RESUMO
BACKGROUND:With the innovation of examination technique,the number of patients with spinal metastases in different stages is increasing year by year.Percutaneous vertebroplasty is an important treatment for spinal metastases;however,there is no report on the biomechanical effect in different stages and different activities after operation. OBJECTIVE:To simulate thoracic T10 bone stress and displacement of the different locations of the tumor metastasis based on the three-dimensional finite element model. METHODS:According to thoracic three-dimensional CT images of a 30-year-old healthy male,Mimics software was used to construct a three-dimensional geometric model of thoracic vertebrae(T9-T11),including ribs,ligaments and intervertebral discs.Three-dimensional models of T9-T11 vertebral bodies and different parts of the posterior thoracic vertebrae invaded by thoracic metastatic tumors were simulated,including the control group with intact vertebral structure,unilateral metastasis involving the vertebral body area(experimental group 1),unilateral metastasis involving the vertebral body and pedicle area(experimental group 2),unilateral metastasis involving the vertebral body,pedicle and transverse process area(experimental group 3),and bilateral metastasis involving the vertebral body,pedicle and transverse process area(experimental group 4).Abaqus software was used to create a three-dimensional finite element model.The von Mises stress distribution and the displacement of the model were analyzed under the loading condition,buckling condition,extension condition,and rotation condition. RESULTS AND CONCLUSION:(1)In the study of the maximum total displacement of loading points in different experimental groups under loading,flexion,extension,and rotation conditions,with the increase of metastatic tumor invasion site and invasion surface,the total displacement of loading points increased,and the overall stiffness decreased,especially the total displacement of loading points in experimental group 4 was the largest.(2)Under flexion condition,the maximum Von Mises stress value increased significantly after vertebral body and pedicle destruction,while the maximum Von Mises stress value was almost unchanged when the thoracocostal joint destruction was added.(3)On the basis of finite element analysis and simulation of bone tumor model,the elements in the bone cement region were set as a single set,and the bone cement region was set as the corresponding material properties to simulate bone cement filling.The results showed that the maximum total displacement under loading,flexion,extension,and rotation conditions was less than that of each experimental group.(4)The maximum stress values of the simulated percutaneous vertebroplasty patients in the loading,flexion,extension and rotation conditions were significantly lower than those of the femoral model.(5)It is concluded that the three-dimensional finite element model based on thoracic T9-T11 conducive to the biomechanics characteristics of thoracic vertebrae tumor metastasis,and on the basis of the thoracic vertebrae tumor metastasis model can accurately simulate load point after percutaneous vertebral body under different conditions of total displacement and the maximum Von Mises stress situation.
RESUMO
Objective To investigate surgical indications,techniques and effects for intraeranial arachnoid cyst in children. Methods Clinical data from 82 surgical cases were analyzed retrospectively,and different methods of operation were analyzed comparatively.Four operation-methods were adopted,in which cyst removal were performed in 19,cyst removal plus cisternal opening in 23,cyst-peritoneal shunt in 28,and cyst-peritoneal drainage in 16.Results Upon following up from six months to five years after operation,the chief symptoms got improved in 89.0% of the patients,and CT or MRI scan showed that the size of cvst became smaller in 72 of the patients.Four operation methods were compared,cyst removal was not better than the other three operation methods.Conclusions The treatment of operation methods could make the svmptoms improved and the cyst thrunk of intracranial arachnoid cyst in children.The operation of cyst removal plus cisternal opening or cyst-peritoneal shunt and cyst-peritoneal drainage is preferred.
