ResearchPad - spine https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Effect of experimental, morphological and mechanical factors on the murine spinal cord subjected to transverse contusion: A finite element study]]> https://www.researchpad.co/article/elastic_article_8463 Finite element models combined with animal experimental models of spinal cord injury provides the opportunity for investigating the effects of the injury mechanism on the neural tissue deformation and the resulting tissue damage. Thus, we developed a finite element model of the mouse cervical spinal cord in order to investigate the effect of morphological, experimental and mechanical factors on the spinal cord mechanical behavior subjected to transverse contusion. The overall mechanical behavior of the model was validated with experimental data of unilateral cervical contusion in mice. The effects of the spinal cord material properties, diameter and curvature, and of the impactor position and inclination on the strain distribution were investigated in 8 spinal cord anatomical regions of interest for 98 configurations of the model. Pareto analysis revealed that the material properties had a significant effect (p<0.01) for all regions of interest of the spinal cord and was the most influential factor for 7 out of 8 regions. This highlighted the need for comprehensive mechanical characterization of the gray and white matter in order to develop effective models capable of predicting tissue deformation during spinal cord injuries.

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<![CDATA[Giant intrathoracic ganglioneuroma with scoliosis treated by one-stage posterior resection and scoliosis correction: a case report]]> https://www.researchpad.co/article/N663ab5ef-d8e3-4365-b391-7015a5352d85 Spinal ganglioneuroma occurs mostly in the thoracic spine causing various manifestations including scoliosis that can be misdiagnosed as idiopathic scoliosis. Few reports exist in the literature on the diagnosis and management of scoliosis secondary to huge ganglioneuroma and usually staged treatment is preferred. In this report, we present a 17-year-old female patient presented with back pain, lower limbs numbness, spinal deformity, and shortness of breath. Plain X-rays showed a 50° right thoracic scoliotic curve. MRI and chest CT revealed a huge extra pulmonary mass shifting the mediastinum with intra spinal extension through the left neural foramina compressing the spinal cord. Percutaneous US guided needle biopsy confirmed the diagnosis of ganglioneuroma. One-stage posterior instrumented correction of scoliosis, spinal cord decompression, and excision of the whole mass from the mediastinum and the spine through posterior approach was done for the patient with smooth postoperative recovery. Chest CT scan was done 2 years after surgery and excluded any local recurrence.

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<![CDATA[Cervical spine clearance after blunt trauma: current state of the art]]> https://www.researchpad.co/article/N905d7f6c-5c10-4663-b02a-1251c0ef849f No definite consensus exists for the clearance of the cervical spine (C-spine) after blunt trauma, despite many validated algorithms, recommendations and guidelines. We intend to answer the most relevant questions with which physicians are confronted when clearing C-spines after blunt trauma in emergency departments (EDs). To exclude significant C-spine injuries we designed an algorithm to be compatible with clinical practice, to simplify patient management and avoid unrewarding evaluation.We conducted an exploratory PubMed search including articles published from January 2000 to October 2018. Keywords used were “cervical spine”, “injury”, “clearance”, “Canadian C-spine Rule”, “CCR” and “national emergency x-radiography utilization study”. Clinical and experimental studies were included in a detailed review.We based our literature review on 33 articles. While answering fundamental triage questions from daily clinical practice, the current literature is discussed in detail. We designed an algorithm for the C-spine clearance suitable for any trauma centre with a high-quality multiplanar reconstruction computerized tomography (CT) scan continuously available.The high sensitivity of the Canadian C-spine Rule (CCR) prevents missing C-spine injuries while limiting the amount of unnecessary radiologic examinations. Plain radiographs were fully abandoned for C-spine clearance. A negative CT scan is sufficient to clear the majority of C-spine injuries and allows for collar removal. In case of motor symptoms or radio-clinical discrepancy, the advice of a specialized spine surgeon must be requested. Magnetic resonance imaging must not be routinely used. Neck pain despite negative imaging is not a reason to delay removal of stiff cervical collars.

