Vertebral Shape Research Articles

Bone Disease in Patients with Ehlers-Danlos Syndromes.

To summarize the bone findings, mainly bone mass and fracture risk, in Ehlers-Danlos syndromes (EDS). Low bone mineral density and fractures seem to be frequent in some of the rare EDS types (kyphoscoliotic, arthrochalasia, spondylodysplastic, and classic-like EDS). For the more prevalent hypermobile and classic EDS types, some case-control studies found mildly decreased bone mineral density, but it was not clear that fracture rates were increased. Nevertheless, abnormalities in vertebral shape seem to be common in classical and hypermobile EDS types. In a cohort of individuals with EDS followed since birth, no fractures were observed during infancy. Bone mineral density varies widely among the different types of EDS, and vertebral abnormalities seem to be common in classical and hypermobile EDS. It might be justified to perform spine radiographs and bone mineral density assessments in newly diagnosed EDS.

Diagnostic performance of morphometric vertebral fracture analysis (MXA) in children using a 33-point software program.

There is significant inter and intraobserver variability in diagnosing vertebral fractures in children. We aimed to evaluate the diagnostic accuracy of morphometric vertebral fracture analysis (MXA) using a 33-point software program designed for adults, on dual-energy x-ray absorptiometry (DXA) images of children. Lateral spine DXA images of 420 children aged between 5 and 18years were retrospectively reviewed. Vertebral fracture assessment (VFA) by an expert pediatric radiologist using Genant's semiquantitative scoring system served as the gold standard. All 420 DXA scans were analyzed by a trained radiographer, using semi-automated software (33-point morphometry). VFA of a random sample of 100 DXA was performed by an experienced pediatric clinical scientist. MXA of a random sample of 30 DXA images were analyzed by three pediatric radiologists and the pediatric clinical scientist. Diagnostic accuracy and inter and intraobserver agreement (kappa statistics) were calculated. Overall sensitivity, specificity, false positive (FP) and false negative (FN) rates for the radiographer using the MXA software were 80%, 90%, 10%, and 20% respectively and for mild fractures alone were 46%, 92%, 8%, and 54% respectively. Overall sensitivity, specificity, FP, and FN rates for the four additional observers using MXA were 89%, 79%, 21%, and 11% respectively and for mild fractures alone were 36%, 86%, 14%, and 64% respectively. Agreement between two expert observers was fair to good for VFA and MXA [kappa=0·29 to 0·76 (95% CI: 0·17-0·88) and 0·29 to 0·69 (95% CI: 0·17-0·83)] respectively. MXA using a 33-point technique developed for adults is not a reliable method for the identification of mild vertebral fractures in children. A pediatric standard is required which not only incorporates specific vertebral body height ratios but also the age-related physiological changes in vertebral shape that occur throughout childhood.

The Effect of Early Limited Activity after Bipedicular Percutaneous Vertebroplasty to Treat Acute Painful Osteoporotic Vertebral Compression Fractures

