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R. V. Routal - One of the best experts on this subject based on the ideXlab platform.
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MECHANISM OF CHANGE IN THE ORIENTATION OF THE Articular PROCESS OF THE ZYGAPOPHYSEAL JOINT AT THE THORACOLUMBAR JUNCTION
Journal of Anatomy, 1999Co-Authors: G. P. Pal, R. V. RoutalAbstract:The orientation of the superior Articular Processes in thoracic and lumbar vertebrae differs. The present study was undertaken to investigate the possible mechanism for the change from a posterolaterally facing superior Articular surface in the thoracic region to a posteromedially facing curved Articular surface in the lumbar region. The material of the study consisted of dry macerated bones of 44 adult human vertebral columns. The orientation of the superior Articular process and its relation to the mamillary tubercle (process) was examined between T9 and L5 vertebrae in each column. An abrupt change from the thoracic to lumbar type of Articular process was observed in 3 columns (7%). Forty-one (93%) columns showed a gradual change extending over either 2 or 3 successive vertebrae. The present study suggests that the change in the orientation of the superior Articular process, from the coronal to the sagittal plane (sagittalisation), occurs due to the change in the direction of weight transmission through zygapophyseal joints at the thoracolumbar junction. It was observed that the gradual sagittalisation of the superior Articular process in the transitional zone brought it close to the mamillary tubercle which eventually fused with it. Thus the study suggests that the characteristic posteromedially facing concave superior Articular process of lumbar vertebrae may have formed because of the fusion of the Articular process and the mamillary tubercle.
G. P. Pal - One of the best experts on this subject based on the ideXlab platform.
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MECHANISM OF CHANGE IN THE ORIENTATION OF THE Articular PROCESS OF THE ZYGAPOPHYSEAL JOINT AT THE THORACOLUMBAR JUNCTION
Journal of Anatomy, 1999Co-Authors: G. P. Pal, R. V. RoutalAbstract:The orientation of the superior Articular Processes in thoracic and lumbar vertebrae differs. The present study was undertaken to investigate the possible mechanism for the change from a posterolaterally facing superior Articular surface in the thoracic region to a posteromedially facing curved Articular surface in the lumbar region. The material of the study consisted of dry macerated bones of 44 adult human vertebral columns. The orientation of the superior Articular process and its relation to the mamillary tubercle (process) was examined between T9 and L5 vertebrae in each column. An abrupt change from the thoracic to lumbar type of Articular process was observed in 3 columns (7%). Forty-one (93%) columns showed a gradual change extending over either 2 or 3 successive vertebrae. The present study suggests that the change in the orientation of the superior Articular process, from the coronal to the sagittal plane (sagittalisation), occurs due to the change in the direction of weight transmission through zygapophyseal joints at the thoracolumbar junction. It was observed that the gradual sagittalisation of the superior Articular process in the transitional zone brought it close to the mamillary tubercle which eventually fused with it. Thus the study suggests that the characteristic posteromedially facing concave superior Articular process of lumbar vertebrae may have formed because of the fusion of the Articular process and the mamillary tubercle.
M. Herrera - One of the best experts on this subject based on the ideXlab platform.
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Trabecular trajectory in the Articular Processes of the human fourth cervical vertebra.
Journal of Anatomy, 2001Co-Authors: M. Herrera, A. Panchón, M. Perez‐baceteAbstract:The Articular Processes (AP) of the neural arch have been implicated in weight transmission through the cervical spine. To analyse the mechanism of weight transmission in the AP, we studied the direction of forces within it, in pArticular, the pattern of trabecular trajectories. Twenty-two AP from C4 vertebrae were studied in anatomical sections, and corresponding photoelastic models from selected sections were constructed and analysed. Anatomical and photoelastic findings show the subArticular spongiosa of the superior Articular process (SAP) to be orthogonally arranged with vertical and oblique trabeculae in the direction of compressive forces and additional trabeculae always oriented perpendicular to the former. Vertical and oblique trabeculae are divided into rostral, middle and posterior groups. Rostral and middle trabeculae end in the anterior wall of the SAP and the transitional zone with the pedicle. Posterior trabeculae end in the subArticular spongiosa of the inferior Articular process (IAP). The findings relating to trabecular trajectories in the SAP differ from previous descriptions and instead suggest that a part of the weight forces distributed within the AP transmit to the subchondral zone of the IAP. Knowledge of the trajectorial architecture of the AP may contribute to refining finite element analytical models for investigating its weight-bearing function.