Cite this article: EFORT Open Rev 2020;5:253-259. DOI: 10.1302/2058-5241.5.190047

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<![CDATA[Unexpected discovery of a diffuse astrocytoma of the conus medullaris in an elderly NF1 patient]]> https://www.researchpad.co/article/N70434690-93f6-402a-9755-ede5efd5c01a

Neurofibromatosis type 1 (NF1) is one of the most common genetic neurocutaneous disorders, and it is well known to be associated with peripheral or central nervous system malignancies. The most common malignant tumors are malignant peripheral nerve sheath tumors (MPNSTs); MPNSTs are the most common cause of death in patients with NF1. Central nervous system malignancies rarely occur. So far, the occurrence of spinal cord malignancies is exceedingly rare. Herein, we report a rare case of a 69-year-old male with NF1 following tumor resection twice for cutaneous MPNSTs developing intramedullary diffuse astrocytoma in the conus medullaris, which initially presented with traumatic spinal cord injury associated with a compression fracture from fall. Contrast-enhanced magnetic resonance imaging and biopsy of the spinal cord were required to establish the final diagnosis.

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<![CDATA[Rosai-Dorfman disease with paravertebral and epidural thoracic spine involvement: A case report and literature review]]> https://www.researchpad.co/article/N50fba08a-3915-4b74-81cb-eacba1ceb600

Rosai–Dorfman disease (RDD) with spinal cord involvement is a rare clinical entity. We report a case of RDD with paravertebral and intraspinal epidural involvement in a 24-year-old male Bangladeshi patient who presented with progressive bilateral lower limb weakness for 20 days duration associated with spasticity and muscle spasm. MRI demonstrated an enhancing paravertebral soft tissue lesion extending from C7 through T4 with intraspinal epidural extension encasing the spinal cord with focal cord oedema. Histopathology of the paraspinal-epidural lesion reported a finding consistent with RDD. The patient was initiated on high-dose steroids. Follow up after 2 months demonstrated symptomatic improvement as the patient was able to move on the crutch and repeated MRI showed lesion regression.

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<![CDATA[How I do it? Uniportal full endoscopic contralateral approach for lumbar foraminal stenosis with double crush syndrome]]> https://www.researchpad.co/article/N76763066-b1e2-4bc2-a74c-4d8ab3d957c5

Background

Evolution of endoscopic surgery provides equivalent results to open surgery with advantages of minimal invasive surgery. The literature on technique Uniportal Full endoscopic contralateral approach is scarce.

Methods

The endoscopic contralateral approach technique applies for patients presenting with double crush syndrome with foraminal and extraforminal stenosis. The key steps focus on contralateral ventral overriding superior articular process decompression, foraminal and extraforaminal discectomy, and lateral vertebral syndesmophyte decompression leading to enlargement of the contralateral foramen and extraforamen size.

Conclusion

The Uniportal Full endoscopic contralateral approach is a good alternative to open surgery or minimally invasive microscopic surgery through direct endoscopic visualization of the entire route of exiting nerve with no neural retraction allowing both lateral recess and foraminal and extraforaminal decompression all in one approach.

Electronic supplementary material

The online version of this article (10.1007/s00701-019-04157-z) contains supplementary material, which is available to authorized users.

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<![CDATA[Lumbar disc extrusions reduce faster than bulging discs due to an active role of macrophages in sciatica]]> https://www.researchpad.co/article/N404a9d84-a4a8-4452-9ef9-9ba99849f0ba

Objective

This retrospective observational histological study aims to associate the size and type of disc herniation with the degree of macrophage infiltration in disc material retrieved during disc surgery in patients with sciatica.

Methods

Disc tissue of 119 sciatica patients was embedded in paraffin and stained with hematoxylin and CD68. Tissue samples were categorized as mild (0–10/cm2), moderate (10–100/cm2), and considerable (> 100/cm2) macrophage infiltration. All 119 patients received an MRI at baseline, and 108 received a follow-up MRI at 1-year. MRIs were reviewed for the size and type of the disc herniations, and for Modic changes in the vertebral endplates.

Results

Baseline characteristics and duration of symptoms before surgery were comparable in all macrophage infiltration groups. The degree of macrophage infiltration was not associated with herniation size at baseline, but significantly associated with reduction of size of the herniated disc at 1-year post surgery. Moreover, the degree of macrophage infiltration was higher in extrusion in comparison with bulging (protrusion) of the disc. Results were comparable in patients with and without Modic changes.

Conclusion

Macrophage infiltration was positively associated with an extruded type of disc herniation as well as the extent of reduction of the herniated disc during 1-year follow-up in patients with sciatica. This is an indication that the macrophages play an active role in reducing herniated discs. An extruded disc herniation has a larger surface for the macrophages to adhere to, which leads to more size reduction.

