The Experimental Study Of A Novel Spiral Nucleus Pulposus Prosthesis

Background:Degenerative spine disease is common clinical phenomenon, at present more attention for it. Traditional treatment is discectomy and vertebral fusion. But the discectomy disadvantage is intervertebral height loss, then it leads to spinal verterbral instability and spinal stenosis. Although the vertebral fusion can resolve the loss of intervertebral height and the occurrence of instability, but the fusion can lead to lose the movement function of intervertebral joint, and accelerate adjacent segments degeneration. In recent years, the prosthetic nucleus pulposus technology develops by leaps and bounds. It includes pre-fabricated and injectable prosthetic nucleus pulposus. However, the former will be damage the annulus fibrosus and cartilage endplate. The latter shortcomings are liquid monomer leak, heat damage and low rigidity. In order to avoid the above shortcomings, we develop a new type of spiral artificial nucleus pulposus prosthesis.Purpose:The purpose of this project is to do biomechanical research of new sprial prosthetic nucleus pulposus, testing whether the new type of prosthetic nucleus pulposus accords with physiological nucleus. Another it can supply the reference for the improving and perfecting of the new prosthetic nucleus pulposus.Methods:In this experiment, we have designed the new spiral nucleus pulposus prosthesis, using the polyvinylalcohol and made it. The size are10x6x5mm,10x6x4mm,10x6x3mm. Make the dehydration and swelling test in vitro. Ten four-month-old pigs were randomly divided into three groups:healthy controls, the removal of nucleus pulposus and artificial prosthesis implantation group. Radiographs were evaluated. Analysis of variance of the intervertebral height was used to compare preoperative and postoperative data. After24W to be put to death animals, make spine specimens including operation section and the upper and lower vertebral. Before then, biomechanical tests, including bending, stretching, bending, left and right rotation around after six directions of activity and neutral zone for testing. Finally, use SPSS14.0statistics analysis software with the result of the data for statistical analysis.Results:The new spiral nucleus pulposus prosthesis in deionized water for72hours to secondary swelling balance, fully recover spiral shape of the structure and size before drying. Simulation implanation process proved that the spirals nucleus pulposus prosthesis has a excellent shape memory function, implant process does not cause damage to materials. Intervertebral disc height measurement results show that the health control group has no statistically significant difference before and after operation (P>0.05), and each time after removal of nucleus pulposus group were significant differences compared with preoperative (P<0.05or0.01), the nucleus pulposus prosthesis placement group compared with the preoperative and postoperative each time there is significant difference (P<0.05or0.01). At all time points, the nucleus pulposus removal group and health control group differences had statistical significance (P<0.05or0.01); Implant group and nucleus pulposus removal of nucleus pulposus of the differences between groups was statistically significant (P<0.05or0.01); Nucleus pulposus implanted there was no statistically significant difference between group and healthy control group (P>0.05). Nucleus pulposus removal group in each direction of movement range and the difference between healthy controls was statistically significant (P<0.05or0.01); Nucleus pulposus into groups in each direction of movement range and nucleus pulposus removed the difference between groups was statistically significant (P<0.05or0.01); Nucleus pulposus implant group compared with healthy control group, there was no statistically significant difference between the scope of its movement (P>0.05). Nucleus pulposus removal values of each to the NZ group and health control group differences had statistical significance (P<0.05or0.01); Nucleus pulposus into groups to NZ and nucleus pulposus removed the difference between groups was statistically significant (P<0.05or0.01); Nucleus pulposus implant group and healthy controls to NZ value between the difference is not significant (P>0.05).Conclusion:The new spiral nucleus pulposus prosthesis can satisfy the demands and minimally invasive surgery of human service, can carry on the swelling under liquid environment, filled with intervertebral disc gap and effectively restore intervertebral height, restore physiological function and biomechanical characteristics of nucleus pulposus.