Glazer P A, Heilmann M R, Lotz J C, Bradford D S
Department of Orthopaedic Surgery, University of California, San Francisco, USA.
Spine (Phila Pa 1976). 1997 Oct 15;22(20):2351-6. doi: 10.1097/00007632-199710150-00007.
The biomechanical and histologic characteristics of posterolateral spinal fusion in a rabbit model with and without the application of a pulsed electromagnetic field were analyzed in a prospective, randomized trial. In addition, fusion rate with and without a pulsed electromagnetic field in this model was assessed by biomechanical testing, radiographs, and manual palpation.
To evaluate the influence of a pulsed electromagnetic field on the spinal fusion rate and biomechanical characteristics in a rabbit model.
Previous studies performed to assess the benefits of a pulsed electromagnetic field in spinal fusion have been complicated by the use of instrumentation, and the animal models used do not have a pseudarthrosis rate comparable to that seen in humans. In contrast, the posterolateral intertransverse process fusion in the rabbit is uncomplicated by the use of instrumentation and has been shown to have a pseudarthrosis rate similar to that found in humans (5-35%).
Ten New Zealand white rabbits each were randomly assigned to undergo spinal fusion using either 1) autologous bone with electromagnetic fields, or 2) autologous bone without electromagnetic fields. A specially designed plastic constraint was used to focus the pulsed electromagnetic field over the rabbits' lumbar spine 4 hours per day. Animals were killed at 6 weeks for biomechanical and histologic testing.
The rate of pseudarthrosis, as evaluated radiographically and manually in a blinded fashion, decreased from 40% to 20% with the pulsed electromagnetic field, but this decrease in the nonunion rate was not statistically significant given the number of animals per group. Biomechanical analysis of the fusion mass showed that a pulsed electromagnetic field resulted in statistically significant increases in stiffness (35%), area under the load-displacement curve (37%), and load to failure of the fusion mass (42%). Qualitative histologic assessment showed increased bone formation in those fusions exposed to a pulsed electromagnetic field.
This study demonstrates the reproducibility of a rabbit fusion model, and the ability of a pulsed electromagnetic field to induce a statistically significant increase in stiffness, area under the load-displacement curve, and load to failure of the fusion mass. This investigation provides a basis for continued evaluation of biologic enhancement of spinal arthrodesis with the use of a pulsed electromagnetic field.
在一项前瞻性随机试验中，分析了在有或没有应用脉冲电磁场的兔模型中后外侧脊柱融合的生物力学和组织学特征。此外，通过生物力学测试、X线片和手动触诊评估了该模型中有或没有脉冲电磁场时的融合率。
评估脉冲电磁场对兔模型中脊柱融合率和生物力学特征的影响。
以往评估脉冲电磁场在脊柱融合中益处的研究因使用内固定器械而变得复杂，且所使用的动物模型假关节形成率与人类所见的不具有可比性。相比之下，兔的后外侧横突间融合术不受内固定器械使用的影响，并且已显示其假关节形成率与人类相似（5% - 35%）。
将20只新西兰白兔随机分为两组，每组10只，分别接受以下脊柱融合术：1）自体骨联合电磁场；2）自体骨不联合电磁场。使用一种专门设计的塑料约束装置，每天将脉冲电磁场聚焦于兔的腰椎4小时。6周时处死动物进行生物力学和组织学测试。
以盲法通过X线片和手动触诊评估，假关节形成率在脉冲电磁场组从40%降至20%，但鉴于每组动物数量，骨不连率的这种降低无统计学意义。融合块的生物力学分析表明，脉冲电磁场使融合块的刚度（增加35%）、负荷 - 位移曲线下面积（增加37%）和破坏负荷（增加42%）有统计学意义的增加。定性组织学评估显示，暴露于脉冲电磁场的融合中骨形成增加。
本研究证明了兔融合模型的可重复性，以及脉冲电磁场能使融合块的刚度、负荷 - 位移曲线下面积和破坏负荷有统计学意义的显著增加。本研究为继续评估使用脉冲电磁场生物增强脊柱融合术提供了依据。
