Disc wall structural abnormalities can act as initiation sites for herniation.

Both posture and loading rate are key factors in the herniation process and can determine the failure mechanism of the disc. The influence of disc structure on the herniation process has yet to be directly observed, thus the aim of this study was to test the hypothesis that discs containing greater levels of pre-existing disruption would be more vulnerable to herniation when subjected to severe levels of posture and loading. 30 ovine lumbar motion segments were subjected to combinations of 4 loading conditions (0 - 12° flexion,0 - 9° lateral bending, 0 - 4° axial rotation, 0-1500 N axial compression) for 1000 loading cycles at 2 Hz in a dynamic disc loading simulator. The discs were scanned in an ultra-high field MRI (magnetic resonance imaging, 11.7 T) prior to and following testing. 4 discs herniated and 7 discs suffered nucleus displacement. These discs contained pre-existing defects in the central dorsal annulus. Generally, following testing, discs contained more dorsal annulus disruption, including 7 discs which developed similar characteristic defects although these did not herniate. Overall, more severe complex postures produced more disruption. While more severe postures such as twisting and bending increased disc damage, these results are probably the first directly showing that naturally occurring defects in the disc can act as initiation sites for herniation. The clinical significance of these findings is that, in principle at least, MRI based techniques could be capable of identifying vulnerable discs, with the obvious caveat that further correlation with clinical techniques is required.

Inactivation of FAM20B causes cell fate changes in annulus fibrosus of mouse intervertebral disc and disc defects via the alterations of TGF-ß and MAPK signaling pathways.

Intervertebral disc (IVD) disorder is often caused by the defect of annulus fibrosus (AF), especially that of the outer AF. Studies about the mechanisms governing the development of the outer AF are needed for a better understanding of pathogenesis of IVD defects. Glycosaminoglycans (GAGs) are essential components of extracellular matrix (ECM) in AF. FAM20B is a newly identified xylose kinase that catalyzes the biosynthesis of GAGs. In this study, we created Fam20B conditional knockout (cKO) mice in which FAM20B was inactivated in type I collagen-expressing cells, the main type of cells in the outer AF of IVD. The cKO mice showed severe spine deformity and remarkable IVD defects associated with AF malformation. The AF of cKO mice had a lower level of chondroitin sulfate and heparan sulfate, and the outer AF cells lost their normal fibroblast-like morphology and acquired chondrocyte phenotypes, expressing a higher level of Sox 9 and type II collagen along with a reduced level of type I collagen. The level of phospho-Smad 2 and phospho-Smad 3, and that of scleraxis, a downstream target molecule of canonical TGF-ß signaling pathway were significantly lower in the AF of cKO mice. The AF in cKO mice also manifested altered levels in the molecules associated with the activations of MAPK pathway; the changes included the increase of phospho-P38 and phospho-ERK and a decrease of phospho-JNK. These results indicate that FAM20B plays an essential role in the development of AF by regulating the TGF-ß signaling and MAPK signaling pathways.

Energy supply and demand in the intervertebral disc / Fornecimento e demanda de energia no disco intervertebral / Suministro de energía y demanda en el disco intervertebral

ABSTRACT The intervertebral disc (IVD) is one of the parts of the body most commonly affected by disease, and it is only recently that we have come closer to understanding the reasons for its degeneration, in which nutrient supply plays a crucial role. In this literature review, we discuss the basic principles and characteristics of energy supply and demand to the IVD. Specifically, we review how different metabolites influence IVD cell activity, the effects of mechanical loading on IVD cell metabolism, and differences in energy metabolism of the annulus fibrous and nucleus pulposus cell phenotypes. Determining the factors that influence nutrient supply and demand in the IVD will enhance our understanding of the IVD pathology, and help to elucidate new therapeutic targets for IVD degeneration treatment.

