BackgroundAnatomical variations in the branching patterns of the aortic arch affect endovascular access, surgical planning, and cerebral perfusion strategies. However, the quantitative relationship between branching topology and the frequency distribution of these variations remains unclear. We aimed to explore whether topological differences among final aortic arch branching configurations are associated with their reported frequencies.MethodsThis retrospective, cross-sectional, observational study analyzed seven representative aortic arch branching types as independent anatomical phenotypes using data derived from a large meta-analysis. Each configuration was quantified using two newly defined topological indices: the Node-Shift Score, representing differences in the relative positions of branching nodes, and the Edge-Loss-Change Score, describing alterations in arterial connectivity relative to the reference configuration. Regression analyses using linear, logarithmic, and exponential models were performed to evaluate the relationship between the topological scores and frequencies.ResultsHigher topological scores were associated with lower configuration frequencies. In the exponential model, each one-unit increase in the Node-Shift Score and Edge-Loss-Change Score was associated with approximately 0.11-fold and 0.013-fold decreases in configuration frequency, respectively.ConclusionsThe frequency distribution was described by an exponential model based on the two topological scores. This study proposes an exploratory quantitative framework for characterizing the frequency distribution of common and rare aortic arch branching configurations from a topological perspective.

Cervical myelopathy (CM) often presents with gait disturbances, which can lead to falls and spinal cord injury. As the presence of gait disturbances negatively affects postoperative improvement in patients with CM, early detection of gait disturbances is crucial. However, current gait analysis methods require specialisation, limiting their feasibility for screening. This study aimed to perform gait analysis in patients with CM using wearable in-shoe inertial measurement unit (IMU) sensors and to develop a screening system using machine learning. This study included 26 patients with CM and 26 age-matched healthy controls. Gait parameters were measured using IMU sensors while participants walked along a 16 m corridor. Eleven gait parameters and their coefficients of variation (CV) were analysed. A machine learning model using the extreme gradient boosting algorithm was developed for CM classification. Patients with CM exhibited significantly lower gait speed, stride length, dorsiflexion angle, plantarflexion angle, and foot height, along with increased stance time and stance phase. CVs of gait parameters were higher in patients with CM, with an increased stance phase observed from the early stages. The classification model achieved high performance (AUC = 0.89, sensitivity = 81

Hip arthroscopy requires a capsulotomy to achieve adequate visualization and access; however, an excessive incision can increase the risk of postoperative instability. This technical note describes a less-invasive capsulotomy technique guided by the "gluteus minimus sign," a fibrous membrane connecting the main tendon of the gluteus minimus to the joint capsule. Cadaveric analysis confirmed that this fibrous membrane corresponds to the anterosuperior region of the femoral neck. Most gluteus minimus functions can be preserved by limiting the anterior extension of the capsulotomy to within this sign. When additional anterior exposure is necessary, superficial tendon fibers can be incised using an arthroscopic knife. This technique offers a safe, anatomically informed, and strategically targeted capsulotomy that balances preservation of joint stability with adequate surgical access.

Accurate and efficient image segmentation is crucial in anatomy, histology, and pathology research. Conventional manual approaches are time-consuming, whereas fully automated artificial intelligence segmentation requires substantial manual correction owing to inaccuracy. To address this, we developed SegRef3D, a tool integrating the Segment Anything Model 2 with multiframe tracking and interactive refinement functions, enabling streamlined segmentation workflows for anatomical research. SegRef3D is implemented as a standalone, offline desktop application that operates entirely in a local environment, eliminating the need for cloud-based services. SegRef3D provides a unified workflow from data import to segmentation, object tracking, refinement, and three-dimensional model export. Users can specify segmentation prompts through bounding box input, track objects across multiple frames with start-end range selection, and refine results using intuitive Add to Mask and Erase from Mask tools. Up to 20 objects can be handled simultaneously, with each assigned a unique color. The software supports the Standard Tessellation Language output for three-dimensional modeling and includes volume measurement functions. The SegRef3D prototype, called Seg&Ref, has been applied in studies using serial histological sections, correlative microscopy with block-face imaging, and pelvic magnetic resonance imaging. Building on these applications, SegRef3D further enhances usability and enables a seamless workflow. SegRef3D offers an accessible, efficient, and accurate segmentation environment tailored for morphological and anatomical studies. Combining artificial intelligence-powered automatic segmentation with human-guided refinement in a user-friendly graphical user interface bridges the gap between research needs and computational methods. By supporting applications that span traditional anatomy and modern pathology, SegRef3D provides a versatile platform for integrative morphological analysis. Its open-source availability ensures its broad applicability in research, education, and clinical training in the anatomical sciences.

