Empirical Study Of The Effect On Dog's Intervertebral Disc Adjacent To Operative Segments By Using Prosthetic Disc Nucleus With Flexible Stabilization Devices

Objective: To study the effect on intervertebral disc adjacent to operative segments by using prosthetic disc nucleus with flexible stabilization devices or by using plate systems comparatively. Method: 23 dogs of medical fitness were included, 1.5~2.5 years old, weight 20.0~30.0kg. Reference value of cervical intervertebral disc was measured by 5 dogs of force-empirical group. 18 empirical dogs were divide in 2 groups, group A (prosthetic disc nucleus with flexible stabilization devices), 9 dogs, and group B (plate systems), 9 dogs. All cases were deal with anterior discectomy on C3/4, and implanted with internal fixators. The pressure of intervertebral disc adjacent to operative segmen(tC4/5)was measured in the operation. The pressure change from preoperative to postoperative in group A and group B was evaluated by t-test. All animals were killed after 6 months. The degeneration degrees of intervertebral disc adjacent upon operative segments(C2/3) were evaluated by imaging (by Pearce standard) and histological anatomy. Result: There were no significant difference between group A and group B in pressure change of intervertebral disc adjacent to operative segments (P>0.05). The instability of intervertebral disc adjacent to operative segment(C4/5)were observed by dynamic X-ray at 6 months post operation, and 4 cases of instability were all in group B(44.4%). There were significant difference on Pearce classify by MRI T2 weighting between group A(mean 1.78) and group B(mean 3.22)(P<0.05), and on degeneration degrees of histological anatomy between group A(mean 1.56) and group B(mean 2.78), there were significant difference(P<0.05). The significant positive correlations were discovered between the pressure change and degeneration degrees in each group(P<0.05). Conclusion: Exorbitant brace pressure wound induce the degeneration on dog's intervertebral disc adjacent to operative segments, and the degeneration can be decreased in effect by using prosthetic disc nucleus with flexible stabilization devices compared with plate systems. ASIPDNFD, which is designed in this experiment with the concept and techniques of flexible stability, rebuilded intervertebral disc structure and biomechanics function, avoids the drawbacks in cervical intervertebral discectomy or cervical spinal fusion and prevents the cataplasia in adjacent segment.