RESUMO O disco intervertebral (IVD) é uma das partes mais comuns do corpo e apenas recentemente nos aproximamos de compreender as razões da sua degeneração, em que o suprimento de nutrientes desempenha um papel crucial. Nesta revisão da literatura, discutimos os princípios básicos e as nuances do fornecimento e da demanda de energia para o IVD. Específicamente, analisamos como os diferentes metabólitos influenciam na atividade das células IVD, os efeitos da carga mecânica no metabolismo das células IVD, a diferença no metabolismo energético dos fenótipos das células fibrosas e do núcleo do pulposus anelar. A determinação de fatores que influenciam o suprimento e a demanda de nutrientes no IVD aumentará nossa compreensão da patologia IVD e ajudará a elucidar novos alvos terapêuticos para o tratamento da degeneração IVD.

RESUMEN El disco intervertebral (IVD, por sus siglas en inglés) es una de las partes más comúnmente enfermas del cuerpo y solo recientemente nos acercamos a la comprensión de los motivos de su degeneración, de los cuales el suministro de nutrientes juega un papel crucial. En esta revisión de la literatura discutimos los principios básicos y los matices de la oferta y demanda de energía para el IVD. Específicamente, revisamos cómo los diferentes metabolitos influyen en la actividad de las células IVD, los efectos de la carga mecánica sobre el metabolismo de las células IVD y las diferencias en el metabolismo energético de los fenotipos de las células del anillo fibroso y el núcleo pulposo. La determinación de los factores que influyen en la oferta y demanda de nutrientes en el IVD mejorará nuestra comprensión de la patología IVD y ayudará a dilucidar nuevos objetivos terapéuticos para el tratamiento de la degeneración IVD.

Corpectomia lateral parcial para o tratamento de compressão ventral extradural crônica entre T9-T10 em um cão / Partial lateral corpectomy for treatment of chronic ventral extradural compression between T9-T10 in a dog

Objetivou-se relatar um caso de protrusão do disco intervertebral com localização atípica e descrever a técnica cirúrgica de corpectomia lateral parcial no tratamento da afecção em um cão. Um cão de sete anos de idade, macho, raça Pug, foi atendido com ataxia proprioceptiva dos membros pélvicos havia três meses, associada à doença do disco intervertebral entre a nona e 10ª vértebras torácicas. Após um mês de tratamento conservativo sem melhora, o paciente foi encaminhado para o tratamento cirúrgico, quando foi realizada corpectomia lateral parcial esquerda para descompressão da medula espinhal. Após a cirurgia, o paciente apresentou melhora considerável do quadro, sendo a técnica eficaz na remoção da compressão extradural, sem manipulação da medula espinhal ou outras complicações.(AU)

The aim of this study is to report a case of intervertebral disc protrusion with atypical location and describe the surgical technique of partial lateral corpectomy in the treatment of this disease in a dog. A dog, seven -years-old, male, Pug breed was attended with proprioceptive ataxia of the hind limbs for three months correlated with intervertebral disc disease between the 9th and 10th thoracic vertebrae. After a month of conservative treatment without improvements, the patient was referred for surgical treatment, which was performed as a partial left lateral corpectomy for decompression of the spinal cord. After surgery, the patient showed considerable improvement, this technique being shown to be effective in the removal of extradural compression, without manipulation of the spinal cord or other complications.(AU)

BIOMECHANICS OF THERAPEUTIC RIDING DURING THE DISEASES OF I-II DEGREE DYSPLASTIC LUMBAR AND STATIC (SHORT LEG) SCOLIOSIS.

The goal of the paper is to substantiate the essence of ridetherapy biomechanics as the pathogenetic therapeutic and prophylactic method at lumbar dysplastic (the I and II degrees) and static (short-legged induced) scoliosis. Uneven lower extremities caused by any reason and asymmetric support induce the change in the arrangement of trochantin to the vertebra and correspondingly the uneven loading of lumbar muscles. The asymmetric strength of lumbar muscles evoked by the change in rotator condition becomes the cause of the formation of scoliosis primary arc which, in its turn, causes a compensatory spinal curvature. In case of dysplastic scoliosis a leading role belongs to the beginning of dystrophic changes in intervertebral discs and its further decentration. At riding position the lower extremities are completely disengaged from the antigravity redistribution, the child is in direct contact with vibrations and jolts coming from the horseback; the antigravity loading is distributed on the muscles of the torso and thus, it creates an opportunity to purposefully affect the correction of the spine. During scoliosis the pathogenic essence of ridetherapy is due to the comprehensiveness of its procedures, expressed in the fact that during one procedure several factors are influenced simultaneously: nucleus pulpous, the torso and iliopsoas muscles, the antigravity system, etc. According to the clinical-functional and radiographic studies carried out in the dynamics on 11-16 years old adolescents it has been established that in those groups where the rehabilitation was conducted in a complex with ridetherapy the authentically higher results were obtained as compared to the groups where the rehabilitation was held using therapeutic exercises and massage.