Although percutaneous vertebroplasty (PVP) can effectively relieve the pain for patients with acute osteoporotic vertebral compression fractures (OVCFs), many patients still complain of mild back pain in the early postoperative period. The aim of this study was to assess the effect of early limited activity (LA) on prognosis after bipedicular small-cement-volume (i.e., PVP) to treat single-segment acute OVCFs. A prospective study and retrospective observations were performed on 125 patients with a minimum of 1 year of follow-up. A university hospital orthopedics and pathology departments. All patients were allocated into an LA group (n = 64) and an unlimited activity group (ULA group, n = 61). Patients in the LA group were suggested to keep time of off-bed activity < 4 hours per day in the first 3 weeks postoperatively. Patients in the ULA group did not limit activity. The demographic, clinical, and radiologic outcomes were assessed, such as pain intensity Numeric Rating Scale (NRS-11) and vertebral height ratio (i.e., fractured vertebral height/adjacent nonfractured vertebral height). Based on outcomes following surgery, all patients were classified as responders (NRS-11 score 1-day postoperation < 50% of preoperative NRS-11 score) or low responders (NRS-11 score 1-day postoperation >= 50% of preoperative NRS-11 score). The demographic results and complications were similar. In the LA group, NRS-11 scores at 1 and 3 months postoperation respectively were 2.23 ± 0.42 and 1.46 ± 0.40, and corresponding scores respectively were 2.85 ± 0.80 and 1.73 ± 0.77 in the ULA group, and there was a difference in the 2 groups in both time points (P < 0.05). At 12 months postoperation, anterior and middle vertebral height ratio respectively were 78.42% ± 3.52% and 82.37% ± 3.49% in the LA group, which were higher than 76.87% ± 3.68% and 81.10% ± 3.31% in the ULA group (P < 0.05). Thirty-two cases were low responders. Among those, NRS-11 scores at 1 and 3 months postoperation respectively were 2.29 ± 0.45 and 1.53 ± 0.46 in the LA group, which were lower than 3.67 ± 0.80 and 2.56 ± 0.79 in the ULA group (P < 0.05), and at 12 months postoperation, anterior vertebral height ratio was 79.81% ± 3.25% in the LA group and 75.60% ± 3.50% in the ULA group (P < 0.05). First, some patients lacked the results of bone mineral density during follow-up; second, the limited time in our study was chosen from our previous working experience, which may lack an objective basis; third, NRS-11 is solely used as an indicator of clinical outcomes in our study; finally, our next studies can increase the sample size to improve the clinically difference. LA in the early period after PVP can help patients achieve more pain relief postoperatively and maintain better vertebral shape, especially for low responders. Osteoporotic vertebral compression fractures, percutaneous vertebroplasty, Numeric Rating Scale, vertebral height, responders, low responders, limited activity, complications.

Spondylolysis and spinal adaptations for bipedalism: The overshoot hypothesis.

Background and objectivesThe study reported here focused on the aetiology of spondylolysis, a vertebral pathology usually caused by a fatigue fracture. The goal was to test the Overshoot Hypothesis, which proposes that people develop spondylolysis because their vertebral shape is at the highly derived end of the range of variation within Homo sapiens.MethodologyWe recorded 3D data on the final lumbar vertebrae of H. sapiens and three great ape species, and performed three analyses. First, we compared H. sapiens vertebrae with and without spondylolysis. Second, we compared H. sapiens vertebrae with and without spondylolysis to great ape vertebrae. Lastly, we compared H. sapiens vertebrae with and without spondylolysis to great ape vertebrae and to vertebrae of H. sapiens with Schmorl’s nodes, which previous studies have shown tend to be located at the ancestral end of the range of H. sapiens shape variation.ResultsWe found that H. sapiens vertebrae with spondylolysis are significantly different in shape from healthy H. sapiens vertebrae. We also found that H. sapiens vertebrae with spondylolysis are more distant from great ape vertebrae than are healthy H. sapiens vertebrae. Lastly, we found that H. sapiens vertebrae with spondylolysis are at the opposite end of the range of shape variation than vertebrae with Schmorl’s nodes.ConclusionsOur findings indicate that H. sapiens vertebrae with spondylolysis tend to exhibit highly derived traits and therefore support the Overshoot Hypothesis. Spondylolysis, it appears, is linked to our lineage’s evolutionary history, especially its shift from quadrupedalism to bipedalism.Lay summary: Spondylolysis is a relatively common vertebral pathology usually caused by a fatigue fracture. There is reason to think that it might be connected with our lineage’s evolutionary shift from walking on all fours to walking on two legs. We tested this idea by comparing human vertebrae with and without spondylolysis to the vertebrae of great apes. Our results support the hypothesis. They suggest that people who experience spondylolysis have vertebrae with what are effectively exaggerated adaptations for bipedalism.

