Cranial Endplate Research Articles

Morphological examination of abdominal vertebral bodies from grass carp using high-resolution micro-CT scans.

The vertebral column, a defining trait of all vertebrates, is organized as a concatenated chain of vertebrae, and therefore its support to the body depends on individual vertebral morphology. Consequently, studying the morphology of the vertebral centrum is of anatomical and clinical importance. Grass carp (GC) is a member of the infraclass Teleostei (teleost fish), which accounts for the majority of all vertebrate species; thus, its vertebral anatomical structure can help us understand vertebrate development and vertebral morphology. In this study, we have investigated the morphology and symmetry of the grass carp vertebral centrum using high-resolution micro-CT scans. To this end, three abdominal vertebrae (V9, V10, & V11) from eight grass carp were micro-CT scanned and then segmented using Dragonfly (ORS Inc.). Grass carp vertebral centrum conformed to the basic teleost pattern and demonstrated an amphicoelous shape (biconcave hourglass). The centrum's cranial endplate was smaller, less circular, and shallower compared to the caudal endplate. While the vertebral centrum demonstrated bilateral symmetry along the sagittal plane (left/right), the centrum focus was shifted dorsally and cranially, breaking dorsoventral and craniocaudal symmetry. The sum of these findings implies that the caudal aspect of grass carp vertebral centrum is bigger and more robust. Currently, we have no information whether this is due to nature, for example, differences in gene expression, or nurture, for example, environmental effect. As the vertebral parapophyses and spinous processes are slanted caudally, the direction of muscle action during swimming may create a gradient of stresses from cranial to caudal, resulting in a more robust caudal aspect of the vertebral centrum. Expanding our study to include additional quadrupedal and bipedal (i.e., human) vertebrae, as well as testing if these morphological aspects of the vertebrae are indeed plastic and can be affected by environmental factors (i.e., temperature or other stressors) may help answer this question.

Pedicle screws close to the cranial endplate cause accelerated adjacent segment degeneration - a clinical cohort study supported by finite element analysis

Pedicle screws close to the cranial endplate cause accelerated adjacent segment degeneration - a clinical cohort study supported by finite element analysis

Use of a Smartphone Digital Goniometer Combined with the Freehand Pedicle-Probing Technique for Repair of a Comminuted L6 Fracture in a 4 kg Dog

AbstractA 10-month-old, 4 kg, Bichon Frise cross was referred for surgical stabilization of a highly comminuted L6 vertebral fracture after a road traffic accident. Nonambulatory paraparesis was present, with weak voluntary motor function in both pelvic limbs. Computed tomography (CT) of T6 to Cd1 identified a highly comminuted fracture of vertebral body and cranial endplate of L6 with severe narrowing of vertebral canal. A left-sided L6 pediculectomy was performed. The cauda equina was mildly bruised. Smaller bone fragments were removed, whereas larger bone fragments were depressed ventrally. Two 1.5-mm cortical screws were inserted into pedicles of L7 and a further two 2.0-mm screws into L5 vertebral body using the pedicle-probing technique. Following exposure of underlying cancellous bone, a smartphone digital goniometer, held by a nonsterile assistant, was used to guide advancement of a blunted Kirschner wire acting as a probe according to preoperative CT-determined safe angles. Postoperative CT identified excellent vertebral column alignment with improvement in spinal cord compression and optimal placement of implants at L5 and L7 (grade 1 modified Zdichavsky). Repeat CT at 3 months postoperatively identified well-seated implants. This report highlights that use of a smartphone goniometer may be a useful adjunct to the freehand pedicle-probing technique to guide correct trajectory of the probe and may also have application in other regions of the spine.

Computed tomographic diaphragmatic thickness: a promising method for the evaluation of diaphragmatic muscle in cardiopulmonary diseased cats.

Diaphragmatic dysfunction (DD) is defined as a weakening of the diaphragmatic muscle and can be an undetected cause of dyspnea. The objectives of this study were to explore the appropriate diaphragmatic location, measure diaphragmatic thickness (DT), evaluate the effect of intrinsic factors on DT, and compare DT between healthy and diseased cats, using 33 healthy cats and 15 diseased cats. A retrospective, analytical, case-control study using thoraco-abdominal feline computed tomography (CT) was performed. Two radiologists independently reviewed all images to verify inter- and intra-observer reliabilities and the best position for measuring DT. The effects of sex, age, and body weight were also studied, and cutoff values for detecting DT abnormalities were established. The results showed that the appropriate location for DT measurement was at the ventral border of the cranial endplate of the first lumbar vertebral body (L1) due to its highest intra- and inter-observer reliabilities. At this location, a significant difference in DT between the right and left hemidiaphragms (p = 0.01) was observed. Only sex had an impact on DT values. Interestingly, the DTs of cardiorespiratory-affected cats, both on the right and left sides, were significantly thinner than those of healthy cats. In conclusion, CT imaging is a reliable imaging method for determining diaphragmatic muscular atrophy. The ventral border of the cranial endplate of L1 is recommended for measuring the DT, and sex was the only factor affecting the DT measurement.