Loss of HIF-1α in the notochord results in cell death and complete disappearance of the nucleus pulposus.

The intervertebral disc (IVD) is one of the largest avascular organs in vertebrates. The nucleus pulposus (NP), a highly hydrated and proteoglycan-enriched tissue, forms the inner portion of the IVD. The NP is surrounded by a multi-lamellar fibrocartilaginous structure, the annulus fibrosus (AF). This structure is covered superior and inferior side by cartilaginous endplates (CEP). The NP is a unique tissue within the IVD as it results from the differentiation of notochordal cells, whereas, AF and CEP derive from the sclerotome. The hypoxia inducible factor-1α (HIF-1α) is expressed in NP cells but its function in NP development and homeostasis is largely unknown. We thus conditionally deleted HIF-1α in notochordal cells and investigated how loss of this transcription factor impacts NP formation and homeostasis at E15.5, birth, 1 and 4 months of age, respectively. Histological analysis, cell lineage studies, and TUNEL assay were performed. Morphologic changes of the mutant NP cells were identified as early as E15.5, followed, postnatally, by the progressive disappearance and replacement of the NP with a novel tissue that resembles fibrocartilage. Notably, lineage studies and TUNEL assay unequivocally proved that NP cells did not transdifferentiate into chondrocyte-like cells but they rather underwent massive cell death, and were completely replaced by a cell population belonging to a lineage distinct from the notochordal one. Finally, to evaluate the functional consequences of HIF-1α deletion in the NP, biomechanical testing of mutant IVD was performed. Loss of the NP in mutant mice significantly reduced the IVD biomechanical properties by decreasing its ability to absorb mechanical stress. These findings are similar to the changes usually observed during human IVD degeneration. Our study thus demonstrates that HIF-1α is essential for NP development and homeostasis, and it raises the intriguing possibility that this transcription factor could be involved in IVD degeneration in humans.

Long-term outcomes of lumbar posterior apophyseal end-plate lesions in children and adolescents.

BACKGROUND: A lesion of the lumbar posterior apophyseal end plate in children and adolescents causes symptoms similar to those associated with a herniated disc. However, the end-plate lesion and the herniated disc differ in terms of pathology. The purpose of this study was to clarify the long-term clinical and radiographic outcomes in children and adolescents who were treated either surgically or conservatively for a lumbar posterior apophyseal end-plate lesion. METHODS: We identified twenty-four consecutive patients who had been treated in the sports clinic of our hospital. The mean age at the first medical examination was 14.5 years. The mean follow-up time was 13.8 years. The mean age at the time of final follow-up was 28.4 years. All twenty-four patients had symptomatic low back pain with sciatica. All but two were active in sports. Sixteen patients were treated conservatively, and eight patients underwent surgical intervention. Skeletal maturity was evaluated on the basis of the appearance of the secondary ossification center of L3. RESULTS: The apophyseal stage ("A" stage), which was assigned when the secondary ossification center of the vertebral body was visible on radiographs, was seen most frequently. Both the surgically treated group and the conservatively treated group demonstrated progressive disc degeneration at the involved level. The average Roland-Morris Disability Questionnaire (RDQ) score was 1.3 for the patients treated conservatively and 1.8 for those treated surgically, a nonsignificant difference. One patient developed spinal stenosis after twelve years of conservative treatment. One patient treated surgically demonstrated severe lumbar instability. There were no significant associations between the magnetic resonance imaging (MRI) findings and RDQ scores. Histological examination of surgical specimens showed irregular alignment of the anulus fibrosus, with degenerative matrix and chondrocytes without a nucleus. CONCLUSIONS: The long-term outcome for patients with a posterior end-plate lesion is favorable, regardless of whether it is treated surgically or nonsurgically.

