Primary research of intervertebral fibrous fusion for rabbit spine segmental instability: an experimental study

English Keywords:Fibrous Fusion  Poly L-lactic-co-glycolic acid(PLGA)  New Zea-land white rabbits  Spine segmental instability

English Abstract:

  【Abstract】 Objectives: To investigate the spinal stability and the feasibility of fibrous fusion for spine segmental instability. Methods: 18 New Zealand white rabbits（6 months old） were randomly divided into 2 groups: nucleotomy and PLGA implantation after drilling holes on the vertebral endplate(group A) and nucleotomy alone(group B). In group A, after L4/5 nucleotomy, a ring-like PLGA scaffold was implanted. X-ray weas performed before and 12 weeks after the operation. The DHI was measured by using Image J software while evaluating the disc height, segmental stability, segmental range of motion(ROM), and immunohistochemical analysis was performed at 4, 8, and 12 weeks and their results were recorded． Results: 17 animals were survived after operation(no additional animal). 12 weeks later, disc height decreased in both groups, showing significant difference between group A and group B(P＜0.05), no significant difference of ROM between two groups with preoperation(P＞0.05). The flexion-tension lateral X-ray of group A did not show vertebral surge or reverse angle. But in group B, 1 animal′s flexion lateral X-ray showed recurvation deformity and adjacent segment endplate calcification, and the operation intervertebral space became narrower than the preoperative. No PLGA scaffold structure was found at 4 weeks postoperatively, fibrillar tissue formation was evidenced in both groups, but few of chondrocyte-like cells and neocapillaries proliferated in group A. At 8 weeks postoperatively, chondrcyte cells and a large number of disordered fiber tissues occurred, a few of collagenous fiber and fibrocyte cells were found in group A, while fiber cells and scar tissues in group B. Amount of collagenous fiber and cartilage interactively compacted into the intervertebral space, and the collagenous fiber increased than before in group A while still fiber cells and scar tissues in group B, that more type Ⅰ collgen than type Ⅱ collagen was evidenced. Conclusions: Bone marrow blood of vertebrae can form relatively effective fiber fusion as well as reconstructive segmental stability, which can preserve segmental motion, but its long term effects need further research.