Sagittal Axis Research Articles

Variation of Wormian and Inca Bones in Adult Skulls

Objective: Irregular and abnormal small additional bones called Wormian bones can be encountered between the skull bones. This study aimed to investigate the incidence, topographical distribution, morphology, and interrelationship of the Wormian and Inca bones in Central Anatolia Region dry adult skulls. Methods: In the study, 119 adult skulls were examined. The location and frequency of additional bones (Wormian) in the sutures in the cranium were determined. Skulls with Inca bones were identified. The Inca bones were typified in accordance with the literature and their dimensions in the transverse and sagittal axis were measured with a digital caliper. Results: Wormian bone was present in 33 of 119 adult skulls (27.7%). Of the 33 bones, 22 were detected in the male (66.66%) and 11 female (33.34%) skulls. The locations of the Wormian bones in the order of decreasing incidence were the lambdoid suture (16.0%, 19/119), pterion (16.0%, 19/119), lambda (7.6%, 9/119), asterion (2.5%, 3/119), and bregma (1.7%, 2/119). Nine Inca bones were found in the lambdoid region (27.3%, 9/33). Six of these bones (66.7%) were in the male skull. We found that two of these bones were incomplete lateral asymmetric, two were complete symmetric bipartite, two were incomplete asymmetric bipartite and three were incomplete median type. We found that 13 (10.9%) of the skulls in the study had metopic sutures and 0.8% had craniosynostosis. When the craniums with metopic suture were evaluated, it was found that 8 of them (61.5%) had additional bone. 50% of the Wormian bones were found in the lambdoid suture. Conclusion: It has been found that the incidence of Wormian bone increases with suture variations. It was determined that the frequency of Inca bone variation may vary depending on regional differences.

A Novel Method in Restoring Form and Function Following Malunited Isolated Zygomatic Arch Fractures- A Technical Note

Isolated zygomatic arch fractures of the facial skeleton are rare. Blunt force to the cheek can result in an isolated zygomatic arch fracture, with resulting aesthetic issues such as indendations and functional impairments such as trismus. Symptomatic or visible isolated zygomatic arch fractures are commonly treated using either the Keen (intraoral) or Gillies (temporal) approaches to reduce the fracture while avoiding visible scars. Typically, the reduced fractures are not rigidly fixated but rather held in place by the native periosteal sleeve. However, cold fractures of the zygomatic arch are difficult to treat as they require a wide area of exposure for re-osteotomy and fixation. In the present technical note, we describe a novel technique to overcome this. Through a minimally invasive approach, two osteotomies were made proximally and distally to the fracture segment, and the segment was rolled 180 degrees along the sagittal axis. The medially depressed zygomatic arch is now projected laterally and was found to give adequate prominence and relieve restrictions in mouth opening. This is a novel method for reestablishing the prominence of the zygomatic arch and aiding in mandibular function following malunion of the fractured, isolated zygomatic arch.

Fractional anisotropy within zone of destruction, tremor evaluation and MRI manifestation follow up after focused ultrasound thalamotomy for patients with Parkinson’s disease

Purpose. Assessment of MRI manifestation including fractional anisotropy within nucleus of destruction after focused ultrasound thalamotomy and estimation of its correlation with tremor severity.Material and methods. 7 patients with clinically approved Parkinson's disease were included. MRI examinations of the brain were performed before FUS-thalamotomy, within 3 hours, after 24 hours, after 3 and 6 months after the operation. The study protocol included routine MR sequences; fractional anisotropy maps were generated. Before surgery, after a day, 3 and 6 months, the severity of tremor was assessed by the CRST scale; CRST values correlation with the values of fractional anisotropy, as well as the correlation of the coordinates of the destruction focus with the residual therapeutic effect of the operation was estimated using a linear regression model.Results. The general patterns of the MRI manifestation were revealed: the appearance after the operation of the nucleus of destruction with the accumulation of paramagnetic substances in the structure and perifocal edema. The severity of the MRI-changes reached a maximum one day after the operation, regressed and were practically not visualized after 3 and 6 months. There was a high correlation between the volumes of the nucleus of destruction and perifocal edema, no correlation between the severity of tremor and the values of fractional anisotropy in the nucleus of destruction, a weak correlation between the localization of the nucleus of destruction and the value of the residual therapeutic effect of FUS-thalamotomy 6 months after surgery.Conclusions. The MRI manifestation during 6 months after FUS-thalamotomy had a similar character in all patients, reached a maximum severity one day after the operation and had gradual regression. Fractional anisotropy values did not correlate with tremor severity. For a prolonged therapeutic effect the contribution of the localization of the focus along the sagittal axis is possible.

