Jenis Louis G, Wheeler Donna, Parazin Stephen J, Connolly Raymond J
New England Baptist Hospital, 125 Parker Hill Avenue, Department of Orthopaedic Surgery, Boston, MA 02120, USA.
Spine J. 2002 May-Jun;2(3):173-8. doi: 10.1016/s1529-9430(02)00183-3.
The use of rigid instrumentation combined with bone graft makes intuitive sense given the requirements for vascular ingrowth, bone formation and a stable environment for the cellular events of healing to develop. However, with the advances of potent osteoinductive growth factors, the role of internal fixation may come into question. Whether bone morphogenic proteins (BMPs) would benefit from a more "stable" spinal segment for bone production and modeling remains unknown. In addition, it is unknown whether BMP and rigid fixation may have an additive effect on fusion healing.
This study is proposed to test the hypothesis that rigid fixation in the lumbar spine would be advantageous to achieve fusion for autogenous bone grafting, but fusion would occur regardless of fixation with the use of osteogenic protein (OP)-1.
STUDY DESIGN/SETTING: A histologic and radiographic analysis of BMP in a rabbit lumbar fusion model.
Thirty-two rabbits were randomized into four groups: 1) control animals: in situ posterolateral L5-L6 arthrodesis using autogenous iliac crest bone graft; 2) fixation group: posterolateral arthrodesis L5-L6 with autogenous bone graft and interspinous fixation; 3) OP-1 group: in situ posterolateral L5-L6 arthrodesis using OP-1 and 4) combined OP-1 and fixation group. Radiographic fusion analysis was performed with computed tomography scans at 3 and 12 weeks after surgery. Decalcified histology was performed to assess tissue morphology and cellularity.
Minimal evidence of fusion was noted at 3 weeks with autograft or OP-1. By 12 weeks, all OP-1-treated animals had solid fusion, whereas no fusion was noted in autograft animals. The addition of fixation slightly increased radiographic fusion at 3 weeks in autograft and OP-1 groups but did not affect OP-1 animals at 12 weeks where all were fused. Decalcified histologic results confirmed the proliferative bone formation noted with OP-1 and the variable cellular response with autograft.
The results of the present study suggest that the osteoinductive effect of OP-1 may be only minimally enhanced early in the bone healing process but does not appear to be affected in the long term by spinal fixation in the rabbit intertransverse fusion model. Fixation appeared to enhance early fusion in the autograft group.
鉴于骨生长、骨形成以及愈合过程中细胞活动所需的稳定环境等要求，使用刚性内固定器械并结合骨移植在直观上是合理的。然而，随着强效骨诱导生长因子的发展，内固定的作用可能受到质疑。骨形态发生蛋白（BMP）是否会从更“稳定”的脊柱节段中受益以促进骨生成和塑形仍不清楚。此外，BMP与刚性固定对融合愈合是否具有相加作用也尚不清楚。
本研究旨在验证以下假设：腰椎的刚性固定有利于自体骨移植实现融合，但无论是否使用成骨蛋白（OP）-1进行固定，融合都会发生。
研究设计/地点：对兔腰椎融合模型中的BMP进行组织学和影像学分析。
32只兔子被随机分为四组：1）对照组：使用自体髂嵴骨移植进行L5-L6节段原位后外侧关节融合术；2）固定组：使用自体骨移植并进行棘突间固定的L5-L6后外侧关节融合术；3）OP-1组：使用OP-1进行L5-L6节段原位后外侧关节融合术；4）OP-1与固定联合组。术后3周和12周通过计算机断层扫描进行影像学融合分析。进行脱钙组织学检查以评估组织形态和细胞构成。
在术后3周时，自体骨移植或OP-1组融合的证据极少。到12周时，所有接受OP-1治疗的动物均实现了牢固融合，而自体骨移植组未观察到融合。在自体骨移植组和OP-1组中，添加固定在3周时略微增加了影像学融合，但在12周时对所有已融合的OP-1组动物没有影响。脱钙组织学结果证实了OP-1组有增殖性骨形成，以及自体骨移植组有不同的细胞反应。
本研究结果表明，在兔横突间融合模型中，OP-1的骨诱导作用在骨愈合早期可能仅略有增强，但从长期来看似乎不受脊柱固定的影响。固定似乎增强了自体骨移植组的早期融合。
