Biomechanical analysis of newly developed interspinous process device based on finite element model

Abstract

Objective: This study aimed to investigate the biomechanical effects of a

newly developed interspinous process device (IPD), called TAU. This

device was compared with another IPD (SPIRE) and the pedicle screw

fixation (PSF) technique at the surgical and adjacent levels of the lumbar

spine.

Methods: A three-dimensional finite element model analysis of the L1-S1

segments was performed to assess the biomechanical effects of the

proposed IPD combined with an interbody cage. Three surgical models—

two IPD models (TAU and SPIRE) and one PSF model—were developed. The biomechanical effects, such as range of motion (ROM), intradiscal

pressure (IDP), disc stress, and facet loads during extension were analyzed

at surgical (L3-L4) and adjacent levels (L2-L3 and L4-L5).

Results: The study analyzed biomechanical parameters at surgical and

adjacent levels assuming that the implants were perfectly fused with the

lumbar spine. Compared to the SPIRE model, TAU demonstrated

advantages in stabilizing the surgical level, in all directions. Further, the

TAU model exhibited less compensation at adjacent levels than the PSF

model in terms of ROM, IDP, disc stress, and facet loads, which may

lower the incidence of the adjacent segment disease (ASD).

Conclusion: The TAU model demonstrated more stabilization at the

surgical level than SPIRE but less stabilization than the PSF model.

Further, the TAU model demonstrated less compensation at adjacent levels

than the PSF model in terms of ROM, IDP, disc stress, and facet loads,

which may lower the incidence of ASD in the long term. Moreover, TAU

has several advantages over SPIRE in its design. The TAU device can be

used as an alternative system for treating degenerative lumbar disease

while maintaining the physiological properties of the lumbar spine and

minimizing the degeneration of adjacent segments.