The accurate alignment of serial histological sections is essential for preserving anatomical continuity in 3D reconstruction. Although automated registration tools can efficiently correct global alignment errors, they often fail to resolve local misalignments caused by sectioning artifacts, tissue deformation, staining variability, or missing slices. Thus, we propose a practical two-step registration workflow that uses MultiStackReg (an ImageJ/Fiji plugin) for automatic alignment and AlignRef (a standalone application for interactive adjustment) for manual refinement. In the first step, MultiStackReg performs global registration by using rigid body transformations. In the second step, AlignRef corrects residual misalignments through semi-transparent overlay visualization, keyboard-based translation and rotation, and batch propagation of recorded transformations across selected slice ranges. We applied our workflow to 135 serial sections of a Carnegie Stage 15 embryo from the Virtual Human Embryo dataset that were stained with hematoxylin and eosin. MultiStackReg resolved most global inconsistencies, whereas AlignRef enabled the precise adjustment of subtle local deviations, particularly in curved structures such as neural tubes and limb buds. After automatic registration with MultiStackReg, the subsequent manual refinement step using AlignRef was completed in approximately 30 min and produced a suitable stack for 3D reconstruction. This two-step workflow balances automation with expert-guided correction and provides an accessible, reproducible, and anatomically precise method for the serial section alignment of morphological and developmental anatomy.

We aimed to clarify the attachment architecture between the levator ani and the rectum and vagina using integrated macroscopic and histological analyses of human pelvic floor specimens. Macroscopic dissection demonstrated whitish soft tissue at the interface between the levator ani and the lateral walls of the rectum and vagina. Histological and immune histochemical analyses of the corresponding regions revealed abundant smooth muscle components that appeared topographically continuous with the outer muscular layers of each organ within individual coronal sections. In both organs, the smooth muscle extended beyond the organ walls, spread over the superior and inferior surfaces of the levator ani, and interdigitated between skeletal muscle bundles, forming a serrated (saw tooth-like) interface. No dense connective tissue structures resembling tendons or aponeuroses were identified, indicating that levator ani–visceral attachment does not conform to a classical tendon-mediated enthesis. Distinct attachment patterns were observed between the two organs. At the rectal interface, a subset of levator ani muscle fibers coursed toward smooth muscle that appeared topographically continuous with the rectal longitudinal layer and formed an insertion-like arrangement. In contrast, at the vaginal interface, no insertion-like arrangement of levator ani muscle fibers into the vaginal wall was observed. Abundant vaginal smooth muscle extended laterally and enveloped adjacent levator ani muscle bundles. These findings provide a clearer anatomical characterization of a non-tendinous skeletal–smooth muscle interface between the levator ani and deformable pelvic visceral walls. This provides an anatomical basis for future studies investigating how the levator ani interacts mechanically with these deformable pelvic organs.

