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1.
J Am Chem Soc ; 146(11): 7822-7830, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38456811

RESUMO

Understanding the effects of pressure on actinide compounds is an integral part of safe nuclear waste storage in deep geologic repositories and provides a means of systematically altering the structure and properties. However, detailing how the effects of pressure evolve across the actinide series in the later elements is not typically undertaken because of the challenges of conducting research on these unstable isotopes. Here, a family of bimetallic actinide complexes, [(An(pmtz)2(H2O)3)2(µ-pmtz)]2(pmtz)2·nH2O (An3+ = Cm3+, Bk3+, and Cf3+, pmtz- = 5-(pyrimidyl)tetrazolate; Cm1, Bk1, and Cf1), are reported and represent the first structurally characterized bimetallic berkelium and californium compounds. The pressure response as determined from UV-vis-NIR transitions varies for Cm1, Bk1, and Cf1. The 5f → 5f transitions in Cm1 are notably more sensitive to pressure compared to those in Bk1 and Cf1 and show substantial bathochromic shifting of several 5f → 5f transitions. In the case of Bk1, an ingrowth of a metal-to-ligand charge-transfer transition occurs at elevated pressures because of the accessible Bk3+/Bk4+ couple. For Cf1, no substantial transition shifting or emergence of MLCT transitions is observed at elevated pressures because of the prohibitive energetics of the Cf3+/Cf4+ couple and reduced sensitivity of the 5f → 5f transitions to the local coordination environment because of the more contracted 5f shell versus Cm3+ and Bk3+.

2.
Phys Rev Lett ; 132(25): 251601, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38996230

RESUMO

We compute the potential-photon contributions to the classical relativistic scattering angle of two charged nonspinning bodies in electrodynamics through fifth order in the coupling. We use the scattering amplitudes framework, effective field theory, and multiloop integration techniques based on integration by parts and differential equations. At fifth order, the result is expressed in terms of cyclotomic polylogarithms. Our calculation demonstrates the feasibility of the corresponding calculations in general relativity, including the evaluation of the encountered four-loop integrals.

3.
Eur Spine J ; 33(4): 1574-1584, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37466720

RESUMO

BACKGROUND: Paediatric thoracolumbar spine injuries are rare, and meaningful epidemiological data are lacking. OBJECTIVES: The aim of this study was to provide epidemiological data for paediatric patients with thoracolumbar spinal trauma in Germany with a view to enhancing future decision-making in relation to the diagnostics and treatment of these patients. MATERIALS AND METHODS: A retrospective multicentre study includes patients up to 16 years of age who were suffering from thoracolumbar spine injuries who had been treated in six German spine centres between 01/2010 and 12/2016. The clinical database was analysed for patient-specific data, trauma mechanisms, level of injury, and any accompanying injuries. Diagnostic imaging and subsequent treatment were investigated. Patients were divided into three age groups for further evaluation: age group I (0-6 years), age group II (7-9 years) and age group III (10-16 years). RESULTS: A total of 153 children with 345 thoracolumbar spine injuries met the inclusion criteria. The mean age at the time of hospitalization due to the injury was 12.9 (± 3.1) years. Boys were likelier to be affected (1:1.3). In all age groups, falls and traffic accidents were the most common causes of thoracolumbar spine injuries. A total of 95 patients (62.1%) were treated conservatively, while 58 (37.9%) of the children underwent surgical treatment. Minimally invasive procedures were the most chosen procedures. Older children and adolescents were likelier to suffer from higher-grade injuries according to the AOSpine classification. The thoracolumbar junction (T11 to L2) was the most affected level along the thoracolumbar spine (n = 90). Neurological deficits were rarely seen in all age groups. Besides extremity injuries (n = 52, 30.2%), head injuries represented the most common accompanying injuries (n = 53, 30.8%). Regarding spinal injuries, most of the patients showed no evidence of complications during their hospital stay (96.7%). CONCLUSIONS: The thoracolumbar junction was more frequently affected in older children and adolescents. The majority of thoracolumbar spinal column injuries were treated conservatively. Nevertheless, 37.9% of hospitalized children had to be treated surgically, and there was an acceptable complication rate for the surgeries that were performed.