Magnetic resonance imaging findings in the painful adult coccyx.

OBJECTIVE: Imaging of the painful coccyx currently relies on standard and dynamic radiography. There are no literature data on MRI of the coccyx. This examination could provide information on the cause of pain. METHODS: 172 patients with severe chronic coccydynia underwent MRI and dynamic radiography of the coccyx. RESULTS: Disc abnormalities (seen in 70 patients) were related to either the presence of intradiscal liquid effusion (17/70), or abnormality of the endplates similar to Modic 1 changes (38/70), or uncertain abnormalities (15/70). Abnormalities of the tip of the coccyx (seen in 41 patients) were located in the surrounding soft tissues: venous dilatations (18/41), soft tissue inflammation (13/41) and ambiguous images (9/41). Vertebral bone oedema was observed in five cases and a benign tumour was observed once. The type of imaging feature depend broadly on the mobility of the coccyx: the 105 cases with a mobile coccyx mainly presented abnormal features mainly in a disc (63 cases vs. 4 cases for the tip), whereas the 67 patients with a rigid coccyx mainly showed abnormal features at the tip (37 cases vs. 7 for the joints, p < 0.001). CONCLUSIONS: We recommend MRI of the painful coccyx when dynamic radiography fails to reveal clearly a pathological lesion (i.e., normal or slightly increased mobility of the coccyx or a rigid coccyx lacking a spicule).

Incidencia y factores de riesgo de degeneración de los discos límites a una fusión lumbar / Incidence and risk factors of adjacent disc degeneration after lumbar fusion

Objetivo. Determinar la incidencia y analizar los posibles factores de riesgo de desarrollar una degeneración del disco adyacente después de una artrodesis lumbar instrumentada. Material y método. Estudio retrospectivo consecutivo de 230 pacientes con patología degenerativa lumbar, tratados entre los años 1990 y 2000 mediante una artrodesis instrumentada posteroexterna lumbar o lumbosacra. Se ha valorado la afectación del disco adyacente, mediante un criterio radiológico con RX y RM, y se han analizado los siguientes factores de riesgo: la edad, el sexo, el número de niveles instrumentados, el estado del disco límite previo a la cirugía, la lordosis del segmento instrumentado y la lordosis lumbosacra, y la sagitalización de las facetas articulares del disco límite. Resultados. Hemos observado 41 pacientes (17,82%) afectos de síndrome del disco adyacente, con un seguimiento medio de 8,5 años. La edad media fue de 59 años con predominio del sexo femenino. La fusión L5-S1 presenta menos incidencia de afectación del disco límite (p<0,05). Se afectó mayoritariamente el disco adyacente proximal en 36 pacientes (87,8%) y 19 pacientes (46%) requirió cirugía. El tiempo medio hasta el diagnóstico del disco adyacente radiológico ha sido de 6,1 años. Conclusiones. Existe un riesgo del 17,82% (41 pacientes) de presentar disco adyacente radiológico a los 6 años después de la primera cirugía con un riesgo de 6,26% (19 pacientes) de ser intervenido. El sexo, el número de niveles fusionados y la fusión hasta el sacro han sido los principales factores de riesgo (AU)

Objective. The aim of this retrospective study is to determine the incidence, the rate of adjacent disc degeneration (ADD) and to analyse the major risk factors after instrumented lumbar fusion. Materials and methods. Retrospective consecutive study of 230 patients, with lumbar degenerative disease, who underwent lumbar or lumbosacral instrumented spine fusion between 1990 and 2000. We used radiographic criteria (X-RAY and MRI) in order to determine ADD, and we analysed the following risk factors: age, gender, number of levels fused, adjacent disc status before surgery, segmental lordosis and lumbosacral lordosis, and finally, the facet joint angle of adjacent disc. Results. ADD was found in 41 (17.82%) patients, the mean follow-up period was 8.5years. The average age was 59years with female predominance. L5-S1 fusion showed a significant (P<.05) lower risk for developing degenerative changes at the adjacent segments than any other fusions. The cranial level of the fused segment was mainly affected in 36 (87.8%) patients and 19 (46%) patients required surgery. The average interval from surgery to the development of ADD was 6.1years. Conclusions. There is a risk of 17.82% (41 patients) of being affected by radiographic ADD in an average of 6years after the first surgery, with a risk of 6.26% (19 patients) of having surgery. The gender, number of levels fused and fusion to the sacrum were the main risk factors (AU)

Progressive anterior vertebral bars: a study of 16 cases.