Comparison of the Optical Efficiency of Two Designs of the Maksutov–Cassegrain Telescope

The research aims to develop the best possible design for the widely used Cassegrain telescope. The system consists of two models of different designs: (a) the telescope consists of a Maksutov lens, a spherical primary mirror, and a secondary mirror attached to the lens; (b) it consists of a Maksutov lens and a spherical primary mirror, plus a non-lens attached secondary mirror located between the lens and the primary mirror. The image was evaluated and analyzed using the analysis tools in Zemax software. The results of the two designs showed that the telescope whose secondary mirrors are not adjacent to the Maksutov lens produces high quality image that is almost free from aberration, and then comes the telescope whose secondary mirrors are adjacent to the Maksutov lens in terms of image quality. In the first design, the tangential and sagittal axes in the MTF function of the remaining angles (0.1, 0.2, 0.3, 0.4, and 0.5) contain two curves, which show how the loss of symmetry has changed the value of the function for the two axes. In the second design, the sagittal and tangential axes are identical in the angles of incidence (0, 0.1, and 0.2), and the transverse and sagittal axes of the remaining angles (0.3, 0.4, and 0.5) contain two curves. In PSF for the first design, there are several pretty high peaks on the surface of the image at the angle of incidence (0, 0.1). Since the shape is regular, the point spread function indicates that there isn't an aberration, but in terms of the angles (0.2, 0.3, 0.4, 0.5), we observe a gradual loss in intensity and the appearance of elevations on both sides of the picture. In the second design, at the angles (0, 0.1, 0.2, 0.3), we observe in Figure 5 that there are several high peaks free from aberration.

The efficacy and safety of patient-specific instrumentation versus conventional instrumentation for unicompartmental knee arthroplasty: Evidence from a meta-analysis.

The aim of this study was to compare the efficacy and safety of patient-specific instrumentation (PSI) and conventional instrumentation (CI) for unicompartmental knee arthroplasty. Our hypothesis was that the PSI would be superior to CI in improving implant positioning and clinical function. We searched electronic databases (PubMed, Web of Science, Embase, and Cochrane) to identify relevant studies published before July 1, 2023 that met our inclusion criteria. The identified reports at least included one of the following outcome variables: coronal component alignment, sagittal component alignment, number of outliers, hip-knee-ankle angle, postoperative complications, operative time and knee joint functional evaluation. For dichotomous variables, we calculated the risk ratio and its 95% confidence interval (CI). For continuous variables, we calculated the mean difference (MD) and its 95% CI. Heterogeneity of the included studies was assessed using the standard chi-square test. Meta-analyses were performed using RevMan 5.4. software. The meta-analysis was registered with PROSPERO (No. CRD42023454160). A total of 9 articles were included in the analysis, consisting of 4 randomized controlled trials and 5 cohort studies. The study population comprised 494 patients, with 262 in the PSI group and 232 in the CI group. Our findings demonstrate that the PSI group exhibits superior tibial component coronal alignment compared to the CI group (MD = -0.66, 95% CI: -1.21 to -0.12, P = .02). Conversely, the CI group demonstrates better femoral component coronal alignment than the PSI group (MD = 0.89, 95% CI: 0.17-1.60, P = .01). No significant between 2 groups differences were observed in tibial component sagittal alignment, femoral component sagittal alignment, tibial coronal axis outliers, tibial sagittal axis outliers, femoral coronal axis outliers, femoral sagittal axis outliers, postoperative complications, operative time, hip-knee-ankle angle, and postoperative knee joint function score. Our study findings suggest that the PSI confer an advantage in achieving superior tibial component coronal alignment, whereas the CI associated with better femoral component coronal alignment. However, no significant differences were observed between the groups in terms of other parameters. Future studies with larger sample sizes are needed to validate these findings.