Assuntos
Fraturas da Coluna Vertebral , Traumatismos da Coluna Vertebral , Masculino , Adolescente , Humanos , Criança , Recém-Nascido , Lactente , Pré-Escolar , Vértebras Torácicas/diagnóstico por imagem , Vértebras Torácicas/cirurgia , Vértebras Torácicas/lesões , Traumatismos da Coluna Vertebral/diagnóstico por imagem , Traumatismos da Coluna Vertebral/epidemiologia , Traumatismos da Coluna Vertebral/terapia , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/cirurgia , Vértebras Lombares/lesões , Alemanha/epidemiologia , Estudos Retrospectivos , Fraturas da Coluna Vertebral/diagnóstico por imagem , Fraturas da Coluna Vertebral/epidemiologia , Fraturas da Coluna Vertebral/terapia
4.
Phys Rev Lett ; 130(2): 021601, 2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36706419

RESUMO

We compute the conservative two-body Hamiltonian of a compact binary system with a spinning black hole through O(G^{3}) to all orders in velocity, including linear and quadratic spin terms. To obtain our results we calculate the classical limit of the two-loop amplitude for the scattering of a massive scalar particle with a massive spin-1 particle minimally coupled to gravity. We employ modern scattering amplitude and loop integration techniques, in particular numerical unitarity, integration-by-parts identities, and the method of regions. The conservative potential in terms of rest-frame spin vectors is extracted by matching to a nonrelativistic effective field theory. We also apply the Kosower-Maybee-O'Connell (KMOC) formalism to calculate the impulse in the covariant spin formalism directly from the amplitude. We work systematically in conventional dimensional regularization and explicitly evaluate all divergent integrals that appear in full- and effective-theory amplitudes, as well as in the phase-space integrals that arise in the KMOC formalism.

5.
Eur Spine J ; 32(4): 1291-1299, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36757616

RESUMO

OBJECTIVES: The aim of this study was to provide epidemiological data of pediatric patients suffering from cervical spinal trauma in Germany, in order to integrate these data in future decision-making processes concerning diagnosis and therapy. MATERIALS AND METHODS: Retrospective multicenter study includes all patients up to 16 years suffering from cervical spine injuries who were treated in six German spine centers between 01/2010 and 12/2016. The clinical databases were screened for specific trauma mechanism, level of injury as well as accompanying injuries. Diagnostic imaging and the chosen therapy were analyzed. Patients were divided into three age groups for further evaluation: age group I (0-6 years), age group II (7-9 years), age group III (10-16 years). RESULTS: A total of 214 children with 265 cervical spine injuries were included during the mentioned period. The mean age at the time of injury was 11.9 (± 3.9) years. In age group I, 24 (11.2%) patients were included, age group II consisted of 22 patients (10.3%), and 168 patients belonged to age group III (78.5%). Girls and boys were equally affected. In all age groups, falls and traffic accidents were the most common causes of cervical spine injuries. A total of 180 patients (84.1%) were treated conservatively, while 34 (15.9%) children underwent surgery. Distorsion/whiplash injury was the most common entity (n = 165; 68.2%). Children aged 0-9 years had significantly (p < 0.001) more frequent injuries of the upper cervical spine (C0-C2) compared to older age groups. Patients of age group III were more likely to suffer from injuries in subaxial localizations. Neurological deficits were rarely seen in all age groups. Head injuries did represent the most common accompanying injuries (39.8%, n = 92). CONCLUSIONS: The upper cervical spine was more frequently affected in young children. Older children more often suffered from subaxial pathologies. The majority of cervical spinal column injuries were treated conservatively. Nevertheless, 15% of the hospitalized children had to be treated surgically.


Assuntos
Lesões do Pescoço , Traumatismos da Coluna Vertebral , Masculino , Feminino , Criança , Humanos , Idoso , Adolescente , Pré-Escolar , Traumatismos da Coluna Vertebral/epidemiologia , Traumatismos da Coluna Vertebral/terapia , Traumatismos da Coluna Vertebral/diagnóstico , Vértebras Cervicais/diagnóstico por imagem , Vértebras Cervicais/cirurgia , Vértebras Cervicais/lesões , Estudos Retrospectivos , Acidentes de Trânsito
6.
J Anat ; 240(1): 120-130, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34346505

