Vertebral Position Research Articles

Accuracy of Stereovision-Updated Versus Preoperative CT-Based Image Guidance in Multilevel Lumbar Pedicle Screw Placement: A Cadaveric Swine Study.

Background:Change in vertebral position between preoperative imaging and the surgical procedure reduces the accuracy of image-guided spinal surgery, requiring repeated imaging and surgical field registration, a process that takes time and exposes patients to additional radiation. We developed a handheld, camera-based, deformable registration system (intraoperative stereovision, iSV) to register the surgical field automatically and compensate for spinal motion during surgery without further radiation exposure.Methods:We measured motion-induced errors in image-guided lumbar pedicle screw placement in 6 whole-pig cadavers using state-of-the-art commercial spine navigation (StealthStation; Medtronic) and iSV registration that compensates for intraoperative vertebral motion. We induced spinal motion by using preoperative computed tomography (pCT) of the lumbar spine performed in the supine position with accentuated lordosis and performing surgery with the animal in the prone position. StealthStation registration of pCT occurred using metallic fiducial markers implanted in each vertebra, and iSV data were acquired to perform a deformable registration between pCT and the surgical field. Sixty-eight pedicle screws were placed in 6 whole-pig cadavers using iSV and StealthStation registrations in random order of vertebral level, relying only on image guidance without invoking the surgeon’s judgment. The position of each pedicle screw was assessed with post-procedure CT and confirmed via anatomical dissection. Registration errors were assessed on the basis of implanted fiducials.Results:The frequency and severity of pedicle screw perforation were lower for iSV registration compared with StealthStation (97% versus 68% with Grade 0 medial perforation for iSV and StealthStation, respectively). Severe perforation occurred only with StealthStation (18% versus 0% for iSV). The overall time required for iSV registration (computational efficiency) was ∼10 to 15 minutes and was comparable with StealthStation registration (∼10 min). The mean target registration error was smaller for iSV relative to StealthStation (2.81 ± 0.91 versus 8.37 ± 1.76 mm).Conclusions:Pedicle screw placement was more accurate with iSV registration compared with state-of-the-art commercial navigation based on preoperative CT when alignment of the spine changed during surgery.Clinical Relevance:The iSV system compensated for intervertebral motion, which obviated the need for repeated vertebral registration while providing efficient, accurate, radiation-free navigation during open spinal surgery.

Evaluation of 3D vertebral and pelvic position by surface topography in asymptomatic females: presentation of normative reference data

BackgroundDeviations from a conventional physiologic posture are often a cause of complaint. According to current literature, the upright physiological spine posture exhibits inclinations in the sagittal plane but not in the coronal and transverse planes, but individual vertebral body positions of asymptomatic adults have rarely been described using surface topography. Therefore, this work aims to form a normative reference dataset for the thoracic and lumbar vertebral bodies and for the pelvis in all three planes in asymptomatic women.MethodsIn a prospective, cross-sectional, monocentric study, 100 pain-free asymptomatic women, aged 20–64 years were enrolled. Habitual standing positions of the trunk were measured using surface topography. Data were analyzed in all three planes. Age sub-analysis was: 1) ages ≤ 40 years and 2) ages ≥ 41 years. Two-sample t-tests were used for age comparisons of the vertebral bodies, vertebra prominence (VP)–L4, and global parameters. One-sample t-tests were used to test deviations from symmetrical zero positions of VP–L4.ResultsCoronal plane: on average, the vertebral bodies were tilted to the right between the VP and T4 (maximum: T2 − 1.8° ± 3.2), while between T6 and T11 they were tilted to the left (maximum: T7 1.1° ± 1.9). T5 and L2 were in a neutral position, overall depicting a mean right-sided lateral flexion from T2 to T7 (apex at T5). Sagittal plane: the kyphotic apex resided at T8 with − 0.5° ± 3.6 and the lumbar lordotic apex at L3 with − 2.1° ± 7.4. Transverse plane: participants had a mean vertebral body rotation to the right ranging from T6 to L4 (maximum: T11 − 2.2° ± 3.5). Age-specific differences were seen in the sagittal plane and had little effect on overall posture.ConclusionsAsymptomatic female volunteers standing in a habitual posture displayed an average vertebral rotation and lateral flexion to the right in vertebral segments T2–T7. The physiological asymmetrical posture of women could be considered in spinal therapies. With regard to spinal surgery, it should be clarified whether an approximation to an absolutely symmetrical posture is desirable from a biomechanical point of view? This data set can also be used as a reference in clinical practice.Trial registration: This study was registered with WHO (INT: DRKS00010834) and approved by the responsible ethics committee at the Rhineland–Palatinate Medical Association (837.194.16).