Mapping Subchondral Bone Density Distribution in the Canine C6-C7 Vertebral Endplates: A CT-OAM Study.

Intervertebral cage subsidence is a common complication in treating disc-associated cervical spondylomyelopathy in dogs. The mechanical stability of the vertebral endplate in contact with the cage is crucial to preventing subsidence. This study aims to assess subchondral bone mineral density (sBMD) in the canine vertebral endplate (specifically, the C6-C7 vertebral motion unit) as a measure of its mechanical stability. The sBMD distribution was mapped for the C6 caudal and C7 cranial vertebral endplates in 15 middle- to large-breed dogs using computed tomography osteoabsorptiometry. The sBMD distribution in the canine C6 and C7 vertebral endplates exhibited a heterogeneous pattern, with lower density observed in the central and dorsal contact areas of the nucleus pulposus, where common subsidence occurs. Our results suggest a potential need to redesign intervertebral cages to ensure that contact areas align with regions of higher bone density. A broad-based design extending toward the lateral and dorsal aspects of the annulus fibrosus contact area may enhance stability.

Effect of bone cement distribution on adjacent disc degeneration after vertebral augmentation for osteoporotic vertebral compression fractures in aging patients.

The influence of vertebral augmentation on adjacent intervertebral discs remains controversial. The purpose of this study is to evaluate the effect of bone cement distribution on adjacent disc degeneration after vertebral augmentation for osteoporotic vertebral compression fractures (OVCFs). Patients with single level OVCF and upper endplate injury who underwent vertebral augmentation were enrolled. The patients were divided into four groups: Group A: bone cement contacted both the cranial and the distal endplates; Group B: bone cement only contacted the cranial endplate; Group C: bone cement only contacted the distal endplate; and Group D: bone cement contacted neither the cranial nor the distal endplates. The cranial discs of the fractured vertebrae were defined as adjacent discs and the upper discs proximally to the adjacent discs were defined as control discs. Degenerative disc change (DDC) was defined as a deteriorated postoperative Pfirrmann score compared with the preoperative score on MR images. The number of DDC cases and the disc heights were analyzed among the groups. A total of 184 patients with an average follow-up time of 28.6 months were included. The number of DDC cases in the adjacent discs was significantly higher than in the control discs in groups A (p < 0.001), B (p = 0.002), and D (p = 0.028), whereas the difference in group C was not statistically significant (p = 0.237). The incidence of adjacent disc degeneration was significantly higher in group A than that in group C (p = 0.06). The adjacent disc heights decreased significantly in groups A, B, and D (p < 0.001, p < 0.001, and p = 0.012, respectively), but did not decrease significantly in group C (p = 0.079). However, no statistical differences were detected among the four groups with respect to the preoperative adjacent disc height, follow-up adjacent disc height, preoperative control disc height, or follow-up control disc height. Bone cement distribution influences adjacent disc degeneration after vertebral augmentation in OVCFs. Cement distribution proximal to the injured endplate can accelerate adjacent disc degeneration, and cement in contact with both the cranial and distal endplates can induce a higher incidence of adjacent disc degeneration.

Evaluation of Disc and Endplate Degeneration in AO Type A Fractures Using Magnetic Resonance Imaging Analysis

Disc degeneration following trauma has been the focus of several investigations, while vertebral endplate changes have received comparatively less attention. The main aim of the study is to radiologically evaluate the prevalence of degree of degeneration of the adjacent discs and endplates following AO type A thoracolumbar fractures. We retrospectively reviewed 25 patients with AO type A injury (50 discs, and 150 endplates). The type of disc lesion adjacent to the fractured vertebra was classified based on Pfirrmann's and Oner's classifications, immediately after trauma and at 1-year follow-up. The endplate defects were assessed using the endplate scoring system (TEPS - grade 1 to 6) in T1 weighted images. The kyphosis angle and the vertebral body height were also measured. The study population consisted of 18 males (72%) and 7 females (28%) with a mean age of 38.9 ±11.3 years. Overall, 28% of fractures were type A1, 4% were type A2, 24 % were type A3 and 44% were type A4. On statistical analysis, there was a significant change in the degree of degeneration in the cranial adjacent disc based on both Oner (p=0.004) and Pfirrmann (p=0.001) classification at the end of 1-year. The morphological changes at the cranial adjacent discs at 1-year follow-up showed a strong positive correlation with superior endplate degeneration. The present study indicates that endplate fractures of vertebrae in patients with thoracolumbar burst fractures may cause disc degeneration, especially at the cranial endplate.

