The neural crest is an important stem cell population characterized by its multipotency, migratory behaviour and broad ability to differentiate into numerous derivatives throughout the vertebrate body, as diverse as cell types contributing to the cardiovascular system, craniofacial skeleton, peripheral nervous system and pigmentation of the skin. The developmental trajectory of the neural crest is governed by a complex gene regulatory network (GRN) that mediates induction and specification at the neural plate border, emergence of neural crest cells (NCCs) from the neural tube, their migration through the periphery and cell fate determination en route to different final destinations. In this Review, we discuss the significant progress in investigating the neural crest GRN, which has increased our understanding of how NCCs impact vertebrate development and evolution, their role in adult tissue regeneration and their contribution to diseases derived from abnormalities in NCCs.

Background/Objectives: When analyzing human skeletal remains for human identification, the assessment of sexual dimorphism is fundamental because it underlies sex estimation, a key parameter of the biological profile, which reduces the number of candidates to approximately one half. Ideally, the most dimorphic bones (the pelvis and long bones) are used, but this analysis may be compromised when the skeletal remains are badly preserved, which is often the case in older skeletons. It is, therefore, necessary to investigate sexual dimorphism in alternative skeletal elements as the quantity and quality of bone structures present in ancient skeletons represent crucial aspects when assessing biological differences between the sexes. The present study aims to evaluate the degree of sexual dimorphism in selected skeletal elements as a preliminary step toward identifying sexually dimorphic parameters with potential applicability in future research on poorly preserved skeletons. Methods: A metric assessment of sexual dimorphism was performed on the clavicle, sternum, and seventh cervical vertebra from a 20th Century collection of identified skeletons from the Portuguese population from CESPU (CEIC), showing a variable degree of bone preservation. Results: Our preliminary data suggest that although all bones analyzed may have exhibited some degree of sexual dimorphism, five parameters—sternal body length, manubrium width, first stern-vertebrae width, clavicle maximum length, and cervical vertebral body height—showed the most promising results. Nevertheless, further studies are needed to validate these observations, using a bigger sample of badly preserved bones. Conclusions: These results represent a preliminary assessment of sexually dimorphic parameters, which may be of interest in circumstances where skeletal elements are poorly preserved.

The use of deep-learning (DL) models to support and automate medical imaging diagnostic procedures has become an ongoing focus of research and development. Despite advances in the subject, the integration of such solutions into clinical diagnostic workflows remains challenging. Especially focused on end users, the integration of image-based diagnostic functionalities and access to DL models in a single framework is key to ensuring clinical adoption and usability. This paper proposes a native integration strategy that enables the direct use of DL segmentation models within a CE-marked open-source DICOM viewer without relying on external software, containerised environments, or complex APIs. Unlike previous approaches, which often require technical expertise or infrastructure overhead, the proposed method embeds the model execution pipeline directly into the viewer via a dedicated DL module, maintaining compatibility with clinical standards and allowing model parameters to be set directly from the interface or via a configuration file. To validate the feasibility and versatility of this native integration strategy, two use cases are implemented using models trained in different DL libraries: vertebral bodies segmentation and liver segmentation. The approach proves compatible with heterogeneous model architectures, requires minimal user interaction, and preserves clinical usability without disrupting existing workflows. A new DL integration methodology is presented that combines simplicity, flexibility, and clinical readiness. The proposed framework represents a significant step towards standardised, viewer-native deployment of DL tools, facilitating their adoption in regulated healthcare environments and enabling efficient sharing and reuse of DL models across institutions.

A novel bicortical alternating screw exchange lagging technique for reduction of cervical spinal deformity.

Postoperative function of lower extremity muscles and walking ability after total en bloc spondylectomy for lumbar spinal tumors.

