Escuela de Doctorado, Universitat Politècnica de Valencia, Camí de Vera, s/n, 46022 Valencia, Spain.
University of Valencia, Avenida de Blasco Ibáñez, 13, 46010 Valencia, Spain.
ACS Appl Bio Mater. 2022 Jan 17;5(1):172-182. doi: 10.1021/acsabm.1c01027. Epub 2021 Dec 14.
: Biomechanical study of a nucleus replacement with a finite element model. : To validate a Bionate 80A ring-shaped nucleus replacement. : The ANSYS lumbar spine model made from lumbar spine X-rays and magnetic resonance images obtained from cadaveric spine specimens were used. All materials were assumed homogeneous, isotropic, and linearly elastic. We studied three options: intact spine, nucleotomy, and nucleus implant. Two loading conditions were evaluated at L-L, L-L, and L-S discs: a 1000 N axial compression load and this load after the addition of 8 Nm flexion moment in the sagittal plane plus 8 Nm axial rotation torque. : Maximum nucleus implant axial compression stresses in the range of 16-34 MPa and tensile stress in the range of 5-16 MPa, below Bionate 80A resistance were obtained. Therefore, there is little risk of permanent implant deformation or severe damage under normal loading conditions. Nucleotomy increased segment mobility, zygapophyseal joint and end plate pressures, and annulus stresses and strains. All these parameters were restored satisfactorily by nucleus replacement but never reached the intact status. In addition, annulus stresses and strains were lower with the nucleus implant than in the intact spine under axial compression and higher under complex loading conditions. : Under normal loading conditions, there is a negligible risk of nucleus replacement, permanent deformation or severe damage. Nucleotomy increased segmental mobility, zygapophyseal joint pressures, and annulus stresses and strains. Nucleus replacement restored segmental mobility and zygapophyseal joint pressures close to the intact spine. End plate pressures were similar for the intact and nucleus implant conditions under both loading modes. Manufacturing customized nucleus implants is considered feasible, as satisfactory biomechanical performance is confirmed.
生物力学研究表明，使用有限元模型进行核置换可有效验证 Bionate 80A 环形核置换。研究使用了来自尸体脊柱标本的腰椎 X 射线和磁共振图像制作的 ANSYS 腰椎模型。所有材料均假设为均匀、各向同性和线弹性。我们研究了三种方案：完整脊柱、核切除术和核植入物。在 L-L、L-L 和 L-S 椎间盘处评估了两种加载条件：1000 N 轴向压缩载荷和在此基础上增加 8 Nm 矢状面弯曲力矩以及 8 Nm 轴向旋转扭矩后的载荷。最大核植入物的轴向压缩应力范围为 16-34 MPa，拉伸应力范围为 5-16 MPa，低于 Bionate 80A 的阻力。因此，在正常加载条件下，植入物永久变形或严重损坏的风险很小。核切除术增加了节段活动度、关节突关节和终板压力以及环的应变和应力度。通过核置换可以很好地恢复所有这些参数，但从未达到完整状态。此外，与完整脊柱相比，在轴向压缩下，核植入物的环的应变和应力度较低，在复杂加载条件下则较高。在正常加载条件下，核置换、永久变形或严重损坏的风险可以忽略不计。核切除术增加了节段活动度、关节突关节压力以及环的应变和应力度。核置换恢复了节段活动度和关节突关节压力，接近完整脊柱。在两种加载模式下，终板压力在完整脊柱和核植入物条件下相似。制造定制化的核植入物是可行的，因为已经确认其具有令人满意的生物力学性能。