Kyphosis types of the spine cervical-thoracic junction

Introduction. The strengthening of thoracic kyphosis and forward head posture is one of the urgent problems of modern man. Such changes are most often detected for elderly and senile people. However, today these features are also detected for young people. Digital radiography can objectively assess the position of the cervical and thoracic vertebrae. However, the criteria for reliably registering the position of the vertebrae of the cervicalthoracic junction have not yet been developed.The aim of the study — to develop a method for assessing the position of the vertebrae of the cervical-thoracic junction according to digital radiographs; to develop a typology of the vertebra positions of the cervical-thoracic junction; to study the frequency of vertebral position types for the cervical-thoracic junction for different age groups.Materials and methods. Spine X-ray images in the sagittal plane for 141 adult patients with dorsopathies were studied. The selection of patients was random and there were four age groups: 32 persons aged 21 to 45, 32 persons aged 46 to 59, 50 persons aged 60 to 74 and 21 persons aged 75 to 88 year-old. The study was conducted on PC screen, without the patient′s presence. A single digital X-ray image of the spine for each patient in the sagittal plane was obtained. On the combined digital radiograph, the occipital vertical was drawn along all parts of the spine, starting from the external hillock of the occipital bone downwards, and the anteroposterior CV–TV axes of the vertebrae (r axes) were applied. At the points of intersection of the axes with the occipital vertical, the perpendiculars to the axis were restored, and the angles between the perpendiculars and the vertical — the angles of the anteroposterior axes of the vertebrae (r angles) — were measured. Statistical analysis was performed using the MS Offi ce Excel 2007 and Statistica 12 software packages.Results. It was found that the values of the anteroposterior axe angles r of CVII–TIII vertebrae can serve as criteria for determining the spatial position of the cervical-thoracic junction vertebrae. There are 4 types of the shape of the cervical-thoracic junction. Type I is a straightened kyphosis («giraffe neck»); type II is physiological («harmonious»); type III — enhanced kyphosis («bear withers»); type IV–hyperkyphosis («buffalo hump»). Types III and IV are accompanied by a forward displacement of the head. Straightened cervical-thoracic junction kyphosis — type I — was diagnosed in 21 (15 %) people, 52 (37 %) patients were assigned to type II, another 48 (34 %) patients had type III, and 20 (14 %) patients had type IV cervical-thoracic junction kyphosis. In young patients aged 21 to 45, as well as in middle-aged patients aged 46 to 59, the most common type was the harmonious type II of cervical-thoracic junction, in elderly patients aged 60 to 74 — type III and close to it in frequency was type III. In elderly patients aged 75 to 88, the IV type of the position of the vertebrae of the cervical-thoracic junction prevailed in frequency.Conclusion. The proposed diagnostic method allows to register the type of the vertebra positions in cervicalthoracic junction for each patient. Four position types of the cervical-thoracic junction vertebrae were determined: straightened kyphosis «giraffe neck», physiological kyphosis «harmonious», enhanced kyphosis «bear withers» and hyperkyphosis «buffalo hump». Increased kyphosis and hyperkyphosis are accompanied by a forward head posture.

Evaluation of the three-dimensional (3D) position of cervical vertebrae in individuals with unilateral posterior crossbite.

To evaluate the three-dimensional (3D) position of the cervical vertebrae of growing subjects with unilateral posterior crossbite (UPC). In this cross-sectional study, cone beam computed tomography (CBCT) scans of 1455 patients were screened, and ultimately 58 scans (26 patients with UPC and 32 controls with normal occlusion) were included after imposing inclusion/exclusion criteria. Roll, yaw, and deviation of the geometric center of C1, C2, and C3 vertebrae were measured and compared between groups. A correlation between these parameters and different variables on mandibular positioning was also carried out. A statistically significant difference (p < 0.05) was observed between groups for the deviation of pogonium (Pog), mandibular plane roll, and C3 roll, and patients with UPC showed higher cant or deviation. A significant correlation was reported for the roll of C2 and C3 with the deviation of Pog, a roll of the occlusal plane, and roll of the mandibular plane (p < 0.05). The greater the deviation of the Pog to one side, the greater the roll of the vertebrae with this same side up. The same tendency was observed between the roll of the occlusal plane or the mandibular plane with the roll of these cervical vertebrae. There is a positive correlation between transverse occlusal changes and positional deviations of the cervical vertebrae, especially C2 and C3. The study results do not allow us to infer the clinical/functional consequences of these deviations, as well as if malocclusion's treatment would result in an improvement of intervertebral relationships.