Experimentally dissociating the overuse mechanisms of endplate fracture lesions and Schmorl's node injuries using the porcine cervical spine model

BackgroundCompared to the documented overuse mechanisms of endplate fracture lesions, the cause of Schmorl's node injuries remains unknown, despite existing hypotheses. Therefore, this study aimed to examine and dissociate the overuse injury mechanisms of these spinal pathologies. MethodsForty-eight porcine cervical spinal units were included. Spinal units were randomly assigned to groups that differed by initial condition (control, sham, chemical fragility, structural void) and loading posture (flexed, neutral). Chemical fragility and structural void groups involved a verified 49% reduction in localized infra-endplate trabecular bone strength and removal of central trabecular bone, respectively. All experimental groups were exposed to cyclic compression loading that was normalized to 30% of the predicted tolerance until failure occurred. The cycles to failure were examined using a general linear model and the distribution of injury types were examined using chi-squared statistics. FindingsThe incidence of fracture lesions and Schmorl's nodes was 31(65%) and 17(35%), respectively. Schmorl's nodes were exclusive to chemical fragility and structural void groups and 88% occurred in the caudal joint endplate (p = 0.004). In contrast, 100% of control and sham spinal units sustained fracture lesions, with 100% occurring in the cranial joint endplate (p < 0.001). Spinal units tolerated 665 fewer cycles when cyclically loaded in flexed postures compared to neutral (p = 0.015). Furthermore, the chemical fragility and structural void groups tolerated 5318 fewer cycles compared to the control and sham groups (p < 0.001). InterpretationThese findings demonstrate that Schmorl's node and fracture lesion injuries can result from pre-existing differences in the structural integrity of trabecular bone supporting the central endplate.

Applying a homogeneous pressure distribution to the upper vertebral endplate: Validation of a new loading system, pilot application to human vertebral bodies, and finite element predictions of DIC measured displacements and strains

Image-based personalized Finite Element Models (pFEM) could detect alterations in physiological deformation of human vertebral bodies, but their accuracy has been seldom reported. Meaningful validation experiments should allow vertebral endplate deformability and ensure well-controlled boundary conditions. This study aimed to (i) validate a new loading system to apply a homogeneous pressure on the vertebral endplate during vertebral body compression regardless of endplate deformation; (ii) perform a pilot study on human vertebral bodies measuring surface displacements and strains with Digital Image Correlation (DIC); (iii) determine the accuracy of pFEM of the vertebral bodies.Homogeneous pressure application was achieved by pressurizing a fluid silicone encased in a rubber silicone film acting on the cranial endplate. The loading system was validated by comparing DIC-measured longitudinal strains and lower-end contact pressures, measured on three homogeneous pseudovertebrae of constant transversal section at 2.0 kN, against theoretically calculated values. Longitudinal strains and contact pressures were rather homogeneous, and their mean values close to theoretical calculations (5% underestimation).DIC measurements of surface longitudinal and circumferential displacements and strains were obtained on three human vertebral bodies at 2.0 kN. Complete displacement and strain maps were achieved for anterolateral aspects with random errors ≤0.2 μm and ≤30 μstrain, respectively. Venous plexus and double curvatures limited the completeness and accuracy of DIC data in posterior aspects.pFEM of vertebral bodies, including cortical bone mapping, were built from computed tomography images. In anterolateral aspects, pFEM accuracy of the three vertebrae was: (i) comparable to literature in terms of longitudinal displacements (R2>0.8); (ii) extended to circumferential displacements (pooled data: R2>0.9) and longitudinal strains (zero median error, 95% error: <27%). Circumferential strains were overestimated (median error: 39%).The new methods presented may permit to study how physiological and pathologic conditions influence the ability of vertebral endplates/bodies to sustain loads.

The role of endplate injury in intervertebral disc degeneration after vertebral augmentation in OVCF patients.