3D shape analyses of extant primate and fossil hominin vertebrae support the ancestral shape hypothesis for intervertebral disc herniation

BackgroundRecently we proposed an evolutionary explanation for a spinal pathology that afflicts many people, intervertebral disc herniation (Plomp et al. [2015] BMC Evolutionary Biology 15, 68). Using 2D data, we found that the bodies and pedicles of lower vertebrae of pathological humans were more similar in shape to those of chimpanzees than were those of healthy humans. Based on this, we hypothesized that some individuals are more prone to intervertebral disc herniation because their vertebrae exhibit ancestral traits and therefore are less well adapted for the stresses associated with bipedalism. Here, we report a study in which we tested this “Ancestral Shape Hypothesis” with 3D data from the last two thoracic and first lumbar vertebrae of pathological Homo sapiens, healthy H. sapiens, Pan troglodytes, and several extinct hominins.ResultsWe found that the pathological and healthy H. sapiens vertebrae differed significantly in shape, and that the pathological H. sapiens vertebrae were closer in shape to the P. troglodytes vertebrae than were the healthy H. sapiens vertebrae. Additionally, we found that the pathological human vertebrae were generally more similar in shape to the vertebrae of the extinct hominins than were the healthy H. sapiens vertebrae. These results are consistent with the predictions of the Ancestral Shape Hypothesis. Several vertebral traits were associated with disc herniation, including a vertebral body that is both more circular and more ventrally wedged, relatively short pedicles and laminae, relatively long, more cranio-laterally projecting transverse processes, and relatively long, cranially-oriented spinous processes. We found that there are biomechanical and comparative anatomical reasons for suspecting that all of these traits are capable of predisposing individuals to intervertebral disc herniation.ConclusionsThe results of the present study add weight to the hypothesis that intervertebral disc herniation in H. sapiens is connected with vertebral shape. Specifically, they suggest that individuals whose vertebrae are towards the ancestral end of the range of shape variation within H. sapiens have a greater propensity to develop the condition than other individuals. More generally, the study shows that evolutionary thinking has the potential to shed new light on human skeletal pathologies.

Individualized treatment with denosumab in children with osteogenesis imperfecta \u2013 follow up of a trial cohort

BackgroundOsteogenesis imperfecta (OI) is a rare disease leading to hereditary bone fragility. Nearly 90% of cases are caused by mutations in the collagen genes COL1A1/A2 (classical OI) leading to multiple fractures, scoliosis, short stature and nonskeletal findings as blue sclera, hypermobility of joints, bone pain and delayed motor function development. Bisphosphonates are used in most moderate and severely affected patients assuming that an increase of bone mineral density might reduce fractures and bone pain in patients with OI. Denosumab as a RANK ligand antibody inhibiting osteoclast maturation has been approved for osteoporosis treatment in adults. First data from small clinical trials promised a high efficacy of Denosumab in children with OI. Aim of this analysis was a retrospective evaluation of an individualized biomarker-associated treatment regime with Denosumab in 10 children with classical OI which were followed for 1 year after their participation in a pilot trial with Denosumab. Therefore urinary deoxypyridinoline levels were evaluated frequently as an osteoclastic activity marker and depending on that levels Denosumab injections were scheduled individually.MethodsTen patients (age range: 6.16–12.13 years; all participated in the former OI-AK phase 2 trial (NCT01799798)) were included in the follow-up period. Denosumab was administered subcutaneously depending on the individual urinary excretion course of deoxypyridinoline (DPD/Crea) as osteoclastic activity marker with 1 mg/kg body weight. DPD/Crea levels were evaluated before denosumab administration and afterwards. If patients present after an initial decrease after injection with a re-increase up to the DPD/crea level before Denosumab injection next dosage was planned. Changes of areal bone mineral density (aBMD) using dual energy x-ray absorptiometry of the lumbar spine after 12 month was evaluated. Safety was assessed by bone metabolism markers and side effect reporting.ResultsDuring follow-up mean relative change of lumbar aBMD was − 6.4%. Lumbar spine aBMD z-Scores decreased from − 1.01 ± 2.61 (mean ± SD) to − 1.91 ± 2.12 (p = 0.015). Mobility changed not significantly (GMFM-88 -6.49 ± 8.85% (p = 0.08). No severe side effects occurred. Dose intervals could be extended in the mean from 12 weeks previously to 20.3 weeks.ConclusionsOn average, it was possible to prolong the intervals between drug administrations and to reduce the total dose about by 25% without a decrease of mobility or change of vertebral shape despite a reduction of lumbar aBMD during 1 year of biomarker-directed Denosumab treatment. Further trials are necessary to balance side effects and highest efficacy in children.