Motion characteristics of the lower lumbar spine in individuals with different pelvic incidence: An in vivo biomechanical study

BackgroundPelvic incidence is the quantification of the pelvis anatomical shape which has significant effect on the occurrence of various lumbar degenerative diseases. The aim of this study was to measure the in vivo dynamic motion characteristics of the lower lumbar spine in people with different pelvic incidence. MethodsA total of 55 volunteers were included in the study. The participants were devided into 3 groups (A: pelvic incidence≤40°, B: 40° < pelvic incidence <60° and C: pelvic incidence ≥60°). The L3–S1 vertebrae of each subject was MRI scanned to construct 3D models. The lumbar spine was then imaged using a dual fluoroscopic imaging system as the subject performed physiological position. The 3D vertebral models and the fluoroscopic images were used to reproduce the in vivo vertebral positions along the motion path. The relative translations and rotations of each motion segment were analyzed. FindingsAt the L5-S1 segment, the primary ranges of motion for left-right axial rotation and flexion-extension of the patients with large pelvic incidence (3.28° ± 0.79°, 7.56° ± 1.81°) were significantly larger than normal pelvic incidence (2.61° ± 1.01°, 6.57° ± 2.18°) and small pelvic incidence (2.00° ± 0.60°, 5.83° ± 1.67°). InterpretationThe anatomic variable pelvic incidence is associated with the ranges of motion in lower lumbar vertebrae, especially in the L4–5 and L5-S1 segments.

Automatic Vertebrae Localization and Spine Centerline Extraction in Radiographs of Patients with Adolescent Idiopathic Scoliosis.

Adolescent Idiopathic Scoliosis (AIS) is lifetime disorder indicated by the abnormal spinal curvature, and it is usually detected in children and adolescents. Traditional radiographic assessment of scoliosis is time-consuming and unreliable due to high variability in images and manual interpretation. Vertebrae localization and centerline extraction from a biplanar X-ray is essential for pathological diagnosis, treatment planning, and decision making. The aim of this paper is to develop a fully automated framework to provide correct evaluation of anatomical landmarks and to extract vertebral and intervertebral discs' centroids. By knowing coordinates of each centroid, developed framework will estimate 2D deformity curve (centerline) called Middle Spinal Alignment (MSA) in frontal plane. By analyzing the MSA lines and deformity segments, many deformity parameters can be calculated which include vertebral transpositions, Cobb angles, apex vertebra position, etc., for planning spinal correction strategies and monitoring.

Discovering the association between the pre- and post-operative 3D spinal curve patterns in adolescent idiopathic scoliosis.

The advantage of considering the three-dimensional curve patterns, including the patterns of the vertebral position and alignment, in classification of adolescent idiopathic scoliosis (AIS) patients and whether such classification system relates to the surgical outcomes are not fully determined. A total of 371 AIS patients who received posterior spinal fusion surgery with 2-year follow-up were included retrospectively and consecutively. The 3D positions and orientations of the T1-L5 vertebrae were calculated from the 3D reconstructions of the spines at pre-operative and 2-year follow-up, a total of 102 variables per patient. A probabilistic clustering method was used to cluster the pre-operative and 2-year follow-up 3D spinal curve patterns separately. The distributions of the Lenke types and 3D pre-operative clusters in the post-operative clusters were determined. A total of nine pre-operative clusters including, four right thoracic types, three left thoracolumbar/lumbar types, one low apex right thoracic/thoracolumbar, and one left thoracic/right lumbar were determined. Three post-operative 3D curve patterns were Type 1 with higher residual proximal Cobb angle, Type 2 with lower T5-T12 kyphosis and highest pelvic incidence-lordosis mismatch, and Type 3 with larger lumbar curve magnitude and rotation compared to the other two groups. More than 50% of patients in each of the 3D pre-operative clusters had the same post-operative group. We developed a 3D classification of the AIS patients before and two-year after spinal fusion surgery. The link between the pre- and post-operative clusters lends itself to application of this classification system in developing predictive models of the AIS surgical outcomes.

