Stippick Timothy Wade, Sheller Michael Richard
Escape Velocity Mechanical Design, 7229 S. Golfside Lane, Phoenix, AZ, 85042, USA.
Sheller Biomedical Innovations, 2517 N 61st Way, Scottsdale, AZ, 85257, USA.
Med Biol Eng Comput. 2016 Jan;54(1):113-22. doi: 10.1007/s11517-015-1319-2. Epub 2015 Jun 5.
Electromagnetic fields generated by spinal bone growth stimulation devices have been computationally modelled to determine coverage of the lumbar spinal vertebrae. The underlying assumption of these models was that the electric field, but not the magnetic field, was therapeutically relevant. However, there are no published studies examining the therapeutic coverage of spinal fusion sites by stimulators utilizing combined magnetic fields. To assess the coverage, an anatomical model of the vertebrae and discs of the lumbar spine was developed to represent interbody and posterolateral fusion sites. Computer simulations of the induced electromagnetic fields were analysed to determine coverage of the fusion sites. For both interbody and posterolateral fusion models, combined magnetic fields provided 100% coverage of the fusion sites for all intervertebral disc spaces and for all posterior planes from L1 to L5, respectively. Within the vertebral column, the magnitude of the electric field reached a maximum value of 3.6 × 10(-4) V/m, which is several orders of magnitude less than any reported study demonstrating a biological effect. Given its clinical efficacy, a bone growth stimulator utilizing combined magnetic fields must rely on the action of its magnetic field rather than its electric field for a therapeutic effect.
已对脊柱骨生长刺激装置产生的电磁场进行了计算建模，以确定腰椎椎体的覆盖范围。这些模型的基本假设是，电场而非磁场具有治疗相关性。然而，目前尚无已发表的研究探讨利用组合磁场的刺激器对脊柱融合部位的治疗覆盖范围。为评估覆盖范围，构建了腰椎椎体和椎间盘的解剖模型，以代表椎间融合和后外侧融合部位。对感应电磁场进行计算机模拟分析，以确定融合部位的覆盖范围。对于椎间融合和后外侧融合模型，组合磁场分别为所有椎间盘间隙以及从L1至L5的所有后平面的融合部位提供了100%的覆盖。在脊柱内，电场强度达到最大值3.6×10(-4)V/m，比任何已报道的显示生物学效应的研究低几个数量级。鉴于其临床疗效，利用组合磁场的骨生长刺激器必须依靠其磁场而非电场来产生治疗效果。
