.e., shape or central fixation type). Abbreviations 3D, three dimensional; CT, computed tomography; FE, finite element; LSBS, length of the supporting bone stock; RTSA, reverse total shoulder arthroplasty Declarations Ethics approval and informed consent The hospital’s IRB does not review cadaver studies that do not identify or use individuals’ personal information. Thus, IRB approval and informed consent were not required for this study. Consent for publication Not applicable. Availability of data and materials All data generated or analyzed during this study are included in this published article. The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request. Competing interests The authors declare that they have no competing interests. Funding This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2019R1I1A1A01062350). 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Optimizing baseplate position in reverse total shoulder arthroplasty in small-sized japanese females: Technical notes and literature review. J Med Invest. 2016;63:8–14. Frankle MA, Teramoto A, Luo ZP, Levy JC, Pupello D. Glenoid morphology in reverse shoulder arthroplasty: Classification and surgical implications. J Shoulder Elbow Surg. 2009;18:874–85. Stephens BF, Hebert CT, Azar FM, Mihalko WM, Throckmorton TW. Optimal baseplate rotational alignment for locking-screw fixation in reverse total shoulder arthroplasty: A three-dimensional computer-aided design study. J Shoulder Elbow Surg. 2015;24:1367–71. Ahir SP, Walker PS, Squire-Taylor CJ, Blunn GW, Bayley JI. Analysis of glenoid fixation for a reversed anatomy fixed-fulcrum shoulder replacement. J Biomech. 2004;37:1699–708. Nigro PT, Gutierrez S, Frankle MA. Improving glenoid-side load sharing in a virtual reverse shoulder arthroplasty model. J Shoulder Elbow Surg. 2013;22:954–62. Gutierrez S, Walker M, Willis M, Pupello DR, Frankle MA. Effects of tilt and glenosphere eccentricity on baseplate/bone interface forces in a computational model, validated by a mechanical model, of reverse shoulder arthroplasty. J Shoulder Elbow Surg. 2011;20:732–9. Virani NA, Harman M, Li K, Levy J, Pupello DR, et al. In vitro and finite element analysis of glenoid bone/baseplate interaction in the reverse shoulder design. J Shoulder Elbow Surg. 2008;17:509–21. Zhang Y, Ahn PB, Fitzpatrick DC, Heiner AD, Poggie RA, et al. Interfacial frictional behavior: Cancellous bone, cortical bone, and a novel porous tantalum biomaterial. Journal of Musculoskeletal Research. 1999;3:245–51. Gupta S, van der Helm FC, van Keulen F. The possibilities of uncemented glenoid component--a finite element study. Clin Biomech (Bristol, Avon). 2004;19:292–302. Roche CP, Stroud NJ, Martin BL, Steiler CA, Flurin PH, et al. The impact of scapular notching on reverse shoulder glenoid fixation. J Shoulder Elbow Surg. 2013;22:963–70. Sutton LG, Werner FW, Jones AK, Close CA, Nanavati VN. Optimization of glenoid fixation in reverse shoulder arthroplasty using 3-dimensional modeling. J Shoulder Elbow Surg. 2010;19:664–9. Churchill RS, Brems JJ, Kotschi H. Glenoid size, inclination, and version: An anatomic study. J Shoulder Elbow Surg. 2001;10:327–32. Nyffeler RW, Werner CM, Gerber C. Biomechanical relevance of glenoid component positioning in the reverse delta iii total shoulder prosthesis. J Shoulder Elbow Surg. 2005;14:524–8. Simovitch RW, Zumstein MA, Lohri E, Helmy N, Gerber C. Predictors of scapular notching in patients managed with the delta iii reverse total shoulder replacement. J Bone Joint Surg Am. 2007;89:588–600. Chae SW, Lee H, Kim SM, Lee J, Han SH, et al. Primary stability of inferior tilt fixation of the glenoid component in reverse total shoulder arthroplasty: A finite element study. J Orthop Res. 2016;34:1061–8. Wall B, Nove-Josserand L, O'Connor DP, Edwards TB, Walch G. Reverse total shoulder arthroplasty: A review of results according to etiology. J Bone Joint Surg Am. 2007;89:1476–85. Hoenig MP, Loeffler B, Brown S, Peindl R, Fleischli J, et al. Reverse glenoid component fixation: Is a posterior screw necessary? J Shoulder Elbow Surg. 2010;19:544–9. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 01 Jan, 2026 Read the published version in Journal of Orthopaedic Surgery and Research → Version 1 posted Editorial decision: Revision requested 13 Oct, 2025 Reviews received at journal 11 Oct, 2025 Reviews received at journal 08 Oct, 2025 Reviewers agreed at journal 06 Oct, 2025 Reviews received at journal 05 Oct, 2025 Reviewers agreed at journal 03 Oct, 2025 Reviewers agreed at journal 03 Oct, 2025 Reviewers agreed at journal 03 Oct, 2025 Reviewers invited by journal 03 Oct, 2025 Editor assigned by journal 02 Oct, 2025 Submission checks completed at journal 01 Oct, 2025 First submitted to journal 29 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7738651","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":528586580,"identity":"16f439ae-fc83-4db3-ac69-a2f1c63c18a6","order_by":0,"name":"Soung-Yon Kim","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7ElEQVRIiWNgGAWjYFADHsYGhg9Amo2dFC2MM0BamInXwsDAzANiENIi395j9vBrm00eA8/h1s02v7bJ8zEzMH74mINbi8GZM+bGsm1pxQy8jW23c/tuG7YxMzBLztyGR4tEjpm0ZNvhxAZ+RqCWntuMQC1szLx4tMjPQNZi2XPbnqAWhhs5ZpIfQVpADmP4cTuRoBaDM8fKpBnOpSW28Rxsu9nbcDu5jZmxGa9f5Nubt0n+KLNJ7OdJf3bjx5/btvPbmw9++IjPYUDAzMsGjEEQi7ENTDbgVw9S8uMPjPkHn7pRMApGwSgYqQAASVlP8zmw/yoAAAAASUVORK5CYII=","orcid":"","institution":"Gyeongsang National University Hospital, Gyeongsang National University","correspondingAuthor":true,"prefix":"","firstName":"Soung-Yon","middleName":"","lastName":"Kim","suffix":""},{"id":528586581,"identity":"ca71c7c0-9f0b-4198-b9cc-245d8f53d3ce","order_by":1,"name":"Soo-Won Chae","email":"","orcid":"","institution":"Korea University","correspondingAuthor":false,"prefix":"","firstName":"Soo-Won","middleName":"","lastName":"Chae","suffix":""}],"badges":[],"createdAt":"2025-09-29 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02:10:57","extension":"html","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":112154,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7738651/v1/cb48f2d2f4b0902d17e0feaa.html"},{"id":93728340,"identity":"f6141403-b065-4f96-8877-9915b83a554f","added_by":"auto","created_at":"2025-10-17 02:10:56","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":115563,"visible":true,"origin":"","legend":"\u003cp\u003eBoundary and loading conditions\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7738651/v1/4ef0f4cd44ff694c287e946d.png"},{"id":93728377,"identity":"b0723312-c3c5-4ce0-8995-88f177641968","added_by":"auto","created_at":"2025-10-17 02:11:02","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":422988,"visible":true,"origin":"","legend":"\u003cp\u003eThe measuring points of the relative micromotion of the bone–baseplate interface\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7738651/v1/f3bfb137fc4917418a6d08db.png"},{"id":93728287,"identity":"62fd4da1-cc1a-4911-9818-e918422c79aa","added_by":"auto","created_at":"2025-10-17 02:10:51","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":437793,"visible":true,"origin":"","legend":"\u003cp\u003eLength of the supporting bone stock (LSBS) for the posterior screw of the (a) 25- and (b) 29-mm baseplates inserted into a small glenoid\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7738651/v1/44d9f0107631195a04e6a6c2.png"},{"id":93728374,"identity":"d8efa7ed-d6fa-4d9b-851e-646bb3fa7b8c","added_by":"auto","created_at":"2025-10-17 02:11:01","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":120675,"visible":true,"origin":"","legend":"\u003cp\u003eRelative micromotion of the bone–baseplate interface of the 25- and 29-mm baseplates at 30°, 60°, and 90° abductions inserted into a (a) small or (b) large