CT KUB scans for renal colic: Optimisation of scan range to reduce patient radiation burden

IntroductionNon-contrast CT KUB scans performed to assess renal colic should be limited to scanning between the upper pole of the highest kidney and the pubic symphysis to minimise unnecessary irradiation. This audit aimed to assess the amount of overscanning in CT KUBs outside this range. MethodsCT KUB scans taken over a 10-day period were assessed. Unnecessary overscan above the highest kidney was measured as a percentage of the total scan range. A target of less than 10% overscanning was set. The vertebral position of the upper pole of the highest kidney was also measured and compared to the actual level of the scan. Results88 patients were assessed. 89.8% (79/88) of scans didn't meet the target of less than 10% overscanning above the highest kidney, and were associated with a higher radiation dose to the patient. The average overscanning above the highest pole of the kidney was 16.4% of the whole scan. The average overscan below the pubic symphysis was 1.54%. We also found that 100% of scanned kidneys lied below the upper border of the T11 vertebra, in spite of scans starting as high as T7. ConclusionA large proportion of scans included unnecessary overscanning above the highest kidney. We have identified the upper border of the T11 vertebral body as a potential location from which to begin the upper margin of a CT KUB scan. Implications for practiceBy starting CT KUB scans at the upper border of the T11 vertebral body, we can allow the whole kidney to be imaged while minimising unnecessary overscanning above the kidney, thus lowering excess patient irradiation while still producing high quality scans.

Taxonomic utility of Early Cretaceous Australian plesiosaurian vertebrae

Despite their broad occurrence in Australian basins, lower-level taxonomy of Australian Early Cretaceous plesiosaurs is hindered by the scarcity of skulls and other diagnostic elements. This paper presents a morphological and morphometric analysis of the vertebrae of Australian plesiosaurs and a comparison with selected non-Australian elasmosaurids (basal elasmosaurs, styxosaurines, aristonectines). Biometric analysis involved measurements that include centrum height (CH), centrum width (CW), centrum length (CL), width of zygapophyses, and others. Principal component analysis (PCA) and multivariate analysis of variance (MANOVA) were carried out on CH, CW, and CL. Morphometric ratios [Vertebral Length Index (VLI), Height Index (HI), and Breadth Index (BI)] were plotted along the length of the vertebral column and on bivariate graphs where the analysis is independent of vertebral position and correct sequencing. Direct comparison of homologous groups of vertebrae (especially anterior cervicals) easily distinguished an Australian polycotylid from all elasmosaurids in all plots. Most Australian elasmosaurid specimens plotted near basal ‘Cimoliasaurus’- grade elasmosaurs, where they clustered as a group relatively distinct from, but overlapping coeval non-Australian forms. However, one specimen plotted consistently with the non-Australian styxosaurines and Opallionectes andamookaensis plotted with the aristonectines. Although it is not possible to distinguish phylogenetic relationships from morphological convergence in the plotted positions, the analyses provide potential hypotheses to be tested with additional data. Hence, vertebrae have some taxonomic value for potential assignment of Australian plesiosaurs, even in the absence of skulls or other diagnostic material.

Spinal motor mapping by epidural stimulation of lumbosacral posterior roots in humans.

SummaryEpidural electrical stimulation of the spinal cord is an emergent strategy for the neurological recovery of lower-extremity motor function. Motoneuron pools are thought to be recruited by stimulation of posterior roots. Here, we linked electromyographic data of epidurally evoked lower-extremity responses of 34 individuals with upper motoneuron disorders to a population model of the spinal cord constructed using anatomical parameters of thousands of individuals. We identified a relationship between segmental stimulation sites and activated spinal cord segments, which made spinal motor mapping from epidural space possible despite the complex anatomical interface imposed by the posterior roots. Our statistical approach provided evidence for low-threshold sites of posterior roots and effects of monopolar and bipolar stimulation previously predicted by computer modeling and allowed us to test the impact of different upper motoneuron disorders on the evoked responses. Finally, we revealed a statistical association between intraoperative and postoperative mapping of the spinal cord.

Automatic detection and segmentation of lumbar vertebrae from X-ray images for compression fracture evaluation

For compression fracture detection and evaluation, an automatic X-ray image segmentation technique that combines deep-learning and level-set methods is proposed. Automatic segmentation is much more difficult for X-ray images than for CT or MRI images because they contain overlapping shadows of thoracoabdominal structures including lungs, bowel gases, and other bony structures such as ribs. Additional difficulties include unclear object boundaries, the complex shape of the vertebra, inter-patient variability, and variations in image contrast. Accordingly, a structured hierarchical segmentation method is presented that combines the advantages of two deep-learning methods. Pose-driven learning is used to selectively identify the five lumbar vertebrae in an accurate and robust manner. With knowledge of the vertebral positions, M-net is employed to segment the individual vertebra. Finally, fine-tuning segmentation is applied by combining the level-set method with the previously obtained segmentation results. The performance of the proposed method was validated by 160 lumbar X-ray images, resulting in a mean Dice similarity metric of 91.60±2.22%. The results show that the proposed method achieves accurate and robust identification of each lumbar vertebra and fine segmentation of individual vertebra.

