ABSTRACT
Objective: The aim of the present study was to develop a more realistic finite element [FE] model of the human anterior cruciate ligament [ACL] tibial insertion and to analyze the stress distribution in the ACL internal fibers under load. Methods: The ACL tibial insertions were processed histologically. With Photoshop software, digital images taken from the histological slides were collaged, contour lines were drawn, and different gray values were filled based on the structure. The data were exported to Amira software and saved as ".hmascii" file. This document was imported into HyperMesh software. The solid mesh model generated using HyperMesh software was imported into Abaqus software. The material properties were introduced, boundary conditions were set, and load was added to carry out the FE analysis. Results: The stress distribution of the ACL internal fibers was uneven. The lowest stress could be observed in the ACL lateral fibers under tensile and shear load. Conclusion: The establishment of ACL tibial insertion FE model and mechanical analysis could reveal the stress distribution in the ACL internal fibers under load. There was greater load carrying capacity in the ACL lateral fibers which could sustain greater tensile and shear forces
ABSTRACT
Objective To investigate the clinical effect of the bone graft fusion of the posterior lumbar interbody fusion (PLIF) combined with posterolateral fusion(PLF) in treating lumbar spondylolisthesis .Methods 63 cases of lumbar spondylolisthesis were performed the posterior unilateral or bilateral vertebral plate resection ,nerve root canal decompression ,clearing the slippage space , reduction ,fixation short-segment vertebral pedicle nail-stick system for reduction and fixation ,bone graft fusion with the interverte-bral space Cage and posterior-lateral bone graft fusion ,vertebral pedicle isthmus cracking was performed the clearance and bone graft fusion(PLIF combined with PLF ) .The JOA scores ,lumbar lordosis ,segment lordosis ,intervertebral space height ,slippage rate and complications were recorded before operation ,in postoperative 1 week ,6 ,12 months .Results All cases had no serious complications .The JOA scores were increased to some different degrees from the beginning of postoperative 1 week ,with the reha-bilitation time extension ,the JOA scores were gradually increased ,the improvement rate of the postoperative JOA score averaged 85 .00% .The lumbar lordosis ,segment lordosis ,intervertebral space height and slippage rate after operation were significantly im-proved compared with before operation ,the fusion failure rate was 4 .76% .Conclusion The bone graft fusion of PLIF combined with PLF is one of ideal methods to treat lumbar spondylolisthesis .
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Objective To investigate the selection and curative effect of surgical approach for thoracolumbar fractures. Methods A retrospective analysis was conducted on 212 patients with thoracolumbar fractures treated surgically from January 1995 to January 2009 to observe the spinal column and the neurological function recovery. Results Anterior surgery was performed in 73 patients and posterior surgery in 139. The patients were followed up for average 23.7 months ( range, 12-52 months). The height of injury vertebral, the Cobb' s angle and the volume of vertebral canal were improved significantly (P <0.01 ). The patients with incomplete paralysis all got nerve function recovery at different extents ( from one grade to three grades). Conclusions Surgical treatment for thoracolumbar fractures can effectively recover the spine structure and promote the nerve function recovery. The surgical approach should be selected based on the fracture type.
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Objective To observe the histomorphological changes of sciatic nerves following pasteurizing warm temperature treatment. Methods The 12 mm left sciatic nerve from healthy adult male Wistar rats was pasteurized at 60℃ for 30 minutes and observed at the first week (1-week group) and the sixth week (6-week group), 15 rats per group. Number, diameter and area ratio of the myelinated axons in the control (proximal to the treated part), treatment and peripheral nerves (distal to the treated part) were calculated. The histomorphological changes were examined with electrophysiological and electron microscopies. Results (1) In the peripheral part, the number of the myelinated axons was significantly decreased in the 1-week group compared with the control group (P
ABSTRACT
Objective To explore diagnosis and treatment of thoracolumbar spine and spinal cord trauma complicated by thoracoabdominal viscera injury. Methods A retrospective study was performed on 84 cases with thoracolumbar spine and spinal cord trauma complicated by thoracoabdominal viscera injuries treated in our unit from January 1986 to December 2002, of which there were 52 cases with thoracic vertebra fracture (T_6-T_(12)), 32 with lumbar fracture (L_1-L_4), 70 with complicated chest injury, 14 with abdominal injury and 34 with injuries of cranium, extremities and pelvis. Spinal fixation or decompression of spinal cord was performed in 62 cases, drainage in 22, laparotomy in 10 and exploration of skull in nine. Results Eighty-two cases survived, with follow up period for 6-36 months. According to Frankel standard nerve function recovery showed that among 36 cases at grade A, 10 had partial or sensation recovery and the other got nerve function improvement for gradeⅠ-Ⅲ. Delayed diagnosis and missed injuries totaled seven cases (12%). Two cases were died of postoperative MODS. Conclusions As for patients with thoracolumbar spine and spinal cord trauma complicated by thoracoabdominal viscera injury, a comprehensive clinical examination including X-ray or CT is necessary. The treatment should first focus on thoracoabdominal viscera trauma and try to avoid aggravation of spine and spinal cord injury.