COMPARAçãO DOS PARâMETROS SAGITAIS NOS DIFERENTES TIPOS MORFOLóGICOS DA CURVATURA CERVICAL

ABSTRACT Objective: Evaluate and compare sagittal parameters of the spine in different morphological types of cervical curves. Method: ten lateral radiographs of the cervical spine of each morphological type of cervical curvature (lordotic, straightened, sigmoid and kyphotic) were used to measure the C1-C2 angle, C2-C7 angle using the Cobb method, T1 inclination, T1-lordosis inclination C2-C7 cervical and axial sagittal cervical axis. Parameter measurements were compared in the different morphological types of cervical spine curvature. Results: a statistical difference was observed in the C2-C7 angle, T1 inclination and T1 inclination-C2-C7 cervical lordosis in the different morphological types of cervical curvature. No statistical difference was observed in the C1-C2 angle and axial sagittal cervical axis in the different morphological types of cervical curvature.Conclusion: sagittal parameters (C2-C7 angle by Cobb method, T1 inclination, T1 inclination-C2-C7 cervical lordosis) present differences in the different morphological types of cervical curvatures and must be considered in the evaluation and therapeutic development. Evidence level III, retrospective comparative study.

Drusen classification and quantification in pseudophakic postmortem eyes implanted with or without blue-light filtering intraocular lenses

Abstract Purpose: To investigate the effect of blue-light filtering intraocular lenses on drusen formation in postmortem eyes via histopathological analysis. Materials and Methods: One hundred and ninety-three postmortem pseudophakic eyes (100 with a clear intraocular lenses [cIOL] and 93 with a yellow, yellow intraocular lenses [yIOL]) were obtained from the Lions Gift of Sight eye bank. Sex, age-at-surgery, age-at-death, surgery-to-death time, and clinical history were collected. Eyes were sectioned on their coronal and sagittal axes, and formalin-fixed paraffin-embedded macular cross sections were obtained. Sections were stained with hematoxylin and eosin and scanned with the Zeiss Axio Scan. Z1 scanner. Drusen were classified by type, size or subtype, and quantity. Results: Large, soft drusen were present in 49% (n = 95) of eyes, 9% (n = 17) had cuticular drusen, 16% (n = 30) had hard drusen, and 26% (n = 51) had no drusen. There were significantly more cIOL eyes with large, soft drusen (P < 0.001). There were significantly more yIOL eyes with no drusen (P < 0.0001). No significant differences in the presence of hard or cuticular drusen were found. yIOL eyes had significantly higher mean age-at-surgery (P < 0.001) and mean age-at-death (P < 0.05), while cIOL eyes had a significantly higher mean surgery-to-death time (P < 0.05). Finally, significantly more yIOL eyes had a history of smoking (P < 0.01) and hypertension (P < 0.05), while significantly more cIOL eyes had a history of glaucoma (P < 0.05). Conclusions: Large, soft drusen were significantly less prevalent in yIOL eyes than in cIOL eyes and significantly more yIOL eyes had no drusen. These findings suggest that yIOLs may prevent the incidence and development of age-related macular degeneration after cataract surgery.

Monte Carlo-based in-depth morphological analysis of medullary cavity for designing personalized femoral stem.

The design of femoral stem prostheses requires a precise understanding of the femoral marrow cavity. Traditional measurements of morphological parameters in the upper femur, particularly the medullary cavity and cortical region, are primarily based on coronal and sagittal axes, which may not fully capture the true three-dimensional structure of the femur. Propose a Monte Carlo-based method for a more comprehensive analysis of the femoral marrow cavity, using CT scans of femurs from a selected group of patients. The study aimed to define and calculate anatomically semantic morphological parameters to enhance the understanding of the femoral marrow cavity's anatomical morphological changes, ultimately improving the design and clinical selection of femoral stem prostheses. To enhance the accuracy of femoral stem prosthesis design, this study aims to develop a Monte Carlo-based method for a more comprehensive analysis of the femoral marrow cavity. The proposed method transforms the non-random problem of determining cross-sectional size into a random issue, allowing for the calculation of the size of the medullary cavity and cortical region. Anatomically semantic morphological parameters are then defined, calculated, and analyzed. The experimental results indicate that the newly defined parameters complement existing ones, providing a more rational scientific basis for understanding the anatomical morphological changes of the femoral marrow cavity. This research offers essential scientific theoretical support for improved morphologic research, design, and clinical selection of femoral stem prostheses. It holds significant importance and application value in clinical practice, contributing to a more accurate and comprehensive understanding of femoral anatomy for prosthetic design.