glenoid\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7738651/v1/58e9f1fb53e97dd0b3c9db87.png"},{"id":93728375,"identity":"12460b94-fa56-4e56-a2a9-44002f0774df","added_by":"auto","created_at":"2025-10-17 02:11:01","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":462674,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of the von Mises stress of the bone when the 25- and 29-mm baseplates are inserted into a small or large glenoid\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7738651/v1/0174efa535361b932745bc12.png"},{"id":93728413,"identity":"8c88e252-cf3d-42b3-bbb8-3bd113953dbf","added_by":"auto","created_at":"2025-10-17 02:11:04","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":166457,"visible":true,"origin":"","legend":"\u003cp\u003evon Mises stress of the bone around screws and the baseplate post of the 25- and 29-mm baseplates at 30°, 60°, and 90° abduction inserted into a (a) small or (b) large glenoid\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7738651/v1/a4fec43a821e0e6da72bea72.png"},{"id":99545414,"identity":"3517b6ef-6ac5-4ecc-86d1-6846eed7ef0e","added_by":"auto","created_at":"2026-01-05 16:07:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2475393,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7738651/v1/609dd2ee-5473-4aee-a343-e966c6329845.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The effect of adjusting the baseplate size to the glenoid on primary fixation stability in reverse total shoulder arthroplasty: A finite element analysis","fulltext":[{"header":"Background","content":"\u003cp\u003eThe indications for reverse total shoulder arthroplasty (RTSA) have expanded to include various pathologic shoulder conditions; therefore, its use has markedly increased worldwide [\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. However, baseplate fixation failure and glenoid component loosening are common complications of RTSA [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] and remain a concern [\u003cspan additionalcitationids=\"CR9 CR10\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Various baseplate designs have been developed to improve the fixation stability and longevity of the glenoid component by altering various parameters, such as the baseplate profile, baseplate size, center of rotation, baseplate central fixation, configurations of the baseplate back surface, and peripheral screw diameter, number, and type [\u003cspan additionalcitationids=\"CR13 CR14 CR15\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eDifferent baseplate sizes are required that correspond with ethnic variations in patients\u0026rsquo; bone size [\u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Optimizing the size of the baseplate is one factor for design improvement to enhance the stable fixation of the glenoid component. Among Asian populations, particularly female patients with a short stature, the regular 29-mm baseplate is too large for insertion [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], and screw fixation into the glenoid is difficult because of insufficient bone stock [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. These issues raise concerns regarding insufficient fixation stability of the baseplate and glenoid component loosening and have led to a recent increase in applying the smaller 25-mm baseplate, particularly in Asian populations. However, the biomechanical effects of adjusting the size of the baseplate to different glenoid dimensions on the primary fixation stability of the glenoid component in RTSA have not been completely elucidated. No comparative study has substantiated the usefulness of a small baseplate versus other baseplate sizes\u0026mdash;relative to glenoid dimensions\u0026mdash;in terms of the fixation stability of the glenoid component.\u003c/p\u003e\u003cp\u003eThe aim of this study was to evaluate the biomechanical effects of adjusting the baseplate size to different glenoid dimensions on the primary fixation stability of the glenoid component and to analyze the structural relationship between the baseplate and glenoid when adjusting the baseplate size to the glenoid size in RTSA. We hypothesized that (1) the effect of adjusting the baseplate size to the glenoid size on primary fixation stability would vary depending on the size and (2) adjusting the baseplate size to the glenoid size would have different findings regarding the structural relationship between the baseplate and glenoid, which would be related to the primary fixation stability of the glenoid component.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFE \u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cem\u003emodeling\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFourteen fresh-frozen cadaveric scapulae (from 7 female and 7 male donors; average age 62.9 years) with no obvious bony deformity or degenerative arthritis were scanned with computed tomography (CT). The cadavers utilized in this research were donated to Catholic University (Seoul, Republic of Korea) in compliance with Korean legal requirements. Catholic University of Korea\u0026apos;s Institutional Review Board (IRB) holds certification from the Association for the Accreditation of Human Research Protection Programs. Since this cadaver study does not involve identification or use of personal information from individuals, IRB approval was not necessary under the institution\u0026apos;s review policies. The CT images (Siemens Somatom Drive by Siemens, Erlangen, Germany; 1-mm thick; 0.24-mm pixel dimension) were imported into Mimics software (Materialise, Leuven, Belgium) to generate 3D point cloud data for the scapulae. CT image threshold values were used to differentiate and identify the boundaries of cortical bone and cancellous bone. The 3D point cloud data of the glenoid component (AequalisReversed Shoulder prosthesis; Tornier, Inc., Edina, MN, USA), consisting of 25- and 29-mm baseplates and a 36-mm glenosphere, were generated using 3D laser scanning (3D Scanner Freedom UHD; DOF Inc., Seoul, Korea; 5-megapixel resolution; \u0026lt;10-\u0026micro;m accuracy). The 3D point cloud data of each scapula and glenoid component were converted into a nonuniform rational B-spline surface (NURBS 3D models) using reverse engineering software (Rapidform 3D Systems, Inc., Rock Hill, SC, USA).\u003c/p\u003e\n\u003cp\u003eThe reference axis of the scapula and geometric measurements of the glenoid length and width were computed using SolidWorks software 2011 (SolidWorks Corporation, Concord, MA, USA). The reference axis of the scapula was determined using orthogonal coordinates (that is, \u003cem\u003ex\u003c/em\u003e,\u003cem\u003e y\u003c/em\u003e,\u003cem\u003e \u003c/em\u003eand\u003cem\u003e z\u003c/em\u003e). These coordinates were defined by the most dorsal aspect of the inferior angle of the scapula, the intersection of the scapular spine and medial border, and the center of the glenoid surface, respectively [20]. Glenoid length was defined as the maximum superior\u0026ndash;inferior dimension of the glenoid rim. Glenoid width was defined as the maximum anterior\u0026ndash;posterior dimension of the glenoid rim orthogonal to the superior\u0026ndash;inferior dimension.