STUDY DESIGN: In a retrospective study, we report on 16 patients with congenital kyphosis due to progressively ossifying anterior unsegmented bars. OBJECTIVE: To specify the therapeutic strategy in such malformation. SUMMARY OF BACKGROUND DATA: Congenital kyphosis due to progressively ossifying anterior unsegmented bars is a particular and uncommon entity of congenital kyphosis. Progressive anterior vertebral bars result in slowly progressive kyphosis, which rarely lead to neurological compromise. Sagittal equilibrium of the spine is maintained by compensatory curves adjacent to the primary curve. METHODS: All patients had clinical assessment and successive measurements of segmental angle made on a standing lateral radiograph of the spine. Magnetic resonance imaging was obtained in four patients. Six patients were just observed. A brace was used in three. And seven were treated surgically. RESULTS: The compensatory capacity of the spine is reduced in lumbar area where there are few discs spaces below the bar. Presentation therefore tends to be at an earlier age and pain is more common.Magnetic resonance imaging enables definition of the structures immediately posterior to the bar and provides information regarding the integrity of the intervertebral disc. CONCLUSION: There is usually no need for surgery in thoracic and thoracolumbar localization. In lumbar localization, if the diagnosis is done early in childhood and if magnetic resonance imaging shows beyond the anterior ossification a normal T2-weighted magnetic resonance imaging disc space signal, desepiphysiodesis bar resection and cement interposition is mandatory. If the disc magnetic resonance imaging signal is abnormal or if the disc space is totally ossified, we propose a surgical correction of the kyphosis. For such cases a posterior wedge osteotomy seems to be the more suitable procedure.

How's your disk? Illustrative glossary of degenerative disk lesions using standardized lexicon.

The growing demand for structured reporting in radiology requires acceptance and familiarity of standard terms. This article clearly summarizes and illustrates the standard lexicon and classification scheme for degenerative lumbar disk pathology. First-year residents and veteran radiologists will gain/refresh knowledge of the lexicon for standard reporting. We provide an example-based illustrated glossary that contains diagrams and referenced descriptive explanations to illustrate disk lesions in the current standardized lexicon. Collected cross-sectional imaging of the spine from our tertiary care institution provides a clear patient-based representation of elements in the lexicon.

A rare anatomical variation of the C7 pedicle and intraspinal course of the C7 nerve root.

We report a 58 year old man who presented with severe C7 radiculopathy which failed to respond to conservative measures. Subsequent CT and MR imaging of his cervical spine demonstrated C6/7 foraminal stenosis as well as unusual low take-off of the C7 nerve root in relation to a congenital low-set C7 pedicle, findings which were subsequently confirmed intra-operatively. The relevance of the bony and neural anatomy is described and its implications for surgical management are discussed. To our knowledge, this anatomical anomaly has not been previously highlighted in the published English literature.

Central precocious puberty associated with pituitary duplication and midline defects.

Central precocious puberty (CPP) is due to premature activation of the hypothalamic-pituitary-gonadal axis. It may be idiopathic or result from congenital or acquired CNS lesions. We describe a 7.4 year-old Brazilian girl with CPP who also presented hypertelorism, limitation of lateral neck rotation and synkinesis of the hands. Sellar and cervical column MRIs revealed pituitary duplication and rudimentary intervertebral disks. We present the clinical and imaging observations of this case, and a thorough literature review of this rare developmental abnormality.

Compartmentalised expression of Delta-like 1 in epithelial somites is required for the formation of intervertebral joints.