Head-turning morphologies: Evolution of shape diversity in the mammalian atlas-axis complex.

Mammals flex, extend, and rotate their spines as they perform behaviors critical for survival, such as foraging, consuming prey, locomoting, and interacting with conspecifics or predators. The atlas-axis complex is a mammalian innovation that allows precise head movements during these behaviors. Although morphological variation in other vertebral regions has been linked to ecological differences in mammals, less is known about morphological specialization in the cervical vertebrae, which are developmentally constrained in number but highly variable in size and shape. Here, we present the first phylogenetic comparative study of the atlas-axis complex across mammals. We used spherical harmonics to quantify 3D shape variation of the atlas and axis across a diverse sample of species, and performed phylogenetic analyses to investigate if vertebral shape is associated with body size, locomotion, and diet. We found that differences in atlas and axis shape are partly explained by phylogeny, and that mammalian subclades differ in morphological disparity. Atlas and axis shape diversity is associated with differences in body size and locomotion; large terrestrial mammals have craniocaudally elongated vertebrae, whereas smaller mammals and aquatic mammals have more compressed vertebrae. These results provide a foundation for investigating functional hypotheses underlying the evolution of neck morphologies across mammals.

In Vivo Assessment of Thoracic Vertebral Shape From MRI Data Using a Shape Model

Study DesignFeasibility study on characterizing thoracic vertebral shape from magnetic resonance images using a shape model. ObjectivesAssess the reliability of characterizing thoracic vertebral shape from magnetic resonance images and estimate the normal variation in vertebral shape using a shape model. Summary of Background DataThe characterization of thoracic vertebra shape is important for understanding the initiation and progression of deformity and in developing surgical methods. Methods for characterizing shape need to be comprehensive, reliable, and suitable for use in vivo. MethodsMagnetic resonance images of the thoracic vertebrae were acquired from 20 adults. Repeat scans were acquired, after repositioning the participants, for T4, T8, and T12. Landmark points were placed around the vertebra on the images and used to create a shape model. The reliability was assessed using relative error (E%) and intraclass correlation (ICC). The effect of vertebral level, sex and age on vertebral shape was assessed using repeated measures analysis of variance. ResultsFive modes of variation were retained from the shape model. Reliability was excellent for the first two modes (mode 1: E% = 7, ICC = 0.98; mode 2: E% = 11, ICC = 0.96). These modes described variation in the vertebral bodies, the pedicle width and orientation, and the facet joint position and orientation with respect to the pedicle axis. Variation in vertebral shape was found along the thoracic spine and between individuals, but there was little effect of age and sex. ConclusionsMagnetic resonance images and shape modeling provides a reliable method for characterizing vertebral shape in vivo. The method is able to identify differences between vertebral levels and between individuals. The use of these methods may be advantageous for performing repeated measurements in longitudinal studies. Level of EvidenceN/A.

Computer-assisted pedicle screw trajectory planning using CT-inferred bone density: A demonstration against surgical outcomes.

Image-guided spine surgery and preoperative computer-assisted planning provide spine surgeons with tools to improve the safety, accuracy, and reliability of pedicle screw placement. The purpose of this study is to demonstrate a computer-assisted pedicle screw placement planning tool in comparison to screws as delivered by a spine surgeon. We describe a novel computer-assisted tool for preoperative pedicle screw placement planning in computed tomography (CT) images, designed with respect to the vertebral shape and structure, and augmented with respect to the considerations of surgical practice. The approach is based on three-dimensional (3D) modeling of the vertebral body and pedicles, and planning of the pedicle screw size and insertion trajectory by maximizing the screw fastening strength, evaluated through CT-inferred bone density maps. The approach is augmented by yielding screw plans consistent with the straight-forward surgical technique of aligning screws parallel to vertebral endplates, and the screw entry points following the spinal curvature to facilitate rod attachment. For a cohort of 25 patients, placement plans were retrospectively obtained for 204 pedicle screws with the computer-assisted tool from preoperative CT images, while reference trajectories of inserted pedicle screws were reconstructed in 3D from postoperative biplanar radiographs. The best performing version of the computer-assisted tool achieved clinically acceptable preoperative pedicle screw placement plans in 96.6% of the cases, while the comparison to the postoperative reconstructions resulted in 3.4±2.5mm for the screw entry point location, 2.7±1.6mm for the screw crossing point location, and 7.4±5.3∘ for the screw sagittal inclination (mean absolute difference±standard deviation). Quantitative comparison revealed that the preoperative placement plans are consistent with the postoperative results, and that the computer-assisted tool integrating bone density and surgical constraints can successfully incorporate important aspects of pedicle screw placement. The results therefore confirm the accuracy of the tool prior to being integrated in an image-guidance system.