Whether vertebral augmentation can induce or aggravate the degeneration of adjacent intervertebral discs remains controversial. The purpose of this study is to explore the role of endplate injury in intervertebral disc degeneration after vertebral augmentation. The imaging data of patients with single-segment osteoporotic vertebral compression fractures (OVCFs) were retrospectively analyzed. The upper and lower discs of the fractured vertebrae were defined as cranial and caudal discs, and the discs adjacent to the cranial discs were defined as control discs. According to the integrity of the cranial and caudal endplates, they were divided into an injury group and a noninjury group. At follow-up, the increase in the modified Pfirrmann score on MRI compared with the baseline grade was defined as the occurrence of a degenerative disc change (DDC). The changes in the disc height and the number of DDC cases on MRI during the follow-up in each group were analyzed. A total of 56 patients with OVCFs were included in this study, with an average follow-up time of 18.8 ± 14.1 months (3-62 months). In the cranial and caudal discs, the number of DDC cases in the endplate injury group was significantly higher than that in the noninjury group (P = 0.007 and P = 0.018). However, the number of DDC cases in the whole endplate injury group (including the cranial and caudal endplates) was significantly higher than that of the whole noninjury group (P = 0.000) and the control group (P = 0.000). The number of DDC cases in the whole noninjury group was not different from that of the control group (P = 0.192). At follow-up, the disc height of the cranial and caudal endplate injury group was significantly lower than the baseline (P = 0.000 and P = 0.001), but the disc height of the noninjury group was not significantly lower than the baseline (P = 0.074 and P = 0.082). Endplate injury is associated with adjacent intervertebral disc degeneration in OVCF patients after vertebral augmentation. Evaluation of endplate damage before vertebral enhancement in OVCF patients has an important reference value for predicting the outcome of adjacent intervertebral discs after surgery.

Posterior lumbar interbody fusion for dysplastic lumbar spondylolisthesis with high-grade slippage in two adolescent siblings: two case reports

BackgroundLumbar spondylolisthesis is reported to present with a familiar pattern, with the dysplastic type of spondylolysis being minor but more hereditary than the isthmic type. Siblings presenting during adolescence with neurological symptoms owing to high-grade dysplastic-type spondylolisthesis are rare.Case presentationThe older brother suffered from left leg pain and numbness and dysesthesia of the right posterior thigh and calf and could not walk without a crutch at the age of 15 years. He had canal stenosis with disc bulging and dysplastic bilateral facet joint at L5/S1. The L5 vertebral body was slipped anterior downward to S1, with a round-shaped S1 cranial endplate. We diagnosed dysplastic-type spondylolisthesis and performed posterior lumbar interbody fusion at L5/S with mild reduction and sublaminar wiring at L4/5. The younger brother had no neurological symptoms at age 14 years but suffered from bilateral lower leg numbness at age 18 years. He had canal stenosis with disc bulging at L4/5 and L5/S1 and dysplastic bilateral facet joint at L5/S1 with right pars defect. The L5 vertebral body was vertically displaced anterior to the S1 vertebral body, with an S1 round-shaped cranial endplate. We diagnosed dysplastic-type spondylolisthesis, and posterior lumbar interbody fusion at L4/5 and L5/S with reduction was performed. Their neurological symptoms of the lower legs disappeared, and interbody bone fusion was obtained.ConclusionsThe surgical technique for high-grade dysplastic spondylolisthesis remains controversial in terms of in situ fusion versus reduction. We recommend that surgery be performed promptly at the end of bone maturation because neurological symptoms often appear at the end of bone maturation. Because high-grade slips are rare but siblings may be present, the sibling should also be screened when dysplastic spondylolisthesis is detected.

Morphological Examination of Vertebral Bodies (Centrum) From Grass Carp (Ctenopharyngodon idella) Using High‐Resolution Micro‐CT Scans