\u003c/p\u003e\n\u003cp\u003eThe 3D models of the glenoid component were virtually implanted into 3D models of the scapulae, based on the manufacturer\u0026rsquo;s instructions. The baseplate was positioned inferiorly so that the inferior margin of the baseplate was aligned with the inferior margin of the glenoid rim and rotated 11\u0026deg; anteriorly toward the coracoid base for maximal screw fixation [21]. Glenoid reaming and baseplate implantation were performed with a tilt of 0\u0026deg;. The screw insertion angles for baseplate fixation were applied equally in all models. The anterior screw was inserted toward the middle of the baseplate at an angle of 7\u0026deg; inferiorly and 4\u0026deg; posteriorly. The posterior screw was inserted toward the middle of the baseplate at an angle of 7\u0026deg; superiorly and 4\u0026deg; anteriorly. The superior screw was positioned toward the coracoid base at an angle of 30\u0026deg; superiorly and 7\u0026deg; anteriorly. The inferior screw was positioned into the scapular pillar at an angle of 30\u0026deg; inferiorly and 15\u0026deg; anteriorly. Each glenoid component with a 25-mm or 29-mm baseplate was implanted into a small or large glenoid. Therefore, four groups of seven FE models were generated, based on the baseplate and glenoid sizes. The FE models of the scapulae and glenoid components were constructed using HyperMesh software (ver. 11.0, Altair Engineering, Troy, MI, USA) using 10-node linear tetrahedral elements (C3D10M).\u003c/p\u003e\n\u003cp\u003eA mesh convergence test was performed by varying the number of elements. The number of elements was determined via a convergence study that calculated the relative micromotion of the bone\u0026ndash;baseplate interface and maximum bone stress around the inferior screw. The values of relative micromotion and maximum bone stress would be constant when the total number of elements was greater than approximately 200,000. The variance among consecutively converged models was \u0026lt;2.2%. Therefore, an element number greater than 200,000 was considered reasonable. The average total number of elements in the resulting meshes was 260,861. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eMaterial properties and boundary conditions\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe scapular and glenoid components were modeled using linear elastic properties. The scapula was modeled using the material properties of cortical and cancellous bones (Young\u0026rsquo;s modulus of 10 GPa and 1 GPa, and Poisson\u0026rsquo;s ratio of 0.3 and 0.4, respectively) [22]. The glenoid component was modeled using the material properties of cobalt\u0026ndash;chrome (CoCr; glenosphere) and titanium-aluminum-vanadium alloy (Ti6Al4V8; baseplate and screws) (Young\u0026rsquo;s modulus 230 GPa and 117 GPa, respectively, and Poisson\u0026rsquo;s ratio of 0.3 for both) [23-25]. The contact condition between the baseplate and glenosphere was tied to the assumption that the baseplate and glenosphere are completely tightened and function as one unit. All screws were modeled as cylinders and rigidly bonded to the baseplate. The interface between the screw and bone was modeled as the frictional contact with a friction coefficient of 0.98 [26]. A friction coefficient of 0.74 was applied to the contact surface between the bone and baseplate back surface [23-25]. Fixed boundary conditions were applied to the medial border of the scapula to prevent movement. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFE analysis\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAbaqus 6.10 (Dassault Systemes, Waltham, MA, USA) was used to simulate 30\u0026deg;, 60\u0026deg;, and 90\u0026deg; glenohumeral abduction in the scapular plane, which represents a common arc of motion in daily activities [27]. Single axial loads of 750 N at 30\u0026deg;, 60\u0026deg;, and 90\u0026deg; abduction angles were applied to the center of the glenosphere, such that they were parallel to the long axis of the humeral shaft (Fig. 1) [28].\u003c/p\u003e\n\u003cp\u003eWe measured the relative micromotion of the bone\u0026ndash;baseplate interface at the upper portion of the baseplate (measuring point 1), upper portion of the baseplate post (measuring point 2), lower portion of the baseplate post (measuring point 3), and lower portion of the baseplate (measuring point 4) along the axis connecting the superior and inferior screw holes of the baseplate (Fig. 2). The von Mises stress of the bone under the baseplate and around the screws was calculated at 2-mm intervals along a reference line from the node of the maximum bone stress to the baseplate screw entrance hole, parallel to the screw/post axis. The contact surface area between the bone and baseplate back surface, contact surface area between the bone and screws, and the LSBS for screws from the glenoid margin to the point of screw penetration were also measured (Fig. 3). All statistical analyses were performed using SPSS version 25.0 (IBM Corp., Armonk, NY, USA). Differences between two groups were evaluated with the Wilcoxon rank-sum test and all data are presented as the mean \u0026plusmn; the standard deviation. Reported p-values were two-tailed and p-values \u0026lt;0.05 were considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eGlenoid measurement\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe mean length and width of the small glenoid group were 31.8 \u0026plusmn; 1.0 mm and 21.9 \u0026plusmn; 0.6 mm, respectively. The mean length and width of the large glenoid group were 36.9 \u0026plusmn; 1.8 mm and 27.5 \u0026plusmn; 0.7 mm, respectively. The glenoid length and width were significantly different between the small and large glenoid groups (both: p = 0.006).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eRelative micromotion of the bone\u0026ndash;baseplate interface\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRelative micromotion of the bone\u0026ndash;baseplate interface increased from measuring point 1 to measuring point 4. A greater relative micromotion occurred during the loading condition at measuring point 4. In the small glenoid group, relative micromotion at measuring points 2, 3, and 4 at 30\u0026deg; abduction was significantly greater with the 29-mm baseplate than with the 25-mm baseplate (measuring point 2, p = 0.0012; measuring point 3, p = 0.0006; and measuring point 4, p = 0.0006). Relative micromotion at measuring points 2, 3, and 4 at 60\u0026deg; abduction in the small glenoid group was also significantly greater with the 29-mm baseplate than with the 25-mm baseplate (measuring point 2, p = 0.0070; measuring point 3, p = 0.0006; and measuring point 4, p = 0.0006). No significant difference was observed in the relative micromotion at any measuring point at 90\u0026deg; abduction between the 25- and 29-mm baseplates (p \u0026gt; 0.05) (Fig. 4a). In the large glenoid group, values of the relative micromotion for any measuring points at 30\u0026deg;, 60\u0026deg;, and 90\u0026deg; abductions were greater with the 25-mm baseplate than with the 29-mm baseplate. However, no significant differences existed between the 25- and 29-mm baseplates (p \u0026gt; 0.05) (Fig. 4b).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eStress distribution of the bone under the baseplate and around the screws\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe highest value for the maximum von Mises stress of the bone under the baseplate and around screws was typically around the inferior screw (Table 1). Concentration of the maximum bone stress around the inferior screw was more prominent in the small glenoid than in the large glenoid (Fig. 5). In the small glenoid group, the maximum bone stress at the inferior screw was significantly greater with the 29-mm baseplate than with the 25-mm baseplate at 30\u0026deg; and 60\u0026deg; abductions (p = 0.0006 and p = 0.0262, respectively). Maximum bone stress between the 25- and 29-mm baseplates at 90\u0026deg; abduction showed no significant difference (p \u0026gt; 0.05) (Fig. 6a). In the large glenoid group, the maximum bone stress between the 25- and 29-mm baseplates was not significantly different at 30\u0026deg;, 60\u0026deg;, and 90\u0026deg; abduction (p \u0026gt; 0.05) (Fig. 6b).