Neural crest cells (NCCs) are a key component of the vertebrate body plan and contribute to a variety of different traits. Recent advances in single-cell transcriptomics (scRNA-seq) have significantly improved our understanding of NCC biology. However, their dynamic migratory behavior and spatiotemporal heterogeneity in the developing embryo pose significant challenges for their identification and isolation. Consequently, most studies of NCCs have been confined to model organisms with established transgenic tools or established methods for in ovo manipulation. To overcome this limitation, we present a novel approach that combines antibody labeling with fluorescence activated cell sorting to enrich for NCCs and we demonstrate the approach in the common wall lizard (Podarcis muralis). Through microscopy, reverse transcription quantitative polymerase chain reaction and single-cell RNA sequencing, we show that the method enriches for NCCs as efficiently as methods relying on transgenic animals. Using this technique, we successfully characterize transcriptional profiles of NCCs in wall lizard embryos. We anticipate that this method can be applied to a wide range of vertebrates that lack transgenic tools, enabling deeper insights into the diverse roles of neural crest cells in development and evolution.

In anterior lumbar interbody fusion, implant subsidence remains a major complication, influenced by both patient- and implant-related factors. Cage sizing has been shown to influence the subsidence load and is dependent on both the surgical approach and the patient's anatomic characteristics. Larger cage footprints have been shown to increase axial stability by allowing for a greater area of contact, but their limited sizes and footprints are not always able to accommodate the significant variance in vertebral body shape, endplate dimensions, and epiphysial rim depth. Therefore, the current study aims to quantify the incremental resistance to subsidence conferred by the use of novel endplate-specific expandable implants over conventional, static implants. Fifteen cadaveric spines were reconstructed via computed tomography (CT) scans of the L5 vertebra, and the endplates and cortical shell were isolated from the inner trabecular core to recreate bone surrogates. The novel implant was positioned on each bone surrogate in the unexpanded (control) or expanded (endplate-specific expandable) configuration and compressed at a rate of 5mm/min. The subsidence load and construct stiffness were evaluated for each group. The subsidence load of the expandable implants quantified in 3478 N ± 588 was 20% greater than that of the control group (p < 0.05). No difference was found in construct stiffness (p > 0.05). There was no correlation (r = 0.260, p = 0.350) between the stiffness and epiphyseal rim contact, whereas a positive correlation (r = 0.796, p < 0.001) was found between the subsidence load and increased epiphyseal rim contact in the expandable implant group only. In our study, endplate-specific expandable ALIF implants have shown higher resistance to subsidence than static implants. While, these results must be corroborated by clinical data, the superiority here identified indicates the potential for these implants to be advantageous over static implants. The linear correlation between the epiphyseal rim cross-sectional area of the endplate and the subsidence load, as found in the current study, highlights the potential for estimating the subsidence load during preoperative planning.

The neurocentral synchondrosis (NCS) may play an essential role in the formation and progression of scoliosis in pediatric populations. Previous experimental studies have primarily focused on modulating NCS growth through epiphysiodesis with unilateral pedicle screw fixation, which is associated with significant trauma. However, no study has explored the effect of minimally invasive intervention on the NCS to date. Fifteen 6-week-old piglets were randomly assigned to three groups, each containing five animals. In the NCS group, the piglets were subjected to microwave ablation (MWA) of the NCS on the left side under CT guidance. In the sham group, the ipsilateral NCS was punctured under CT guidance, but no particular intervention was carried out, and the puncture needles were removed. In the control group, no intervention was performed. CT scans of the spinal alignment were obtained and analyzed every month after the respective interventions. No scoliotic curvature developed in the sham and control groups. A structured scoliosis was observed in all five animals of the NCS group at the first month following the intervention, with increasing deformity every month. All curves were located at the operated levels, with the convexity toward the unablated side. The coronal angle was 13.46 ± 1.62°, 15.49 ± 1.51°, and 19.63 ± 3.22° in the NCS group at the first, second, and third months following the operation, respectively. The height of the vertebral body and the pedicle length on the ablated side in the NCS group decreased compared to those of the other two groups and the contralateral side, showing significant differences. In addition, the spinal canal area in the NCS group was significantly smaller than that of the sham and control groups. Mild vertebral rotation was observed in the NCS group. Histological analysis revealed unilateral chondrocyte necrosis and fibrotic remodeling of NCS at the ablated area. Unilateral ablation of the NCS under CT guidance is a minimally invasive procedure that can effectively modulate asymmetric growth of the spine in piglets, leading to scoliosis with convexity toward the unablated side. The ablation of the NCS can adversely affect the growth of the vertebral height, pedicle length, and spinal canal in piglets.

