Analysis of biomechanical properties of a new type of self－stabilizing artificial vertebral body L5 spine by finite element

English Keywords:Artificial vertebral body  Titanium cage  Finite element analysis  Spine  Biomechanics

English Abstract:

  【Abstract】 Objectives: To evaluate the mechanical properties of the new self stabilizing artificial vertebral body after L5 subtotal corpectomy and its influence on the surrounding tissues used finite element analysis, so as to provide a new choice for the treatment of lumbosacral spinal tuberculosis and other diseases. Methods: The CT thin-slice scan data of lumbosacral segment of a healthy volunteer were extracted and 3D reconstruction was performed to construct the finite element analysis model of lumbosacral segment(L3-S1) intact group and verify its validity. After the L5 vertebral body and adjacent discectomy, the new artificial vertebral body and the titanium cage combined with the anterior titanium rod were placed respectively, and then the finite element analysis models of the new prosthesis group and the titanium cage group were constructed. For the inferior surface of S1 vertebral bodies of all models of all degrees of freedom, 400N axial loads of simulated physiological compression were applied on the superior surface of L3 vertebral body, and then 8Nm bending loads were applied were also applied on the superior surface of L3 vertebral body surface to simulate the six movements of flexion, extension, left/right lateral bending, and left/right rotation of lumbar spine. The ROM of L4-S1 and the maximum von Mises stress of adjacent end plate were analyzed statistically. Results: The ranges of motion in the flexion, extension, lateral flexion and rotation of the new prosthesis group and the titanium cage group were 0.38°-0.56° and 0.53°-1.41°, respectively, which were significantly lower than those in the intact group(4.48°－10.12°). The maximum von Mises stress of the endplate at the operation site(lower endplate of L4 and upper endplate of S1) of the new prosthesis group and the titanium cage group were significantly increased in the flexion, extension, lateral bending and rotation directions, but the maximum von Mises stress of the new prosthesis group was significantly decreased compared with the titanium cage group in the above directions. Conclusions: The self-stabilizing artificial vertebral body can not only reconstruct the immediate stability of the surgical site, but also effectively reduce the local stress on the endplate of the surgical site, and to some extent reduce the postoperative subsidence rate of the prosthesis. However, the mechanical properties of the new prosthesis, such as long-term stability and fatigue resistance, need to be further studied.