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u0026nbsp;\u003c/strong\u003eMaximum von Mises stress (MPa) of the bone around screws and the baseplate post\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"633\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 248px;\"\u003e\n \u003cp\u003eSmall glenoid\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 255px;\"\u003e\n \u003cp\u003eLarge glenoid\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e25-mm baseplate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e29-mm baseplate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e-value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e25-mm baseplate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e29-mm baseplate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cem\u003ep-\u003c/em\u003evalue\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 217px;\"\u003e\n \u003cp\u003e\u003cem\u003eAt 30\u003csup\u003e\u0026deg;\u003c/sup\u003e abduction\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eAnterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e17.3 \u0026plusmn; 6.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e16.2 \u0026plusmn; 5.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.6200\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e17.1 \u0026plusmn; 3.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e18.6 \u0026plusmn; 3.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.3176\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003ePosterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e22.9 \u0026plusmn; 8.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e29.1 \u0026plusmn; 8.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.2086\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e12.5 \u0026plusmn; 2.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e12.1 \u0026plusmn; 2.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.7104\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSuperior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e16.3 \u0026plusmn; 4.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e17.6 \u0026plusmn; 4.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.7104\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e16.0 \u0026plusmn; 1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e19.4 \u0026plusmn; 4.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.0973\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eInferior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e45.2 \u0026plusmn; 2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e57.1 \u0026plusmn; 7.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.0006\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e24.0 \u0026plusmn; 2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e23.3 \u0026plusmn; 2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.9015\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eBaseplate post\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e7.7 \u0026plusmn; 1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e6.2 \u0026plusmn; 1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.0728\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e7.3 \u0026plusmn; 0.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e7.4 \u0026plusmn; 0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.7104\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 217px;\"\u003e\n \u003cp\u003e\u003cem\u003eAt 60\u0026deg; abduction\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eAnterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e17.2 \u0026plusmn; 4.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e15.6 \u0026plusmn; 4.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.7104\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e11.7 \u0026plusmn; 1.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e11.7 \u0026plusmn; 3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.7104\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003ePosterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e16.2 \u0026plusmn; 5.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e15.1 \u0026plusmn; 6.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.9015\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e10.1 \u0026plusmn; 1.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e10.2 \u0026plusmn; 2.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.9272\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSuperior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e11.9 \u0026plusmn; 2.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e12.6 \u0026plusmn; 4.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.9289\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e10.6 \u0026plusmn; 3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e10.6 \u0026plusmn; 2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.8048\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eInferior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e29.4 \u0026plusmn; 5.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e37.3 \u0026plusmn; 5.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.0262\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e17.9 \u0026plusmn; 3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e17.4 \u0026plusmn; 5.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.6200\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eBaseplate post\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e6.4 \u0026plusmn; 1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e6.5 \u0026plusmn; 1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.9289\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e4.4 \u0026plusmn; 1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e5.5 \u0026plusmn; 1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.3176\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 217px;\"\u003e\n \u003cp\u003e\u003cem\u003eAt 90\u0026deg; abduction\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eAnterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e6.7 \u0026plusmn; 2.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e7.6 \u0026plusmn; 3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.4557\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e8.8 \u0026plusmn; 2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e7.8 \u0026plusmn; 1.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.2220\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003ePosterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e4.9 \u0026plusmn; 1.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e6.4 \u0026plusmn; 2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.4557\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e8.5 \u0026plusmn; 2.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e7.4 \u0026plusmn; 2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.4557\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSuperior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e10.3 \u0026plusmn; 2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e9.7 \u0026plusmn; 3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.7104\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e10.3 \u0026plusmn; 1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e9.1 \u0026plusmn; 2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.6200\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eInferior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e13.1 \u0026plusmn; 3.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e13.8 \u0026plusmn; 2.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.8048\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e12.4 \u0026plusmn; 0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e12.1 \u0026plusmn; 1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026gt;0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eBaseplate post\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e3.6 \u0026plusmn; 0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e3.7 \u0026plusmn; 0.