In rectal cancer surgery, dissection on either side of the endopelvic fascia (EPF) determines whether this layer remains on the pelvic wall or is included with the specimen. However, its continuity with adjacent pelvic wall and rectal supporting tissues, and the anatomical meaning of these local dissection planes, remain unclear. This cadaveric study aimed to clarify the macroscopic and histological characteristics of the EPF in relation to the obturator fascia, rectal wall, and hiatal ligament. Macroscopic examination of three formalin-fixed cadavers assessed fascial architecture around the levator ani, obturator internus, and rectum. Histological analysis of eight formalin-fixed cadavers used Masson’s trichrome staining and α-smooth muscle actin immunohistochemistry. EPF thickness was measured in six specimens at defined distances from the obturator fascia and rectal wall. The EPF formed a dense connective tissue layer on the superior surface of the levator ani and continued laterally into the obturator fascia without a distinct boundary. Medially, it transitioned into interfascicular connective tissue between rectal longitudinal muscle bundles and the smooth muscle-rich hiatal ligament. In four obturator-side specimens, thickness ranged from 0.03 to 0.65 mm. In two rectal side specimens, thickness at the rectal interface was 1.69 and 2.82 mm; these limited descriptive observations do not establish a regional difference. The EPF is continuous with pelvic wall and rectal supporting tissues rather than a discrete membrane. These cadaveric findings define its local morphology but do not establish implications for surgical dissection planes, circumferential resection margin status, operative or oncological outcomes, or pelvic function.

The acetabular labrum plays an essential role in resisting distraction stress by closely coupling the femoral head. A previous cadaveric study suggested that specific hip postures allow the joint capsule to approximate the labrum, potentially enhancing labral adherence to the femoral head. However, whether such position-dependent changes occur in vivo remains unclear. This study aimed to investigate differences in the capsulolabral gap-the distance between the anterosuperior-joint capsule and labrum-between the hip neutral and flexion-abduction-external rotation (FABER) positions, and the location where these differences occur. Twenty-four hips of 24 healthy volunteers were examined using magnetic resonance imaging. A capsulolabral gap was evident around the anterior inferior iliac spine (AIIS) in the hip neutral but not in the FABER position. The largest capsulolabral gap (2.11 ± 0.93 mm) was significantly associated with the AIIS location (r = 0.65, p = 0.004). The maximal gap distance in the hip neutral position was positively significantly correlated with the articular-cavity area at the femoral neck in FABER (r = 0.85, p < 0.001). The capsulolabral gap around the AIIS in the hip neutral position was reduced in FABER owing to close capsule-labrum contact as the entire joint capsule changed, suggesting that the hip capsule contributes to a position-dependent labral-support mechanism.

Purpose The tissue deep to the posterior wall of the inguinal canal, between the transversalis fascia and peritoneum, remains insufficiently understood. We aimed to develop a compartment-like three-dimensional morphological model of this tissue by clarifying its structure-associated organization, continuity, and spatial relationships around the deep inguinal ring. Methods Five inguinal regions from three formalin-fixed adult male cadavers were examined: one by anterior dissection, three by peritoneal dissection, and one by serial block-face imaging using the CoMBI system. Three-dimensional reconstruction was performed from the serial block-face images. Results The tissue between the transversalis fascia and peritoneum was not arranged as a uniform layer of preperitoneal fat. Three structure-associated fibroadipose units related to the inferior epigastric vessels, ductus deferens, and testicular vessels were delineated, together with the vesicoumbilical fibroadipose territory (VFT) and median-paramedian adipose region (MPAR). The ductus deferens- and testicular vessel-associated units extended directly toward the deep inguinal ring, whereas the inferior epigastric vessel-associated unit, VFT, and MPAR occupied adjacent territories. Conclusion The findings support a compartment-like three-dimensional morphological model in which the fibroadipose units and territories remain open and continuous, rather than a set of histologically closed, independent anatomical compartments. Distinguishing ring-directed fibroadipose units from adjacent territories may help clarify how established fascia-, space-, and ring-based concepts relate to the internal fibroadipose arrangement.