Experience in Managing Posttraumatic Lumbar Kyphosis Patients with Multi-level Ponte Osteotomies and Posterior Spinal Fusion

Posttraumatic kyphosis (PTK) is a spinal deformity resulting from severe trauma, posing significant challenges for surgical correction. PTK can lead to chronic pain and disability, necessitating careful evaluation and individualized treatment strategies. We present the case of a 50-year-old male with a decade-long history of PTK following a traumatic fall from a truck. Despite initial mobility, his condition worsened, affecting his posture and causing pain. Radiographic assessments revealed marked lumbar lordosis (LL) loss, positive sagittal vertebral axis, and pelvic parameters mismatch. Surgical planning involved multilevel Ponte osteotomy from L1 to L4 and posterior spinal fusion from Th10 to S1 to restore sagittal balance. Treating PTK is complex and technically demanding, with no universal approach due to the diversity of cases. Detailed diagnostics, including spinal alignment analysis and neurologic assessments, guide surgical decisions. Our patient’s successful treatment employed grade 1/2 Ponte osteotomies for lumbar correction, achieving improved sagittal balance and LL. However, an increase in pelvic incidence (PI) and persistent PI-LL mismatch was noted postsurgery, suggesting potential effects on the sacroiliac joint. Severe trauma can lead to PTK, necessitating meticulous evaluation and individualized surgical strategies. The primary goal is to alleviate neurological deficits and restore sagittal balance, with surgical choices tailored to each patient’s unique circumstances. Surgical correction may influence pelvic parameters, emphasizing the importance of comprehensive postoperative assessment and follow-up care.

Sex-based differences in clinical and radiological presentation of patients with degenerative lumbar scoliosis: a cross-sectional study

BackgroundTo evaluate the sex-based differences in clinical and radiological presentation of patients with degenerative lumbar scoliosis (DLS) and to explore whether the difference is helpful in investigating the etiology and progression of DLS.MethodA retrospective review of 199 patients (41 males, 158 females) with DLS was included. Patient demographics including age, gender, bone mineral density were collected. Back and leg pain was assessed by visual analog scale, and general physical condition was assessed by Oswestry Disability Index. Cobb’s angle was measured, and direction of scoliosis, position of the superior, inferior and apex vertebrae, number of vertebrae included in the scoliosis, rotation of apex vertebrae (Nash-Mo index), translation of apex vertebrae were recorded. Sagittal longitudinal axis, thoracolumbar kyphosis, lumbar lordosis (LL), pelvic incidence angle (PI), sacral slope, apex of lumbar lordosis and coronal balance distance were measured by whole spine lateral radiographs, and type of coronal imbalance was evaluated in all patients. Fat infiltration rate (FIR) of the paraspinal muscles at the vertebral apex was measured by MRI.ResultCompared to female patients, male patients showed more back and leg pain on clinical presentation and smaller Cobb angle, less parietal rotation, larger LL, smaller PI-LL and lower paravertebral muscle FIR on radiologic features.ConclusionGender differences do exist in DLS patients with regard to clinical and radiological presentation, low back pain was more pronounced in male patients, and scoliosis was more severe in female patients based on this cross-sectional study.

Long-term outcome evaluation in ankylosing spondylitis with high-angle thoracolumbar kyphotic deformity corrected by one-stage single-level pedicle subtraction osteotomy augmented with Ponte osteotomy: A case series