The vertebral column, a defining trait of all vertebrates, is organized as a concatenated chain of vertebrae, and therefore its support to the body depends on individual vertebral morphology. Consequently, studying the morphology of the vertebral body (centrum) is of anatomical and clinical importance. In this study, we have investigated the morphology of Grass carp (Ctenopharyngodon idella) vertebral centrum using high‐resolution micro‐CT scans. Grass carp is a member of the interclass Teleostei (teleost fish), part of the class Actinopterygii, which accounts for the majority of all vertebrate species; thus, Grass carp vertebral morphology can help us understand normal vertebrate vertebral morphology and development. Based on previous studies done on teleost fish, we hypothesized that vertebral centrum will demonstrate bilateral symmetry along the sagittal (left/right) and transverse (cranial/caudal) planes. To this end, three vertebrae (numbers V9‐11) from eight Grass carps that were housed in a Living Stream Systems for 8 weeks at 15⁰C were harvested and micro‐CT scanned at a resolution of 19.29 µm (SkyScan1173, Bruker Inc). The scans were reconstructed into 16‐bit TIFF image stacks and then imported into Dragonfly (ORS Inc.) for segmentation using an Otsu algorithm. After centering each vertebrae along its three principal axes various morphological measurements were performed. Grass carp vertebral centrum demonstrated an hourglass shape where both endplates are concave. While the vertebral centrum demonstrated bilateral symmetry along the sagittal plane (left/right, in line with our hypothesis), vertebral centrum demonstrated deviation from bilateral symmetry along the transverse plane (cranial/caudal, refuting our hypothesis). The vertebral centrum cranial endplate size (perimeter and area) was found to be smaller and less circular compared to the caudal endplate. This implies that the vertebral body tapers off from caudal to cranial. In addition, the cranial endplate was found to be shallower (i.e. more obtuse angles, α &gt; β, see figure 1) compared to the caudal endplate. As a result of the shallower cranial endplate, the center of the vertebrae (narrowest part of the hourglass, between the two endplates) was shifted cranially (A &lt; B, see figure 1). The sum of these findings implies that the caudal aspect of Grass carp vertebral centrum is bigger and more robust. Currently we have no information whether this is due to nature, e.g. differences in gene expression, or nurture, e.g. environmental effect. As the vertebral transverse and spinous processes are slanted caudally, the direction of muscle action during swimming may create a gradient of stresses from cranial to caudal, resulting in a more robust caudal aspect of the vertebral centrum. Expanding our study to include additional quadrupedal and bipedal (i.e. humans) vertebrae, as well as testing if these morphological aspects of the vertebrae are indeed plastic and can be affected by environmental factors (i.e. temperature or other stressors) may help answering this interesting question.

Cervical and First Thoracic Spine Hounsfield Units Assessment and Relationship to Clinical Outcomes and Cervical Sagittal Parameters in Patients Undergoing Anterior Cervical Spine Surgery

This study had 3 objectives: to compare bone mineral density (BMD) from 3 axial slices, subchondral trabecular bone 2 mm inferior to the cranial endplate, middle of the vertebral body, and subchondral trabecular bone 2 mm superior to the caudal endplate; assess BMD variations and correlations of C1-T1 vertebrae; and correlate BMD with clinical outcomes and cervical sagittal parameters in patients undergoing anterior cervical discectomy and fusion. The study enrolled 71 patients who underwent anterior cervical discectomy and fusion between March 2017 and January 2020. Patient demographics, clinical outcomes, cervical sagittal parameters, and Hounsfield units (HUs) of C1-T1 vertebrae were recorded. Analysis of variance was performed to compare HUs from the axial slices. Pearson correlation coefficient was performed to calculate the relationship between mean HUs of C1-T1 and to assess correlations of mean HUs with clinical outcomes and cervical sagittal parameters. There were no significant differences between HUs of 3 axial levels. Mean HUs were highest in the mid-cervical spine (C4). Significant correlations in mean HUs among all measured spinal levels were observed. Age, sex, and body mass index were not related to mean HUs. Visual analog scale, Neck Disability Index, and Patient Health Questionnaire-9 scores were not related to HUs before and after surgery. There were significant correlations among mean HUs of C2-T1 vertebrae, C2-C7 sagittal vertical axis, and cranial tilt. Mean HUs of C4 had the strongest correlation with C2-C7 sagittal vertical axis. To our knowledge, this is the first study of cranial and caudal subchondral trabecular BMD using HUs and comparing them with the middle of the vertebral body and study of correlations between mean HUs of C1-T1 vertebrae and clinical outcomes and cervical sagittal parameters. Correcting C2-C7 sagittal vertical axis and cranial tilt would improve BMD of C1-T1 vertebrae.

Anterior 1-2 Level Cervical Corpectomy and Fusion for Degenerative Cervical Disease: A Retrospective Study With Lordotic Porous Tantalum Cages. Long-Term Changes in Sagittal Alignment and Their Clinical and Radiological Implications After Cage Subsidence.