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.9015\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e4.4 \u0026plusmn; 0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e4.7 \u0026plusmn; 0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.5350\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eContact surface area between the bone and the baseplate back surface\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe contact surface area between the bone and baseplate back surface was significantly greater with the 29-mm baseplate than with the 25-mm baseplate, regardless of glenoid size (small glenoid group: 278.8 \u0026plusmn; 24.6 mm\u003csup\u003e2\u003c/sup\u003e and 240.9 \u0026plusmn; 14.8 mm\u003csup\u003e2\u003c/sup\u003e, respectively, p = 0.007; large glenoid group: 348.9 \u0026plusmn; 39.3 mm\u003csup\u003e2\u003c/sup\u003e and 255.5 \u0026plusmn; 7.7 mm\u003csup\u003e2\u003c/sup\u003e, respectively, p = 0.0006).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eContact surface area between the bone and the screws\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe contact surface area of the anterior and posterior screws with the bone was significantly greater with the 25-mm baseplate than with the 29-mm baseplate in the small glenoid group (p = 0.0262 and p = 0.0262, respectively). In the large glenoid group, no significant differences were observed in the contact surface area between the bone and screws between the 25- and 29-mm baseplates (p \u0026gt; 0.05) (Table 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;2\u0026nbsp;\u003c/strong\u003eContact surface area (mm\u003csup\u003e2\u003c/sup\u003e) between the bone and screws\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"584\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e25-mm baseplate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e29-mm baseplate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e\u003cem\u003eSmall glenoid\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eAnterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e154.4 \u0026plusmn; 21.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e127.5 \u0026plusmn; 12.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.0262\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003ePosterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e138.3 \u0026plusmn; 16.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e113.6 \u0026plusmn; 13.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.0262\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSuperior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e271.3 \u0026plusmn; 32.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e266.9 \u0026plusmn; 30.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.4557\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eInferior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e435.3 \u0026plusmn; 35.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e430.1 \u0026plusmn; 30.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.8048\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e\u003cem\u003eLarge glenoid\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eAnterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e193.8 \u0026plusmn; 20.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e189.9 \u0026plusmn; 17.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026gt;0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003ePosterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e153.2 \u0026plusmn; 18.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e150.2 \u0026plusmn; 16.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.8048\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSuperior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e254.2 \u0026plusmn; 29.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e249.8 \u0026plusmn; 29.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.9015\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eInferior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e466.7 \u0026plusmn; 10.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 180px;\"\u003e\n \u003cp\u003e466.2 \u0026plusmn; 15.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026gt;0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eLSBS for screws\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe LSBS for the anterior and posterior screws was significantly greater with the 25-mm baseplate than with the 29-mm baseplate in the small glenoid group (p = 0.0006, both). The LSBS for screws was not significantly different between the 25- and 29-mm baseplates in the large glenoid group (p \u0026gt; 0.05) (Table 3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;3\u0026nbsp;\u003c/strong\u003eLength of the supporting bone stock (mm) for screws\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"584\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e25-mm baseplate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e29-mm baseplate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e\u003cem\u003eSmall glenoid\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eAnterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e2.7 \u0026plusmn; 0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e1.6 \u0026plusmn; 0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0006\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003ePosterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e3.2 \u0026plusmn; 0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e2.0 \u0026plusmn; 0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0006\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSuperior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e6.2 \u0026plusmn; 1.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e5.3 \u0026plusmn; 1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.1282\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eInferior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e2.2 \u0026plusmn; 0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e2.1 \u0026plusmn; 0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.9015\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e\u003cem\u003eLarge glenoid\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eAnterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e3.3 \u0026plusmn; 1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e3.3 \u0026plusmn; 1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026gt;0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003ePosterior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e3.3 \u0026plusmn; 1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e3.3 \u0026plusmn; 1.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.9015\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSuperior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e9.7 \u0026plusmn; 1.