Vertebra In Relation Research Articles

The Impact of the Placement of the L5 Vertebra in Relation to the Intercrest Line on the Level of Disc Herniation.

To determine whether there is a correlation between a deeply seated L5 vertebra in relation to the intercrest line (ICL) and the level of degeneration of lumbar discs. The study included 152 patients who underwent surgery for lumbar disc herniation. After analyzing the radiographs, the patients were separated into two groups. Group 1 patients had an ICL that passed through the L4 corpus, and Group 2 patients had an ICL that passed through the L4-5 disc distance or the L5 vertebra. Group 1 patients were classified as having a deeply seated L5 vertebra, while Group 2 patients were classified as not having a deeply seated L5 vertebra. The study found that male patients had a significantly higher incidence of a deeply seated L5 vertebra compared to female patients (p=0.003). Patients who underwent surgery at the L4?5 level exhibited disc heights that were notably higher than those who underwent surgery at the L5-S1 level. In Group 1, 68% of the patients had surgery at the L4-5 level, compared to only 41.7% in Group 2 (p=0.009). When investigating the effects of the position of the L5 vertebra in relation to the ICL at the L4-5 and L5-S1 disc levels, the study found that having a deeply seated L5 vertebra protected against L5-S1 disc herniation and that L4-5 disc herniation was more common in these patients. This is believed to be due to the L5?S1 segment being less mobile when the L5 vertebra is deeply seated.

Traumatic L5-S1 spondylolisthesis: A case report

Purpose: Here, we report the diagnosis and management of a patient with a traumatic lumbosacral spondylolisthesis, a rare clinical entity that is characterized by unilateral or bilateral facet dislocations causing displacement at the level of the fifth lumbar vertebra in relation to the sacrum. 
 Case presentation: We report a case of a traumatic L5-S1 unilateral lumbosacral dislocation. Based on the preoperative CT and MRI findings, the patient sustained a right-side unilateral L5–S1 subluxation with an L5 right inferior articular process fracture, a torn anterior longitudinal ligament and posterior ligamentous complex, and L5-S1 disc protrusion. Decompression, reduction with L4, L5, S1 pedicular screw fixation, L5-S1 disc excision, and interbody cage insertion were performed. The patient had an uneventful recovery and returned to his previous activities 6 months after surgery.

Relook into the Risk Factors of Proximal Junctional Kyphosis in Early Onset Scoliosis Patients: Does the Location of Upper Instrumented Vertebra in Relation to the Sagittal Apex Matter?

ObjectiveGrowing rods surgery is the mainstay of treatment for early‐onset scoliosis (EOS) while proximal junctional kyphosis (PJK) is one of the most commonly reported postoperative complications. We sought to investigate the impact of the location of upper instrumented vertebra (UIV) in relation to the sagittal apex on proximal junctional kyphosis in EOS after traditional growing rods (GRs) treatment.MethodsA total of 102 EOS patients who received traditional growing rods treatment with a follow‐up of at least 2 years between 2009 and 2020 were retrospectively reviewed. Radiographic measurements were performed before and after the index surgery and at the latest follow‐up. We investigated the coronal Cobb angle and spinopelvic parameters of the whole spine. The location of the UIV, apex, lower instrumented vertebra (LIV), inflection vertebra (IV), the number and distance of UIV‐apex, LIV‐apex and IV‐apex were also recorded. Risk factors for PJK were analyzed by logistic regression analysis.ResultsPJK was observed in 21 patients (20.6%) during the follow‐up period. The PJK group showed a younger age at the index surgery (5.9 vs. 7.1 years, P = 0.042), more lengthening procedure times (5.0 vs. 4.0, P = 0.032), larger preoperative coronal Cobb angle (82.0 vs. 75.6°, P = 0.038), higher correction rate (51.2% vs. 44.4%, P = 0.047) and larger postoperative proximal junctional angle (PJA) (13.9 vs. 5.5°, P < 0.001) than the non‐PJK group. The ratio of the number and distance from UIV‐apex to IV‐apex also differed significantly between the two groups. The logistic regression revealed that age at the index surgery ≤ 7 years, the ratio of the number from UIV‐ apex to IV‐ apex ≤ 0.6 and the ratio of the distance from UIV‐ apex to IV‐ apex ≤ 0.6 were independent risk factors for postoperative PJK.ConclusionBesides younger age, a closer location of UIV relative to the sagittal apex is identified to be an independent risk factor of postoperative PJK. Selection of UIV at a relatively farther location away from the sagittal apex might help prevent occurrence of PJK.