Abstract Cauda equina syndrome (CES) associated with dural ectasia is a rare manifestation in patients with ankylosing spondylitis (AS). We report a case of a 53-year-old female with a 10-year history of AS who developed CES in the past 1 year. The CT and MRI findings revealed the unique appearances of dural ectasia, multiple ventral dural diverticula, erosion of lumbar vertebral bodies, adhesion of the nerve roots of the cauda equine, and the conus medullaris to the wall of the dural sac. Due to progressive clinical deterioration, surgical decompression was performed via laminoplasty with filum terminale resection to release adhesions involving the conus medullaris and nerve root. Postoperatively, constipation, urinary incontinence, and muscle strength improved. The possible mechanisms of CES associated with chronic AS are discussed.

Heterotopic ossification (HO) arising from inflammatory processes often results in bony transformation of soft tissue. While the occurrence of HO is well-documented, its biomechanical influence on clavicular fractures remains less explored. We present acase report of apatient with aclavicular fracture following abicycle accident, accompanied by incidental findings of HO around the coracoclavicular (CC) ligaments. A59-year-old man presented with adisplaced right-sided clavicular fracture and acervical vertebral body fracture following abicycle fall. Incidental findings revealed pronounced HO around the CC ligaments. The patient underwent surgical stabilization for the cervical vertebral body fracture and clavicular fracture using open reduction and internal fixation. The presence of ossified CC ligaments may influence the biomechanical considerations for clavicular fractures. The present case report suggests that ossified CC ligaments may impact clavicular biomechanics, potentially offering increased stability at the CC attachment and acting as aprotective shield during trauma. This observation may indicate apossible predisposition to fractures in the clavicular region medial to the CC ligaments. While we cannot determine causality based on this single case, pronounced ossification of the CC ligaments could increase local stiffness and alter load distribution.

Severe cervical kyphosis concurrent with neurofibromatosis type 1 (NF-1) and large intraspinal tumors presents a dual challenge of oncological control and biomechanical reconstruction. We report a rare case of a 14-year-old male with NF-1 secondary to C1-C6 cervical spondylolisthesis, cervical retroversion, retrolisthesis of the C3 vertebral body (less than 1/2 of the vertebral diameter), C2 dislocation, atlantoaxial rotational dislocation, and a large intradural tumor, which caused acute spinal cord compression and neurofunctional deficits. An integrated surgical strategy combining microsurgical tumor resection with 3D-printed corrective fusion was implemented. Intraoperatively, gross total resection (GTR) of the tumor was achieved, followed by precise pedicle screw fixation assisted by patient-specific 3D-printed guides. This comprehensive approach prevented further neurological damage, and the patient achieved satisfactory clinical outcomes postoperatively. NF-1 is an autosomal dominant genetic disorder with an incidence of 1/3,000–1/4,000, characterized by diverse manifestations including skin abnormalities, neurological tumors, and musculoskeletal abnormalities. Approximately 50% of cases arise from de novo mutations. Case description A 14-year-old Han male student with no prior medical history was admitted for a 1-year history of a large right neck mass (15 × 9 cm) and 2 months of progressive generalized weakness. Physical examination revealed multiple café-au-lait macules (&amp;gt;30 mm) and a large cervical mass, consistent with NF-1. Neurological assessment showed decreased muscle strength in all limbs (grade 3), indicating incomplete spinal cord injury. Imaging (MRI/CT) demonstrated an intradural-intramedullary tumor extending through the intervertebral foramen, causing severe spinal cord compression and multiplanar instability (C1–C6).The patient was diagnosed with NF-1, severe cervical kyphosis, and an intraspinal tumor. He underwent posterior decompression, microsurgical GTR of the tumor (confirmed as neurofibroma via intraoperative frozen section), and occipitocervicothoracic fusion assisted by 3D-printed guides. The integrated surgery successfully restored spinal stability and decompressed the spinal cord. Conclusion Severe cervical retroversion combined with large NF-1 tumors is rare and technically demanding. A precision-medicine-based model integrating tumor management and digital orthopedic technology is essential for such high-risk cases. Preoperative planning using 3D digital technology enabled precise screw placement, while microsurgical techniques ensured safe and complete tumor resection. This integrated strategy effectively prevented permanent neurological deficits and resulted in satisfactory postoperative outcomes.