Short-term foetal immobility temporally and progressively affects chick spinal curvature and anatomy and rib development.

Congenital spine deformities may be influenced by movements in utero, but the effects of foetal immobility on spine and rib development remain unclear. The purpose of the present study was to determine (1) critical time-periods when rigid paralysis caused the most severe disruption in spine and rib development and (2) how the effects of an early, short-term immobilisation were propagated to the different features of spine and rib development. Chick embryos were immobilised once per single embryonic day (E) between E3 and E6 and harvested at E9. To assess the ontogenetic effects following single-day immobilisation, other embryos were immobilised at E4 and harvested daily between E5 and E9. Spinal curvature, vertebral shape and segmentation and rib development were analysed by optical projection tomography and histology. The results demonstrated that periods critical for movement varied for different aspects of spine and rib development. Single-day immobilisation at E3 or E4 resulted in the most pronounced spinal curvature abnormalities, multiple wedged vertebrae and segmentation defects, while single-day immobilisation at E5 led to the most severe rib abnormalities. Assessment of ontogenetic effects following single-day immobilisation at E4 revealed that vertebral segmentation defects were subsequent to earlier vertebral body shape and spinal curvature abnormalities, while rib formation (although delayed) was independent from thoracic vertebral shape or curvature changes.A day-long immobilisation in chicks severely affected spine and rib development, highlighting the importance of abnormal foetal movements at specific time-points and motivating targeted prenatal monitoring for early diagnosis of congenital scoliosis.

Late vertebral side effects in long-term survivors of irradiated childhood brain tumor.

PurposeLong-term side effects of the treatments are common in survivors of irradiated pediatric brain tumors. Ionizing radiation in combination with surgery and chemotherapy during childhood may reduce vertebral height and bone mineral density (BMD), and cause growth failure. The aim of this study was to evaluate the late consequences of tumor treatments on vertebrae in survivors of childhood brain tumors.Methods72 adult survivors (mean age 27.8 years, standard deviation 6.7) of irradiated childhood brain tumor were studied by spinal magnetic resonance imaging (MRI) for vertebral abnormalities from the national cohort of Finland. Patients were treated in five university hospitals in Finland between the years 1970 and 2008. Subject height and weight were measured and body mass index (BMI) was calculated. The morphology and height/depth ratio of the vertebrae in the middle of the kyphotic thoracic curvature (Th8) and lumbar lordosis (L3) were examined. Vertebrae were analyzed by Genant’s semiquantative (SQ) method and spinal deformity index (SDI) was calculated. BMD was measured by using dual X-ray absorptiometry.Results4.2% (3/72) of the patients had undiagnosed asymptomatic vertebral fracture and 5.6% (4/72) of patients had radiation-induced decreased vertebral body height. Male patients had flatter vertebrae compared with females. Patient age at the time of irradiation, BMI and irradiation area correlated to vertebral morphology differentially in males and females. BMD had no association with the vertebral shape. Patients who had received craniospinal irradiation were shorter than the general population.ConclusionChildhood brain tumor survivors had a high number of vertebral abnormalities in young adulthood. Irradiation was associated with abnormal vertebral morphology and compromised final height. Male gender may predispose vertebrae to the side effects of irradiation.