RESUMO

The morphology of the rib cage affects both the biomechanics of the upper body's musculoskeletal structure and the respiratory mechanics. This becomes particularly important when evaluating skeletal deformities, as in adolescent idiopathic scoliosis (AIS). The aim of this study was to identify morphological characteristics of the rib cage in relation to the lung in patients with non-deformed and scoliotic spines. Computed tomography data of 40 patients without any visible spinal abnormalities (healthy group) and 21 patients with AIS were obtained retrospectively. All bony structures as well as the right and left lung were reconstructed using image segmentation. Morphological parameters were calculated based on the distances between characteristic morphological landmarks. These parameters included the rib position, length, and area, the rib cage depth and width, and the rib inclination angle on either side, as well as the spinal height and length. Furthermore, we determined the left and right lung volumes, and the area of contact between the rib cage and lung. Differences between healthy and scoliotic spines were statistically analysed using the t-test for unpaired data. The rib cage of the AIS group was significantly deformed in the dorso-ventral and medio-lateral directions. The anatomical proximity of the lung to the ribs was nearly symmetrical in the healthy group. By contrast, within the AIS group, the lung covered a significantly greater area on the left side of the rib cage at large thoracic deformities. Within the levels T1-T6, no significant difference in the rib length, depth to width relationship, or area was observed between the healthy and AIS groups. Inferior to the lung (T7-T12), these parameters exhibited greater variability. The ratio between the width of the rib cage at T6 and the thoracic spinal height (T1-T12) was significantly increased within the thoracic AIS group (1.1 ± 0.08) compared with the healthy group (1.0 ± 0.05). No statistical differences were found between the lung volumes among all the groups. While the rib cage was frequently strongly deformed in the AIS group, the lung and its surrounding ribs appeared to be normally developed. The observed rib hump in AIS appeared to be formed particularly by a more ventral position of the ribs on the concave side. Furthermore, the rib cage width to spinal height ratio suggested that the spinal height of the thoracic AIS-spine is reduced. This indicates that the spine would gain its growth-related height after correcting the spinal deformity. These are the important aspects to consider in the aetiology research and orthopaedic treatment of AIS.


Assuntos
Cifose , Escoliose , Adolescente , Humanos , Pulmão/diagnóstico por imagem , Estudos Retrospectivos , Caixa Torácica/diagnóstico por imagem , Escoliose/diagnóstico por imagem , Vértebras Torácicas/diagnóstico por imagem
7.
Phys Rev Lett ; 128(16): 161103, 2022 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-35522489

RESUMO

We complete the calculation of conservative two-body scattering dynamics at fourth post-Minkowskian order, i.e., O(G^{4}) and all orders in velocity, including radiative contributions corresponding to the tail effect in general relativity. As in previous calculations, we harness powerful tools from the modern scattering amplitudes program including generalized unitarity, the double copy, and advanced multiloop integration methods, in combination with effective field theory. The classical amplitude involves complete elliptic integrals, and polylogarithms with up to transcendental weight 2. Using the amplitude-action relation, we obtain the radial action directly from the amplitude, and match the known overlapping terms in the post-Newtonian expansion.

8.
Eur Spine J ; 31(1): 28-36, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34773149

RESUMO

PURPOSE: Surgical treatment of thoracolumbar A3-fractures usually comprises posterior fixation-in neutral position or distraction-potentially followed by subsequent anterior support. We hypothesized that additional posterior compression in circumferential stabilization may increase stability by locking the facets, and better restore the sagittal profile. METHODS: Burst fractures Type A3 were created in six fresh frozen cadaver spine segments (T12-L2). Testing was performed in a custom-made spinal loading simulator. Loads were applied as pure bending moments of ± 3.75 Nm in all six movement axes. We checked range of motion, neutral zone and Cobb's angle over the injured/treated segment within the following conditions: Intact, fractured, instrumented in neutral alignment, instrumented in distraction, with cage left in posterior distraction, with cage with posterior compression. RESULTS: We found that both types of instrumentation with cage stabilized the segment compared to the fractured state in all motion planes. For flexion/extension and lateral bending, flexibility was decreased even compared to the intact state, however, not in axial rotation, being the most critical movement axis. Additional posterior compression in the presence of a cage significantly decreased flexibility in axial rotation, thus achieving stability comparable to the intact state even in this movement axis. In addition, posterior compression with cage significantly increased lordosis compared to the distracted state. CONCLUSION: Among different surgical modifications tested, circumferential fixation with final posterior compression as the last step resulted in superior stability and improved sagittal alignment. Thus, posterior compression as the last step is recommended in these pathologies.