The specific anatomical features of the obturator internus, particularly those of its medial surface, remain insufficiently characterized. This study investigated the morphology of the obturator internus muscle by focusing on the shape of its medial surface and potential age-related changes. Through dissection of anatomical specimens and in vivo pelvic magnetic resonance imaging (MRI) analysis, we identified a consistent groove-like structure on the medial surface of the muscle and divided it into distinct regions: a superior portion with radiating muscle fibers and an inferior portion with parallel-aligned fibers. This division was characterized by differing fascicle orientations, with interspersed adipose tissue occasionally observed at the boundary. MRI scans of 27 women aged 25-83 years demonstrated that this groove was consistently visible; its location and depth were quantified. The groove position showed a weak negative trend with age, but this relationship was not statistically significant and may have been underpowered. No significant correlation was found for groove depth. By delineating the consistent bipartite architecture of the obturator internus and identifying its age-related variation, this study provides a detailed anatomical characterization of the medial surface of the obturator internus that may serve as a reference for future anatomical and clinical investigations involving the hip-pelvic interface.

BACKGROUND:Variations in the anatomical branching patterns of the celiac trunk and superior mesenteric artery (SMA) directly affect vascular identification, surgical planning, and risk of intraoperative vascular injury. However, despite the extensive classification of these variations, the principles governing the occurrence of certain branching patterns remain unclear. METHODS:We analyzed 28 branching subtypes of the celiac trunk-SMA system described by Adachi. Each branching pattern was quantified relative to the standard configuration by using Node-Shift (relative displacement of branching nodes), Edge-Gain (number of additional branches), and Edge-Loss (number of missing branches). The relationships between these topological parameters and branching frequency were examined using linear, log-linear, and exponential regression models. RESULTS:Branching frequency consistently decreased as topological complexity increased. In subtypes without branch loss, the branching frequency showed a strong exponential decline with increasing Node-Shift and Edge-Gain (R2 = 0.979). When all subtypes were included, the exponential model maintained a similarly high explanatory power (R2 = 0.979), whereas the linear and log-linear models showed a limited fit. Branch loss was exclusively associated with very-low-frequency patterns. CONCLUSIONS:Arterial branching variations do not arise in a purely random manner and are consistent with the probabilistic constraints of developmental and anatomical pattern formation.

PURPOSE:To clarify the histological architecture of the intersphincteric region of the anal canal by delineating the layer-specific organization and spatial relationships among the anal sphincter complex and associated muscular and connective tissue components. METHODS:Tissue blocks containing the lateral wall of the anal canal were obtained from 11 adult human cadavers donated for anatomical research. Specimens were examined using descriptive histological and immunohistochemical analyses in transverse and coronal planes. The internal and external anal sphincters, longitudinal muscle, levator ani, interbundle gaps, and connective tissue compartments were identified and analyzed with respect to their three-dimensional organization. RESULTS:The intersphincteric region exhibited a heterogeneous and layered architecture rather than a uniform plane. The longitudinal muscle demonstrated a mosaic organization consisting of dense and loose components. The dense component terminated near the mid-height of the internal anal sphincter (mean, 54% of its length), whereas the loose component expanded inferiorly and formed a spacious compartment characterized by sparse smooth muscle fibers and loose connective tissue. Inferiorly, loose longitudinal muscle fibers branched and traversed natural interbundle gaps within the external anal sphincter. In addition, two partially overlapping layers of the levator ani were consistently observed, with interposed gaps contributing to the structural complexity of the intersphincteric region. CONCLUSION:The intersphincteric region of the anal canal is a structurally complex and compartmentalized anatomical entity. Its heterogeneous histological architecture provides an anatomical substrate that may explain the initiation and directional spread of anal fistulas, including pathways described in classical fistula classifications.