Adaptation and constraint in the evolution of the mammalian backbone

BackgroundThe axial skeleton consists of repeating units (vertebrae) that are integrated through their development and evolution. Unlike most tetrapods, vertebrae in the mammalian trunk are subdivided into distinct thoracic and lumbar modules, resulting in a system that is constrained in terms of count but highly variable in morphology. This study asks how thoracolumbar regionalization has impacted adaptation and evolvability across mammals. Using geometric morphometrics, we examine evolutionary patterns in five vertebral positions from diverse mammal species encompassing a broad range of locomotor ecologies. We quantitatively compare the effects of phylogenetic and allometric constraints, and ecological adaptation between regions, and examine their impact on evolvability (disparity and evolutionary rate) of serially-homologous vertebrae.ResultsAlthough phylogenetic signal and allometry are evident throughout the trunk, the effect of locomotor ecology is partitioned between vertebral positions. Lumbar vertebral shape correlates most strongly with ecology, differentiating taxa based on their use of asymmetric gaits. Similarly, disparity and evolutionary rates are also elevated posteriorly, indicating a link between the lumbar region, locomotor adaptation, and evolvability.ConclusionVertebral regionalization in mammals has facilitated rapid evolution of the posterior trunk in response to selection for locomotion and static body support.

Functional and developmental influences on intraspecific variation in catarrhine vertebrae

We tested whether patterns of intraspecific variation in catarrhine vertebral shape are consistent with developmental or functional predictions. Intraspecific variation was compared across column regions, morphological features, and species. Transitional regions and later ossifying morphological features were predicted to exhibit increased variation. The lumbosacral region, biomechanically important morphological features, and species with high locomotor demand and/or dedicated pronogrady were predicted to exhibit decreased variation. We used a modified Levene's test to compare intraspecific variation in dimensions of the neural canal, vertebral bodies, and spinous and transverse processes in lower thoracic to proximal sacral vertebrae. The sample included all hominoid genera and one cercopithecoid (Chlorocebus). We found little difference in variation across regions of the vertebral column. In hominoids, vertebral body dimensions were the least variable, neural canal dimensions the most variable, with spinous and transverse processes generally intermediate. Among species, there was a general though not always significant pattern for Chlorocebus to exhibit the least variation, followed by Homo or Hylobates. Patterns of variation across morphological features may reflect the complex interaction of functional constraints, developmental timing, and/or variable biomechanical forces. Pongo's elevated variation in spinous process length suggests a release from functional constraint, consistent with its suspensory locomotion and reduced spinous processes. Interspecific differences in vertebral variation based on locomotor demand or posture are generally consistent with patterns previously reported for vertebral formula and other aspects of morphology. Future research would benefit from an expanded taxonomic sample and more detailed analyses of vertebral modularity and developmental timing.

Vertebral morphometrics and lung structure in non-avian dinosaurs.

The lung-air sac system of modern birds is unique among vertebrates. However, debate surrounds whether an avian-style lung is restricted to birds or first appeared in their dinosaurian ancestors, as common osteological correlates for the respiratory system offer limited information on the lungs themselves. Here, we shed light on these issues by using axial morphology as a direct osteological correlate of lung structure, and quantifying vertebral shape using geometric morphometrics in birds, crocodilians and a wide range of dinosaurian taxa. Although fully avian lungs were a rather late innovation, we quantitatively show that non-avian dinosaurs and basal dinosauriforms possessed bird-like costovertebral joints and a furrowed thoracic ceiling. This would have immobilized the lung's dorsal surface, a structural prerequisite for a thinned blood-gas barrier and increased gas exchange potential. This could have permitted high levels of aerobic and metabolic activity in dinosaurs, even in the hypoxic conditions of the Mesozoic, contributing to their successful radiation.

Gravidity, Parity, and Vertebral Dimensions in the Northern Finland Birth Cohort 1966.