Electronic supplementary material

The online version of this article (10.1007/s00701-019-04117-7) contains supplementary material, which is available to authorized users.

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<![CDATA[A new finite element based parameter to predict bone fracture]]> https://www.researchpad.co/article/N73efbb2c-4546-457e-9797-023764c15f47

Dual Energy X-Ray Absorptiometry (DXA) is currently the most widely adopted non-invasive clinical technique to assess bone mineral density and bone mineral content in human research and represents the primary tool for the diagnosis of osteoporosis. DXA measures areal bone mineral density, BMD, which does not account for the three-dimensional structure of the vertebrae and for the distribution of bone mass. The result is that longitudinal DXA can only predict about 70% of vertebral fractures. This study proposes a complementary tool, based on Finite Element (FE) models, to improve the DXA accuracy. Bone is simulated as elastic and inhomogeneous material, with stiffness distribution derived from DXA greyscale images of density. The numerical procedure simulates a compressive load on each vertebra to evaluate the local minimum principal strain values. From these values, both the local average and the maximum strains are computed over the cross sections and along the height of the analysed bone region, to provide a parameter, named Strain Index of Bone (SIB), which could be considered as a bone fragility index. The procedure is initially validated on 33 cylindrical trabecular bone samples obtained from porcine lumbar vertebrae, experimentally tested under static compressive loading. Comparing the experimental mechanical parameters with the SIB, we could find a higher correlation of the ultimate stress, σULT, with the SIB values (R2adj = 0.63) than that observed with the conventional DXA-based clinical parameters, i.e. Bone Mineral Density, BMD (R2adj = 0.34) and Trabecular Bone Score, TBS (R2adj = -0.03). The paper finally presents a few case studies of numerical simulations carried out on human lumbar vertebrae. If our results are confirmed in prospective studies, SIB could be used—together with BMD and TBS—to improve the fracture risk assessment and support the clinical decision to assume specific drugs for metabolic bone diseases.

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<![CDATA[Ventrolateral disc herniation causes psoas muscle compression: A case report]]> https://www.researchpad.co/article/Na54a0b16-6e69-415e-bfc5-7987834ab119

We report a case of a 39-year old male patient who presented to us with several months of lower back pain. Following clinical assessment, the patient underwent a magnetic resonance imaging exam, which after using advanced imaging protocols showed a ventrolateral disc hernation toward the psoas muscle. Based upon the findings in the magnetic resonance and the electromyoneurographic examination, the decision was made to treat the patient conservatively. Coronal planes are useful for discerning changes of various origins not usually seen on the sagital and axial planes. If needed, additional advanced protocol is available for increased specificity and diagnostic accuracy.

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<![CDATA[International Standards for Neurological Classification of Spinal Cord Injury: factors influencing the frequency, completion and accuracy of documentation of neurology for patients with traumatic spinal cord injuries]]> https://www.researchpad.co/article/Na804a48d-d9c2-4b38-90f2-3e0c2715d02b

Introduction

We aim to evaluate the effects of injury-related factors and clinician training grades on the frequency, completion and accuracy of International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) charts in a tertiary care neurosurgery unit.

Materials and methods

We retrospectively analysed 96 ISNCSCI charts of 24 traumatic spinal cord-injured (SCI) patients and 26 controls (vertebral fracture but neurologically intact), written by 50 clinicians. Seven components of each ISNCSCI charts (motor scores, sensory scores, sensory levels, motor levels, neurological level of injury, SCI severity and AIS) were reviewed to evaluate the effect of injury factors and clinician grade on the completion and accuracy of the ISNCSCI components.

Results

The ISNCSCI chart was used 1.9 times on average during admission. The number of ISNCSCI assessments was significant in those with isolated spinal injuries (p = 0.03). The overall completion and accuracy rates of the assessed ISNCSCI chart components were 39% and 78.1%, respectively. Motor levels and AIS had the lowest completion rates. Motor levels and sensory levels had the lowest accuracy rates. The completion rate was higher in the charts of male patients, tetraplegic patients, and in patients with isolated spinal injuries. The junior clinicians had a significantly greater ISNCSCI chart completion rate than their seniors. However, the senior clinicians were more accurate in completing the ISNCSCI chart components.