BACKGROUND: Expression of the mouse Delta-like 1 (Dll1) gene in the presomitic mesoderm and in the caudal halves of somites of the developing embryo is required for the formation of epithelial somites and for the maintenance of caudal somite identity, respectively. The rostro-caudal polarity of somites is initiated early on within the presomitic mesoderm in nascent somites. Here we have investigated the requirement of restricted Dll1 expression in caudal somite compartments for the maintenance of rostro-caudal somite polarity and the morphogenesis of the axial skeleton. We did this by overexpressing a functional copy of the Dll1 gene throughout the paraxial mesoderm, in particular in anterior somite compartments, during somitogenesis in transgenic mice. RESULTS: Epithelial somites were generated normally and appeared histologically normal in embryos of two independent Dll1 over-expressing transgenic lines. Gene expression analyses of rostro-caudal marker genes suggested that over-expression of Dll1 without restriction to caudal compartments was not sufficient to confer caudal identity to rostral somite halves in transgenic embryos. Nevertheless, Dll1 over-expression caused dysmorphologies of the axial skeleton, in particular, in morphological structures that derive from the articular joint forming compartment of vertebrae. Accordingly, transgenic animals exhibited missing or reduced intervertebral discs, rostral and caudal articular processes as well as costal heads of ribs. In addition, the midline of the vertebral column did not develop normally. Transgenic mice had open neural arches and split vertebral bodies with ectopic pseudo-growth plates. Endochondral bone formation and ossification in the developing vertebrae were delayed. CONCLUSION: The mice overexpressing Dll1 exhibit skeletal dysmorphologies that are also evident in several mutant mice with defects in somite compartmentalisation. The Dll1 transgenic mice demonstrate that vertebral dysmorphologies such as bony fusions of vertebrae and midline vertebral defects can occur without apparent changes in somitic rostro-caudal marker gene expression. Also, we demonstrate that the over-expression of the Dll1 gene in rostral epithelial somites is not sufficient to confer caudal identity to rostral compartments. Our data suggest that the restricted Dll1 expression in caudal epithelial somites may be particularly required for the proper development of the intervertebral joint forming compartment.

A novel murine gene, Sickle tail, linked to the Danforth's short tail locus, is required for normal development of the intervertebral disc.

We established the mutant mouse line, B6;CB-SktGtAyu8021IMEG (SktGt), through gene-trap mutagenesis in embryonic stem cells. The novel gene identified, called Sickle tail (Skt), is composed of 19 exons and encodes a protein of 1352 amino acids. Expression of a reporter gene was detected in the notochord during embryogenesis and in the nucleus pulposus of mice. Compression of some of the nuclei pulposi in the intervertebral discs (IVDs) appeared at embryonic day (E) 17.5, resulting in a kinky-tail phenotype showing defects in the nucleus pulposus and annulus fibrosus of IVDs in SktGt/Gt mice. These phenotypes were different from those in Danforth's short tail (Sd) mice in which the nucleus pulposus was totally absent and replaced by peripheral fibers similar to those seen in the annulus fibrosus in all IVDs. The Skt gene maps to the proximal part of mouse chromosome 2, near the Sd locus. The genetic distance between them was 0.95 cM. The number of vertebrae in both [Sd +/+ SktGt] and [Sd SktGt/+ +] compound heterozygotes was less than that of Sd heterozygotes. Furthermore, the enhancer trap locus Etl4lacZ, which was previously reported to be an allele of Sd, was located in the third intron of the Skt gene.

Cervicobraquialgia / Neck pain

A dor em região cervical e braços é uma queixa comum. A dor pode ser fruto de alteração em diversas estruturas, por isso, seu diagnóstico diferencial é extenso. Os autores apresentam uma revisão sobre cervicobraquialgia, seu impacto socioeconômico, fatores etiológicos e aspectos importantes a serem observados durante anamnese e exame fisico. O diagnóstico, exames complementares e modalidades terapêuticas também são analisados. Por fim, apresentamos os recentes progressos na área terapêutica e profilática

Lumbar repositioning deficit in a specific low back pain population.