The Effect of Apical Vertebra Position on Growing Rod Treatment: A Clinical and Finite Element Study.

Growing rods (GRs) is a commonly utilized technique for the management of early-onset scoliosis. The significance of the position of the apical vertebrae relative to the rods is not known. The purpose of this study is to analyze the potential effects of the position of the apical vertebrae in relation to the GRs on deformity control through plain radiographs and finite element analysis (FEA) modeling. We identified 140 patients treated with GR between 2000 and 2018. Patients who had a congenital vertebral anomaly or <2-year follow-up were excluded. Curve magnitude, traction radiograph under general anesthesia (TRUGA) flexibility, apical rotation, the lengths of T1-12, T1-S1, and the instrumented segments were recorded. Patients were divided into 3 groups according to the apical position on the postoperative radiographs: group 1 (both pedicles are between the rods), group 2 (convex rod is between the apical vertebra pedicles), group 3 (both pedicles are lateral to the convex rod). FEA models were created simulating the 3 groups. Both radiographic and FEA data were analyzed to compare the deformity control and growth in each group. Fifty-eight patients were included in the final analyses (mean age 84 mo; range: 38 to 148). Ten patients (17%) were in group 1, 34 (59%) in group 2, and 14 (24%) in group 3. Difference between TRUGA flexibilities was statistically insignificant. Group 3 was the least successful in terms of both height gain and rotational control. FEA showed a decrease in rotation and displacement for every group, however, the residual rotation and displacement was highest in group 3. Bringing the apex in line with the GR increases the capacity of growth preservation as it results in largest height gain and better deformity control. FEA model demonstrated that distraction alone is inadequate for controlling rotation, and with increasing apical translation, residual rotation after distraction also increases. Level III.

Outcome of transpedicular screw fixation with posterior interbody fusion in management of Spondylolysthesis.

Background: Spondylolysthesis represents a particular and relatively frequent mechanism of intervertebral instability. It could cause low back pain due to forward or anterior displacement of one vertebra in relation the adjacent lower vertebra. There are many treatment intervention. However, there was no consensus on the ideal approach. Aim of the work: To assess the outcome of trans-pedicular screw fixation with posterior inter-body fusion in management of lumber and lumbosacral Spondylolysthesis. Patients and methods: This is prospective study, included twenty patients who underwent surgical lumbar laminectomy and disc removal with lumbar pedicle screw fixation with inter body fusion for patients with Spondylolysthesis who failed conservative measures. Results: The mean preoperative visual analogue score (VAS) for pain was 7.75 ± 0.72 that decreased to 1.35 ± 0.59 at the end of postoperative sixth month, with statistically significant decrease. In addition, the majority of cases had no significant complications, although complication rate was 25%. Conclusion: Posterolateral fusion with pedicle Screws fixation minimizes dislocation, achieves adequate decompression, corrects the sagittal axis, and accomplishes fusion. We successfully achieved solid fusion with good mechanical alignment in majority of the patients.

Non-mobile Adjacent Level Cervical Spondylolisthesis Does Not Always Require Fusion in Patients Undergoing ACDF.