Restricted elbow flexion sometimes persists even after stretching the triceps brachii. Although prior descriptions have noted that a small muscle bundle is located between the posterior elbow joint capsule and the triceps brachii, its anatomical relationship with surrounding muscles and dynamic changes during forearm rotation remain unclear. We hypothesized that the small muscle bundle separates from the triceps and contributes to forearm rotation. This study aimed to clarify the anatomical structure of the small muscle bundle and its dynamic changes during forearm rotation. We analyzed 19 elbow specimens from 16 Japanese cadavers, donated to the Department of Anatomy, Institute of Science Tokyo, to identify the small muscle bundle covering the joint capsule. One specimen was excluded because of severe osteophytes, leaving 18 specimens randomly allocated to three groups (10, 3, and 5 specimens in the macroscopic examination, intramuscular nerve distribution examination, and histological examination groups, respectively). Additionally, we investigated 10 elbows of five healthy volunteers to evaluate dynamic changes in the small muscle bundle and joint capsule using ultrasonography during forearm rotation. Anatomically, deep to the triceps brachii, a small muscle bundle covering the posterior elbow joint capsule was identified. The small muscle bundle was continuous laterally with the anconeus muscle and was separated from the triceps by loose connective tissue. The small muscle bundle and the anconeus were innervated by the same branches of the radial nerve. Ultrasonically, the small muscle bundle was found to be significantly thicker during forearm supination (6.0 ± 1.4 mm) than pronation (4.1 ± 1.0 mm; p = 0.002), and the distance between the olecranon fossa and the posterior edge of the joint capsule was significantly shorter during supination (8.9 ± 1.1 mm) than pronation (9.6 ± 1.1 mm; p = 0.023). The small muscle bundle formed a muscular complex with the anconeus and was distinct from the triceps. The small muscle bundle deep to the triceps may act during forearm rotation, affecting the posterior elbow joint capsule. These anatomical and ultrasonographic findings may contribute to a better understanding of the pathophysiology of restricted elbow flexion.

Background Biomechanical studies suggest that the triceps brachii muscle generates resistive force against valgus stress on the elbow during baseball pitching. However, given the parallel fiber orientation in the distal tendinous structure of the triceps brachii, the mechanism behind this anti-valgus force remains unclear. In the present study, we aimed to examine the anatomy of the distal tendinous structure of the triceps brachii using bony morphological, macroscopic, and histologic methods. Methods We analyzed 25 elbow specimens from 18 cadavers, all of Japanese ethnicity, using micro-computed tomography. Four specimens were excluded due to severe osteophytes, leaving 21 specimens randomly allocated to 3 groups: 13, 4, and 4 specimens to the macroscopic examination group, the histologic examination group, and the chemically d & eacute;brided bone examination group, respectively. In 6 of the 13 specimens analyzed macroscopically, we quantitatively measured the local thickness of the triceps tendon using micro-computed tomography. Results The distal tendinous portion of the triceps brachii was comprised of an intramuscular tendon and a superficial aponeurosis. The intramuscular tendon, located between the long and medial heads of the triceps, curved medially to laterally and inserted broadly onto the proximal and lateral facets via fibrocartilage. The superficial aponeurosis, attached to the lateral and medial heads, had fibers that ran straight and merged distally with the aponeurosis of the anconeus. The intramuscular tendon (2.2 +/- 0.4 mm) was significantly thicker than the superficial aponeurosis (0.9 +/- 0.2 mm, P < .001). Conclusion The current study revealed a nonuniform distal tendinous structure of the triceps brachii, with a thick intramuscular tendon and a thin superficial aponeurosis. In particular, the intramuscular tendon was curved from the medial-to-lateral direction and had a firm insertion. These findings suggest that the intramuscular tendon can contribute force to prevent valgus stress on the elbow as a dynamic stabilizer during the pitching motion.

