Surgical Biomaterials To Repair The Rupture Annulus Fibrosus: Early Rabbit Intervertebral Disc Degeneration

Objective: This study aims to investigate the influence of surgical biomaterials to close the defects on rabbit disc annulus fibrosus. Methods: Choosing thirty-two healthy 4-6 months New Zealand white rabbits, each rabbit intervertebral disc of L3-4, L4-5, L5-6 were divided into the normal control group(A: only explosuring the intervertebral disc), the control group(B: the intervertebral disc AF was correspondingly injured by rectangular cutting with a surgical scalpel)and the experimental group(C: the AF was cut the incision and sutured with the surgical biomaterial). Six rabbits were randomly taken the disc height index %(DHI%), MRI at each 1,2,4,8,12 weeks postoperative; then, three rabbits were randomly executed for histopathological examination and immunohistochemistry at 1,2,4,8,12 weeks postoperative. Results: The two groups of DHI% decreased in a fast trend at 1,2,4 weeks postoperative and the two groups of DHI% decreased in a slowly trend at 8,12 weeks postoperative. The experimental group and the control group DHI% gradually decreased with the passage of postoperative time, the difference was statistically significant(P<0.05). Comparison of the same time point postoperative, DHI% decreased significantly on group B and C(P>0.05). Whereas, the MRI Pfirrmann classication showed the opposite change uncommonly from 1 weeks postoperative.Between group B and group C at the same time point postoperative were no significance of DHI%, MRI(P>0.05). With the postoperative time, histopathological examination of group B, C demonstrated that nucleus pulposus cell decreased gradually and the defects of disc AF replaced by granulation tissue and fibrous tissue, surgical biomaterials combined with the annulus fibrosus outer; immunohistochemistry showed type II collagen in nucleus pulposus of group B, C from positive to negative. Conclusion: Build a niche on the surface of the annulus fibrosus can lead to disc degeneration early period; biomaterials were integrated with the outside of annulus fibrosus well and closed tightly to gap, which could prevent the nucleus from herniation further. However, this approach could not restrain disc degeneration continuously.