Assuntos
Fraturas da Coluna Vertebral , Articulação Zigapofisária , Animais , Fenômenos Biomecânicos , Cadáver , Humanos , Vértebras Lombares/cirurgia , Amplitude de Movimento Articular , Fraturas da Coluna Vertebral/cirurgia
9.
Phys Rev Lett ; 126(20): 201602, 2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-34110218

RESUMO

We compute the total radiated momentum carried by gravitational waves during the scattering of two spinless black holes at the lowest order in Newton's constant, O(G^{3}), and all orders in velocity. By analytic continuation into the bound state regime, we obtain the O(G^{3}) energy loss in elliptic orbits. This provides an essential step toward the complete understanding of the third-post-Minkowskian binary dynamics. We employ the formalism of Kosower, Maybee, and O'Connell (KMOC), which relates classical observables to quantum scattering amplitudes, and derive the relevant integrands using generalized unitarity. The subsequent phase-space integrations are performed via the reverse unitarity method familiar from collider physics, using differential equations to obtain the exact velocity dependence from near-static boundary conditions.

10.
Phys Rev Lett ; 126(17): 171601, 2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33988437

RESUMO

Using scattering amplitudes, we obtain the potential contributions to conservative binary dynamics in general relativity at fourth post-Minkowskian order O(G^{4}). As in previous lower-order calculations, we harness powerful tools from the modern scattering amplitudes program including generalized unitarity, the double copy, and advanced multiloop integration methods, in combination with effective field theory. The classical amplitude involves polylogarithms with up to transcendental weight two and elliptic integrals. We derive the radial action directly from the amplitude, and determine the corresponding Hamiltonian in isotropic gauge. Our results are in agreement with known overlapping terms up to sixth post-Newtonian order, and with the probe limit. We also determine the post-Minkowskian energy loss from radiation emission at O(G^{3}) via its relation to the tail effect.

11.
Eur Spine J ; 30(1): 217-226, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32936402

RESUMO

PURPOSE: The complement system is a crucial part of innate immunity. Recent work demonstrated an unexpected contribution to tissue homeostasis and degeneration. This study investigated for the first time, in human disc tissues, the deposition profile of the complement activation product terminal complement complex (TCC), an inflammatory trigger and inducer of cell lysis, and its inhibitor CD59, and their correlation with the degree of disc degeneration (DD). METHODS: Disc biopsies were collected from patients diagnosed with DD (n = 39, age 63 ± 12) and adolescent idiopathic scoliosis (AIS, n = 10, age 17 ± 4) and compared with discs from healthy Young (n = 11, age 7 ± 7) and Elder (n = 10, age 65 ± 15) donors. Immunohistochemical detection of TCC and CD59 in nucleus pulposus (NP), annulus fibrosus (AF) and endplate (EP) was correlated with age, Pfirrmann grade and Modic changes. RESULTS: Higher percentage of TCC+ cells was detected in the NP and EP of DD compared to Elder (P < 0.05), and in the EP of Young versus Elder (P < 0.001). In DD, TCC deposition was positively correlated with Pfirrmann grade, but not with Modic changes, whereas for Young donors, a negative correlation was found with age, indicating TCC's involvement not only in DD, but also in early stages of skeletal development. Higher CD59 positivity was found in AIS and DD groups compared to Young (P < 0.05), and it was negatively correlated with the age of the patients. CONCLUSION: TCC deposition positively correlated with the degree of disc degeneration. A functional relevance of TCC may exist in DD, representing a potential target for new therapeutics.


Assuntos
Anel Fibroso , Degeneração do Disco Intervertebral , Disco Intervertebral , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Ativação do Complemento , Complexo de Ataque à Membrana do Sistema Complemento , Humanos , Lactente , Recém-Nascido , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Adulto Jovem
12.
Eur Spine J ; 30(8): 2247-2256, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34169354

