Initial stability of lumbar spine following three types of interbody fusion and bilateral pedicle screw fixation

doi:10.3321/j.issn:1673-8225.2008.52.007

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.