Machine Learning Predicts the 3D Outcomes of Adolescent Idiopathic Scoliosis Surgery Using Patient-Surgeon Specific Parameters.

Retrospective descriptive, multicenter study. The aim of this study was to predict the three-dimensional (3D) radiographic outcomes of the spinal surgery in a cohort of adolescent idiopathic scoliosis (AIS) as a function preoperative spinal parameters and surgeon modifiable factors. Current guidelines for posterior spinal fusion surgery (PSF) in AIS patients are based on two-dimensional classification of the spinal curves. Despite the high success rate, the prediction of the 3D spinal alignment at the follow-ups remains inconclusive. A data-driven surgical decision-making method that determines the combination of the surgical procedures and preoperative patient specific parameters that leads to a specific 3D global spinal alignment outcomes at the follow-ups can lessen the burden of surgical planning and improve patient satisfaction by setting expectations prior to surgery. A dataset of 371 AIS patients who underwent a PSF with two-year follow-up were included. Demographics, 2D radiographic spinal and pelvic measurements, clinical measurements of the trunk shape, and the surgical procedures were collected prospectively. A previously developed classification of the preoperative global 3D spinal alignment was used as an additional predictor. The 3D spinal alignment (vertebral positions and rotations) at two-year follow-up was used as the predicted outcome. An ensemble learner was used to predict the 3D spinal alignment at two-year follow-up as a function of the preoperative parameters with and without considering the surgeon modifiable factors. The preoperative and surgical factors predicted three clusters of 3D surgical outcomes with an accuracy of 75%. The prediction accuracy decreased to 64% when only preoperative factors, without the surgical factors, were used in the model. Predictor importance analysis determined that preoperative distal junctional kyphosis, pelvic sagittal parameters, end-instrumented vertebra (EIV) angulation and translation, and the preoperative 3D clusters are the most important patient-specific predictors of the outcomes. Three surgical factors, upper and lower instrumented vertebrae, and the operating surgeon, were important surgical predictors. The role of surgeon in achieving a certain outcome clusters for specific ranges of preoperative T10-L2 kyphosis, EIV angulation and translation, thoracic and lumbar flexibilities, and patient's height was significant. Both preoperative patient-specific and surgeon modifiable parameters predicted the 3D global spinal alignment at two-year post PSF. Surgeon was determined as a predictor of the outcomes despite including 20 factors in the analysis that described the surgical moves. Methods to quantify the differences between the implemented surgeon modifiable factors are essential to improve outcome prediction in AIS spinal surgery.Level of Evidence: 3.

DRRGenerator: A Three-dimensional Slicer Extension for the Rapid and Easy Development of Digitally Reconstructed Radiographs.

As the interest in image-guided medical interventions has increased, so too has the necessity for open-source software tools to provide the required capabilities without exorbitant costs. A common issue encountered in these procedures is the need to compare computed tomography (CT) data with X-ray data, for example, to compare pre-operative CT imaging with intraoperative X-rays. A software approach to solve this dilemma is the production of digitally reconstructed radiographs (DRRs) which computationally simulate an X-ray-type image from CT data. The resultant image can be easily compared to an X-ray image and can provide valuable clinical information, such as small anatomical changes that have occurred between the pre-operative and operative imaging (i.e., vertebral positioning). To provide an easy way for clinicians to make their own DRRs, we propose DRR generator, a customizable extension for the open-source medical imaging application three-dimensional (3D) Slicer. DRR generator provides rapid computation of DRRs through a highly customizable user interface. This extension provides end-users a free, open-source, and reliable way of generating DRRs. This program is integrated within 3D Slicer and thus can utilize its powerful imaging tools to provide a comprehensive segmentation and registration application for clinicians and researchers. DRR generator is available for download through 3D Slicer’s in-app extension manager and requires no additional software.

283. The position of the L1 vertebra relative to the gravity line does not appear to correlate with proximal junctional kyphosis following adult spinal deformity surgery with two year follow up