RESUMO

PURPOSE: Formation of terminal complement complex (TCC), a downstream complement system activation product inducing inflammatory processes and cell lysis, has been identified in degenerated discs. However, it remains unclear which molecular factors regulate complement activation during disc degeneration (DD). This study investigated a possible involvement of the pro-inflammatory cytokine interleukin-1ß (IL-1ß) and the lysosomal protease cathepsin D (CTSD). METHODS: Disc biopsies were collected from patients suffering from DD (n = 43) and adolescent idiopathic scoliosis (AIS, n = 13). Standardized tissue punches and isolated cells from nucleus pulposus (NP), annulus fibrosus (AF) and endplate (EP) were stimulated with 5% human serum (HS) alone or in combination with IL-1ß, CTSD or zymosan. TCC formation and modulation by the complement regulatory proteins CD46, CD55 and CD59 were analysed. RESULTS: In DD tissue cultures, IL-1ß stimulation decreased the percentage of TCC + cells in AF and EP (P < 0.05), whereas CTSD stimulation significantly increased TCC deposition in NP (P < 0.01) and zymosan in EP (P < 0.05). Overall, the expression of CD46, CD55 and CD59 significantly increased in all isolated cells during culture (P < 0.05). Moreover, cellular TCC deposition was HS concentration dependent but unaffected by IL-1ß, CTSD or zymosan. CONCLUSION: These results suggest a functional relevance of IL-1ß and CTSD in modulating TCC formation in DD, with differences between tissue regions. Although strong TCC deposition may represent a degeneration-associated event, IL-1ß may inhibit it. In contrast, TCC formation was shown to be triggered by CTSD, indicating a multifunctional involvement in disc pathophysiology.


Assuntos
Degeneração do Disco Intervertebral , Disco Intervertebral , Adolescente , Catepsina D , Células Cultivadas , Complexo de Ataque à Membrana do Sistema Complemento , Humanos , Interleucina-1beta
13.
J Pediatr Orthop ; 41(8): e651-e658, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34238864

RESUMO

BACKGROUND: Atlantoaxial fixation is technically challenging in younger children. The C1-C2 screw-rod fixation technique is established for adults but limited data about the clinical and radiographical outcome for the treatment of children with 5 years of age or younger is available. METHODS: All files of children who were consecutively treated for spinal disorders were reviewed. Inclusion criteria for further evaluation were: 0 to 5 years of age at initial procedure; detailed surgical report of a posterior C1-C2 fusion with mass lateral and pedicle screw-rod fixation as described by Harms; a minimum clinical and radiographical follow-up of 24 months. The postoperative and last follow-up computed tomography scan and radiographs were used to assess the positioning and stability of the C1-C2 screw-rod construct. RESULTS: Eleven patients (3 boys) with a mean age of 46 months (range: 8 to 66 mo) fulfilled inclusion criteria and were evaluated retrospectively. The mean clinical and radiographical follow-up was 79 months (range: 24 mo to 170 mo). The diagnosis was atlantoaxial rotatory dislocation (4 cases), C1-C2 instability with subluxation (3 cases), atlantoaxial dislocation and os odontoideum (1 case), type II odontoid fracture (1 case), traumatic odontoid epiphysiolysis (1 case), and traumatic rupture of the transverse ligament with C1 subluxation (1 case). Intraoperatively and postoperatively no new neurovascular or vascular complication occurred. C1 lateral mass screws were placed correctly in all cases. Twenty-two C2 pedicle screws were placed correctly (85.7%), and 3 screws showed penetration of the pedicle wall (14.3%). No implant revision, implant failure, and pseudarthrosis were noted. Loss of correction was noted in 1 patient with unilateral C1-C2 fixation and a repeated dorsal fusion procedures were performed. A repeat procedure for implant removal and segmental release was performed in 3 patients to increase the axial rotation of the head. CONCLUSIONS: The C1-C2 screw-rod fixation is a safe technique that achieves solid fixation of the atlantoaxial complex in young children with various disorders. The technique preserves the joint and allows for segmental release via implant removal.


Assuntos
Articulação Atlantoaxial , Instabilidade Articular , Parafusos Pediculares , Fusão Vertebral , Adulto , Articulação Atlantoaxial/diagnóstico por imagem , Articulação Atlantoaxial/cirurgia , Vértebras Cervicais , Criança , Pré-Escolar , Estudos de Viabilidade , Humanos , Lactente , Instabilidade Articular/diagnóstico por imagem , Instabilidade Articular/cirurgia , Masculino , Estudos Retrospectivos , Resultado do Tratamento
14.
Arch Orthop Trauma Surg ; 141(7): 1163-1174, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32556642