Retrospective review of a prospectively maintained database. Compare outcomes following anterior cervical decompression and fusion (ACDF) between patients with no adjacent level spondylolisthesis (NAS) and adjacent level spondylolisthesis (AS). There are no prior studies evaluating the effect of preoperative adjacent-level cervical spondylolisthesis on outcomes following anterior cervical discectomy and fusion (ACDF). A retrospective review of consecutive patients who underwent ACDF for degenerative cervical disease was performed. Adjacent level spondylolisthesis was defined on radiographs as anterior displacement (> 1 mm) of the vertebra in relation to an adjacent "to be fused" level. Patients were categorized as either AS or NAS. Preoperative and 1-year postoperative outcomes including Short Form-12 Physical and Mental Component Scores, Neck Disability Index, Visual Analog Score for arm and neck pain, and rate of revision surgery were compared between the two groups. Radiographic changes were also analyzed for patients with AS. A total of 264 patients met the inclusion criteria. There were 53 patients (20.1%) with AS and 211 patients (79.9%) with NAS. Both groups improved significantly from baseline with respect to all patient outcomes and there were no significant differences between the two groups. After accounting for confounding variables, the presence of an AS was not a predictor of any postoperative outcome. Revision rates did not differ between the two groups. Patients with an AS had similar postoperative clinical outcomes compared with NAS. Furthermore, the presence of an AS was not a predictor of poorer clinical outcomes. This is the first study to investigate the effect of AS in patients undergoing ACDF and suggests that an adjacent-level spondylolisthesis does not need to be included in a fusion construct if it is not part of the primary symptom generating pathology. 3.

The Importance of the Pedicle Diameters at the Proximal Thoracic Vertebrae for the Correction of Proximal Thoracic Curve in Asian Patients With Idiopathic Scoliosis.

A retrospective comparative radiographic study. The purpose of this study was to evaluate differences in the pedicle diameters of proximal thoracic vertebrae in relation to the severity of the proximal thoracic curve in Asian patients with idiopathic scoliosis. A small pedicle diameter at the proximal thoracic vertebra has been reported in normal population, but the changes of pedicle diameter in patients with a proximal thoracic curve have not been properly evaluated. One hundred eighty-two patients with adolescent idiopathic scoliosis involving a greater than 10-degree proximal thoracic curve were analyzed. Sixty-nine and 113 patients had a structural and nonstructural proximal thoracic curve, respectively. The pedicle width was evaluated from T1 to T4 using a reconstructed computed tomography (CT) scan. The pedicle widths were compared between the convex and concave side, and between the structural and nonstructural proximal thoracic curve groups. The pedicle widths at T3 (0.76 ± 0.92 mm) and T4 (0.50 ± 0.69 mm) on the concave side for the structural proximal thoracic curves were extremely narrow compared with those for the nonstructural proximal thoracic curves (T3,1.17 ± 0.84 mm; T4,0.82 ± 0.72 mm) (P = 0.002, 0.003, respectively). However, the T2 pedicle width was comparable on the concave side in both groups (2.44 ± 0.94 mm for the nonstructural and 2.32 ± 0.97 mm for the structural proximal thoracic curve, P = 0.430). A pedicle screw insertion at the T3 or T4 vertebra on the concave side is not always possible in cases of a structural proximal thoracic curve; however, the pedicle width of the T2 vertebra is very wide and safe for the standard pedicle screw insertion. These results should be considered when the surgeon decides the upper instrumented vertebra or the correction method for the structural proximal thoracic curve. 3.

Does the Severity of the Curve in Lenke 1 and 2 Adolescent Idiopathic Scoliosis Patients Affect the Distance and Position of the Aorta From Vertebra?

Retrospective study of a prospectively-collected data. To determine whether the severity of the curve magnitude in Lenke 1 and 2 Adolescent Idiopathic Scoliosis (AIS) patients affects the distance and position of the aorta from the vertebra. There were studies that looked into the position of the aorta in scoliotic patients but none of them documented the change in distance of the aorta to the vertebra in relation to the magnitude of the scoliosis. Patients with Lenke 1 and 2 AIS who underwent posterior spinal fusion using pedicle screw construct and had a preoperative computed tomography (CT) scan performed were recruited. The radiological parameters measured on preoperative CT scan were: Aortic-Vertebral Distance (AVD), Entry-Aortic Distance (EAD), Aortic-Vertebral angle (AVA), Pedicle Aorta angle/Aortic Alpha angle (α angle), and Aortic Beta angle (β angle). Thirty-nine patients were recruited. Significant moderate to strong positive correlation was found between AVD and Cobb angle from T8 to T12 vertebrae (r = 0.360 to 0.666). The EAD was generally small in the thoracic region (T4-T10) with mean EAD of less than 30 mm. Among all apical vertebrae, the mean AVD was 5.9 ± 2.2 mm with significant moderate-strong positive correlation to Cobb angle (r = 0.580). The mean α angle was 37.7 ± 8.7° with significant weak positive correlation with Cobb angle (r = 0.325). The larger the scoliotic curve, the aorta was located further away from the apical vertebral wall. The aorta has less risk of injury from the left lateral pedicle screw breach in larger scoliotic curve at the apical region. The distance from the pedicle screw entry point to the wall of the aorta was generally small (less than 30 mm) in the thoracic region (T4-T10). 4.

