Development of a Three-Dimensional Finite Element Model of Thoracolumbar Kyphotic Deformity following Vertebral Column Decancellation

Abstract

Background. Vertebral column decancellation (VCD) is a new spinal osteotomy technique to correct thoracolumbar kyphotic deformity (TLKD). Relevant biomechanical research is needed to evaluate the safety of the technique and the fixation system. We aimed to develop an accurate finite element (FE) model of the spine with TLKD following VCD and to provide a reliable model for further biomechanical analysis. Methods. A male TLKD patient who had been treated with VCD on L2 and instrumented from T10 to L4 was a volunteer for this study. The CT scanning images of the postoperative spine were used for model development. The FE model, simulating the spine from T1 to the sacrum, includes vertebrae, intervertebral discs, spinal ligaments, pedicle screws, and rods. The model consists of 509580 nodes and 445722 hexahedrons. The ranges of motion (ROM) under different loading conditions were calculated for validation. The stresses acting on rods, screws, and vertebrae were calculated. Results. The movement trend, peak stress, and ROM calculated by the current FE model are consistent with previous studies. The FE model in this study is able to simulate the mechanical response of the spine during different motions with different loading conditions. Under axial compression, the rod was the part bearing the peak stress. During flexion, the stress was concentrated on proximal pedicle screws. Under extension and lateral bending, an osteotomized L1 vertebra bore the greatest stress on the model. During tests, ligament disruption and unit deletion were not found, indicating an absence of fracture and fixation breakage. Discussion. A subject-specific FE model of the spine following VCD is developed and validated. It can provide a reliable and accurate digital platform for biomechanical analysis and surgical planning.

Corrective Mechanism Aftermath Surgical Treatment of Spine Deformity due to Scoliosis: A Systematic Review of Finite Element Studies

“…The majority of the participants were young people, with only a few adults of average age. Nine studies involved adolescences (aged between 10 and 19) [ 1 , 3 , 9 , 11 , 12 , 14 , 15 , 17 ], two articles assessed middle-aged individuals (age range from 30–59) [ 10 , 19 ], and none of the articles involved elderly persons (aged 60 and above). The number of participants in the evaluated publications varied, with the highest number being 20 peoples and seven articles keeping one as patient data for their investigation [ 6 , 9 , 11 , 12 , 16 , 18 , 19 ].…”

“…Ten out of fifteen studies used ANSYS software for FEA studies [ 1 , 2 , 6 , 9 , 15 , 18 , 19 ]. Whereas Abolaeha et al, Little et al, and Guan et al used ABAQUS software [ 3 , 12 , 18 ].…”

“…Several authors used 10 node tetrahedral solid elements [ 1 , 2 , 9 , 11 , 14 ]. However, Wang et al [ 15 ] and Guan et al [ 18 ] used hexahedron elements. Moreover, beam elements for vertebral and pelvic sections, tension-only cable elements for ligaments, surface contact elements for articular facets, and modified beam elements are all included in FE model by Dumas et al [ 10 ].…”

“…In order to produce an accurate reconstruction, the image quality is critical. To develop a rebuilt model as accurate as possible, it can be seen that the models in most of the studies were created from computed tomography (CT) scan images that was widely used by the researchers [ 1 , 3 , 6 , 9 – 12 , 15 , 16 , 18 ], either directly or via a previous model's scaling. Meanwhile, only Wang et al [ 13 ] used ADAMS 2005 software (Mechanical Dynamics Inc., Ann Arbor, MI) and the ADAMS Software Development Kit (SDK).…”

“…As for the material, titanium alloy was widely used for both rod and screws compared to cobalt chromium which also has elastoplastic properties [ 1 , 3 , 12 , 15 , 18 , 19 ]. Abolaeha et al [ 12 ] used stainless steel that also has elastoplastic material behaviour as aluminium alloy.…”