A population-based birth cohort study. To investigate the association between gravidity, parity, and vertebral geometry among middle-aged women. Vertebral size is a recognized determinant of vertebral fracture risk. Yet, only a few lifestyle factors that influence vertebral size are known. Pregnancy is a labile period that may affect the maternal vertebral size or shape. The lumbar lordosis angle is permanently deepened by pregnancy, but it remains unclear whether vertebral shape or size contribute to this deepened angle. We aimed to investigate whether gravidity and parity were associated with vertebral cross-sectional area (CSA) and height ratio (anterior height to posterior height) among 705 middle-aged women from the Northern Finland Birth Cohort 1966. We measured the corpus of their fourth lumbar vertebra using magnetic resonance imaging of the lumbar spine at the age of 46. Gravidity and parity were elicited using a questionnaire also at the age of 46. Linear regression analysis was used with adjustments for body mass index, vertebral CSA (height ratio models), and vertebral height (CSA models). We also ran a subgroup analysis that did not include nulliparous women, and we compared nulliparous women with grand multiparous women. The models found no statistically significant associations between the predictors and outcomes. Crude and adjusted results were highly similar, and the subgroup analyses provided analogous results. Pregnancy, or even multiple pregnancies, do not seem to have long-term effects on vertebral geometry. In order to enhance the prevention of vertebral fractures, future studies should aim to reveal more lifestyle determinants of vertebral size. 3.

Homeotic transformations reflect departure from the mammalian \u2018rule of seven\u2019 cervical vertebrae in sloths: inferences on the Hox code and morphological modularity of the mammalian neck

BackgroundSloths are one of only two exceptions to the mammalian ‘rule of seven’ vertebrae in the neck. As a striking case of breaking the evolutionary constraint, the explanation for the exceptional number of cervical vertebrae in sloths is still under debate. Two diverging hypotheses, both ultimately linked to the low metabolic rate of sloths, have been proposed: hypothesis 1 involves morphological transformation of vertebrae due to changes in the Hox gene expression pattern and hypothesis 2 assumes that the Hox gene expression pattern is not altered and the identity of the vertebrae is not changed. Direct evidence supporting either hypothesis would involve knowledge of the vertebral Hox code in sloths, but the realization of such studies is extremely limited. Here, on the basis of the previously established correlation between anterior Hox gene expression and the quantifiable vertebral shape, we present the morphological regionalization of the neck in three different species of sloths with aberrant cervical count providing indirect insight into the vertebral Hox code.ResultsShape differences within the cervical vertebral column suggest a mouse-like Hox code in the neck of sloths. We infer an anterior shift of HoxC-6 expression in association with the first thoracic vertebra in short-necked sloths with decreased cervical count, and a posterior shift of HoxC-5 and HoxC-6 expression in long-necked sloths with increased cervical count.ConclusionAlthough only future developmental analyses in non-model organisms, such as sloths, will yield direct evidence for the evolutionary mechanism responsible for the aberrant number of cervical vertebrae, our observations lend support to hypothesis 1 indicating that the number of modules is retained but their boundaries are displaced. Our approach based on quantified morphological differences also provides a reliable basis for further research including fossil taxa such as extinct ‘ground sloths’ in order to trace the pattern and the underlying genetic mechanisms in the evolution of the vertebral column in mammals.

Vertebral Fracture: Diagnostic Difficulties of a Major Medical Problem.

Vertebral Fracture: Diagnostic Difficulties of a Major Medical Problem.

Some Osteological Studies of &lt;i&gt;Coptodon zillii&lt;/i&gt; (Gervais 1848) and &lt;i&gt;Oreochromis aureus&lt;/i&gt; (Steindachner 1864) Collected Shatt al-Arab River, Basrah, Iraq

This paper presents the results of a comparative study of the vertebral column regionalization of Coptodon zillii and Oreochromis aureus of the fish family Cichlidae. Osteological features that may prove valuable for taxonomic indications are defined, and on the basis of the material handled, their use to separate the two cichlid species. The morphological characteristics of the vertebral column of C. zillii and O. aureus allowed the separation of this bony structure into five morphologically distinct regions and the features of their specified vertebral shape. This regionalization is more complex than the classical division in truncal and caudal parts only. The vertebral length and height express a morphotype that may be linked with the cichlid mode of swimming.

Age and growth of sharks: do vertebral band pairs record age?