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Morphology of the Articular Processes of the sixth cervical vertebra in humans
Journal of Anatomy, 1998Co-Authors: M. Herrera, Alfonso Puchades-ortsAbstract:With the exception of the 7th vertebra, both past and recent literature describe the lower cervical vertebrae as possessing similar morphological characteristics (Soemmering, 1794; Cruveilhier, 1862; Luschka, 1862; Henle, 1871; Braus-Elze, 1954; Romanes, 1981; Williams et al. 1989; Benninghof, 1994). Gross anatomical differences from the 3rd to the 7th cervical vertebrae comprise the shapes of the vertebral body and uncinate and spinous Processes (Putz, 1976; Penning, 1988; Lang, 1990) and the more developed anterior tubercle and anterior root of the transverse process of the 6th cervical vertebra (C6) (Paturet, 1951). During routine examination of a series of dried skeletons, the Articular Processes (AP) of C6 were found to be distinct from the rest of the cervical vertebrae. The aim of this study was to confirm this unusual appearance of the C6 process by inspecting a sample of dried skeletons. We report the morphology of the AP of C6 in 76 well preserved complete adult skeletons (58 males, 18 females; age 31–77 y) and 5 young specimens from the Anatomical Institutes of Alicante, Valencia and Murcia (Spain) and Munich (Germany). Another 12 skeletons were excluded from the study due to arthritic changes in their cervical APs.
Alexander J Ghanayem - One of the best experts on this subject based on the ideXlab platform.
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spondylolisthesis and spondylolysis
Journal of Bone and Joint Surgery American Volume, 2008Co-Authors: Serena S Hu, Clifford B Tribus, Mohammad Diab, Alexander J GhanayemAbstract:The term “spondylolisthesis” refers to slipping, or olisthesis, of a vertebra (“spondylos” in Greek) relative to an adjacent vertebra. The term “spondylolysis” refers to dissolution of, or a defect in, the pars interArticularis of a vertebra. To these original terms has been added “spondyloptosis,” from the Greek “ptosis” (falling off or down) to indicate a vertebra that is completely or essentially completely dislocated. There are five types of spondylolisthesis: dysplastic, isthmic, degenerative, traumatic, and pathologic1. In the dysplastic type, facet joints allow anterior translation of one vertebra on another. Because the neural arch of the olisthetic vertebra is intact, it can compress the cauda equina as it translates. This type accounts for the only reported case of spondylolisthesis at birth2. “Isthmic” is from the Greek, meaning narrow. The isthmic type involves a lesion of the pars interArticularis (the narrow part of bone between the superior and inferior Articular Processes) (Fig. 1). There are three subclasses: A, which is due to a stress fracture of the pars interArticularis; B, an elongation of the pars interArticularis; and C, which is due to an acute fracture of the pars interArticularis. Dysplastic and isthmic are the two subtypes found in children, with the latter accounting for approximately 85% of cases. Fig. 1 Lateral radiograph showing isthmic spondylolisthesis. The arrow points to the pars interArticularis defect. Degenerative spondylolisthesis is secondary to osteoarthritis leading to facet incompetence and disc degeneration. This condition allows anterior translation of one vertebra on another. Traumatic spondylolisthesis is due to a fracture of the posterior elements, other than the pars interArticularis, leading to instability and olisthesis. A pathologic spondylolisthesis is due to a tumor or another primary disease of bone affecting the pars interArticularis or the facet joints and leading to instability and olisthesis. The dysplastic and isthmic patterns …
J-c-y. Cheng - One of the best experts on this subject based on the ideXlab platform.
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Relative anterior spinal overgrowth in adolescent idiopathic scoliosis—result of disproportionate endochondral-membranous bone growth?
