European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society
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Anterior longitudinal ligament (ALL) injuries following whiplash have been documented both in vivo and in vitro; however, ALL strains during the whiplash trauma remain unknown. A new in vitro whiplash model and a bench-top trauma sled were used in an incremental trauma protocol to simulate whiplash at 3.5, 5, 6.5 and 8 g accelerations, and peak ALL strains were determined for each trauma. Following the final trauma, the ALLs were inspected and classified as uninjured, partially injured or completely injured. ⋯ Peak ALL strains were largest in the lower cervical spine, and increased with impact acceleration, reaching a maximum of 29.3% at C6-C7 at 8 g. Significant increases ( P<0.05) over the physiological strain limits first occurred at C4-C5 during the 3.5 g trauma and spread to lower intervertebral levels as impact severity increased. The complete ligament injuries were associated with greater increases in ALL strain, intervertebral extension, and flexibility parameters than were observed at uninjured intervertebral levels ( P<0.05).
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Anterior plate fixation with unicortical screw purchase does not involve the risk of posterior cortex penetration and possible injuries of the spinal cord. However, there are very few biomechanical data about the immediate stability of non-locking plate fixation with unicortical or bicortical screw placement. The aim of the present study was to evaluate the immediate biomechanical properties in terms of flexibility of a non-locking anterior plate system with 4.5-mm screw fixation and unicortical or bicortical screw purchase applied to a single destabilized cervical spine motion segment. ⋯ Therefore, we demonstrated that both uni- and bicortical screw purchase with non-locking plate fixation can decrease immediate flexibility of the tested motion segment, with better results for bicortical purchase. No significant differences were found comparing the two groups of screw fixation. These data suggest that unicortical screw fixation can be used for anterior plate fixation with a comparable immediate stability to bicortical screw fixation.
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It is generally recognized that progressive adolescent idiopathic scoliosis (AIS) evolves within a self-sustaining biomechanical process involving asymmetrical growth modulation of vertebrae due to altered spinal load distribution. A biomechanical finite element model of normal thoracic and lumbar spine integrating vertebral growth was used to simulate the progression of spinal deformities over 24 months. Five pathogenesis hypotheses of AIS were represented, using an initial geometrical eccentricity (gravity line imbalance of 3 mm or 2 degrees rotation) at the thoracic apex to trigger the self-sustaining deformation process. ⋯ Overall, the thoracic segment predominantly was sensitive to imbalances in the frontal plane, although unidirectional geometrical eccentricities in different planes produced three-dimensional deformities at the regional and vertebral levels, and their deformities did not cumulate when combined. These results support the hypothesis of a prime lesion involving the precarious balance in the frontal plane, which could concomitantly be associated with a hypokyphotic component. They also suggest that coupling mechanisms are involved in the deformation process.
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This prospective comparative study was carried out to investigate the blood supply to the anterior chest wall by measurement of several anatomical and haemodynamic flow parameters of the internal mammary artery, with the use of colour Doppler ultrasonography, in female scoliotics with idiopathic right convex scoliosis in adolescence. Previous investigations have postulated that asymmetry of the breasts in female adolescents may be linked with the development of right convex thoracic scoliosis. This breast asymmetry is supposed to be linked with anatomical and functional asymmetry of the internal mammary artery that is the main supplier to the mammary gland. ⋯ Left internal mammary artery cross-sectional area increases with convex apical rib-vertebra angle ( P<0.01) and concave rib-vertebra angle one level above the apical vertebra ( P<0.01). Conclusively, this investigation showed that haemodynamic flow parameters of the right internal mammary artery and anatomical parameters of the left internal mammary artery are significantly correlated with the magnitude of rib-vertebra angles close to the apex of right thoracic scoliosis in female adolescents. This study did not find any evidence for side-difference in vascularity of the anterior thorax wall and, thus, it could not clearly justify previous theories for development of right thoracic scoliosis in female adolescents.
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To determine the risk of postoperative hemorrhage during a 3-year period of early postoperative administration of nadroparin (Fraxiparin) plus compression stockings in a large cohort of patients who underwent spinal surgery. ⋯ Although retrospective, this is to date the largest study providing information about the hemorrhage rate associated with early postoperative anticoagulation following spinal surgery. The results confirm that early postoperative pharmacological thromboembolic prophylaxis using nadroparin in patients with spinal surgery is not associated with an increased risk of postoperative hemorrhage.