As the population ages, the incidence of osteoporotic vertebral compression fractures (OVCF) continues to rise, leading to an increased use of cement augmentation procedures. Consequently, clinicians are more frequently encountering patients with cement-augmented vertebrae who require additional spinal instrumentation. However, pedicle screw insertion into previously cement-augmented vertebral bodies remains technically challenging. This study aimed to describe a simple and reproducible technique for a safe and effective insertion of a pedicle screw into cement-augmented vertebral bodies. Ten patients with a history of cement augmentation for OVCF, who subsequently developed severe kyphotic deformity or degenerative spinal disease requiring posterior instrumentation, were treated using this technique. Pedicle screws were successfully inserted into all cement-augmented vertebrae without any intraoperative complications, including drill tip breakage, cement dislodgement, or anterior wall violation. In conclusion, pedicle screw insertion into cementaugmented vertebral bodies can be performed safely and reliably. This method may simplify a procedure that has traditionally been regarded as technically demanding.

Anterior lumbar interbody fusion (ALIF) is an effective treatment for lumbar degenerative diseases, but it usually requires combined posterior fixation. Currently, Currently, there is no high-strength fixation technique for single-position anterior approach. This study aimed to introduce L5 vertebral body screws combined with S1 vertebral body-pedicle screw fixation (BPSF) as a novel single-position anterior fixation technique for ALIF, and to evaluate its clinical and biomechanical outcomes. Sixty-three patients with L5/S1 degenerative disease undergoing ALIF were divided into BPSF (n = 22) and posterior pedicle screw fixation (PPSF, n = 41) groups. Clinical outcomes, radiographic parameters, and complications were collected and compared between groups. Biomechanically, an adult lumbar spine model was used to simulate two ALIF fixation configurations under normal and osteoporotic conditions. Each construct was loaded with 500N compression and 10N·m torque to simulate flexion/extension, lateral bending, and axial rotation. Kinematic analyses included ROM, interbody cage stress, and fixation device strain. The BPSF group showed significantly shorter operative duration (152.5min (127.5, 173.1) vs. 165.0min (140.0, 262.5), less intraoperative blood loss (115.0 ± 56.9ml vs. 160.0ml (110.0, 222.5) mL), and lower postoperative low back pain scores (1.6 ± 0.8 vs. 2.2 ± 0.7) compared to the PPSF group. And there were no statistically significant differences between the two groups in JOA improvement rate (49.9 ± 14.2% vs. 54.7 ± 18.1%), lumbar lordosis correction (6.9 ± 7.3° vs. 7.6 ± 7.1°), fusion rate (90.9% vs. 92.7%), or complication rate (27.3% vs. 19.5%). Biomechanically, BPSF reduced ROM during flexion (12% reduction) and axial rotation (63% reduction) compared to PPSF, with higher interbody cage stress but lower posterior fixation device stress under most loading conditions. BPSF provides safe anterior fixation for ALIF, reducing operative time and early postoperative pain. Its biomechanical stability, especially in rotational resistance, supports it as an alternative to PPSF for L5/S1 fusion.