Despite the advances in anterior cervical corpectomy and fusion (ACCF) as a reconstructive surgical technique, the rate of complications related to artificial implants remains high. The purpose of this study was to investigate the long-term clinical course of ACCF with tantalum trabecular metal (TTM)-lordotic implants. Focus is placed on the relevance and influence of implant subsidence on sagittal alignment and the related clinical implications. Retrospective, observational study of prospectively collected outcomes including 56 consecutive patients with degenerative cervical disc disease (myelopathy and/or radiculopathy). All patients underwent 1-level or 2-level ACCF with TTM-lordotic implants. The mean duration of follow-up was 4.85 years. The fusion rate at the end of follow-up was 98.11% (52/53). Implant subsidence occurred in 44 (83.01%) cases, including slight subsistence (<3 mm) in 37 (69.81%) and severe subsidence (>3 mm) in 7 cases (13.2%). The greatest degree of subsidence developed in the first 3 months postoperatively (P = 0.003). No patients presented a significant increase in implant subsidence beyond the second year of follow-up. The most common site of severe subsidence was the anterior region of the cranial end plate (4/7). At the end of follow-up, C1-C7 lordosis and segmental-Cobb angle of the fused segment increased on average by 5.06 ± 8.26 and 1.98 ± 6.02 degrees, respectively, though this difference failed to reach statistical significance (P > 0.05). Visual analog scale and Neck Disability Index scores improved at the conclusion of follow-up (P < 0.05). ACCF with anterior cervical reconstruction using TTM-lordotic implants and anterior cervical plating for treatment of cervical degenerative disease has high fusion rates and good clinical outcome. The osteoconductive properties of TTM provide immediate stabilization and eliminate the need for bone grafts to ensure solid bone fusion. Before fusion occurs, asymptomatic implant settlement into the vertebral body is inevitable. However, lack of parallelism and reduced contact surface between the implant and the vertebral end plate are major risk factors for severe further subsidence, which may negatively affect the clinical outcomes.

A deep learning pipeline for automatized assessment of spinal MRI

BackgroundThis work evaluates the feasibility, development, and validation of a machine learning pipeline that includes all tasks from MRI input to the segmentation and grading of the intervertebral discs in the lumbar spine, offering multiple different radiological gradings of degeneration as quantitative objective output. MethodsThe pipelines’ performance was analysed on 1′000 T2-weighted sagittal MRI. Binary outputs were assessed with the harmonic mean of precision and recall (DSC) and the area under the precision-recall curve (AUC-PR). Multi-class output scores were averaged and complemented by the Top-2 categorical accuracy. The processing success rate was evaluated on 10′053 unlabelled MRI scans of lumbar spines. ResultsThe midsagittal plane selection achieved an DSC of 74,80% ± 2,99% and an AUC-PR score of 81.71% ± 2.72% (96.91% Top-2 categorical accuracy). The segmentation network obtained a DSC of 91.80% ± 0.44%. The Pfirrmann grading of intervertebral discs in the midsagittal plane was classified with a DSC of 64.08% ± 3.29% and an AUC-PR score of 68.25% ± 6.00% (91.65% Top-2 categorical accuracy). Disc herniations achieved a DSC of 61.57% ± 3.39% and an AUC-PR score of 66.86% ± 5.03%. The cranial endplate defects reached a DSC of 49.76% ± 3.45% and 52.36% ± 1.98% AUC-PR (slightly superior predictions of caudal endplate defect). The binary classifications for the caudal Schmorl's nodes obtained a DSC of 91.58% ± 2.25% with an AUC-PR metric of 96.69% ± 1.58% (similar performance for cranial Schmorl's nodes). Spondylolisthesis was classified with a DSC of 89.03% ± 2.42% and an AUC-PR score of 95.98% ± 1.82%. Annular Fissures were predicted with a DSC of 78.09% ± 7.21% and an AUC-PR score of 86.31% ± 7.45%. Intervertebral disc classifications in the parasagittal plane achieved an equivalent performance. The pipeline successfully processed 98.53% of the provided sagittal MRI scans. ConclusionsThe present deep learning framework has the potential to aid the quantitative evaluation of spinal MRI for an array of clinically established grading systems.

Repeatability and accuracy of a novel, quantitative radiographic method for differentiating normal canine sacroiliac joints from joints with subluxation or luxation: Pilot study.

Canine sacroiliac (SI) joint subluxation or luxation is most commonly diagnosed based on qualitative radiographic assessments. Aims of this two-part, retrospective, diagnostic accuracy, pilot study were to develop and evaluate a novel quantitative method based on measuring the angle between a line connecting the iliac wings and parallel lines across three anatomical landmarks (cranial endplate of L7, caudal endplate of L6, cranial endplate of L6) on a single ventrodorsal radiograph. For the first part of the study, angle measurements from a single observer were compared for 20 normal canine pelvic radiographs and 20 pelvic radiographs with SI luxation or subluxation. Mean values significantly differed between datasets (P<0.001). The angles for the normal pelves ranged from 0.6° to 1.5°, while abnormal angles ranged from 3.8° to 7.1°. For the second part of the study, a dataset of 25 normal and 25 abnormal canine pelvic radiographs was evaluated using the novel technique by three blinded readers with varying levels of expertise at two different time points. There was excellent reliability among the three readers with an intraclass correlation (ICC) value of 0.90 and an excellent agreement between day 0 and day 30 readings with an ICC value of 0.91. It was also determined that a cut-off angle of 2.0°, using the line parallel to the cranial endplate of L6, provided overall the best accuracy, sensitivity, and specificity to differentiate normal versus abnormal pelves. These findings may be helpful for clinical cases with equivocal diagnoses and for future development of automated diagnostic tools.