Introduction and importanceA high-angle thoracolumbar kyphotic deformity (TLKD) may complicate surgical rectification of AS patients since one-stage two-level pedicle subtraction osteotomy (PSO), which provides high-angular correction, leads to excessive blood loss, neurological deficits and fixation failures. This case series presents the long-term results of one-stage single level PSO with Ponte osteotomy (PO) in the treatment of AS patients with high-angle TLKD. Case presentationThis case series presents two AS patients with high kyphotic angles (KAs) of 86.1o. We collected data retrospectively from our institution's database between 2019 and 2023. A sagittal axis imbalance was the only complaint initially, no neurological deficits or other problems. A PSO augmented by PO was performed with a decompression laminectomy. Intraoperative monitoring (IOM) during reduction was used to observe neurological deficits. Blood loss at the highest rate was 1000 cc. It corrected 57.8o of KA postoperatively without neurological deficits. We found consistent results over 36 months. Clinical discussionA thorough analytical approach may help diagnose AS. One-stage single-level PSO may correct high-angle TLKD in AS patients effectively. To achieve greater angular correction, PO, a less risky osteotomy, must be added. Decompression laminectomy is vital before osteotomy and IOM is crucial during reduction to prevent nerve injury. Even with two osteotomies, there was less blood loss than previously reported. These impressive long-term results call for further research. ConclusionCombined PSO and PO with IOM efficiently magnifies the angular correction without postoperative neurological deficits or excessive blood loss in AS patients with high-angle TLKD.

Face Age is Mapped Into Three-Dimensional Space.

People can represent temporal stimuli (e.g., pictures depicting past and future events) as spatially connoted dimensions arranged along the three main axes (horizontal, sagittal, and vertical). For example, past and future events are generally represented, from the perspective of the individuals, as being placed behind and in front of them, respectively. Here, we report that such a 3D representation can also emerge for facial stimuli of different ages. In three experiments, participants classified a central target face, representing an individual at different age stages, as younger or older than the reference face of 40 years. Manual responses were provided with two keys placed along the horizontal axis (Experiment 1), the sagittal axis (Experiment 2), and the vertical axis (Experiment 3). The results indicated that the younger faces were represented on the left/back/top side of the space, whereas the older faces were represented on the right/forward/bottom side of the space. Furthermore, in all experiments, the latencies decreased with the absolute difference between the age of the target face and that of the reference face (i.e., a distance effect). Overall, this work suggests that the spatial representation of time includes social features of the human face.

A comparative study of the anatomy and MRI images of the lumbar foraminal ligaments at the L1-L5 levels.

The purpose of this study was to evaluate the ability of MRI images to reveal foraminal ligaments at levels L1-L5 by comparing the results with those of anatomical studies. Eighty lumbar foramina were studied. First, the best MRI scanning parameters were selected, and the transverse and sagittal axes of each lumbar foramina were scanned to identify and record the ligament-like structures in each lumbar foramen. Then, the cadaveric specimens were anatomically studied, and all ligament structures in the lumbar foramina were retained. The number, morphology and distribution of ligaments under anatomical and MRI scanning were observed. Histological staining of the dissected ligament structures was performed to confirm that they were ligamentous tissues. Finally, the accuracy of ligament recognition in MRI images was statistically analyzed. A total of 233 foraminal ligaments were identified in 80 lumbar intervertebral foramina through cadaveric anatomy. The radiating ligaments (176, 75.5%) were found to be attached from the nerve root to the surrounding osseous structures, while the transforaminal ligaments (57, 24.5%) traversed the intervertebral foramina without any connection to the nerve roots. A total of 42 transforaminal ligament signals and 100 radiating ligament signals were detected in the MRI images of the 80 intervertebral foramina. The MRI can identify the lumbar foraminal ligament, and the recognition rate of the transforaminal ligament is higher than that of the radiating ligament. This study provides a new method for the clinical diagnosis of the relationship between the lumbar foraminal ligament and radicular pain.

Does walking/running experience shape the sagittal mental time line?

A growing body of evidence suggested that time could be separately represented either on the lateral or sagittal axis. And the lateral mental time line has an origin associated with sensorimotor experience, e.g., reading/writing. However, it is still not clear whether the sagittal mental time line also originates from sensorimotor experience, e.g., walking/running. To address this question, we examined how the movement experience affected the space–time mapping on the lateral and sagittal axes using the virtual reality technique in two experiments. The results showed that the virtual movement experience had significant effects on the space–time mapping on the lateral axis (Experiment 1), but not on the sagittal axis (Experiment 2). This finding supported that the space–time mapping on the lateral axis does originate from sensorimotor experience, while the space–time mapping on the sagittal axis more likely originates from spatial metaphors in languages or other cultural experiences.

Three-dimensional changes in the cranial base associated with soft-diet feeding.