Study DesignRetrospective study.ObjectiveTo evaluate and compare bone density along the traditional pedicle trajectory(TPT), cortical bone trajectory(CBT), and modified cortical bone trajectory(mCBT) using computed tomography(CT)-derived Hounsfield unit(HU) measurements.MethodsCT scans of the lumbar spine (L1-L5) of adult patients undergoing CT for non-spinal indications (predominantly younger adults) were retrospectively analyzed. Three pedicle screw trajectories were virtually simulated: TPT, CBT, and mCBT. For each trajectory, CTHU values were measured in sagittal section at four anatomical points along the screw path: posterior cortex, mid-pedicle, mid-vertebral body, and anterior vertebral body cortex using multiplanar reconstruction. Mean CTHU values, maximum screw lengths were compared across trajectories, and subgroup analyses were performed for age and sex.ResultsA total of 350 patients (1750 vertebrae) were analyzed. Mean CTHU values differed significantly among trajectories: CBT (538.2 ± 73.1HU) >mCBT (472.6 ± 87.9HU) >TPT (362.8 ± 68.4HU) (P < .001). At the posterior cortex, density was highest for CBT (1128.9 ± 147.6 HU), followed by mCBT (962.4 ± 192.7 HU) and TPT (582.1 ± 162.3HU). Across mid-pedicle, mid-body, and anterior cortex, CBT and mCBT showed comparable values, both significantly greater than TPT. mCBT showed significantly increased length of screw compared to CBT and TPT(P < .001). Age negatively correlated with CTHU across all trajectories, most pronounced in TPT (r = -0.36,R2 = 0.13). Gender differences were significant only for TPT (P < .05).ConclusionIn this radiographic anatomical study of predominantly young adults, CBT and mCBT trajectories traversed higher CT-HU than the traditional pedicle path. These observations are hypothesis-generating and require validation in DEXA-verified osteoporotic cohorts and biomechanical and clinical studies before clinical recommendations can be made.

Stress concentration is a primary pathogenesis of adjacent vertebral fracture (AVF) following percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fractures (OVCF). Disc degeneration (DD) is highly prevalent in the elderly, including OVCF patients. As a key biomechanical function of the intervertebral disc (IVD) is to ensure uniform load distribution, the progression of DD may impair this capacity, leading to localized stress concentrations. This study aims to investigate the impact of DD on AVF risk and elucidate its underlying biomechanical mechanisms. Clinical data from 65 patients were retrospectively reviewed. The cohort was stratified by the presence or absence of cranial AVF. The cranial IVDs adjacent to the fractured vertebrae were classified based on their degeneration phenotype, specifically the presence of disc fibrosis or collapse. We compared the incidence of these phenotypes between the AVF and non-AVF groups. Furthermore, regression analysis was employed to identify potential risk factors for AVF. In parallel, PVP simulations were conducted using biomechanical models that simulated disc fibrosis and collapse. Stress distributions within the cranial vertebral body and the motion range of the corresponding segment were computed and compared across the different models. Clinically, neither the incidence of disc fibrosis (P = 0.549) nor collapse (P = 0.586) differed significantly between cohorts with and without AVF, nor did they serve as independent risk factors (OR: 1.428 and 1.385, respectively). Biomechanical simulations aligned with clinical findings, demonstrating that neither disc fibrosis nor collapse altered stress distributions in the cranial vertebral body. Conversely, DD models exhibited a reduced motion-quantified by the overall model displacement-across all loading conditions when compared to the non-degenerated model. Our clinical and biomechanical analysis did not demonstrate an increased incidence of AVF in DD patients with wedge-type OVCF following PVP. This phenomenon may be attributed to a reduction in segmental motion, which subsequently lowers the stress values within the degenerative segment.

To evaluate the visualization of the ice ball during cryoablation of vertebral bodies and the bony pelvis in an in vivo swine model using virtual non-calcium imaging (VNCa) derived from photon-counting detector computed tomography (PCD-CT). Cryoablation was performed at six locations in the spine and pelvis of three live swine. Spectral ultra-high resolution image acquisition using PCD-CT was conducted before ablation and at 2, 4, 6 and 8min after initiation of the cryoablation cycle. Artifacts were suppressed using iterative metal artifacts reduction. Ice ball visualization within bone and soft tissue was assessed on both, conventional and VNCa images. At each time point the presence and size of the ice ball visualization was evaluated. A total of 12 needle placements was analyzed. In conventional images the ice ball could not be seen within bone at any time. In contrast, in VNCa images the ice ball became visible after 2min in all cases. However, the ice ball was less clearly visualized in the soft tissue on VNCa images. Mean ice ball volume at 2, 4, 6, 8min was 1.6 ± 0.9, 2.8 ± 1.7, 5.5 ± 2.9 and 8.3 ± 3.2ml in the vertebral bodies and 0.8 ± 0.3, 2.0 ± 0.4, 4.4 ± 0.6, 6.2 ± 1.1ml in the bony pelvis, respectively. PCD-CT enables early visualization of the ice ball within vertebral bodies and the bony pelvis in a swine model using VNCa images.