European Spine Journal, 2005Co-Authors: W-w. Chau, Y-l. Chan, J-c-y. Cheng, R.g. Burwell, P.h. DangerfieldAbstract:There is no generally accepted scientific theory for the etiology of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The text for this EFG was written by Professor Jack Cheng and his colleagues who used whole spine magnetic resonance imaging (MRI) to re-investigate the relative anterior spinal overgrowth of progressive AIS in a cross-sectional study. The text is drawn from research carried out with his co-workers including measurement of the height of vertebral components anteriorly (vertebral body) and posteriorly (pedicles) in girls with AIS and in normal subjects. The findings confirm previous anatomical studies and support the consensus view that in patients with thoracic AIS there is relatively faster growth of anterior and slower growth of posterior elements of thoracic vertebrae. The disproportionate anteroposterior vertebral size is associated with severity of the scoliotic curves. In interpretating the findings they consider the Roth/Porter hypothesis of uncoupled neuro-osseous growth in the spine but point out that knowledge of normal vertebral growth supports the view that the scoliosis deformity in AIS is related to longitudinal vertebral body growth rather than growth of the canal. In the mechanical mechanism (pathomechanism) they implicitly adopt the concept of primary skeletal change as it affects the sagittal plane of the spine with anterior increments and posterior decrements of vertebral growth and, in the biological mechanism (pathogenesis) propose a novel histogenetic hypothesis of uncoupled endochondral-membranous bone formation. The latter is viewed as part of an ‘intrinsic abnormality of skeletal growth in patients with AIS which may be genetic’. The hypothesis that AIS girls have intrinsic anomalies (not abnormalities) of skeletal growth related to curve progression and involving genetic and/or environmental factors acting in early life is not original. While the findings of Professor Cheng and his colleagues have added MRI data to the field of relative anterior spinal overgrowth in AIS their interpretation engenders controversy. Three new hypotheses are proposed to interpret their findings: (1) hypoplasia of Articular Processes as a risk factor for AIS; (2) selection from the normal population to AIS involves anomalous vertebral morphology and soft tissue factors—this hypothesis may also apply to certain types of secondary scoliosis; and (3) a new method to predict the natural history of AIS curves by evaluating cerebro-spinal fluid (CSF) motion at the cranio–cervical junction. What is not controversial is the need for whole spine MRI research on subjects with non-idiopathic scoliosis.
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relative anterior spinal overgrowth in adolescent idiopathic scoliosis
Journal of Bone and Joint Surgery-british Volume, 2003Co-Authors: Xia Guo, Y-l. Chan, Waiwang Chau, J-c-y. ChengAbstract:There is no generally accepted scientific theory for the etiology of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The text for this EFG was written by Professor Jack Cheng and his colleagues who used whole spine magnetic resonance imaging (MRI) to re-investigate the relative anterior spinal overgrowth of progressive AIS in a cross-sectional study. The text is drawn from research carried out with his co-workers including measurement of the height of vertebral components anteriorly (vertebral body) and posteriorly (pedicles) in girls with AIS and in normal subjects. The findings confirm previous anatomical studies and support the consensus view that in patients with thoracic AIS there is relatively faster growth of anterior and slower growth of posterior elements of thoracic vertebrae. The disproportionate anteroposterior vertebral size is associated with severity of the scoliotic curves. In interpretating the findings they consider the Roth/Porter hypothesis of uncoupled neuro-osseous growth in the spine but point out that knowledge of normal vertebral growth supports the view that the scoliosis deformity in AIS is related to longitudinal vertebral body growth rather than growth of the canal. In the mechanical mechanism (pathomechanism) they implicitly adopt the concept of primary skeletal change as it affects the sagittal plane of the spine with anterior increments and posterior decrements of vertebral growth and, in the biological mechanism (pathogenesis) propose a novel histogenetic hypothesis of uncoupled endochondral-membranous bone formation. The latter is viewed as part of an ‘intrinsic abnormality of skeletal growth in patients with AIS which may be genetic’. The hypothesis that AIS girls have intrinsic anomalies (not abnormalities) of skeletal growth related to curve progression and involving genetic and/or environmental factors acting in early life is not original. While the findings of Professor Cheng and his colleagues have added MRI data to the field of relative anterior spinal overgrowth in AIS their interpretation engenders controversy. Three new hypotheses are proposed to interpret their findings: (1) hypoplasia of Articular Processes as a risk factor for AIS; (2) selection from the normal population to AIS involves anomalous vertebral morphology and soft tissue factors—this hypothesis may also apply to certain types of secondary scoliosis; and (3) a new method to predict the natural history of AIS curves by evaluating cerebro-spinal fluid (CSF) motion at the cranio–cervical junction. What is not controversial is the need for whole spine MRI research on subjects with non-idiopathic scoliosis.