BACKGROUND CONTEXT It is known that upper instrumented vertebrae (UIV) position relative to sagittal vertical axis (SVA) is associated with PJK. Over correction of the lumbar spine, resulting in posterior displacement of L1 relative to the GL, may be associated with PJK. PURPOSE Patients who are over corrected with hyper-lordotic spines may develop junctional problems because of forward compensatory leaning of the thoracic spine. Because L1 represents the thoracolumbar junction, its position relative to the gravity line (GL) may correlate with proximal junctional kyphosis (PJK). We investigated if the sagittal position of L1 relative to the GL correlates with PJK. STUDY DESIGN/SETTING Retrospective study. PATIENT SAMPLE Patients who undergoing ASD correction ≥6 levels from the lower thoracic (LT) spine to S1 with a minimum 2-year follow-up were reviewed. OUTCOME MEASURES Demographic data and radiographic spinopelvic parameters included: pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI–LL, sacral slope (SS), T1 pelvic angle (TPA), L1 pelvic angle (L1PA), T5-T12 thoracic kyphosis (TK), sagittal vertical axis (SVA) and L1-GL (cm). METHODS Patients who undergoing ASD correction ≥6 levels from the LT spine to S1 with a minimum 2-year follow-up were reviewed. Demographic data and radiographic spinopelvic parameters included: PI, PT, LL, PI–LL, SS, TPA, L1PA, TK, SVA and L1-GL (cm). GL is defined as the plumb line from external auditory canal. L1-GL is the distance from the center of L1 to GL. RESULTS A total of 76 patients met inclusion criteria including 36 patients with PJK and 40 patients without PJK, with a minimum 2-year follow up. There was no difference in age, gender, and follow-up time in the two groups. There was no statistical difference between groups with regard to PI, SS, PT, LL and TPA (P > 0.05). Preoperative L1PA was 16.00 ± 9.97°for PJK group and 15.75 ± 8.89° for non- PJK group (P =0.914). Preoperative L1-GL was 8.94 ± 6.45 cm for PJK group and 7.09 ± 5.43 cm for non-PJK group (P =0.178). Postoperative L1PA was 13.95 ± 6.76° for PJK group and 14.17 ± 9.35° for non-PJK group (P =0.908). Preoperative L1-GL was 6.00 ± 4.02 cm for PJK group and 7.6 ± 5.38 cm for non-PJK group (P =0.994). CONCLUSIONS The position of L1 vertebra relative to the gravity line does not appear to correlate with PJK after ASD surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. It is known that upper instrumented vertebrae (UIV) position relative to sagittal vertical axis (SVA) is associated with PJK. Over correction of the lumbar spine, resulting in posterior displacement of L1 relative to the GL, may be associated with PJK. Patients who are over corrected with hyper-lordotic spines may develop junctional problems because of forward compensatory leaning of the thoracic spine. Because L1 represents the thoracolumbar junction, its position relative to the gravity line (GL) may correlate with proximal junctional kyphosis (PJK). We investigated if the sagittal position of L1 relative to the GL correlates with PJK. Retrospective study. Patients who undergoing ASD correction ≥6 levels from the lower thoracic (LT) spine to S1 with a minimum 2-year follow-up were reviewed. Demographic data and radiographic spinopelvic parameters included: pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI–LL, sacral slope (SS), T1 pelvic angle (TPA), L1 pelvic angle (L1PA), T5-T12 thoracic kyphosis (TK), sagittal vertical axis (SVA) and L1-GL (cm). Patients who undergoing ASD correction ≥6 levels from the LT spine to S1 with a minimum 2-year follow-up were reviewed. Demographic data and radiographic spinopelvic parameters included: PI, PT, LL, PI–LL, SS, TPA, L1PA, TK, SVA and L1-GL (cm). GL is defined as the plumb line from external auditory canal. L1-GL is the distance from the center of L1 to GL. A total of 76 patients met inclusion criteria including 36 patients with PJK and 40 patients without PJK, with a minimum 2-year follow up. There was no difference in age, gender, and follow-up time in the two groups. There was no statistical difference between groups with regard to PI, SS, PT, LL and TPA (P > 0.05). Preoperative L1PA was 16.00 ± 9.97°for PJK group and 15.75 ± 8.89° for non- PJK group (P =0.914). Preoperative L1-GL was 8.94 ± 6.45 cm for PJK group and 7.09 ± 5.43 cm for non-PJK group (P =0.178). Postoperative L1PA was 13.95 ± 6.76° for PJK group and 14.17 ± 9.35° for non-PJK group (P =0.908). Preoperative L1-GL was 6.00 ± 4.02 cm for PJK group and 7.6 ± 5.38 cm for non-PJK group (P =0.994). The position of L1 vertebra relative to the gravity line does not appear to correlate with PJK after ASD surgery.

Application of the Rapid Entire Body Assessment (REBA) in assessing chairside ergonomic risk of dental students.