BackgroundSpinal tuberculosis (TB), though accounting for up to 50% of skeletal TB cases, typically presents insidiously with back pain, kyphotic deformity, or neurological deficits. Atypical presentations, including initial neutrophilic pleocytosis in cerebrospinal fluid (CSF), can mimic bacterial meningitis and complicate diagnosis.Case PresentationWe report the case of a 46‐year‐old previously healthy male who initially presented with high‐grade fever, headache, neck stiffness, and neutrophilic CSF pleocytosis suggestive of bacterial meningitis. Despite empirical antibiotic therapy, the patient developed progressive neurological symptoms, including paraplegia and hypertonia. MRI of the spine revealed T2–T6 vertebral body involvement with compressive myelopathy consistent with spinal TB. CSF PCR for Mycobacterium tuberculosis was positive. Anti‐TB therapy and adjunct corticosteroids were initiated, leading to marked clinical improvement.ConclusionClinicians should maintain a high index of suspicion for spinal TB in patients with persistent fever, neurological symptoms, and CSF pleocytosis—especially in TB‐endemic regions—even when initial laboratory findings suggest bacterial meningitis. Early imaging and targeted therapy can significantly improve outcomes.

Chronic pelvic pain is a common and multifactorial clinical syndrome that markedly impairs quality of life in both men and women. Superior hypogastric plexus block (SHGPB) is an effective minimally invasive treatment. The sacral notch approach, a modification of the transdiscal technique, offers a more direct and technically simple puncture pathway. However, sex-related pelvic anatomical differences may affect puncture parameters, and imaging-based evidence remains limited. This study aims to evaluate sex-related differences in key anatomical and technical parameters of SHGPB via the sacral notch approach based on computed tomography imaging and explore the potential clinical value of puncture angle, puncture distance, and the SHGPB index for preoperative assessment and individualized approach selection. This retrospective study analyzed abdominal computed tomography images of 200 patients (100 males and 100 females). Measured parameters included: the angle between the simulated needle trajectory and the sagittal plane; the distance from the skin entry point to the target point; and the SHGPB index, defined as the ratio of the inter–posterior superior iliac spine distance to the transverse diameter of the L5 vertebral body. Parameters were compared between sexes using appropriate statistical tests. The angle between the puncture trajectory and the sagittal plane was 25.33 ± 7.26° (range, 10.70–44.40°) in males and 27.18 ± 8.44° (range, 11.90–52.00°) in females, with no significant difference (P > .05). The puncture distance was 13.43 ± 1.53 cm (range, 10.20–17.60 cm) in males and 13.29 ± 2.39 cm (range, 9.90–32.70 cm) in females, also without significant difference (P > .05). However, the SHGPB index was significantly lower in males (1.75 ± 0.23; range, 1.24–2.33) than in females (1.96 ± 0.24; range, 1.53–2.63; P < .05). The sacral notch approach is characterized by a relatively small puncture angle and a straightforward puncture pathway. Puncture angle and distance remain stable across sexes, whereas the SHGPB index shows significant sex-related differences. The SHGPB index may serve as an important imaging marker for preoperative evaluation of pelvic anatomy and individualized selection of the puncture approach, with potential clinical value in the interventional management of chronic pelvic pain.

