Whitehill R, Stowers S F, Fechner R E, Ruch W W, Drucker S, Gibson L R, McKernan D J, Widmeyer J H
Spine (Phila Pa 1976). 1987 Jan-Feb;12(1):12-22. doi: 10.1097/00007632-198701000-00003.
Forty-eight adult mongrel dogs underwent posterior exposure of C4-C5, fixation of the two posterior spinous processes together with a no. 20-gauge cerclage wire, posterior element decortication, wound irrigation and the following: bone fusions (application of a standard volume of iliac crest autograft), polymethylmethacrylate (PMMA) fusions (application of a standard volume of methylmethacrylate cement), Combination 1 fusions (application of one-half the volume of graft used in the bone fusions, over the facet joints. Methylmethacrylate cement was pressed into position centrally to surround the posterior spinous processes and cerclage wire), Combination 2 fusions (application of the same volume of graft used in the bone fusions, over the facet joints. Methylmethacrylate cement was applied as in the Combination 1 fusions). For each preparation, six animals survived 2 weeks or 3 months. All had monthly lateral cervical radiographs. At the appropriate times, they were killed and their C4-C5 segments excised and studied mechanically and histologically. At 2 weeks all of the above preparations were mechanically inferior to normal C4-C5 segments in respect to at least one of the parameters studied. At 3 months, the bone fusions and both combination fusions had developed sufficient mechanical stability so that they were equivalent to normal segments. At this time, the PMMA fusions remained inferior to the "normals." The mechanical data for the PMMA and both combination fusions was corroborated by the histology which demonstrated a fibrosynovial layer between the cement masses and underlying posterior element bone. In the 3-month combination fusions, the lateral aspects of the posterior elements had been spanned by a fusion mass.
Previously, the authors defined some of the problems associated with constructs modeled by their PMMA fusions. This work confirms the previous research. It also demonstrates that ultimate spinal stability is produced by combination constructs. Because of the 2-week mechanical data, it is recommended that when combination constructs are used clinically, the patient's neck be protected by an external orthosis in the early postoperative period.
48只成年杂种犬接受了C4 - C5后路暴露，用20号钢丝将两个后棘突固定在一起，进行后部骨皮质剥脱、伤口冲洗以及以下操作：骨融合（应用标准体积的自体髂骨移植）、聚甲基丙烯酸甲酯（PMMA）融合（应用标准体积的甲基丙烯酸甲酯骨水泥）、组合1融合（在小关节突上应用骨融合中所用移植骨体积的一半，将甲基丙烯酸甲酯骨水泥压入中央位置以环绕后棘突和钢丝）、组合2融合（在小关节突上应用与骨融合中相同体积的移植骨，甲基丙烯酸甲酯骨水泥的应用方式与组合1融合相同）。对于每种制备方法，6只动物存活2周或3个月。所有动物每月进行颈椎侧位X线检查。在适当的时候，将它们处死，切除C4 - C5节段并进行力学和组织学研究。在2周时，上述所有制备方法在至少一项研究参数方面力学性能均低于正常C4 - C5节段。在3个月时，骨融合和两种组合融合均已形成足够的力学稳定性，使其与正常节段相当。此时，PMMA融合仍低于“正常”节段。PMMA和两种组合融合的力学数据得到了组织学的证实，组织学显示骨水泥团块与下方后部骨结构之间存在纤维滑膜层。在3个月的组合融合中，后部结构的外侧已被融合块跨越。
此前，作者确定了一些与他们的PMMA融合所模拟的结构相关的问题。这项工作证实了先前的研究。它还表明，最终的脊柱稳定性是由组合结构产生的。由于2周时的力学数据，建议在临床使用组合结构时，术后早期用外部矫形器保护患者的颈部。