Ex vivo Evaluation of the Dynamic Morphometry of the Caudal Cervical Intervertebral Disc Spaces of Small Dogs and Cats.

The objective of this study was to provide a morphometric description of the caudal cervical intervertebral disc (IVD) spaces of small-breed dogs and cats. Specimens consisting of C4 through C7 from five small-breed dogs and six cats were positioned in neutral, flexion, extension, and lateral bending positions; and CT images were acquired. Height and width of the cranial and caudal vertebral endplates (VEPs), angle between the VEPs (IVD wedge angle), and craniocaudal distance (IVD width) between VEPs for the four loading positions were measured and compared for three segments (C4–C5, C5–C6, and C6–C7). VEP size normalized to body weight from medium-sized dogs was retrieved from a previous study and compared with data from small dogs and cats. A linear mixed model was used to compare outcome measures. Significance was set to p < 0.05. VEP size normalized to body weight was the largest in small dogs compared with cats (p = 0.0422) and medium-sized dogs (p = 0.0064). Cats and medium-sized dogs were similar (p = 0.2763) in this regard. Flexion and extension induced a reduction of IVD width in the ventral portion of the IVD and the area of the nucleus. The dorsal part of the IVD remained unchanged throughout loading conditions. Unique morphometric characteristics of the caudal cervical IVD space of small dogs and cats were detected that are different from those described in sizes of dogs (medium-sized) typically affected by caudal cervical spondylomyelopathy (CSM). These findings may help to understand the different pathomechanisms in cervical spinal disease between small- and medium-sized dogs, including caudal CSM.

168. Minimally invasive hydrogel nucleoplasty in a goat model of moderate severity disc degeneration

<h3>BACKGROUND CONTEXT</h3> Intervertebral disc (IVD) degeneration (IVDD) is implicated as a cause of low back pain. The earliest degenerative changes typically occur in the central nucleus pulposus (NP), where progressive loss of proteoglycans and associated hydration compromise tissue mechanical function. <h3>PURPOSE</h3> We developed a noncrosslinked injectable hydrogel for NP replacement and augmentation together with its percutaneous delivery method and instrument assembly. We then evaluated the short- and long-term performance of this hydrogel in a goat model of moderate IVDD. <h3>Methods</h3> Six goats underwent two percutaneous procedures: one to induce degeneration in 3 lumbar IVDs via injection of 1U C-ABC and, 2 weeks later, a second procedure for the delivery of hydrogel at 2 levels with the third remaining untreated. Animals were euthanized at 6 weeks (n=2) and 12 weeks (n=1); three animals are currently enrolled for long-term survival. Disc height index (DHI) was measured from monthly lateral radiographs in the standing animal. Postmortem, motion segments were imaged using microcomputed tomography (µCT) to assess hydrogel distribution and bone volume fraction values (BV/TV) for cranial and caudal endplates. Volumetric analysis and compression testing were performed on explanted gels. Samples were dried to determine polymer and water content. Explant characteristics were compared to nonimplanted gels. Histology was performed to assess glycosaminoglycans and collagen content, cellularity, and disc morphology. Significant changes in DHI were established using Wilcoxon matched-pairs signed ranks tests and differences in histological grades were established using Kruskal-Wallis test with post-hoc Dunn's tests (p<0.05). <h3>Results</h3> Animals recovered uneventfully from surgical procedures. Extrusion of hydrogel into the spinal canal during delivery occurred in two animals without major clinical repercussions. At 2 weeks after C-ABC injection, DHI was ∼80% of pre-C-ABC levels. For IVDs treated with hydrogel, DHI improved while untreated IVDs continued to degenerate. The hydrogel presents radiographically unremarkable for up to 2 years post nucleoplasty. µCT imaging demonstrated that the majority of hydrogel was localized to the central NP. BV/TV ratio of treated levels at 6-week and 12-week endpoint were similar to controls. Explant analyses showed higher elastic moduli and polymer content compared to nonimplanted gels. Treated IVDs exhibited an overall improved histological grade compared to positive controls. <h3>Conclusions</h3> The results of this work illustrate the practical utility of an injectable hydrogel being effective in normalizing the mechanical function of the degenerating IVD in a clinically relevant animal model. The implant showed successful retention without extrusion following delivery. A critical benchmark for the success of any injectable implant to treat IVDD is the normalization of mechanical properties. We demonstrate through long-term in vivo follow up studies that hydrogel injected into degenerating goat discs can preserve the spine motion segment. There is a critical need for new therapies for patients with symptomatic disc degeneration that preserve joint mobility. A minimally invasive injectable therapy mitigates anulus fibrosus trauma during nucleoplasty and may restore the biomechanics of the motion segment. Moreover, successful biomechanical restoration of the affected motion segment may slow or prevent further IVDD. Motion preservation therapies may also help mitigate adjacent level IVDD in these patient cohorts. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Evaluation of the intervertebral disk, vertebral body, and spinal cord for changes secondary to percutaneous laser disk ablation.