Cervical vertebral body growth and emergence of sexual dimorphism: a developmental study using computed tomography.

The size and shape of human cervical vertebral bodies serve as a reference for measurement or treatment planning in multiple disciplines. It is therefore necessary to understand thoroughly the developmental changes in the cervical vertebrae in relation to the changing biomechanical demands on the neck during the first two decades of life. To delineate sex-specific changes in human cervical vertebral bodies, 23 landmarks were placed in the midsagittal plane to define the boundaries of C2 to C7 in 123 (73M; 50F) computed tomography scans from individuals, ages 6months to 19years. Size was calculated as the geometric area, from which sex-specific growth trend, rate, and type for each vertebral body were determined, as well as length measures of local deformation-based morphometry vectors from the centroid to each landmark. Additionally, for each of the four pubertal-staged age cohorts, sex-specific vertebral body wireframes were superimposed using generalized Procrustes analysis to determine sex-specific changes in form (size and shape) and shape alone. Our findings reveal that C2 was unique in achieving more of its adult size by 5years, particularly in females. In contrast, C3-C7 had a second period of accelerated growth during puberty. The vertebrae of males and females were significantly different in size, particularly after puberty, when males had larger cervical vertebral bodies. Male growth outpaced female growth around age 10years and persisted until around age 19-20years, whereas females completed growth earlier, around age 17-18years. The greatest shape differences between males and females occurred during puberty. Both sexes had similar growth in the superoinferior height, but males also displayed more growth in anteroposterior depth. Such prominent sex differences in size, shape, and form are likely the result of differences in growth rate and growth duration. Female vertebrae are thus not simply smaller versions of the male vertebrae. Additional research is needed to further quantify growth and help improve age- and sex-specific guidance in clinical practice.

Determination of optimal screw number based on correction angle for main thoracic curve in adolescent idiopathic scoliosis

BackgroundReducing the number of screw insertions while maintaining good clinical outcomes can improve the efficiency and cost-effectiveness of scoliosis surgery. However, the optimal minimum number of pedicle screws remains unclear. This study searched for factors to estimate the fewest number of pedicle screws required between end vertebrae in relation to preoperative main thoracic curve flexibility. MethodsSixty-nine subjects (4 male and 65 female, mean age: 14.8 ± 2.5 years) who underwent skip pedicle screw fixation for Lenke type 1–4 or 6 curves and were followed for at least 1 year were enrolled. Intervention technique was selected according to the size and flexibility of the preoperative main thoracic curve. Surgery-related variables included pedicle screw number, rod material and diameter, and extent of Ponte osteotomy. The effect on postoperative correction angle (i.e., the difference between the preoperative supine position maximum bending and postoperative standing Cobb angles of the main thoracic curve) according to surgical intervention technique was estimated using multiple linear mixed regression models with the preoperative supine position maximum bending correction angle (i.e., the difference between the standing preoperative and supine position maximum bending Cobb angles) as a random effect. ResultsThe preoperative maximum bending correction angle was 8–42° and had a moderate negative correlation with postoperative correction angle (r = −0.65, P < 0.01). Multivariate analysis revealed a 1.7° (95% CI 0.7–2.6; P < 0.01) correction gain per single-screw insertion and a 1.8° (95% CI 0.5–3.1; P < 0.01) gain per intervertebral level in Ponte osteotomy. ConclusionsThe number of pedicle screws necessary to correct main thoracic adolescent idiopathic scoliosis curves can be estimated by calculating correction gains of 1.7° per pedicle screw and 1.8° per Ponte osteotomy intervertebral level. Based on these results, it may be possible to reduce invasiveness and cost for patients requiring a smaller degree of correction.