Conclusion

The quality of ISNCSCI documentation remained poor regardless of the clinician training grade and injury factors. Clinicians should be educated on the ISNCSCI protocol and the importance of adequate documentation.

Electronic supplementary material

The online version of this article (10.1007/s00590-019-02502-7) contains supplementary material, which is available to authorized users.

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<![CDATA[An anatomical study on lumbar arteries related to the extrapedicular approach applied during lumbar PVP (PKP)]]> https://www.researchpad.co/article/5c8823e7d5eed0c48463929f

To observe the regional anatomy of the lumbar artery (LA) associated with the extrapedicular approach applied during percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP), we collected 78 samples of abdominal computed tomography angiography imaging data. We measured the nearest distance from the center of the vertebral body puncture point to the LA (distance VBPP-LA, DVBPP-LA). According to the DVBPP-LA, four zones, Zone I, Zone II, Zone III and Zone IV, were identified. LAs that passed through these zones were called Type I, Type II, Type III and Type IV LAs, respectively. A portion of the lumbar vertebrae had an intersegmental branch that originated from the upper segmental LA and extended longitudinally across the lateral wall of the pedicle; it was called Type V LA. Compared with the DVBPP-LA in L1, L2, L3 and L4, the overall difference and between-group differences were significant (P < 0.05). In L1, L2, L3, L4 and L5, there were 8, 4, 4, 0 and 1 Type I LAs, respectively. There were no Type V LAs in L1 and L2, but there were 2, 16 and 26 Type V LAs in L3, L4 and L5, respectively. In L1-L5, the numbers of Type I LA plus Type V LA were 8, 4, 6, 16 and 27, and the presence ratios were 5.1%, 2.6%, 5.6%, 10.3% and 17.3%, respectively. In L4 and L5, the male presence ratios of Type I LA plus Type V LA were 7.1% and 10.7%, respectively, and the female presence ratios were 13.9% and 25.0%, respectively. Thus, extrapedicular PVP (PKP) in lumbar vertebrae had a risk of LA injury and was not suggested for use in L4 and L5, especially in female patients.

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<![CDATA[In-silico pre-clinical trials are made possible by a new simple and comprehensive lumbar belt mechanical model based on the Law of Laplace including support deformation and adhesion effects]]> https://www.researchpad.co/article/5c89779ad5eed0c4847d3130

Lower back pain is a major public health problem. Despite claims that lumbar belts change spinal posture due to applied pressure on the trunk, no mechanical model has yet been published to prove this treatment. This paper describes a first model for belt design, based on the one hand on the mechanical properties of the fabrics and the belt geometry, and on the other hand on the trunk geometrical and mechanical description. The model provides the estimation of the pressure applied to the trunk, and a unique indicator of the belt mechanical efficiency is proposed: pressure is integrated into a bending moment characterizing the belt delordosing action on the spine. A first in-silico clinical study of belt efficiency for 15 patients with 2 different belts was conducted. Results are very dependent on the body shape: in the case of high BMI patients, the belt effect is significantly decreased, and can be even inverted, increasing the lordosis. The belt stiffness proportionally increases the pressure applied to the trunk, but the influence of the design itself on the bending moment is clearly outlined. Moreover, the belt/trunk interaction, modeled as sticking contact and the specific way patients lock their belts, dramatically modifies the belt action. Finally, even if further developments and tests are still necessary, the model presented in this paper seems suitable for in-silico pre-clinical trials on real body shapes at a design stage.

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<![CDATA[Evaluation of the responsiveness of outcome measures after spine injection: A retrospective study]]> https://www.researchpad.co/article/5c803c65d5eed0c484ad8887