Masticatory activity affects the morphology of the maxillo-mandibular complex, however, its influence on the cranial base remains to be elucidated. The recent integration of quantitative morphometric analysis with 3D imaging enabled a comprehensive and high-resolution morphological characterization of the craniofacial complex. We aimed to investigate the influence of masticatory activity on the morphology of the growing cranial base by three-dimensional (3D) geometric morphometric approach using micro-CT. The micro-CT data was reanalyzed to illustrate the 3D shape of the cranial base, and wireframe models were generated by connecting landmarks on the images. In the original study, mice were fed a soft diet (SD) of powdered pellets or a conventional hard diet (HD) for 6 weeks from 3 to 9 weeks of age, immediately after weaning. A principal component (PC) analysis analyzed shape variations and assessed their significance, while canonical variate (CV) analysis facilitated the comparison and differentiation of groups based on shape, unveiling meaningful shape distinctions. Three PCs were extracted that significantly separated the SD and HD groups among those explaining variations in shape. These PCs were related to the length of the sphenoid bone, the width of the anterior part of the sphenoid bone, and the length of the cranial base. Furthermore, one CV effectively distinguished SD from HD, and CV analysis showed that the sphenoid was shortened in the length and narrowed at the border of the temporal bone in SD mice. Masticatory loading affects the skeletal development of the cranial base. The morphology of the sphenoid bone was affected in both the sagittal and transverse axes.

Transvaginal Ultrasound Evaluation Of Cesarean Section Niche Scar During Pregnancy: A Prospective Longitudinal Study

Background and Objectives: To determine the prevalence of a CS scar niche during pregnancy using transvaginal ultrasound imaging, and to determine the relationship between the evolution of the CS scar niche and the ultimate pregnancy result. Materials and Methods: Transvaginal sonography was used in this prospective observational research to look at the uterine scars of 100 women at 11+0-13+6, 18+0-20+6 and 32+0-35+6 weeks of pregnancy. When the region of hypoechogenic myometrial discontinuity of the lower uterine section was discovered, a scar was discernible while pregnant. An indentation at the location of the CS scar with a depth of at least 2 mm in the sagittal axis was designated as the CS scar niche (or "defect"). Myometrial thickness next to the niche and the remaining myometrial thickness were used to quantify the hypoechogenic portion of the CS niche in two dimensions. (RMT). The entire lower uterine segment (LUS) thickness and the myometrial layer thickness were measured during the second and third trimesters of pregnancy at the thinnest portion of the scar area. In a non-selected subset of patients (n=20), CS scars were measured by two separate examiners. Scar visibility was evaluated using descriptive analysis, and the intraclass correlation coefficient (ICC) was computed to demonstrate the degree of absolute agreement between two observers for measuring scars. Maternal age, BMI, smoking status, prior vaginal deliveries, obstetric complications, and a history of uterine curettage were among the factors looked into as potential contributors to the CS scar niche. The hospital's computerized medical database provided clinical statistics on pregnancy outcomes and complications. Results: 80.9% of the ladies could see the scar. A CS scar niche was prevalent in 53.6% of people with a noticeable CS scar. Excellent intra- and interobserver agreement was observed for CS scar niche readings. There was no statistically significant correlation between maternal age, BMI, gestational diabetes, smoking status, previous vaginal delivery after CS, and niche development when subgroups of women were compared in terms of CS scar niche and non-niche. In contrast to 34.4 % of the women who did not have uterine curettage, 56.3% of the women who had done uterine curettage had uterine scar niches. Conclusions: The CS scar niche could be reproducibly measured by a transvaginal scan in half of the cases with a visible CS scar at the first trimester of pregnancy, according to an ultrasonography evaluation. An increased chance of uterine niche formation in a subsequent pregnancy was linked to prior uterine curettage. The CS scar area may be connected to uterine scar dehiscence.

Magnitude, variability and symmetry in head acceleration and jerk and their relationship to cervical and ocular vestibular evoked myogenic potentials.