Traumatic Lumbosacral Dislocation: Current Concepts in Diagnosis and Management.

Traumatic lumbosacral dislocation is a rare, high-energy mechanism injury characterized by displacement of the fifth lumbar vertebra in relation to the sacrum. Due to the violent trauma typically associated with this lesion, there are often severe, coexisting injuries. High-quality radiographic studies, in addition to appropriate utilization of CT scan and MRI, are essential for proper evaluation and diagnosis. Although reports in the literature include nonoperative and operative management, most authors advocate for surgical treatment with open reduction and decompression with instrumentation and fusion. Despite advances in early diagnosis and management, this injury type is associated with significant morbidity and mortality, and long-term patient outcomes remain unclear.

Defining the Role of the Lower Limbs in Compensating for Sagittal Malalignment.

Retrospective review. To investigate the role of lower limbs compensation with progressive sagittal malalignment. Although lower limb compensatory mechanisms are established response to progressive sagittal malalignment, their specific role and potential impact on surgical planning has not been evaluated. Single center retrospective review of full body x-rays was performed in patients of age >20 years. Parameters were measured with dedicated software. Population was stratified by 50 mm intervals of sagittal vertical axis (SVA) and one-way ANOVA was performed to compare P.shift (P.shift = anteroposterior translation of the pelvis vs. the feet) across SVA groups. Anteroposterior offset of each vertebra in relation to a vertical line extended from the distal tibial metaphysis (TM) was investigated. Linear regression was performed to predict pelvic tilt (PT) using Knee angle (KA) and P.shift, whereas controlling for pelvic incidence minus lumbar lordosis mismatch (PI-LL) and SVA. A total of 2124 patient visits were included (PI = 55.1 ± 14.1°, PT=21.0 ± 11°, PI-LL=6.3 ± 17.3°, SVA = 29 ± 51 mm). With progressively increased SVA, P.shift decreased from 30 to -100 mm (all P < 0.005). Analysis of vertebral offset from the distal tibial metaphysis revealed that T9 was aligned with the TM line across all SVA groups. Prediction of PT based on PI-LL and SVA yielded R=0.76 (P < 0.001). Subsequent addition of KA and P.shift as independent parameters using hierarchical multiple regression led to significant improvement in R, demonstrating the independent role of lower limbs parameters in PT prediction. KA and P.shift had a positive standardized coefficient (all P < 0.05). Lower limb compensatory mechanisms increase with progressive sagittal malalignment. Anteroposterior translation of pelvis allows the T9 vertebra to remain in line with the ankle ("conus of economy"). Lower limb compensatory mechanisms are positive predictors of PT and thus do not require additional consideration in surgical realignment planning. 3.

Morphometric analysis of cervical vertebrae in relation to mandibular growth.

Cervical vertebral maturation (CVM) methods have been criticized because of their subjective nature. The aims of this study were (1) to analyze the morphometric changes in the outline of the second to fourth cervical vertebrae with growth and (2) to test the validity of the CVM method for determining the mandibular growth peak. Lateral cephalograms of 25 participants from ages 10 to 16years were acquired from the Burlington Growth Study, and the CVM stage was qualitatively determined. Mandibular and cervical vertebral semilandmarks were then digitized, and point distribution models were used to describe the morphometric templates of the vertebrae in relation to chronologic age and the timing of peak mandibular growth. Mixed model analysis was used to determine the relationship between mandibular length, sex, CVM stage, and chronologic age. Morphometric changes of the second to fourth cervical vertebrae during growth were consistent with the CVM descriptions. However, mandibular length changes were not significantly associated with CVM stages after adjusting for chronologic age. Morphometric templates of vertebral shapes before and during the mandibular growth peak were similar, with changes detectable only after the growth peak had passed. Morphometric vertebral shape changes varied between the sexes. Morphometric changes of the cervical vertebrae and the CVM method could not accurately identify the mandibular growth peak.