RESUMO

INTRODUCTION: Magnetically controlled growing rods (MCGR) for the surgical treatment of early onset scoliosis (EOS) allow non-invasive outpatient based distractions during spinal growth. The purpose of this study is to present the results of a single center case series of 22 patients, evaluate the effect of MCGR treatment on the development of spino-pelvic parameters during growth, and report initial outcomes after end of treatment. MATERIALS AND METHODS: Prospectively collected data of 22 EOS patients with MCGR treatment has been analyzed. The following radiological parameters were measured before index surgery, after index surgery, 1 year after index surgery, and at last follow-up: Cobb angle of the major curves, thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). Mean age at index surgery was 9.5 years (range: 4-14 years). Mean length of follow-up was 47.6 months (range: 25-121 months). Etiology of diagnosis was idiopathic in 14 patients, associated with neurofibromatosis in 2 patients, and neuromuscular or syndromic in 6 patients. RESULTS: Mean Cobb angle of the major curve was 57° preoperatively and 29° at last follow-up (p < 0.0005). Mean TK was 20.1° preoperatively and 20° at last follow-up (p > 0.05). Mean LL was 52.8° preoperatively and 53.2° at last follow-up (p > 0.05). Mean PI was 43.2° preoperatively and 46.3° at last follow-up (p > 0.05). Mean PT was 4.1° preoperatively and 5.8° at last follow-up (p > 0.05). Mean SS was 39.2° preoperatively and 41.7° at last follow-up (p > 0.05). 14 patients finished treatment: nine received final fusion and five received rod removal without fusion. Twelve complications occurred: one deep wound infection, six patients developed proximal junctional kyphosis (PJK), one rod fracture, two rods failed to distract, one deformity progressed after rod removal and required spinal fusion, and one patient developed autofusion of the spine prior to end of treatment. CONCLUSION: MCGR treatment is able to control deformity progression. Complication rate was 54.5%. Sagittal balance was not altered and treatment does not seem to have a negative impact on the development of spino-pelvic parameters during growth. Optimal end of treatment for the individual patient still has to be defined.


Assuntos
Procedimentos Ortopédicos , Escoliose/cirurgia , Adolescente , Criança , Pré-Escolar , Humanos , Imãs , Procedimentos Ortopédicos/efeitos adversos , Procedimentos Ortopédicos/instrumentação , Procedimentos Ortopédicos/métodos , Complicações Pós-Operatórias , Escoliose/diagnóstico por imagem , Coluna Vertebral/diagnóstico por imagem , Coluna Vertebral/cirurgia
15.
Phys Rev Lett ; 125(3): 031601, 2020 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-32745428

RESUMO

We demonstrate the universality of the gravitational classical deflection angle of massless particles through O(G^{3}) by studying the high-energy limit of full two-loop four-graviton scattering amplitudes in pure Einstein gravity as well as N≥4 supergravity. As a by-product, our first-principles calculation provides a direct confirmation of the massless deflection angle in Einstein gravity proposed long ago by Amati, Ciafaloni, and Veneziano, and is inconsistent with a recently proposed alternative.

16.
J Pediatr Orthop ; 40(4): e256-e265, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31923019

RESUMO

BACKGROUND: Congenital scoliosis due to hemivertebra of the cervicodorsal spine is a rare disorder. It might be accompanied by impaired cosmetic appearances such as head tilt and trunk shift. Little is known about the effect of correction of the major curve on head tilt and trunk shift in children. The purpose of this study was to assess radiographic changes of head tilt and trunk shift following posterior hemivertebra resection (PHVR). METHODS: Retrospectively, all children who underwent PHVR at the cervicodorsal spine (C6-Th6) with pedicle screw fixation with a minimum radiographic follow-up of 1 year were identified for further assessment. A total of 5 radiographic parameters were assessed on preoperative, postoperative, and final follow-up radiographs. (1) Head tilt was defined as the angle between the horizontal line and the line through both molars of the maxillary, (2) trunk shift as the angle between the line of the center of C7 to the sacrum and the central sacral vertical line, (3) Cobb angle was used to assess the major curve, (4) cranial, and (5) caudal compensatory curvature. RESULTS: Seven boys and 10 girls with a mean age of 9.0 years at surgery were evaluated. The mean radiographic follow-up was 89.5 months (range: 12 to 166 mo). The mean head tilt reoriented from 6.9 to 1.9 degrees (P<0.001); trunk shift improved from 4.3 to 2.5 degrees after surgery (P=0.100). There was a significant correlation between head tilt and trunk shift on preoperative and postoperative radiographs (P=0.030/0.031). The major curve, and compensatory curvatures were all significantly corrected (P<0.001). Head reorientation was significantly influenced by patient age at surgery. Repeated procedures due to decompensation of the compensatory curvature were performed in 2 cases. CONCLUSIONS: PHVR and pedicle screw fixation is an effective treatment for patients with congenital scoliosis. Surgery achieves a significant correction of the major curve and reorientation of the head postoperatively, and till the last follow-up. LEVEL OF EVIDENCE: Level IV.