Acceleration and changes in acceleration (jerk) stimulate vestibular otolith afferents. Bone-conducted (BC) vibration applied to the skull accelerates the head and produces short latency reflexes termed vestibular evoked myogenic potentials (VEMPs). To determine the magnitude, variability and symmetry in head acceleration/jerk during VEMP recordings and investigate the relationship between head acceleration/jerk and VEMP properties. 3D head accelerometery (sagittal, interaural and vertical axes) was recorded bilaterally in thirty-two healthy subjects during cervical (cVEMP) and ocular (oVEMP) recordings. BC 500 Hz sinusoidal tones were applied to the midline forehead using a positive polarity stimulus. The direction of induced acceleration/jerk was predominately backward, outward and downward on either side of the head during cVEMP and oVEMP recordings.Overall, acceleration/jerk was larger in the sagittal and interaural axes and peaked earlier in the interaural axis bilaterally. Acceleration was more symmetric in the sagittal and interaural axes whereas jerk symmetry did not differ between axes. Regression models did not show a systematic relationship between acceleration/jerk and either VEMP reflex. The pattern of skull acceleration/jerk was relatively consistent between the two sides of the head and across subjects, but there were differences in magnitude, leading to inter-side and inter-subject variability.

The Density-Weighted Foot Center Is Different to the Geometric Foot Center

Category: Basic Sciences/Biologics; Hindfoot Introduction/Purpose: It has become a reality with the advent of weight bearing CT (WBCT) that weight bearing (WB) is a significant element to be considered when analyzing foot and ankle images. Some knowledge has begun to accumulate on the effect of WB on bone positioning, but the effect of WB on bone mineral density (BMD) distribution, apart from being a long for accepted truth since the works of Julius Wolff, could not until now be visualized other than on the biological level. Now, Hounsfield Units allow for bone density analysis on WBCT. The objective of the study was to compare the relative positions of the geometric foot center (GC) and the density-weighted foot center (DC). We hypothesized those to be different. Methods: Ethics approval was obtained. Thrity two feet from our WBCT database were retrospectively randomly selected (Curvebeam Pedcat, Hatfield PA, USA). Datasets were analyzed using Bonelogics software (Disior, Paragon 28, USA). Bone segmentation was performed to obtain all bone orientations and volumes excluding tibia and fibula and all phalanges. The data was computed to obtain the geometric centers (from bone surface coordinates), which were considered as reference and were given a value of 0. Therefore density-weighted centers (from all bone data including density) were calculated. The difference between the two centers represented the shift which was assessed along the sagittal axis (anterior shift), transversal axis (lateral shift) and craniocaudal axis (upward shift). Statistical analysis was conducted using STATA package. Results: The mean age and Body Mass Index of the cohort were 57.2 ± 9.6 years and 22.2 ± 2.8 kg/m2, respectively. The 3D displacement vector between GC and DC had a norm of 10.01 mm. We found that DC was significantly shifted anteriorly by 8.9 ± 0.3 mm (range, 5.6 mm to 13.4 mm), medially by 0.4 ± 0.8 mm (range, -1.3 mm to 0.3 mm) and upwardly by 4.2 ± 0.14 mm (range, 2.8 mm to 5.9 mm) (p < 0.001 in all cases). Conclusion: Our hypothesis was confirmed: the geometric and weighed foot centers were different. DC was more anteriorly and slightly medially situated. Both centers were situated at the interface between the talus and cuboid. The more anterior position may be explained by the fact that human foot is responsible for anteriorly orientated longitudinal movement on average. We deem that BMD is a significant dimension in WBCT datasets that cannot be ignored in the development of new measurement tools that are not currently standardized. Alignment based purely on bone outer shape without considering BMD may not be representative of their true biomechanical state.

Use of global sagittal flexibility to predict proximal junctional kyphosis after spinal deformity surgery.