The aims of this study were to clarify the relationship between the combined forward flexion capacity of the lumbar spine and hip joint, referred to as TrunkAflex, and Lumbar Stiffness Disability Index (LSDI) scores in patients following lumbar spine surgery, and to assess whether TrunkAflex better reflects disabilities with activities of daily living (ADL) than the number of fused segments or lumbar spine flexion alone. This prospective, cross-sectional, multicenter study included 147 patients who underwent lumbar spine surgery and completed LSDI questionnaires. Lateral radiographs were obtained in the maximum seated flexion position. Radiographic parameters included pelvic incidence (PI)-corrected lumbar lordosis in flexion (PI-LLflex), representing lumbar spine flexion ability, pelvic femoral angle in flexion (PFAflex), representing hip joint flexion ability, and TrunkAflex, defined as the angle between the axis of the L1 vertebral body and the proximal femoral shaft, mathematically expressed as the sum of PI-LLflex and PFAflex. Correlation analyses were used to determine the relationships between LSDI and these parameters. Subgroup analyses were performed to compare the lumbar fusion (upper instrumented vertebra [UIV] at L1 or below) and thoracolumbar fusion (UIV at T12 or above) groups. The LSDI score was significantly correlated with the number of fused segments (r = 0.328, p < 0.01), and PI-LLflex showed a significant correlation with LSDI (r = -0.354, p < 0.01). However, TrunkAflex demonstrated the strongest correlation with LSDI (r = -0.491, p < 0.01). Subgroup analysis revealed that PI-LLflex was more influential in the lumbar fusion group, while PFAflex was more impactful in the thoracolumbar fusion group. Nevertheless, TrunkAflex consistently showed the strongest correlation with LSDI across all groups. Notably, TrunkAflex was minimally influenced by PI, making it a practical and consistent parameter for trunk forward flexion assessment. This study demonstrated that the combined forward flexion ability of the lumbar spine and hip joint, represented by TrunkAflex, is a stronger predictor of LSDI scores than the number of fused segments or lumbar spine flexion alone, irrespective of the fusion range. Preoperative assessment of hip joint function is particularly important when planning long-segment fusion, and adjusting surgical strategies to preserve appropriate TrunkAflex may contribute to better postoperative ADL outcomes.

Dual-energy x-ray absorptiometry (DXA) is the standard for assessing bone mineral density (BMD); however, its accuracy is limited by bone architecture, acquisition quality, and clinical context. Hounsfield units (HUs) offer an alternative for osteoporosis risk stratification. Machine learning (ML) models can segment computed tomography (CT) anatomy and integrate HU data to generate BMD metrics previously unavailable. This study elucidates the capabilities of an automated CT segmentation platform and investigates the relationship between vertebral HUs and DXA stratifications of BMD. A retrospective analysis of 229 patients with lumbar CT and DXA scans within 1 year was performed. The TotalSegmentator ML model obtained segmentations of the lumbar spine which were integrated with CT radiographic data to compute volume (cm3) and HU density of vertebral bodies, trabecular bone, and cortical bone. Vertebral body HU means were compared against lumbar, hip, and femoral neck DXA T scores in healthy individuals (T-score > -1.0), patients with osteopenia (-1.0 ≥ T-score ≥ -2.5), and patients with osteoporosis (T-score < -2.5) . Patients (85.2% female) had a mean age of 71.02 ± 13.62 years and body mass index of 28.04 ± 7.51 kg/m2. Mean HUs from L1-L5 correlated with femoral neck (r = 0.54, P < .001), lumbar (r = 0.54, P < .001), and hip (r = 0.46, P < .001) DXA T-scores. Compared with osteopenic individuals, healthy individuals had higher L1-L5 total HU (265.0 vs 226.4, P < .001), trabecular HU (179.3 vs 136.5, P < .001), and cortical HU (312.0 vs 274.8, P < .001). The L1-L5 total, trabecular, and cortical bone were predictive for low BMD (area under the curve [AUC] = 0.77, AUC = 0.80, and AUC = 0.75) and osteoporosis (AUC = 0.79, AUC = 0.75, and AUC = 0.80), respectively. Youden Index analysis identified optimal trabecular and cortical bone threshold values of 141.3 HU and 254.2 HU for low BMD as well as 132.3 HU and 249.0 HU for osteoporosis, respectively. ML-driven CT segmentation correlates with DXA BMD stratifications and can provide a robust, consistent, and efficient assessment of HU density of critical vertebral structures.