Primary Investigation Of Effects Of Nicotine On Posterolateral Fusion Of The Rabbit Spine

Objective: Operate subcutaneous injection of nicotine to rabbit to investigate the effectsof nicotine on rabbit posterolateral lumbar fusion and its mechanism.Methods:26healthy mature female rabbits of2.5-3kg were randomly selected, thenthey were randomly divided into two groups,13rabbits for each group. One group wasexperiment group, the other was control group. Posterior L4-5bilateral lumbar fusion(PLF) was operated respectively. During operation, paraspinal muscles were peeled,fusion zone was exposed, L4and L5transverse processes were decorticated,3g bilateraliliac bone was chose biting into particles with size of3mm3, and bilateral bone graftbetween transverse processes was done respectively, with1.5g bone graft per side. Inexperiment group, subcutaneous injection of6mg/kg nicotine postoperative was doneevery day, and in control group,1ml/kg brine was injected. Nicotine was diluted withnormal saline, with concentration of2mg/ml and injection volume of1ml/kg,3times/day.In control group, normal saline was injected with amount of1ml/kg,3times/day.Injection for eight weeks, after that put the animals to death. All specimens were firstdetected by hand touch, which meant that fusion segments were bended and stretched bythe outside force of hand, to determine fusion rate. Each specimen was tested by twoblind trial physicians. If the activity in bend and stretch directions was not checked out byboth two physicians, solid fusion was achieved. Followed by anteroposterior X-ray andCT scan were took, bone fusion of bone graft area was observed, every specimen wasqualified by two physicians based on the same standard, and fusion rate was judged. Thedetermined fusion rate was compared to the palpated fusion rate, with the latter as thegold standard. Finally,2specimens were selected from two groups respectively to dohistology detection to observe the osteogenesis of bone graft area. The data of the case group and the control group was used for statistical analysis by Fsher’s exacttest(α=0.05).Results: Fusion rate was determined by hand touch method, which was23.1%inexperiment group,69.2%in control group (P=0.047); fusion rate evaluated by X-ray was46.2%in experiment group, and92.3%in control group (P=0.034); fusion rate evaluatedby CT was30.8%in experiment group, and78.6%in control group (P=0.021).Conclusions:(1) The animal model of the rabbit posterolateral transverse process lumbarfusion were similar with people in mode of operation, fusion surrounding environmentand fusion results, which was an ideal animal model for research of human lumbarposterolateral fusion.(2) Through the establishment of animal model, nicotine maydirectly affect the rabbit lumbar posterolateral fusion, and the results indicated thatnicotine reduces the fusion rate of rabbit posterolateral lumbar transverse processes.Comparing fusion rate in experimental and control groups, we conclude that the datahas statistic significance.