ABSTRACT
Through literature method,expert consultation method,K-means algorithm and empirical analysis method,the paper analyzes the methods for evaluation on the layout of first-aid sites,discusses the indexes for scientific evaluation on the rationality of layout of first-aid sites,conducts visualized and practical calculation based on the first-aid related data of Wuhan city in 2015,verifies the rationality and operability of the evaluation indexes,and provides reference for overall allocation of first-aid resources and rational layout of first-aid sites.
ABSTRACT
BACKGROUND:Operative approaches of lumbar interbody fusion include anterior (ALIF),posterior (PLIF) and transforaminal lumbar interbody fusion (TLIF).The resected structures and cage implantation sites are different,and the initial stability of lumbar spine is varied.OBJECTIVE:To compare the initial stability of lumbar spine following ALIF,PLIF or TLIF in combination with bilateral pedicle screw fixation.DESIGN:Comparative observation.MATERIALS:Fifteen samples of fresh calf lumbar spine were used.METHODS:Models ofALIE PLIF and TLIF were simulated.After examination as normal group,the samples were randomly divided into three groups (n=5).Besides anterior,posterior and transforaminal lumbar interbody fusion include anterior,bilateral pedicle screw fixation was performed.MAIN OUTCOME MEASURES:Biomechanical characteristics of the lumbar spine before and after ALIF,PLIF or TLIF in combination with bilateral pedicle screw fixation.RESULTS:Following three approaches of lumbar interbody fusion,the stability of lumbar spine was significantly reduced,which was enhanced after bilateral pedicle screw fixation (torsion indexes were also increased).In addition,rigidity of the lumbar spine was enhanced.The stability indexes of lumbar spine following TLIF were significantly greater than the other approaches,indicating the initial stability of TLIF was the best.The rigidity,stress,and swain of lumbar spine following PLIF were greater than ALIE but torsion indexes were smaller than ALIE CONCLUSION:The stability of lumbar spine following lumbar interbody fusion was significantly reduced compared with normal sample.But bilateral pedicle screw fixation greatly increases the stability.Among three types of lumbar interbody fusion,the initial stability of lumbar spine following TLIF is the best.
ABSTRACT
BACKGROUND:Transforaminal lumbar interbody fusion(TLIF)can be applied in any lumbar segment,and retain integrity of lateral vertebral plate and zygapophysiai joints.However,few studies have been conducted about the biomechanical performance.OBJECTIVE:To explore the stability of lumbar intervertebral segment following TLIF appHed bilateral and unilateral transpedicular screws fixation.DESIGN,TIME AND SETTING:Biomechanical test was performed at the Institute of Biomechanics,Shanghai University and Nantong University between August 2005 and April 2006.MATERIALS:Twenty samples of fresh one-month-old calf lumbar vertebra.METHODS:Twenty samples of calf lumbar vertebra underwent TLIF alone,TLIF in combination with bilateral or unilateral transpedicular screws fixation.Biomechanical test was performed on spinal three dimensional motion testing machine.MAIN OUTCOME MEASURES:Stress,displacement.strain and torsion angle were recorded.RESULTS:After TLIF without fixation.no obvious changes were found in mean stress and strain,but the axes stiffness and rotational stiffness were significantly decreased,indicating TLIF could produce immediate lumbar stability.After TLIF with unilateral or bilateral transpedicular screws fixation,the lumbar stability was significantly enhanced compared with TLIF alone,especially bilateral transpedicular screws fixadon.Although the lumbar stability following unilateral transpedicular screws fixation was inferior to bilateral fixation,it was still greatly enhanced,even bxceeded normal sample,indicating TLIF with unilateral transpedicular screws fixation could produce enough initiallumbar stability.CONCLUSION:TLIF alone cannot support sufficient initial stability,but TLIF with bilateral and unilateral transpedicular screws fixation can enhance lumbar initial stability.