Inaccurate age estimates can have severe consequences in the management of elasmobranchs. Numerous studies in shark age validation have demonstrated a disconnect between band pair counts and age, resulting in age underestimation, particularly in older individuals. To investigate the relationship between band pairs, vertebral shape and growth, we quantified intracolumn differences in centrum morphology (size and structure) and band pair counts in seven shark species: Squatina dumeril, Carcharodon carcharias, Lamna nasus, Isurus oxyrinchus, Alopias vulpinus, Prionace glauca and Carcharhinus obscurus. In all species examined, band pair deposition was closely related to body girth and the structural properties of the cartilaginous skeleton, relative to maximum size, and body type. These results have strong implications for accurately assessing age for fisheries management of these species.

Radiological morphology variances of osteotomized vertebra-disc complex following pedicle subtraction osteotomy for ankylosing spondylitis with thoracolumbar kyphosis: the incidence, mechanisms, and prognosis

Background ContextInaccurate osteotomy cut along with incomplete or even subluxated bone-on-bone closure of osteotomy gap following pedicle subtraction osteotomy (PSO) may be disastrous, hampering the lordosing effect and increasing the likelihood of complications. The inelastic yet osteoporotic spine in ankylosing spondylitis (AS) is specially predisposed to such suboptimal osteotomy, while the relevant data concerning this issue are scarce. PurposeThis study aimed to analyze the incidence of radiological morphology variances (RMV) of osteotomized vertebra-disc complex (OVDC) following PSO in patients with kyphotic AS, conceptualize the mechanisms of the deviated morphology, and investigate the prognosis. Study DesignThis is a retrospective radiological data analysis. Patient SampleThe sample being screened comprises 71 patients with thoracolumbar kyphotic AS who underwent single-level PSO at our hospital between March 2006 and February 2014. They were stratified by the presence of bridging syndesmophytes (BS) locating within the OVDC. Outcome MeasuresAny irregular radiological configuration of OVDC other than the wedge morphology would be considered as RMV and were studied with care to fully describe and classify the spectrum of deviated morphologic features. Multiple spinopelvic sagittal parameters were measured to assess both the regional lordosing effect and the global realignment of sagittal spinal profile. MethodsFor each selected patient with confirmed RMV, the radiological morphology was assessed, defined, and categorized. The prognosis involving surgical corrections and maintenance of spinopelvic sagittal parameters, as well as the remodeling in disordered osteotomized vertebral shape over time, were also investigated. ResultsThe incidence of RMV was 21.9% in positive BS group (PG) and 30.8% in negative BS group (NG). Inappropriate angle and range of osteotomy accounted for the largest share (1 pts for PG and 10 pts for NG, 57.9%) of mechanisms responsible for RMV, followed by vertebral subluxation (VS) (5 pts for PG and 2 pts for NG, 36.8%) and failed osteotomy gap closure (1 pts for PG, 5.3%). For these patients, the mean bony lordosing effect per PSO segment was 36.0°±8.9° postoperatively, and decreased to 34.7°±8.7° by a mean follow-up of 3 years (p=.076). The magnitude of neighboring disc opening was significantly higher in NG (10.2°±6.5° vs. 2.4°±3.2°, p=.009). The global kyphosis and sagittal vertical axis were significantly corrected (77.0°±21.2° vs. 24.4°±18.8°; 160.6°±72.4° vs. 48.2°±38.6 mm, all p<.001) and remained stable by the ultimate follow-up (p>.05). No devastating neurologic deficits were noticed. Patients with VS and failed osteotomy gap closure exclusively showed solid bone healing and adaptive remodeling without rod breakage at final follow-up. ConclusionsRadiological morphology variances of OVDC were a high occurrence following PSO in AS, being mainly attributed to inaccurate osteotomy cut and VS. Neighboring disc opening and rotational or translational subluxation were major available remedial mechanisms strengthening the lordosing effect when that of vertebral wedging was impaired and insufficient. The bone fusion and remodeling concerning the subluxated or dislocated osteotomized vertebra was utterly favorable, maintaining the kyphosis correction and preventing instrumentation failure.