Discrepancies in patients’ responses to various outcome measures challenge clinicians’ evaluation of treatment outcomes. Therefore, we aimed to 1) evaluate the concordance of outcome measures after spine injection, 2) determine the patient variables that lead to discordant responses, and 3) suggest practical outcome measure for spine injections with good responsiveness. From October 2014 to November 2014, 164 patients with neck or low back pain who visited our outpatient clinics and had spine injections on the previous visit were enrolled. We asked patients to report changes in their symptom in the form of outcome measures: numeric rating scale, Oswestry disability index, neck disability index, residual symptom percentage and global perceived effect. The responses were categorized into three groups according to the degree of change; not improved, minimally improved, and significantly improved. The concordances of these categorized answers were evaluated. When “significantly improved” was considered as true improvement, 46 (28%) of the 164 patients had discordant responses to the four measures. There was no significant patients’ variable that affects discordance in the outcome measures. Good agreement was shown between the global perceived effect and residual symptom percentage, while the Oswestry disability index had poor agreement with the other measurements. The calculated numeric rating scale and residual symptom percentage also had low levels of agreement. However, patients with severe pre-treatment pain tended to have better agreement. In conclusion, this result suggest that the residual symptom percentage may be a more practical for clinicians and better represent patients’ improvements after spine injection.

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<![CDATA[Thoracic spine manipulation for the management of mechanical neck pain: A systematic review and meta-analysis]]> https://www.researchpad.co/article/5c6dc9ced5eed0c48452a202

Objective

To investigate the role of thoracic spine manipulation (TSM) on pain and disability in the management of mechanical neck pain (MNP).

Data sources

Electronic databases PubMed, CINAHL, Pedro, Embase, AMED, the Cochrane Library, and clinicaltrials.gov were searched in January 2018.

Study selection

Eligible studies were completed RCTs, written in English, had at least 2 groups with one group receiving TSM, had at least one measure of pain or disability, and included patients with MNP of any duration. The search identified 1717 potential articles, with 14 studies meeting inclusion criteria.

Study appraisal and synthesis methods

Methodological quality was evaluated independently by two authors using the guidelines published by the Cochrane Collaboration. Pooled analyses were analyzed using a random-effects model with inverse variance methods to calculate mean differences (MD) and 95% confidence intervals for pain (VAS 0-100mm, NPRS 0-10pts; 0 = no pain) and disability (NDI and NPQ 0–100%; 0 = no disability).

Results

Across the included studies, there was increased risk of bias for inadequate provider and participant blinding. The GRADE approach demonstrated an overall level of evidence ranging from very low to moderate. Meta-analysis that compared TSM to thoracic or cervical mobilization revealed a significant effect favoring the TSM group for pain (MD -13.63; 95% CI: -21.79, -5.46) and disability (MD -9.93; 95% CI: -14.38, -5.48). Meta-analysis that compared TSM to standard care revealed a significant effect favoring the TSM group for pain (MD -13.21; 95% CI: -21.87, -4.55) and disability (MD -11.36; 95% CI: -18.93, -3.78) at short-term follow-up, and a significant effect for disability (MD -4.75; 95% CI: -6.54, -2.95) at long-term follow-up. Meta-analysis that compared TSM to cervical spine manipulation revealed a non-significant effect (MD 3.43; 95% CI: -7.26, 14.11) for pain without a distinction between immediate and short-term follow-up.

Limitations

The greatest limitation in this systematic review was the heterogeneity among the studies making it difficult to assess the true clinical benefit, as well as the overall level of quality of evidence.

Conclusions

TSM has been shown to be more beneficial than thoracic mobilization, cervical mobilization, and standard care in the short-term, but no better than cervical manipulation or placebo thoracic spine manipulation to improve pain and disability.

Trial registration

PROSPERO CRD42017068287

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<![CDATA[Anatomy of the dinosaur Pampadromaeus barberenai (Saurischia—Sauropodomorpha) from the Late Triassic Santa Maria Formation of southern Brazil]]> https://www.researchpad.co/article/5c76fe1bd5eed0c484e5b4e9

Sauropodomorphs are the most abundant and diverse clade of Triassic dinosaurs, but the taxonomy of their earliest (Carnian) representatives is still poorly understood. One such taxon is Pampadromaeus barberenai, represented by a nearly complete disarticulated skeleton recovered from the upper part of the Santa Maria Formation of Rio Grande do Sul, Brazil. Here, the osteology of Pam. barberenai is fully described for the first time. Detailed comparisons with other Carnian sauropodomorphs reveal a unique anatomy, corroborating its status as a valid species. Potential autapomorphies of Pam. barberenai can be seen in the articulation of the sacral zygapophyses, the length of the pectoral epipodium, the shape of the distal articulation of the femur and the proximal articulation of metatarsal 1. A novel phylogenetic study shows that relationships among the Carnian sauropodomorphs are poorly constrained, possibly because they belong to a “zone of variability”, where homoplasy abounds. Yet, there is some evidence that Pam. barberenai may nest within Saturnaliidae, along with Saturnalia tupiniquim and Chromogisaurus novasi, which represents the sister group to the larger sauropodomorphs, i.e. Bagualosauria.