OBJECTIVES:To anatomically and histologically define the adipose and fascial structures posterior and lateral to the kidney and propose a compartment-based anatomical model aligned with intraoperative observations. METHODS:Seven cadavers were used for macroscopic and histological analyses. In the macroscopic analysis, the spatial relationships between the perirenal fat (PeRF), pararenal fat, posterior renal fascia (PRF), and extraperitoneal fascia (EPF) were examined. Histological observations focused on the distribution and continuity of adipose compartments and the organization of the surrounding dense fibrous connective tissue. RESULTS:Macroscopically, the EPF covered the anteromedial pararenal fat and extended posteriorly to the kidney. Upon incision, a small amount of adipose tissue was observed directly beneath it. Removing this TAC exposes the peritoneum and PRF with a clear demarcation between them. Histological analysis confirmed that the posterior renal and EPF were distinct, with dense connective tissue structures enclosing a separate TAC. This compartment extended anteriorly between the PeRF and peritoneum, and laterally between the peritoneum and EPF. These extensions converge near the peritoneal reflection in the lateral renal region, forming a characteristic triradiate configuration of adipose tissue. CONCLUSIONS:Our findings challenge the classical notion that the renal fascia is a single continuous layer, supporting a compartment-centered anatomical model. The posterior and lateral regions of the kidney contain a distinct third adipose compartment, bordered by the posterior renal and extraperitoneal fasciae. This model offers improved anatomical clarity and may aid understanding during laparoscopic, retroperitoneoscopic, and robot-assisted surgeries.

Background: The hip pericapsular muscles, such as the iliopsoas, gluteus minimus (GMi), complex of the gemelli muscles and obturator internus (OI-complex), and obturator externus (OE), are recognized as vital in hip stability. However, their specific roles in hip stability are still debated. For anatomically elucidating how the pericapsular muscles can act on the femoral head and neck via the joint capsule, this study aimed to investigate their arrangement on the joint capsule with the positional relation to the femoral head and neck and also histological characteristics in anatomic specimens and healthy volunteers. Methods: Eight hips from seven donors (average age, 72.5 years) fixed with 8% formalin were anatomically analyzed. Five hips were macroscopically assessed and three hips, histologically. Ten hips from ten volunteers (average age, 25.3 years) were also analyzed using magnetic resonance imaging (MRI) from center of the femoral head to base of the femoral neck. Results: The pericapsular muscles macroscopically arranged in spiral pattern and ran clockwise around the femoral neck axis on the joint capsule at the right hip as viewed from the outside. The GMi had the histological continuity to the joint capsule via the tendon, the other pericapsular muscles, via their perimysium. On the oblique-sagittal MRIs perpendicular to the femoral neck axis, the iliopsoas on the joint capsule was longitudinally visualized at 1:30–6:30 clock position of the femur. It ran clockwise at the right hip as viewed from the outside without difference in running pattern between slices. The OE were transversely visualized at 6:30–11:00, OI-complex, 8:00–11:30, and GMi, 10:30–1:30. These muscles shifted clockwise at the right hip as viewed from the outside between consecutive slices. Conclusions: The pericapsular muscles arranged even in-vivo on the joint capsule in spiral pattern with histological continuity to the joint capsule. The pericapsular muscles may play an essential role in maintaining the centric position of the femoral head by balancing their centripetal force, which is associated with their spiral contraction forces, via the joint capsule.

Transanal total mesorectal excision for rectal cancer in men poses a risk of urethral injury. The morphology of smooth muscle tissues around the rectum is reportedly characterized by differences in fiber density; however, quantitative analysis of these tissues for surgical applications is lacking. This study aimed to quantitatively analyze the histological properties of fiber density and the spatial extent of the smooth muscle anterior to the male rectum. This descriptive cadaveric study involving six adult cadavers was conducted at the Tokyo Medical and Dental University. Serial histological sections were prepared from tissues in the region anterior to the rectum, and immunostaining and 3D reconstruction were performed to evaluate the spatial distribution of the smooth muscle. Smooth muscle fiber densities were measured in different regions of the smooth muscle anterior to the rectum and statistically analyzed. The three-dimensional heat map revealed a gradual change in fiber density within the smooth muscle anterior to the rectum, with lower density in the superior part and higher density in the inferior part. In mid-sagittal immunostained sections, the smooth muscle anterior to the rectum exhibited a significant difference in fiber density, averaging 23.22