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e8.8 \u0026plusmn; 1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.2086\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eInferior screw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e2.0 \u0026plusmn; 0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 175px;\"\u003e\n \u003cp\u003e2.0 \u0026plusmn; 0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026gt;0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Discussion","content":"\u003cp\u003eEnhancing baseplate fixation to the glenoid is essential and continues to be a major focus. A concern is the optimal design of the baseplate in reverse shoulder arthroplasty for ensuring initial fixation strength and sustaining longevity. Various baseplate design modifications in the shape (i.e., oval or circular), curvature of the surface in contact with the bone (i.e., flat or convex), central fixation type (i.e., central screw or post), and size (i.e., 25-, 29-, or 25 x 34-mm) have been proposed to improve fixation stability and decrease glenoid component loosening in RTSA [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. However, fixation failure at the bone and baseplate interface remains a concern, especially in the presence of insufficient glenoid bone stock [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFixing the regular-sized 29-mm baseplate onto a small glenoid, irrespective of the presence of glenoid wear, can be challenging because of insufficient bone stock [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Churchill et al. reported that the width and height of the female glenoid is 23.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5 mm and 32.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8 mm, respectively, and that the glenoid width and height are significantly larger in men than in women [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Clinical studies on RTSA that have assessed glenoid size report that the mean glenoid radius in Korean women aged over 60 years is 13.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7 mm [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], and the average glenoid in Japanese women of short stature is 23.9 mm wide and 34.2 mm long [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The implantation of a regular-sized 29-mm baseplate (14.5-mm radius) in the small glenoid of female patients with short stature is challenging, thus highlighting the necessity of a more appropriately sized baseplate for RTSA in this population. Therefore, the use of a small 25-mm baseplate has increased, particularly in Asian populations.\u003c/p\u003e\u003cp\u003eSelecting an appropriately sized baseplate will likely minimize the risk of loosening and improve long-term RTSA outcomes. However, no comparative study has thoroughly evaluated the biomechanical effects of adjusting the size of the baseplate to different glenoid dimensions on the primary fixation stability of the glenoid component in RTSA. Furthermore, no comparative study has evaluated the structural relationship between the baseplate and glenoid when varying the baseplate size relative to the glenoid size. This relationship impacts the primary fixation stability of the glenoid component.\u003c/p\u003e\u003cp\u003eIn this study, we aimed to evaluate the biomechanical effects of adjusting the size of the baseplate to the glenoid size on the primary fixation stability in RTSA and to analyze the structural relationship between the baseplate and glenoid when adjusting the size of the baseplate up to the glenoid size. We investigated whether the primary fixation stability of the glenoid component differed between the regular-sized 29-mm and small-sized 25-mm baseplates when they were implanted into a small or large glenoid, and which structural relationship between the bone and baseplate was important for adjusting the baseplate size, based on the glenoid size, in RTSA. We used cadaveric scapulae to reflect the peculiar anatomical and morphological characteristics of the scapula and the glenoid and quantified the bone density of cortical and cancellous bone to better simulate in vivo conditions. In comparison with previous biomechanical or computer-assisted studies that have used a uniform cubical saw bone or polyurethane foam to assess the stability of the glenoid component, we believe that the use of cadaveric scapulae is more appropriate for investigating force transmission, stress distribution, and micromotion upon load application for the RTSA study [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan additionalcitationids=\"CR32\" citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. We used FE analysis, which enables the repetitive application of consistent experimental conditions and a detailed evaluation of relative micromotion and bone stress compared to biomechanical studies.\u003c/p\u003e\u003cp\u003eOur results revealed that the small-sized 25-mm baseplate provided improved primary fixation stability of the glenoid component, compared with the regular-sized 29-mm baseplate, when it was implanted into a small glenoid. The effect of adjusting the baseplate size to the glenoid dimensions was greater in small than in large glienoid. In small glenoids, the use of a 29-mm baseplate resulted in (1) greater relative micromotion of the bone\u0026ndash;baseplate interface, (2) higher stress concentration at the inferior screw, (3) reduced bone-screw contact area at the anterior and posterior screws, and (4) decreased supporting bone stock length at the anterior and posterior screws. These findings suggested that oversizing the baseplate in small glenoids may compromise fixation stability and increase the risk of bone failure or loosening. However, in large glenoids, no significant differences were observed between 25- and 29-mm baseplates in terms of stress, contact surface area, or bone stock length, indicating that both sizes may provide comparable fixation stability.\u003c/p\u003e\u003cp\u003eThe present biomechanical analysis demonstrated that baseplate size significantly influences screw fixation depending on the glenoid size. The bone contact surface area and the LSBS for the anterior and posterior screws were increased significantly when the 25-mm baseplate was inserted into a small glenoid, compared with that of the 29-mm baseplate inserted into a small glenoid. A small glenoid with insufficient bone stock for a regular-sized 29-mm baseplate decreased the bone contact surface area and LSBS for the anterior and posterior screws, resulting in a detrimental effect on primary fixation stability. In the large glenoid, adjusting the baseplate size to the glenoid did not significantly affect the primary stability of the glenoid component and no significant difference existed in the bone contact surface area and the LSBS for any screws between the 25- and 29-mm baseplates. A large glenoid with sufficient bone stock for both 25- and 29-mm baseplates was unaffected by the baseplate size in terms of primary fixation stability. Notably, the regular-sized 29-mm baseplate increased the contact surface area between the bone and baseplate back surface, regardless of the glenoid size. This finding suggested that the contact surface area of the screws with the bone and the LSBS for screws could be more important than the contact surface area between the bone and baseplate back surface for enhancing the primary fixation stability of the baseplate, especially when implanted in a small glenoid. Our findings support the findings of previous studies [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan additionalcitationids=\"CR34\" citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] reporting that optimal screw positioning and purchase are important for ensuring adequate baseplate stability and glenoid component fixation in RTSA. These results clinically highlight the importance of selecting an appropriately sized baseplate, based on glenoid morphology. In particular, for patients with small glenoids, a 25-mm baseplate may provide superior biomechanical advantages by reducing micromotion and stress concentration and optimizing screw engagement. By contrast, for large glenoids, surgeons may choose between 25- and 29-mm baseplates, based on other surgical considerations, without compromising fixation.