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<![CDATA[A novel nonosteocytic regulatory mechanism of bone modeling]]> https://www.researchpad.co/article/5c5df343d5eed0c484581048

Osteocytes, cells forming an elaborate network within the bones of most vertebrate taxa, are thought to be the master regulators of bone modeling, a process of coordinated, local bone-tissue deposition and removal that keeps bone strains at safe levels throughout life. Neoteleost fish, however, lack osteocytes and yet are known to be capable of bone modeling, although no osteocyte-independent modeling regulatory mechanism has so far been described. Here, we characterize a novel, to our knowledge, bone-modeling regulatory mechanism in a fish species (medaka), showing that although lacking osteocytes (i.e., internal mechanosensors), when loaded, medaka bones model in mechanically directed ways, successfully reducing high tissue strains. We establish that as in mammals, modeling in medaka is regulated by the SOST gene, demonstrating a mechanistic link between skeletal loading, SOST down-regulation, and intense bone deposition. However, whereas mammalian SOST is expressed almost exclusively by osteocytes, in both medaka and zebrafish (a species with osteocytic bones), SOST is expressed by a variety of nonosteocytic cells, none of which reside within the bone bulk. These findings argue that in fishes (and perhaps other vertebrates), nonosteocytic skeletal cells are both sensors and responders, shouldering duties believed exclusive to osteocytes. This previously unrecognized, SOST-dependent, osteocyte-independent mechanism challenges current paradigms of osteocyte exclusivity in bone-modeling regulation, suggesting the existence of multivariate feedback networks in bone modeling—perhaps also in mammalian bones—and thus arguing for the possibility of untapped potential for cell targets in bone therapeutics.

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<![CDATA[A new African Titanosaurian Sauropod Dinosaur from the middle Cretaceous Galula Formation (Mtuka Member), Rukwa Rift Basin, Southwestern Tanzania]]> https://www.researchpad.co/article/5c6dca2ad5eed0c48452a874

The African terrestrial fossil record has been limited in its contribution to our understanding of both regional and global Cretaceous paleobiogeography, an interval of significant geologic and macroevolutionary change. A common component in Cretaceous African faunas, titanosaurian sauropods diversified into one of the most specious groups of dinosaurs worldwide. Here we describe the new titanosaurian Mnyamawamtuka moyowamkia gen. et sp. nov. from the Mtuka Member of the Galula Formation in southwest Tanzania. The new specimen preserves teeth, elements from all regions of the postcranial axial skeleton, parts of both appendicular girdles, and portions of both limbs including a complete metatarsus. Unique traits of M. moyowamkia include the lack of an interpostzygapophyseal lamina in posterior dorsal vertebrae, pronounced posterolateral expansion of middle caudal centra, and an unusually small sternal plate. Phylogenetic analyses consistently place M. moyowamkia as either a close relative to lithostrotian titanosaurians (e.g., parsimony, uncalibrated Bayesian analyses) or as a lithostrotian and sister taxon to Malawisaurus dixeyi from the nearby Aptian? Dinosaur Beds of Malawi (e.g., tip-dating Bayesian analyses). M. moyowamkia shares a few features with M. dixeyi, including semi-spatulate teeth and a median lamina between the neural canal and interpostzygapophyseal lamina in anterior dorsal vertebrae. Both comparative morphology and phylogenetic analyses support Mnyamawamtuka as a distinct and distant relative to Rukwatitan bisepultus and Shingopana songwensis from the younger Namba Member of the Galula Formation with these results largely congruent with newly constrained ages for the Mtuka Member (Aptian–Cenomanian) and Namba Member (Campanian). Coupled with recent discoveries from the Dahkla Oasis, Egypt (e.g., Mansourasaurus shahinae) and other parts of continental Afro-Arabia, the Tanzania titanosaurians refine perspectives on the development of African terrestrial faunas throughout the Cretaceous—a critical step in understanding non-marine paleobiogeographic patterns of Africa that have remained elusive until the past few years.