STUDY DESIGN: A cross-sectional observational design study was conducted to determine lumbar repositioning error in 15 subjects who had chronic low back pain with a clinical diagnosis of lumbar segmental instability and 15 asymptomatic participants. OBJECTIVE: To determine whether individuals with lumbar segmental instability have a decreased ability to reposition their lumbar spine into a neutral spinal position. SUMMARY OF BACKGROUND DATA: Proprioception of the lumbar spine has been investigated in individuals who have low back pain with variable results. The testing procedure's lack of sensitivity and the nonhomogeneity of groups may be responsible for the conflicting findings. METHODS: Repositioning accuracy of the lumbar spine was assessed using the 3Space Fastrak to determine error in 15 participants with lumbar segmental instability and 15 asymptomatic subjects. The participants were assisted into a neutral spinal sitting posture and then asked to reproduce this position independently over five trials separated by periods of relaxed full lumbar flexion. RESULTS: Lumbosacral repositioning error was significantly greater in participants with lumbar segmental instability than in the asymptomatic group (t[28] = 2.48; P = 0.02. There also was a significant difference between the groups at each individual sensor. CONCLUSIONS: The results of this study indicate that individuals with a clinical diagnosis of lumbar segmental instability demonstrate an inability to reposition the lumbar spine accurately into a neutral spinal posture while seated. This finding provides evidence of a deficiency in lumbar proprioceptive awareness among this population.

Impaired intervertebral disc formation in the absence of Jun.

Jun is a major component of the heterodimeric transcription factor AP-1 and is essential for embryonic development, as foetuses that lack Jun die at mid-gestation. Ubiquitous mosaic inactivation of a conditional Jun allele by cre/LoxP-mediated recombination was used to screen for novel functions of Jun and revealed that its absence results in severe malformations of the axial skeleton. More-specific Jun deletion by collagen2a1-cre demonstrated the essential function of Jun in the notochord and sclerotome. Mutant notochordal cells showed increased apoptosis, resulting in hypocellularity of the intervertebral discs. Subsequently, fusion of vertebral bodies caused a scoliosis of the axial skeleton. Thus, Jun is required for axial skeletogenesis by regulating notochord survival and intervertebral disc formation.

Surgical treatment of congenital vertebral displacement Type A in the sagittal plane only: a retrospective study involving eleven cases.

STUDY DESIGN: The essence of congenital vertebral displacement Type A pathology is a congenital structure defect including a vertebral or intervertebral disc with instant curvature of the spinal canal in the sagittal plane. Clinically this defect assumes the shape of kyphosis or kyphoscoliosis. A retrospective review of 11 patients with this congenital deformity was conducted. OBJECTIVES: To evaluate the effectiveness of surgical treatment for congenital vertebral displacement, and to establish the optimal operative management. METHODS: Nine patients with a mean age of 3.3 years (range, 1.8-5.5 years) underwent surgery. Two patients were treated conservatively. All the patients underwent radiologic investigation, which included radiographs, three-dimensional computed tomography scans, and magnetic resonance imaging scans. The neurologic condition was assessed by clinical neurologic examination and somatosensory-evoked potentials. The following surgical techniques were performed: 13 posterior fusions in situ in eight patients; 4 anterior fusions in situ in four patients, 8 total or partial vertebrectomies with anterior fusion and stabilization using cylindric cage in 6 patients, 3 total or partial vertebrectomies with anterior fusion and stabilization using fibula graft in 3 patients, and 5 posterior fusions with instrumentation in 2 patients. The total mean follow-up period was 5.7 years (range, 2.1-9.9 years). RESULTS: The mean follow-up period after the last operation was 22 months (range, 2-48 months). The general results observed during the follow-up period were as follows. Deformity stabilization was obtained in six patients, whereas it was still progressive in three patients. In five patients, regression of neurologic deficits was obtained, whereas in patients, it was stable. Progression of neurologic deficits was observed in one patient (paraplegia). Retrospectively, the best clinical results were achieved after extensive decompression of the spinal cord with anterior stabilization of the spine using a cylindric cage or fibula autograft. These procedures were preceded or followed by posterior fusion. CONCLUSIONS: The findings showed that only extensive vertebrectomy and anterior stabilization using a cylindric cage or fibula graft combined in one operative procedure, preceded or followed by posterior fusion, ensures patients against progression of neurologic deficits and deformity of spine.