BACKGROUND:Lumbar pedicle screw placement technique is a very mature technology in spinal surgery.There are many methods for determining the screw entry points and direction in the clinic.However,for patients with severe lumbar facet degeneration,severe osteophytosis can be found in the surgical area.Smooth and accurate screw placement has some difficulties.OBJECTIVE:To observe the effects of screw placement simulation using Mimics software on pedicle screw fixation before repair of severe lumbar facet joint degeneration.METHODS:A total of 78 cases of severe lumbar zygapophysial degeneration evaluated by CT and MR,who received single-segment lumbar pedicle screw fixation,were enroled in this study.They were randomly dividedinto two groups,including simulation screw group (n=39) and control group (n=39).Totaly 312 pedicle screws were implanted in the two groups.In the simulation screw group,Mimics software was used to perform 3D reconstruction before surgery and to simulate vertebral pedicle screw operation.In the 3D images,screw entry points and surrounding bony landmarks of pedicle screw were observed.The angle and depth of screw placement were measured.During the operation,pedicle screw placement was conducted in accordance with above results of observation and measurement.In the control group,pedicle screw was implanted according to the conventional method.After treatment,an X-ray CT examination was performed in the evaluation of the accuracy of pedicle screw placement.RESULTS AND CONCLUSION:No postoperative complication occurred in the simulation screw group.153 of 156 screws were located in vertebral pedicle in the postoperative examination.The correct rate of screw placement was significantly higher in the simulation screw group than in the control group (98.1％,88.5％,χ2=11.49,P＜0.05).The operation time,amount of bleeding and radiation exposure time were significantly shorter in the simulation screw group than in the control group (P＜0.05).These findings indicate that the lumbar facet joint degeneration accounted for a large proportion in patients with lumbar pedicle screw fixation.Facet joint degeneration increases the difficulties on distinguishing anatomical landmarks of insertion point,which brings a great difficulty for screw placement.The simulation of Mimics software in screw placement can improve accuracy in pedicle screw fixation in patients with severe lumbar facet joint degeneration,reduce complications,operation time,amount of bleeding,and radiation exposure time.

Objective To investigate the causes of development of cardiac arrest during the perioperative period in 210 hospitals of Guangxi in 2010 using a questionnaire survey.Two hundred and ten questionnaires were provided,and the valid return rate was 63.3％ (133 copies).There were 64 cases developed cardiac arrest during the perioperative period in 414,676 anesthetized patients from 133 hospitals,and the incidence of cardiac arrest was 0.0154％.Among the patients who developed cardiac arrest,the constituent ratio of the patients who were cured was 25％ (16 cases),the patients who became vegetative state was 3％ (2 cases),and the patients who died was 72％ (46 cases).Among the patients who developed cardiac arrest,the constituent ratio of general anesthesia (77％) was higher than that of intrathecal anesthesia (23％).Among the inducements for cardiac arrest,patient's factor,surgical factor,anesthesia factor,patient-surgery-anesthesia factor and unknown factor accounted for 44％ (28 cases),14％ (9 cases),25％ (16 cases),12％ (8 cases) and 5％ (3 cases),respectively.The constituent ratios of the cured patients under patient's factor,surgical factor,anesthesia factor,patientsurgery-anesthesia factor and unknown factor accounted for 13％ (2 cases),6％ (1 cases),75％ (12 cases),6％ (1 cases) and 0,respectively.The constituent ratio of the cured patients under anesthesia factor was higher than that under the other factors.In conclusion,although cardiac arrest developed during the perioperative period was rare,it endangered the patient' s life.The preoperative severity of disease was the major consideration for patient's factor,and it was not only the main inducement,but also the risk factor for death.For anesthesia factor,the main inducements causing cardiac arrest were poor airway management and circulatory depression induced by anesthetics,so preoperative airway assessment and perioperative monitoring should be strengthened.It was difficult to predict cardiac arrest induced by surgical factor or emergency events during operation,and close monitoring was the key.