Simplified technique for DaVinci view spine presentation

Background DaVinci presentation is a physician friendly picture of scoliotic spine seen from the cephalad side in the horizontal plane. This presentation is complementary to the standard view of the spine in two planes: frontal (anterior-posterior) and sagittal (lateral). DaVinci presentation can be obtained by using a few techniques which allow for three-dimensional reconstructions: CT, MRI, EOS. DaVinci-presentation is useful in analyzing the spinal deformation in 3D space, in horizontal plane: the deviation of each vertebrae in relation to the saggital plane, CLS (center sacral line) or C7PL (C7 plumbline); localization of PMC (plane of maximum curvature) in relation to the saggital and coronal plane.

Mechanical properties of sand tiger sharkCarcharias taurusvertebrae in relation to spinal deformity

Approximately 35% of sand tiger sharks (Carcharias taurus) in public aquaria exhibit spinal deformities ranging from compressed vertebrae and loss of intervertebral space to dislocated spines with vertebral degeneration and massive spondylosis caused by excessive mineralization both within vertebrae and outside the notochordal sheath. To identify the mechanical basis of these deformities, vertebral centra from affected (N=12) and non-affected (N=9) C. taurus were subjected to axial compression tests on an MTS 858 Bionix material testing system, after which mineral content was determined. Vertebral centra from affected sharks had significantly lower mineral content and material behavior in nearly all variables characterizing elasticity, plasticity and failure. These mechanical deficiencies are correlated with size at capture, capture method, vitamin C and zinc deficiency, aquarium size and swimming behavior in public aquaria. Non-affected C. taurus had greater stiffness and toughness even though these properties are generally incompatible in mineralized structures, suggesting that the biphasic (mineralized, unmineralized phases) nature of chondrichthyan vertebrae yields material behavior not otherwise observed in vertebrate skeletons. However, vertebral centra from non-affected sharks had lower mineral content (33%), stiffness (167 MPa), yield strain (14%) and ultimate strength (16 MPa) than other species of sharks and bony vertebrates, indicating that biomechanical precautions must be taken in the husbandry of this species.

L5 spondylolysis/spondylolisthesis: a comprehensive review with an anatomic focus

Spondylolysis is most commonly observed in the lumbar spine, particularly L5, and is associated with spondylolisthesis, or anterior "slippage" of a vertebra in relation to an adjacent vertebra. Isthmic spondylolisthesis is the result of a pars interarticularis defect and will be the only type of spondylolisthesis addressed in this review. Spondylolysis and spondylolisthesis represent a relatively common cause of low back pain, especially in young athletes, and a less common cause of neurologic compromise. When discovered in a symptomatic patient with corroborating imaging findings, early intervention provides an excellent prognosis. Herein, we review the anatomy and pathology of spondylosis and spondylolisthesis of the L5 vertebra.

A ‘Woollgari-Zone Mosasaur’ (Squamata; Mosasauridae) from the Carlile Shale (Lower Middle Turonian) of Central Kansas and the Stratigraphic Overlap of Early Mosasaurs and Pliosaurid Plesiosaurs

Anew specimen of russellosaurine mosasaur (FHSM VP-17564) from the middle Fairport Chalk Member (Collignoniceras woollgari zone, early Middle Turonian), Carlile Shale of central Kansas is among the earliest records of a derived mosasaur known from the North American Western Interior Seaway. Unequivocally the oldest recorded occurrence of a russellosaurine mosasaur from Kansas, and one of only four Kansas occurrences consisting of more than a single element, the specimen includes seven successive proximal caudal vertebrae bearing articulating hemal facets. No demonstrable characters ally the specimen to a more refined taxonomic subgroup, although the relative dimensions of the vertebral centra are significantly longer than equivalent caudal series in Platecarpus and Tylosaurus. This suggests that the tails of early russellosaurines were composed of a lesser number of longer caudal vertebrae than their successors, with less hydrodynamic adaptation from the terrestrial condition. Size of the vertebrae in relation to Platecarpus and Tylosaurus indicates a relatively large animal roughly 3.2 m in total body length, although this may be an over-estimate given the difference in vertebral dimensions as compared to more derived russellosaurines of the Niobrara Formation. The middle of the Fairport Chalk interval continues to produce a large number of vertebrate specimens despite the rarity of exposures. A pliosaurid plesiosaur skull (FHSM VP-321) is known from similar geographic and stratigraphic position as FHSM VP-17564, and the record of pliosaurs (FHSM VP-17469) continues into younger Blue Hill Shale (Prionocyclus hyatti zone, middle Middle Turonian) demonstrating with certainty that pliosaurs and early mosasaurs inhabited the same stretch of seaway for roughly one million years.