Introduction High prevalence of musculoskeletal disorders (MSDs) have been reported among operators in dentistry related to prolonged demanding and awkward operative tasks, in which non-neutral vertebral positions and risky joint articulations are adopted. The aim of the study was to investigate the feasibility and reliability of the application of the Rapid Entire Body Assessment (REBA) among dental students utilising three digital photographs of the operator to determine chairside ergonomic risk.Materials and methods Third-year dental students (n = 28) obtained profile, back and frontal digital photographs of student operators in a clinical session. REBA scorings were assigned per student utilising the photographs by student groups and independently by a physiotherapist. Statistical comparisons were done for both scorings.Results There was substantial interrater reliability (kappa = 0.625; p <0.001) and moderate concordance level (Kendall's Tau-b of 0.568; p <0.01) between the scores derived from students and staff. Medium- and high-risk students based on the REBA scores accounted for 64% and 75% of the class as determined by students and staff, respectively.Discussion The high percentage of medium-to-high-risk REBA values matched the prevalence of MSDs reported by dental students in the literature. Compared to staff, students with moderate reliability were able to produce REBA scores adequately.Conclusion REBA utilising digital photographs may be an easily applicable and moderately reliable tool for alerting static ergonomic risk for clinical dental students. Modification of at-risk behaviour early in training may limit the establishment of bad posture habits and aid in the prevention of MSDs during their clinical years and post-graduation.

Frameless Patient Tracking With Adhesive Optical Skin Markers for Augmented Reality Surgical Navigation in Spine Surgery

Observational study. The aim of this study was to evaluate the accuracy of a new frameless reference marker system for patient tracking by analyzing the effect of vertebral position within the surgical field. Most modern navigation systems for spine surgery rely on a dynamic reference frame attached to a vertebra for tracking the patient. This solution has the drawback of being bulky and obstructing the surgical field, while requiring that the dynamic reference frame is moved between vertebras to maintain accuracy. An augmented reality surgical navigation (ARSN) system with intraoperative cone beam computed tomography (CBCT) capability was installed in a hybrid operating room. The ARSN system used input from four video cameras for tracking adhesive skin markers placed around the surgical field. The frameless reference marker system was evaluated first in four human cadavers, and then in 20 patients undergoing navigated spine surgery. In each CBCT, the impact of vertebral position in the surgical field on technical accuracy was analyzed. The technical accuracy of the inserted pedicle devices was determined by measuring the distance between the planned position and the placed pedicle device, at the bone entry point. The overall mean technical accuracy was 1.65 ± 1.24 mm at the bone entry point (n = 366). There was no statistically significant difference in technical accuracy between levels within CBCTs (P ≥ 0.12 for all comparisons). Linear regressions showed that null- to negligible parts of the effect on technical accuracy could be explained by the number of absolute levels away from the index vertebrae (r ≤ 0.007 for all, β ≤ 0.071 for all). The frameless reference marker system based on adhesive skin markers is unobtrusive and affords the ARSN system a high accuracy throughout the navigated surgical field, independent of vertebral position. 3.

Development and validation of a modeling workflow for the generation of image-based, subject-specific thoracolumbar models of spinal deformity

Quantitative dynamic evaluation of spino-pelvic motion in subjects with spinal deformity using optical motion analysis is currently lacking. The aim of this study was to develop and validate subject-specific, thoracolumbar spine multi-body skeletal models for evaluating spino-pelvic kinematics in a spinal deformity population.A new workflow for creating subject-specific spino-pelvic models in a weight-bearing position through computed tomography (CT) and biplanar radiography is described. As part of a two-step validation process the creation of such a model was first validated against a ground truth CT reconstruction of a plastinated cadaver. Secondly, biplanar radiographic images of one healthy and 12 adult spinal deformity subjects were obtained in two standing positions: upright and bent. Two subject-specific models for each of these subjects were then created to represent both standing positions. The result of inverse kinematics solutions, simulating the specific bending motion using the upright models, are compared with the models created in bent position, quantifying the marker-based spino-pelvic tracking accuracy.The workflow created spinal deformity models with mean accuracies between 0.71–1.95 mm and 1.25–2.27° for vertebral positions and orientations, respectively. In addition, the mean marker-based spino-pelvic tracking accuracies were between 0.9–1.8 mm and 2.9–5.6° for vertebral positions and rotations, respectively.This study presented the first validated biplanar radiography-based method to generate subject-specific spino-pelvic, rigid body models that allows the inclusion of subject-specific bone geometries, the personalization of the 3D weight-bearing spinal alignment with accuracy comparable to clinically used software for 3D reconstruction, and the localization of external markers in spinal deformity subjects. This work will allow new concepts of dynamic functionality evaluation of patients with spinal deformity.

An approximate mathematical model binding the height and position of lumbar vertebrae in the canine spine.