Sagittal alignment is an important predictor of functional outcomes after surgery for adult spinal deformity (ASD). A rigid spinal column may create a large lever arm that may impact the rate of proximal junctional kyphosis (PJK) after ASD surgery. In this study, the authors sought to determine whether relatively low preoperative global spinal flexibility (i.e., rigid spine) predicts increased incidence of PJK at 1 year after ASD surgery. The authors retrospectively reviewed long-segment thoracolumbar fusions with pelvic fixation performed at a single tertiary care center between October 2015 and September 2020 in patients with a minimum of 1-year radiographic and clinical follow-up. Two cohorts were established on the basis of the optimal value for spinal flexibility, as defined by the absolute difference between the preoperative standing and supine C7 sagittal vertical axes, which the authors termed global sagittal flexibility (GSF). Demographic information, radiographs, various associated complications, and patient-reported outcome measures (PROMs) were analyzed. Eighty-five patients met the inclusion criteria. Receiver operating characteristic (ROC) analysis using GSF to predict an increase in the proximal junctional sagittal Cobb angle (PJCA) greater than or equal to 10° at 1-year follow-up provided an area under the curve of 0.64 and identified an optimal GSF threshold value of 3.7 cm. Patients with GSF > 3.7 cm were considered globally flexible (48 patients), and those with GSF ≤ 3.7 cm were classified as rigid (37 patients). Rigid patients were noted to have a significantly higher risk of ΔPJCA ≥ 10° at 1-year follow-up (51.4% vs 29.3%, p = 0.049). No changes in the reoperation rates or PROMs based on GSF were observed in the 1- or 2-year postoperative window. Based on these retrospective data, preoperative global spinal rigidity portends an independently elevated risk for the development of PJK after ASD surgery. No differences in other complication rates or PROMs data were observed between groups. Data collection was limited to a 2-year postoperative window; therefore, longer follow-up is required to further elucidate the relationship between rigidity and reoperation rates. Based on these retrospective data, flexibility may influence the outcomes of patients with ASD.

Y-shaped osteotomy in the apical vertebra for treating congenital complex rigid scoliosis:at least 2-year follow-up

Objective: To investigate the clinical outcome of the coronal Y-shaped osteotomy in the apical vertebra for treating congenital complex rigid scoliosis. Methods: A retrospective analysis was conducted on 66 cases who underwent Y-shaped osteotomy treatment for congenital complex rigid scoliosis in the uppermost vertebra at the Department of Orthopedics,the Second Hospital of Shanxi Medical University from June 2007 to August 2020. There were 19 males and 47 females,with an age of (13.1±5.3) years(range:2 to 30 years).Classification of congenital scoliosis:25 cases (37.9%) were incomplete,13 cases (19.7%) were dysarthritic,and 28 cases (42.4%) were mixed. There were 25 cases (37.9%) with thoracic or rib malformations. 45 cases (68.2%) were complicated with spinal cord malformation.The main radiological indicators included Cobb angle of the curvature,Cobb angle of the local bend,apical vertebral translation (AVT),trunk shift (TS),thoracic trunk shift (TTS),radiographic shoulder height (RSH),coronal balance and sagittal vertebral axis. The preoperative,postoperative immediate,and last follow-up radiological indicators were collected and the operation time,blood loss,hospitalization time,and operation-related complications were recorded. Data were compared by repeated measure ANOVA and paired-t test. Results: All patients underwent surgery successfully. The duration of the first surgery was (221.4±52.8) minutes,and the blood loss during the first surgery was (273.2±41.8) ml. The length of the first hospital stay was (8.8±1.7) days.Unilateral fixation was performed in 19 cases (28.8%),while bilateral fixation was performed in 47 cases (71.2%). The fused segments were 7.5±2.9,and the vertebral pedicle screw density was (68.5±20.6)%. The follow-up time for the 66 patients was (36.7±17.0) months(range:24 to 102 months).The main curve Cobb Angle was improved from (58.5±18.9)°before surgery to (21.1±11.8)°after surgery,and was (23.6±15.3) ° at the last follow-up(F=273.957,P<0.01),with a correction rate of 66.2%. Segmental curve Cobb Angle was improved from (47.9±18.0)° to (16.0±11.3)° after surgery,and was (16.8±12.8) °at the last follow-up (F=270.483,P<0.01)with a correction rate of 69.2%. The AVT,TS,TTS and RSH values improved significantly at the final follow-up (all P<0.05),while coronal balance and sagittal vertical axis were maintained without significant differences between pre-operation and post-operation(both P>0.05). A total of 5 patients underwent staged operation,all of which were residual scoliosis aggravated after the first stage of orthosis operation and had good prognosis after the second stage of operation. Conclusions: Y-shaped osteotomy for the treatment of congenital rigid scoliosis results in good clinical and radiological outcomes without serious complications. This procedure can be considered as an option for the treatment of congenital complex rigid scoliosis.