Assuntos
Anormalidades Musculoesqueléticas , Escoliose , Fusão Vertebral , Criança , Feminino , Alemanha , Humanos , Masculino , Anormalidades Musculoesqueléticas/complicações , Anormalidades Musculoesqueléticas/diagnóstico por imagem , Parafusos Pediculares , Radiografia/métodos , Estudos Retrospectivos , Escoliose/congênito , Escoliose/cirurgia , Fusão Vertebral/instrumentação , Fusão Vertebral/métodos , Resultado do Tratamento
17.
Orthopade ; 49(10): 870-876, 2020 Oct.
Artigo em Alemão | MEDLINE | ID: mdl-32926204

RESUMO

Spinal alignment changes with age and degeneration. Different compensatory mechanisms of the spine are necessary to preserve spinal balance. The capacity of compensation of the spine decreases with age. Thus, the pelvis and the lower limbs become involved in the compensatory mechanism. Concomitant osteoarthritis of the hip could impair this capacity. The biomechanical principles of compensation are described with respect to planning reconstructive hip and spine surgery.


Assuntos
Pelve/cirurgia , Coluna Vertebral/cirurgia , Cirurgiões , Humanos , Extremidade Inferior , Radiografia
18.
Unfallchirurg ; 123(4): 252-268, 2020 Apr.
Artigo em Alemão | MEDLINE | ID: mdl-32215667

RESUMO

BACKGROUND: Severe cervical spine injuries in children under the age of 17 years are rare. Recommendations or even guidelines for the diagnostics and treatment of such injuries in children are currently not available. OBJECTIVE: The aim of the study was to formulate recommendations for diagnostics and treatment of injuries of the cervical spine in pediatric patients. MATERIAL AND METHODS: First, a search of primary and secondary literature on the topic complex of diagnostics and treatment of cervical spine injuries in children was carried out. An appropriate internal literature database was defined and maintained. Second, within the framework of 9 meetings from April 2017 to December 2019 the members of the Pediatric Spinal Trauma Group of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU) systematically formulated recommendations for the diagnostics and treatment of injuries of the cervical spine in pediatric patients by a consensus process. RESULTS: Recommendation for the diagnostics and treatment for injuries of the cervical spine could be formulated for three age groups (age group I: 0-6 years; age group II: 7-9 years; age group III: 10-16 years). The diagnostic and therapeutic principles known from adult patients suffering from injuries to the cervical spine cannot be easily transferred to pediatric patients. CONCLUSION: Injuries to the pediatric spine are rare and should be treated in specialized spine centers. Pediatric patients with a stable cardiopulmonary status should undergo magnetic resonance imaging (MRI) if a spinal trauma is suspected. Classification systems and therapeutic recommendations for injuries to the cervical spine known from adult patients could also be used for adolescent patients. This is not possible for children under the age of 10 years. Only few classification systems exist for this age group. Basic principles of the treatment of spinal trauma in children is the restoration of spinal stability and correct anatomical relationships as well as the protection of all neural structures.


Assuntos
Lesões do Pescoço , Ortopedia , Traumatismos da Coluna Vertebral , Adolescente , Vértebras Cervicais , Criança , Humanos , Imageamento por Ressonância Magnética , Lesões do Pescoço/diagnóstico por imagem , Lesões do Pescoço/cirurgia , Estudos Retrospectivos , Traumatismos da Coluna Vertebral/diagnóstico por imagem , Traumatismos da Coluna Vertebral/cirurgia , Centros de Traumatologia
19.
Unfallchirurg ; 123(4): 269-279, 2020 Apr.
Artigo em Alemão | MEDLINE | ID: mdl-32215668