The lumbosacral region of the spine is the most susceptible to pathology in large breed dogs. The most common pathologies of this segment include intervertebral disc disease, distortion of vertebrae, narrowing of the lumbosacral canal and congenital defects of the spine. The aim of this study is to develop a mathematical model describing the height of each lumbosacral vertebra in the dog in relation to the position of the vertebra. For the mathematical analysis we used the results of two measurements for each lumbar vertebra. The first measurement was made from the top of the spinous process to the center of the spinal cord. The second measure-ment was made from the center of the body of one vertebra to the center of the body of the next one. It is possible to determine an approximate mathematical model that would be uniform for the entire species and would connect the height of the lumbar vertebrae with their location for every breed of the domestic dog. Despite the considerable differences in the constitutional type (small, medium and large breeds), the morphology of the lumbosacral region of the spine exhibits similar proportions. Therefore, it is possible to assess an anomaly of this spinal region objectively. These findings suggest that it is possible to determine an approximate mathematical model that would be uniform for the entire species. The present study was carried out as part of a larger project. This particular work is a pilot study.

The effects of forward head posture on expiratory muscle strength in chronic neck pain patients: A cross-sectional study.

This study aims to investigate the relationship between forward head posture (FHP) and respiratory dysfunctions in patients with chronic neck pain. Between June 2014 and November 2016 , a total of 99 patients (11 males, 88 females; mean age 54.1±9 years; range, 38 to 75 years) with chronic neck pain were evaluated for head posture by cervical lateral radiograph measuring the anterior head translation distance (FHPmm) and C7 vertebrae position (C7°). We examined the chest expansion by subtracting chest circumference from the level of xiphoid during maximal inspiration and expiration. Pain severity and neck disability were assessed using the Visual Analog Scale (VAS) and modified Neck Disability Index (MNDI), respectively. The respiratory functions were evaluated using spirometry tests, lung volumes, and maximal inspiratory and expiratory pressures (Pimax and Pemax, respectively). There was a negative correlation between the FHPmm with Pemax% (rho: -0.314; p=0.005). A negative correlation was also observed between C7° and Pemax, Pemax%, forced expiratory volume in one sec (FEV1)/forced vital capacity (FVC)%, forced expiratory flow (FEF)25-75%, and FEF75% (rho:-0.245, -0.349, -0.218, -0.214, and -0.259 respectively; p=0.028, 0.002, 0.035, 0.040, and 0.012, respectively). There was a positive correlation between neck disability and VAS scores (rho: 0.424; p<0.001), while there was a negative correlation between neck disability and chest expansion, maximum voluntary ventilation (rho: -0.201 and -0.217, respectively; p=0.049 and 0.046, respectively). Based on our study results, FHP is associated with expiratory muscle weakness in chronic neck pain patients. To evaluate respiratory dysfunction, chest expansion tests may be useful, although these tests are not specific to muscle weakness. Interventions about FHP and neck pain should focus on the effects of respiratory muscle training.

Magnetic resonance imaging evaluation of vertebral tumor prediction using hierarchical hidden Markov random field model on Internet of Medical Things (IOMT) platform

Abstract Recently, prediction evaluation of the metastatic spine tumors in therapy is considered a significant area of research. Further, for spinal clinical diagnoses, a large amount of image data from different modalities is often used and interchangeably analyzed based on the automatic vertebra identification. It includes recognition of vertebral positions and recognition in several image modalities. Due to the differences in MR or CT images appearance or shape/size of the vertebras, the identification is however difficult in the present conventional medical research. The segmentation of vertebral tumors that are manually performed by MRI is an important and time-consuming process by the conventional research algorithms. The accuracy of identification of the size and location of spine tumors plays a major role in effective tumor diagnosis and treatment. Therefore, this paper presents the Hierarchical Hidden Markov Random Field Model (HHMRF) to predict the vertebral tumor for the early detection and diagnosis treatment in an effective and efficient manner. The importance of this research is to implement a state-of-the-art strategy for detection of tumors using HHMRF and threshold techniques in MRI images on the Internet of Medical Things Platform (IoMT). HHMRF can coordinate the final section of vertebral tumor homogeneous areas of tissue while preserving the edges between different tissue constituents more effectively using mathematical computation. The proposed method attains the state-of-the-art performance on the diagnosis and segmentation of lumbar spinal stenosis using deep neural network and experimentally analyzed with 97.44% accuracy and 97.11% efficiency ratio on IoMT platform whereas proposed HHMRF achieves 98.5% high precision ratio compared to other existing TDCN (78.2%), DLA (81.6%), M-CNN (78.9%), and DCE-MRI (80.2%) methods.