ObjectivesAdvances in diagnosing carpal tunnel syndrome (CTS) using ultrasonography (US) and artificial intelligence (AI) aim to replace nerve conduction studies. However, a method for accurate severity diagnosis remains unachieved. We explored the potential of comprehensive video data formats for constructing an effective model for diagnosing CTS severity. MethodsWe studied 75 individuals (52 with CTS) from 2019 to 2022, categorizing them into 3 groups based on disease severity. We recorded 132 US videos of carpal tunnel during finger movement. Features of the median nerve (MN) were extracted from automatically segmented US video frames, from which 3 datasets were created: a comprehensive video dataset with full information, a key metrics dataset, and an initial frame dataset with the least information. We compared the accuracy of machine learning algorithms for classifying CTS severity into 3 groups across these datasets using 63-fold cross-validation. ResultsThe cross-sectional area of the MN correlated with severity (P < .05) but MN displacement did not. The algorithm using the comprehensive video dataset exhibited the highest sensitivity (1.00) and accuracy (0.75). ConclusionsOur study demonstrated that utilizing comprehensive video data enables a more accurate US-based diagnosis of CTS severity. This underscores the value of capturing the patterns of MN deformation and movement, which cannot be captured by representative metrics such as medians or maximums. By further developing an AI model based on our findings, a simpler and painless method for assessing CTS severity can be achieved.

Purpose: Few clinical studies have compared the operative outcomes between loose- and press-fit stems in radial head arthroplasty (RHA). We aimed to evaluate the radiographic and clinical results of the two radial head implant concepts. Methods: In this retrospective multicenter study, 32 patients (24 women and 8 men) with a mean age of 63.1 years who underwent RHA for comminuted radial head fractures were reviewed between 2005 and 2021. Seventeen patients underwent RHA with a loose-fit stem (L-group), whereas the remaining fifteen patients underwent RHA with a press-fit stem (P-group). The mean follow-up period was 40.1 +/- 9.9 months, with the minimum follow-up duration of 12 months. The radiographic findings were evaluated for periprosthetic osteolysis; furthermore, clinical outcomes were analyzed to measure the range of motion of the elbow. The rate of reoperations and prosthesis removal were also reviewed. Results: The general characteristics of the patients were similar in the two groups. The rate of periprosthetic osteolysis was 17.6% in the L-group, whereas it was 53.3% in the P-group. The mean elbow flexions were 128 degrees and 133 degrees in the L- and P-groups, respectively. The mean elbow extensions were -12 degrees and -9 degrees in the L- and P-groups, respectively. The rate of reoperation was 23.5% in the L-group and 15.2% in the P-group. One patient in the L-group had the prosthesis removed because of surgical site infection, whereas one patient in the P-group had the prosthesis removed owing to painful loosening. Conclusions: No significant differences in the clinical outcomes and reoperation rate were observed between the two radial head implant concepts in this study. However, osteolysis occurred more frequently in the P-group. Although patients with periprosthetic osteolysis are currently asymptomatic, they should be carefully followed up for the symptoms in the long term. (c) 2024 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

Assessing the flexibility of spine and hip joints is essential for providing appropriate treatment for non-specific low back pain. In general, posture assessment is subjective, and its reliability depends on the experience of physiotherapists. Therefore, there is a need for an automated tool that enables physiotherapists with any level of experience to carry out standardized posture assessments. In this paper, we propose image processingbased automated assessment models of multi-segmental flexion, extension, and rotation postures to comprehensively assess the movements in sagittal and axial planes. In order to achieve detailed movement assessment in the sagittal plane, we used body trunk shape-based features in addition to key points-based features such as angles of joints. Using 94 healthy participants’ data annotated by a musculoskeletal rehabilitation expert, we evaluated the accuracy of our assessment models and confirmed improvements by use of our body trunk shape-based features. Additionally, we discuss the pilot deployment of our models as a supporting tool for posture assessment.