RESUMO
BACKGROUND:Studies have shown that placement, needling point, angle and length of pedicle screws for thoracic vertebral fractures have been unified. Many studies concerned axial pul-out force and biomechanical behavior of a single screw, but few reports addressed the biomechanical behavior after the replacement with three kinds of screw connecting to rods. OBJECTIVE:To further observe and compare biomechanical behavior after three kinds of thoracic screw placement connecting rod using biomechanical testing, to understand the strength of thoracic pedicle screw replacement connecting rods, and the effects of its puling out on the stress of the bone surrounding the placement site. METHODS:The fresh frozen specimens of thoracic vertebra were divided into three groups at random: the pedicle fixation group, the transverse process-vertebral body fixation group, and modified rib transverse process fixation group. Thoracic pedicle screw system was inserted by the standard placement method in each group. The experiment was measured on the mechanical equipment. During puling out, the strength that bone bore was described with dynamic curve, folowed by statistical analysis. The difference in the gripping force on the thoracic vertebra among three kinds of screw placement method was compared. RESULTS AND CONCLUSION: Among three kinds of screw placement methods and among three kinds of screw placement methods on the injured vertebral body, the gripping force was significantly bigger in the pedicle fixation group than in the transverse process-vertebral body fixation group and modified rib transverse process fixation group (P < 0.01). No significant difference in the gripping force was detected between the transverse process-vertebral body fixation group and modified rib transverse process fixation group. Results verified that the stability of loading ability was apparently better in the pedicle fixation group compared with the transverse process-vertebral body fixation group and modified rib transverse process fixation group.
RESUMO
Objective To investigate the relationship between the incidence of dysphagia and the location of brain lesions in patients with acute stroke.Methods Swallowing function was assessed by Watin drinking water test within 48 hours after admission in 226 cases with acute stroke.The location of the brain lesions was identified by CT and / or MRI.According to the US National Institutes of Health Stroke Scale (NIHSS),evaluation of nerve functions was evaluated within 24 hours after admission in stroke patients.Results The incidence of dysphagia was 50.4％ (114 /226) in 226 patients in acute stage.The degree of neurological deficit of stroke patients on admission was significantly correlated with the occurrence of dysphagia (x2 =13.35,P=0.02).The incidence of dysphagia caused by lesions in internal carotid artery trunk (hemisphere in combination with basal ganglia/internal capsule) was more common in anterior circulating territory(internal carotid artery system),dysphagia with internal carotid arterg(ICA) trunk occlusion (hemisphere in combination with basal ganglia/internal capsule) was more common than that caused by cortex branches occlusion (hemisphere-cortex) or penetrating ICA injuries (basal ganglia/internal capsule) and cortex branches occlusion (hemisphere-cortex),respectively(x2 =8.228,P＜0.05).The incidences of dysphagia induced by brain lesions of different cortex lobes had no statistic differences(x2 =0.312,P＞0.05).In posterior circulating territory (vertebro-basilar system),the incidence of swallowing disorders was significantly higher in brain stem group than in the thalamus and cerebellum (x2 =27.292,P＜0.001).The incidence of the dysphagia caused by lesions in cerebral hemispheres,combined basal ganglia / internal capsule and brain stem lesions were significantly higher than those caused by other lesions(x2 =35.639,P＜0.000).Conclusions Brain lesions of hemisphere combined basal ganglia/internal capsule and brain stem are significantly associated with the occurrence of dysphagia after acute stroke.