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<![CDATA[Comparisons of Schansitherium tafeli with Samotherium boissieri (Giraffidae, Mammalia) from the Late Miocene of Gansu Province, China]]> https://www.researchpad.co/article/5c6c7573d5eed0c4843cfdbf

We are describing and figuring for the first time skulls of Schansitherium tafeli, which are abundant in the Gansu area of China from the Late Miocene. They were animals about the size of Samotherium with shorter necks that had two pairs of ossicones that merge at the base, which is unlike Samotherium. The anterior ossicones consist of anterior lineations, which may represent growth lines. They were likely mixed feeders similar to Samotherium. Schansitherium is tentatively placed in a very close position to Samotherium. Samotherium and Schansitherium represent a pair of morphologically very similar species that likely coexisted similarly to pairs of modern species, where the main difference is in the ossicones. Pairs of ruminants in Africa, for example, exist today that differ mostly in their horn shape but otherwise are similar in size, shape, and diet. The absence of Schansitherium from Europe is interesting, however, as Samotherium is found in both locations. While is it challenging to interpret neck length and ossicone shape in terms of function in combat, we offer our hypothesis as to how the two species differed in their fighting techniques.

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<![CDATA[A new baby oviraptorid dinosaur (Dinosauria: Theropoda) from the Upper Cretaceous Nemegt Formation of Mongolia]]> https://www.researchpad.co/article/5c648cf4d5eed0c484c81b9d

Recent discoveries of new oviraptorosaurs revealed their high diversity from the Cretaceous Period in Asia and North America. Particularly, at the family level, oviraptorids are among the most diverse theropod dinosaurs in the Late Cretaceous of Mongolia and China. A new oviraptorid dinosaur Gobiraptor minutus gen. et sp. nov. from the Upper Cretaceous Nemegt Formation is described here based on a single holotype specimen that includes incomplete cranial and postcranial elements. The most prominent characters of Gobiraptor are its thickened rostrodorsal end of the mandibular symphysis and a rudimentary lingual shelf on each side of the dentary. Each lingual shelf is lined with small occlusal foramina and demarcated by a weakly developed lingual ridge. This mandibular morphology of Gobiraptor is unique among oviraptorids and likely to be linked to a specialized diet that probably included hard materials, such as seeds or bivalves. The osteohistology of the femur of the holotype specimen indicates that the individual was fairly young at the time of its death. Phylogenetic analysis recovers Gobiraptor as a derived oviraptorid close to three taxa from the Ganzhou region in southern China, but rather distantly related to other Nemegt oviraptorids which, as the results of recent studies, are also not closely related to each other. Gobiraptor increases diversity of oviraptorids in the Nemegt Formation and its presence confirms the successful adaptation of oviraptorids to a mesic environment.

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<![CDATA[The stability of long-segment and short-segment fixation for treating severe burst fractures at the thoracolumbar junction in osteoporotic bone: A finite element analysis]]> https://www.researchpad.co/article/5c61e8dbd5eed0c48496f278

The majority of compressive vertebral fractures in osteoporotic bone occur at the level of the thoracolumbar junction. Immediate decompression is often required in order to reduce the extent of neurological damage. This study evaluated four fixation methods for decompression in patients with thoracolumbar burst fractures, and presented the most suitable method for osteoporotic patients. A finite element model of a T7–L5 spinal segment was created and subjected to an L1 corpectomy to simulate a serious burst fracture. Five models were tested: a) intact spine; 2) two segment fixation (TSF), 3) up-three segment fixation (UTSF), below-three segment fixation (BTSF), and four segment fixation (FSF). The ROM, stiffness and compression ratio of the fractured vertebra were recorded under various loading conditions. The results of this study showed that the ROM of the FSF model was the lowest, and the ROMs of UTSF and BTSF models were similar but still greater than the TSF model. Decreasing the BMD to simulate osteoporotic bone resulted in a ROM for the four instrumented models that was higher than the normal bone model. Of all models, the FSF model had the highest stiffness at T12-L2 in extension and lateral bending. Similarly, the compression ratio of the FSF model at L1 was also higher than the other instrumented models. In conclusion, FSF fixation is suggested for patients with osteoporotic thoracolumbar burst fractures. For patients with normal bone quality, both UTSF and BTSF fixation provide an acceptable stiffness in extension and lateral bending, as well as a favorable compression ratio at L1.

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