Changes in the cervical spine of children with juvenile idiopathic arthritis evaluated with lateral cephalometric radiographs:A case control study

To evaluate whether plain lateral cephalometric radiographs in the neutral position could be used as a diagnostic tool to investigate changes in the cervical spine related to juvenile idiopathic arthritis (JIA). Lateral cephalometric radiographs of 82 subjects, 21 males and 61 females (8-25 years old), affected with JIA were revised and compared with 82 healthy control subjects matched in age and gender. Changes inspected in the cervical spine were erosions of the dens and fusion of the apophyseal joints. Anterior atlantoaxial subluxation of the first vertebra in relation to the second was examined by measuring the anterior atlanto-dens interval (aADI). Atlantoaxial impaction (AAI) was studied by using the Sakaguchi-Kauppi method. In the JIA sample, erosion was seen in 14.7%, (12 patients), of the patients and apophyseal joint ankylosis (fusion) in 18.3%, (15 patients). Three children and one adult had aADI more than 4.5 or 3 mm, respectively, which is considered to be abnormally increased, and AAI was noted in 13.0% of the subjects. In total, 35%, (29 children), of the children with JIA showed one or several radiographically visible changes as described earlier. Two of the control subjects showed ankylosis of the apophyseal joints, and one had aADI of 4 mm. Compared with the controls, significantly more changes were found in the JIA group. It can be concluded that arthritic changes in the cervical spine can be detected at a young age on plain lateral cephalometric radiographs and should be evaluated when available.

The 3D anatomy of the cervical articular process joints in the horse and their topographical relationship to the spinal cord

REASONS FOR STUDY: Detailed anatomy of the equine cervical articular process joints (APJs) has received little attention in the literature and yet disorders of this joint have been linked to spinal cord compression resulting in severe clinical signs such as ataxia and weakness. This study aimed to describe the 3D anatomy of the APJ in relation to the spinal cord in the horse. Artificial distension of the APJ causes the joint pouches to extend into the vertebral canal, with the potential for APJ effusion to cause spinal cord compressive disease. Six cadaveric necks (C1-C7) of clinically normal horses were used in this study. Computed tomography scans of the cervical APJ were acquired after injection of a negative contrast agent to maximal distension. The resulting images were semi-automatically segmented using greyscale thresholding and reconstructed in 3D by polygonal surface meshing. The 3D reconstructions were used to assess the topographic anatomy of the APJ in relation to the spinal cord and to measure joint volume at each cervical vertebra in relation to vertebrae size. Joint volume varied significantly between joint location (P<0.0001) and was positively correlated to the vertebral site (from cranial to caudal) (r = 0.781, P<0.0001). After distension, the medial outpouch of the APJ extended towards the vertebral canal from a dorsolateral location but in none of the 6 horses was there apparent compression of the dura mater surrounding the spinal cord. There was no significant difference in the extent of medial outpouch at any vertebral level (P = 0.104). Flexion of the neck resulted in minor changes to the shape of the APJ but did not result in the medial outpouch encroaching any closer to the spinal cord. From this study, it appears that in the absence of any other soft tissue or bony changes an effusion of the APJ is unlikely to cause spinal cord compression. However, given that the APJ and spinal cord are in close approximation, in the presence of other anatomical changes, an effusion may have the potential to cause compression. This study confirms that the APJ extend into the dorsolateral aspect of the vertebral canal in a ventromedial direction, suggesting that oblique myelographic views are recommended for the diagnosis of spinal cord compression when pathology of the APJ is suspected.

Maturation of cervical vertebrae in relation to menarche

Maturation of cervical vertebrae in relation to menarche