The Experimental Study On The Effect Of Instrumentation Auto-guided Growing Rod System On Growth Plate And Nucleus Pulposus In Immature Pigs

[Background and objective] AIS means an adolescent spinal specific structural scoliosis, it can serious influence to the patients' height, appearance and splanchnic vascular growth and bring great damage to the children on physical and psychological. Surgery is commonly used and effective means of treatment, there are many kinds of internal fixation instruments was created by researchers, spinal surgery of The First Affiliated Hospital of University of South China already had studies about growth rods and sliding pedicle screw. At present we have a new growing rod system. This study was made to evaluate effect of autoguided growing rod system on spinal growth though test the quantity of growth plate cartilage cell height and nucleus pulposus type II collagen on immature pigs.[Methods] 6 female immature pigs(about 3 months old) with surgery of auto-guided growing rod system fixation. T6, T7, T14, T15, L1 for vertebral pedicle screw fixation group, T8-13 vertebral body is growing rod group, other centrum without surgery above T6 or under L1 is non-fixation group. After 3 months kill the pigs and remove the screws and rods, observe disc height and shape of vertebral body. Get out growth plate and nucleus pulposus in the median sagittal plane, checkout the value of growth plate cartilage cell height and nucleus pulposus type II collagen after HE staining and test integral optical density with Image pro software. Finish statistical analysis of final results between the three groups.[Results] 1. Analysis of growth plate height shows obvious difference(P<0.01) between fixation group and growing rod group, same difference can be found between fixation group and non-fixation group. There is no obvious difference(P=0.061) between non-fixation group and growing rod group. 2. Analysis of nucleus pulposus type II collagen shows obvious difference in each of the two groups among 3 groups(P<0.05).[Conclusion]1. The traditional lock pedicle screw internal fixation will seriously decrease the vertebral growth plate cartilage thickness and nucleus type II collagen content. 2.There is no obvious effect in growth plate for immature pigs with auto-guided growing rod system, but AGGRS lead to nucleus pulposus type II collagen decrease significantly. 3. AGGRS can obviously decrease the depression on growth of spine compare the traditional pedicle screw system.