To evaluate the intervertebral disk, vertebral endplates, and spinal cord for perioperative changes secondary to percutaneous laser disk ablation (PLDA) and correlate findings to clinical outcomes in dogs receiving thoracolumbar PLDA. Blinded study. Thirty dogs. Magnetic resonance imaging (MRI) was performed before PLDA (control/Group C), immediately following PLDA (Group I), and 3 months later (perioperative/GroupP). Dogs were followed 3 years. Groups and dogs were randomized for evaluation. Two radiologists were blinded to each MRI study and dog. Each radiologist evaluated the disk, vertebral body, and spinal cord at each disk space receiving PLDA. Mean disk degeneration was increased in GroupP at L1-2 (p < .0001) and L2-3 (p=.0081). Both radiologists identified mild diskitis (1%-15%) in GroupP (radiologist 1, p < .0001; radiologist 2, p=.0012). Cranial endplate lesions were identified in GroupP at T11-12 (p=.0353), T13-L1 (p=.0026), and L4-5 (p=.0210). Lesions were identified in the caudal endplates of all eight disk spaces in GroupP: T10-11 (p=.0004), T11-12 (p < .0001), T12-13 (p < .0001), T13-L1 (p < .0001), L1-2 (p < .0001), L2-3 (p < .0001), L3-4 (p < .0001), and L4-5 (p < .0001). There was no disk extrusion or spinal cord lesions identified. This study evaluated effects that may occur secondary to PLDA, using MRI. Although vertebral body changes were identified, they did not correlate with clinical complications. PLDA appears to be a safe, effective procedure performed on thoracolumbar disks to reduce recurrence of intervertebral disk herniation (IVDH) in dogs that previously experienced IVDH, despite the appearance of visible vertebral endplate lesions and mild diskitis on MRI.

Endplate injury as a risk factor for cage retropulsion following transforaminal lumbar interbody fusion: An analysis of 1052 cases.

Although transforaminal lumbar interbody fusion (TLIF) is a widely accepted procedure, major complications such as cage retropulsion (CR) can cause poor clinical outcomes. Endplate injury (EI) was recently identified as a risk factor for CR, present in most levels developing CR. However, most EIs occurred in non-CR levels, and the features of EIs in CR levels remain unknown.The aim of this study was to identify risk factors for CR following TLIF; in particular, to investigate the relationship between EIs and CR, and to explore the features of EIs in CR.Between October 2010 and December 2016, 1052 patients with various degenerative lumbar spinal diseases underwent bilateral instrumented TLIF. Their medical records, radiological factors, and surgical factors were reviewed and factors affecting the incidence of CR were analyzed.Twenty-one patients developed CR. Nine had back pain or leg pain, of which six required revision surgery. A pear-shaped disc, posterior cage positioning and EI were significantly correlated with CR (P < .001, P = .001, and P < .001, respectively). Computed tomography (CT) scans revealed the characteristics of EIs in levels with and without CR. The majority of CR levels with EIs exhibited apparent compression damage in the posterior part of cranial endplate on the decompressed side (17/18), accompanied by caudal EIs isolated in the central portion. However, in the control group, the cranial EIs involving the posterior part was only found in four of the total 148 levels (P < .001). Most of the injuries were confined to the central portion of the cranial or caudal endplate or both endplates (35 in 148 levels, 23.6%). Additionally, beyond cage breaching into the cortical endplate on lateral radiographs, a characteristic appearance of coronal cage misalignment was found on AP radiographs in CR levels with EIs.A pear-shaped disc, posterior cage positioning and EI were identified as risk factors for CR. EI involving the posterior epiphyseal rim had influence on the development of CR. Targeted protection of the posterior margin of adjacent endplates, careful evaluation of intraoperative radiographs, and timely remedial measures may help to reduce the risks of CR.