\u003c/p\u003e\u003cp\u003eTo our knowledge, this is the first comparative study to assess the influence of baseplate size on the primary fixation stability of the glenoid component in association with the glenoid size, and to determine which biomechanical considerations are important for varying the baseplate size to improve the fixation stability. This study, however, had some limitations. First, we assessed the time-zero primary fixation stability and did not consider the long-term effects of osseointegration, wear, or loosening. Second, we used normal cadaveric shoulders without glenoid wear in our study. The stability of glenoid components may be affected differently, depending on the type of glenoid wear. Third, we did not consider the stabilizing effects of soft tissues, such as ligaments, joint capsule, or rotator cuff muscles, which may affect the RTSA biomechanics. Finally, we only evaluated baseplates with circular designs and limited this to the Aequalis Reversed baseplate (Tornier, Inc.).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe 25-mm baseplate inserted into a small glenoid improved the primary fixation stability of the glenoid component by the mechanical effect of increased contact surface area of the anterior and posterior screws with the bone, and increased LSBS for the anterior and posterior screws. Baseplate size did not significantly affect the primary stability of the glenoid component in a large glenoid with sufficient bone stock for both 25- and 29-mm baseplates. Our results suggest that ensuring the bone contact surface area and the LSBS for the anterior and posterior screws, rather than the contact surface area between the bone and the baseplate back surface, is an important consideration for adjusting the circular baseplate size, depending on glenoid size, to enhance the primary fixation stability of the glenoid component. For patients with small glenoids, adjusting the baseplate size using a smaller baseplate (e.g., 25-mm) matching the anatomical size is recommended to maintain optimal fixation stability of the glenoid component, whereas adjusting the baseplate size to the glenoid does not affect the primary fixation stability and baseplate size selection can be more flexible for patients with large glenoids. We believe that our findings could help provide information on the criteria for selecting the base plate size, based on the patient's glenoid size. Further studies are needed to determine whether baseplate size affects the fixation stability of the glenoid component differently, depending on the other baseplate design configurations (i.e., shape or central fixation type).\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e3D, three dimensional; CT, computed tomography; FE, finite element; LSBS, length of the supporting bone stock; RTSA, reverse total shoulder arthroplasty\u003cstrong\u003e\u003cbr\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and informed consent\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe hospital\u0026rsquo;s IRB does not review cadaver studies that do not identify or use individuals\u0026rsquo; personal information. Thus, IRB approval and informed consent were not required for this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this study are included in this published article. The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2019R1I1A1A01062350). This work was supported by the New Faculty Research Support Grant from Gyeongsang National University in 2025, GNU-NFRSG-0047.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSYK conceptualized the study and participated in the research design, data interpretation, drafting and revising the paper, and the final approval of the manuscript. SWC participated in the acquisition and analysis of data and drafting the paper. All authors approved the final version of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBoileau P, Gonzalez JF, Chuinard C, Bicknell R, Walch G. Reverse total shoulder arthroplasty after failed rotator cuff surgery. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2009;18:600\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eCuff D, Pupello D, Virani N, Levy J, Frankle M. Reverse shoulder arthroplasty for the treatment of rotator cuff deficiency. J Bone Joint Surg Am.\u003cem\u003e \u003c/em\u003e2008;90:1244\u0026ndash;51.\u003c/li\u003e\n\u003cli\u003eAustin L, Zmistowski B, Chang ES, Williams GR, Jr. Is reverse shoulder arthroplasty a reasonable alternative for revision arthroplasty? Clin Orthop Relat Res.\u003cem\u003e \u003c/em\u003e2011;469:2531\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eSmith CD, Guyver P, Bunker TD. Indications for reverse shoulder replacement: A systematic review. J Bone Joint Surg Br.\u003cem\u003e \u003c/em\u003e2012;94:577\u0026ndash;83.\u003c/li\u003e\n\u003cli\u003eAcevedo DC, Vanbeek C, Lazarus MD, Williams GR, Abboud JA. Reverse shoulder arthroplasty for proximal humeral fractures: Update on indications, technique, and results. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2014;23:279\u0026ndash;89.\u003c/li\u003e\n\u003cli\u003eFlatow EL, Harrison AK. A history of reverse total shoulder arthroplasty. Clin Orthop Relat Res.\u003cem\u003e \u003c/em\u003e2011;469:2432\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eChebli C, Huber P, Watling J, Bertelsen A, Bicknell RT, et al. Factors affecting fixation of the glenoid component of a reverse total shoulder prothesis. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2008;17:323\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eGuery J, Favard L, Sirveaux F, Oudet D, Mole D, et al. Reverse total shoulder arthroplasty. Survivorship analysis of eighty replacements followed for five to ten years. J Bone Joint Surg Am.\u003cem\u003e \u003c/em\u003e2006;88:1742\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eZumstein MA, Pinedo M, Old J, Boileau P. Problems, complications, reoperations, and revisions in reverse total shoulder arthroplasty: A systematic review. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2011;20:146\u0026ndash;57.\u003c/li\u003e\n\u003cli\u003eWierks C, Skolasky RL, Ji JH, McFarland EG. Reverse total shoulder replacement: Intraoperative and early postoperative complications. Clin Orthop Relat Res.\u003cem\u003e \u003c/em\u003e2009;467:225\u0026ndash;34.\u003c/li\u003e\n\u003cli\u003eHopkins AR, Hansen UN, Bull AM, Emery R, Amis AA. Fixation of the reversed shoulder prosthesis. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2008;17:974\u0026ndash;80.\u003c/li\u003e\n\u003cli\u003eHarman M, Frankle M, Vasey M, Banks S. Initial glenoid component fixation in \u0026quot;reverse\u0026quot; total shoulder arthroplasty: A biomechanical evaluation. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2005;14:162S\u0026ndash;7S.\u003c/li\u003e\n\u003cli\u003eJames J, Huffman KR, Werner FW, Sutton LG, Nanavati VN. Does glenoid baseplate geometry affect its fixation in reverse shoulder arthroplasty? J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2012;21:917\u0026ndash;24.\u003c/li\u003e\n\u003cli\u003eRoche CP, Stroud NJ, Flurin PH, Wright TW, Zuckerman JD, et al. Reverse shoulder glenoid baseplate fixation: A comparison of flat-back versus curved-back designs and oval versus circular designs with 2 different offset glenospheres. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2014;23:1388\u0026ndash;94.\u003c/li\u003e\n\u003cli\u003eMiddernacht B, Van Tongel A, De Wilde L. A critical review on prosthetic features available for reversed total shoulder arthroplasty. Biomed Res Int.\u003cem\u003e \u003c/em\u003e2016;2016:3256931.\u003c/li\u003e\n\u003cli\u003eChae SW, Kim SY, Lee H, Yon JR, Lee J, et al. Effect of baseplate size on primary glenoid stability and impingement-free range of motion in reverse shoulder arthroplasty. BMC Musculoskelet Disord.\u003cem\u003e \u003c/em\u003e2014;15:417.\u003c/li\u003e\n\u003cli\u003eAthwal GS, Faber KJ. Outcomes of reverse shoulder arthroplasty using a mini 25-mm glenoid baseplate. Int Orthop.