RESUMO

BACKGROUND: Spinal injuries in pediatric patients are overall very rare. Current reference studies including large patient numbers that enable the formulation of evidence-based recommendations on diagnostics and treatment of these injuries do not exist. OBJECTIVE: The aim of the current study was to formulate recommendations on the diagnostics and treatment for injuries of the thoracic and lumbar spine in pediatric patients. MATERIAL AND METHODS: Firstly, a search for primary and secondary literature on the topic of diagnostics and treatment of spinal injuries in children was carried out. From this, a literature database was established and maintained. Secondly, within the framework of 9 meetings in the time period from April 2017 to December 2019 the members of the Pediatric Spinal Trauma Group of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU) documented recommendations on diagnostics and treatment of injuries of the thoracic and lumbar spine in pediatric patients by a consensus process. RESULTS: Recommendations on the diagnostics and treatment of injuries of the thoracic and lumbar spine could be given for 3 age groups (age group I: 0-6 years; age group II: 7-9 years; age group III: 10-16 years). Diagnostic and therapeutic principles known from adult patients suffering from injuries to the thoracic or lumbar spine cannot easily be transferred to pediatric patients. CONCLUSION: Spinal injuries in childhood are rare and should be treated in specialized spine centers. Pediatric patients with a stable cardiopulmonary status should undergo magnetic resonance imaging (MRI) if a spinal trauma is suspected. The basic principles of the treatment of spinal trauma in children is the restoration of spinal stability and correct anatomical parameters as well as the protection of all neural structures. The potential for correction and regeneration of the individual spinal sections depending on the age of the patient must be considered for deciding between operative vs. conservative treatment. Whenever operative treatment is needed, it should be performed by minimally invasive techniques as a sole instrumentation without spondylodesis. An early removal of the screw-rod-system should be performed.


Assuntos
Fraturas da Coluna Vertebral , Fusão Vertebral , Traumatismos da Coluna Vertebral , Parafusos Ósseos , Criança , Humanos , Vértebras Lombares/lesões , Imageamento por Ressonância Magnética , Fraturas da Coluna Vertebral/diagnóstico por imagem , Fraturas da Coluna Vertebral/cirurgia , Traumatismos da Coluna Vertebral/diagnóstico por imagem , Traumatismos da Coluna Vertebral/cirurgia , Vértebras Torácicas
20.
Unfallchirurg ; 123(4): 280-288, 2020 Apr.
Artigo em Alemão | MEDLINE | ID: mdl-32215669

RESUMO

BACKGROUND: In general, pediatric spinal injuries are rare. No reliable data on the epidemiology of spinal injuries in pediatric patients in Germany are available. Especially in pediatric patients, for whom the medical history, clinical examination and the performance of imaging diagnostics are difficult to obtain, all available information on a spinal injury must be taken into account. OBJECTIVE: The aim of this study was to provide epidemiological data for pediatric patients with spinal trauma in Germany in order to enhance future decision-making for the diagnostics and treatment of these patients. MATERIAL AND METHODS: Within the framework of a national multicenter study, data were retrospectively obtained from 6 German spine centers for 7 years between January 2010 and December 2016. In addition to the demographic data, the clinical databases were screened for specific trauma mechanisms, level of injury as well as accompanying injuries. Furthermore, diagnostic imaging and the treatment selected were also analyzed. RESULTS: A total of 367 children (female: male = 1:1.2) with a total of 610 spinal injuries were included in this study. The mean age was 12 years (±3.5 years). The most frequent trauma mechanisms were falls from <3 m and traffic accidents. The imaging diagnostics were only rarely carried out with the child under anesthesia. Younger children (0-9 years old) suffered more injuries to the cervical spine, whereas injuries to the thoracic and lumbar spine were more frequently found in older children (>10 years old). The children frequently showed accompanying injuries to the head and the extremities. Accompanying spinal injuries mostly occurred in adjacent regions and only rarely in other regions. Around 75% of the children were treated conservatively. CONCLUSION: The results were different from the knowledge obtained from adult patients with spinal trauma and describe the special circumstances for pediatric patients with spinal trauma. Despite certain limitations these facts may help to enhance future decision-making for the diagnostics and treatment of these patients.


Assuntos
Traumatismos da Coluna Vertebral , Acidentes de Trânsito , Adolescente , Criança , Feminino , Alemanha , Humanos , Vértebras Lombares , Masculino , Estudos Retrospectivos , Traumatismos da Coluna Vertebral/diagnóstico por imagem , Traumatismos da Coluna Vertebral/epidemiologia , Traumatismos da Coluna Vertebral/cirurgia
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