\u003cem\u003e \u003c/em\u003e2016;40:109\u0026ndash;13.\u003c/li\u003e\n\u003cli\u003eJi JH, Jeong JY, Song HS, Ok JH, Yang SJ, et al. Early clinical results of reverse total shoulder arthroplasty in the korean population. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2013;22:1102\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eJha SC, Fukuta S, Wada K, Higasino K, Amari-Kita R, et al. Optimizing baseplate position in reverse total shoulder arthroplasty in small-sized japanese females: Technical notes and literature review. J Med Invest.\u003cem\u003e \u003c/em\u003e2016;63:8\u0026ndash;14.\u003c/li\u003e\n\u003cli\u003eFrankle MA, Teramoto A, Luo ZP, Levy JC, Pupello D. Glenoid morphology in reverse shoulder arthroplasty: Classification and surgical implications. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2009;18:874\u0026ndash;85.\u003c/li\u003e\n\u003cli\u003eStephens BF, Hebert CT, Azar FM, Mihalko WM, Throckmorton TW. Optimal baseplate rotational alignment for locking-screw fixation in reverse total shoulder arthroplasty: A three-dimensional computer-aided design study. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2015;24:1367\u0026ndash;71.\u003c/li\u003e\n\u003cli\u003eAhir SP, Walker PS, Squire-Taylor CJ, Blunn GW, Bayley JI. Analysis of glenoid fixation for a reversed anatomy fixed-fulcrum shoulder replacement. J Biomech.\u003cem\u003e \u003c/em\u003e2004;37:1699\u0026ndash;708.\u003c/li\u003e\n\u003cli\u003eNigro PT, Gutierrez S, Frankle MA. Improving glenoid-side load sharing in a virtual reverse shoulder arthroplasty model. J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2013;22:954\u0026ndash;62.\u003c/li\u003e\n\u003cli\u003eGutierrez S, Walker M, Willis M, Pupello DR, Frankle MA. Effects of tilt and glenosphere eccentricity on baseplate/bone interface forces in a computational model, validated by a mechanical model, of reverse shoulder arthroplasty. 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Predictors of scapular notching in patients managed with the delta iii reverse total shoulder replacement. J Bone Joint Surg Am.\u003cem\u003e \u003c/em\u003e2007;89:588\u0026ndash;600.\u003c/li\u003e\n\u003cli\u003eChae SW, Lee H, Kim SM, Lee J, Han SH, et al. Primary stability of inferior tilt fixation of the glenoid component in reverse total shoulder arthroplasty: A finite element study. J Orthop Res.\u003cem\u003e \u003c/em\u003e2016;34:1061\u0026ndash;8.\u003c/li\u003e\n\u003cli\u003eWall B, Nove-Josserand L, O\u0026apos;Connor DP, Edwards TB, Walch G. Reverse total shoulder arthroplasty: A review of results according to etiology. J Bone Joint Surg Am.\u003cem\u003e \u003c/em\u003e2007;89:1476\u0026ndash;85.\u003c/li\u003e\n\u003cli\u003eHoenig MP, Loeffler B, Brown S, Peindl R, Fleischli J, et al. Reverse glenoid component fixation: Is a posterior screw necessary? J Shoulder Elbow Surg.\u003cem\u003e \u003c/em\u003e2010;19:544\u0026ndash;9.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Reverse total shoulder arthroplasty, Adjusting the size, Baseplate, Glenoid, Biomechanical effect, Primary fixation stability","lastPublishedDoi":"10.21203/rs.3.rs-7738651/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7738651/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eThe optimal baseplate size for reverse shoulder arthroplasty in patients with varying glenoid dimensions remains controversial. In this study, we comparatively evaluated the biomechanical effects of adjusting the baseplate size to different glenoid dimensions on primary fixation stability and analyzed the structural relationship between the baseplate and glenoid when adjusting the baseplate size to the glenoid size in reverse total shoulder arthroplasty.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe evaluated the primary fixation stability and structural relationship of the glenoid components with two different baseplate sizes (25- vs. 29-mm diameter) with a circular design in different glenoid sizes (i.e., small vs. large) using finite element analysis. Three-dimensional finite element models were constructed from 14 cadaveric scapulae and glenoid components with 25- and 29-mm baseplates. The relative micromotion of the bone\u0026ndash;baseplate interface, distribution of bone stress under the baseplate and around the screws, contact surface area between the bone and baseplate back surface, contact surface area between the bone and screws, and length of the supporting bone stock (LSBS) for screws were analyzed.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eCompared with the 29-mm baseplate, the 25-mm baseplate improved the primary fixation stability of the glenoid component in the small glenoid via the biomechanical effect of increased contact surface area of the anterior and posterior screws with the bone and increased LSBS of the anterior and posterior screws. In the large glenoid, baseplate size did not significantly affect the primary fixation stability of the glenoid component.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eIn the small glenoid, adjusting the baseplate size using a small baseplate matching the anatomical size improves primary fixation stability of the glenoid component. Optimizing bone-screw contact and LSBS is critical for baseplate stability in the small glenoid. However, in the large glenoid with sufficient bone stock, adjusting the baseplate size to the glenoid does not affect the primary fixation stability. Baseplate size selection can be more flexible in the large glenoid without compromising primary fixation stability.\u003c/p\u003e","manuscriptTitle":"The effect of adjusting the baseplate size to the glenoid on primary fixation stability in reverse total shoulder arthroplasty: A finite element analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-17 02:10:03","doi":"10.21203/rs.3.rs-7738651/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-13T06:21:28+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-11T14:45:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-08T12:05:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"146978343953469082615849619911328734637","date":"2025-10-06T14:58:13+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-06T00:09:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"110323214686871534354092848717787170054","date":"2025-10-03T11:26:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"326851313123684983290296989219035979751","date":"2025-10-03T10:32:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"60804444983447063898239465404828772862","date":"2025-10-03T09:57:38+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-03T09:47:42+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-02T07:17:04+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-01T05:15:36+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Orthopaedic Surgery and Research","date":"2025-09-29T06:24:45+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"75db8b6a-c387-4608-a5e2-f38380c27adc","owner":[],"postedDate":"October 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-05T16:03:09+00:00","versionOfRecord":{"articleIdentity":"rs-7738651","link":"https://doi.org/10.1186/s13018-025-06615-0","journal":{"identity":"journal-of-orthopaedic-surgery-and-research","isVorOnly":false,"title":"Journal of Orthopaedic Surgery and Research"},"publishedOn":"2026-01-01 15:57:50","publishedOnDateReadable":"January 1st, 2026"},"versionCreatedAt":"2025-10-17 02:10:03","video":"","vorDoi":"10.1186/s13018-025-06615-0","vorDoiUrl":"https://doi.org/10.1186/s13018-025-06615-0","workflowStages":[]},"version":"v1","identity":"rs-7738651","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7738651","identity":"rs-7738651","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}