Biomechanical Evaluation of the Lumbar Spine by Using a New Interspinous Process Device: A Finite Element Analysis

Chen-Sheng Chen,Shao-Ming Chuang,Hung-Wen Wei

doi:10.3390/app112110486

Chen-Sheng Chen, Shao-Ming Chuang + Show 1 more

Open Access

https://doi.org/10.3390/app112110486

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Journal: Applied Sciences	Publication Date: Nov 8, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: National Yang Ming Chiao Tung University

Abstract

Minimally invasive decompression is generally employed for treating lumbar spinal stenosis; however, it results in weakened spinal stability. To augment spinal stability, a new interspinous process device (NIPD) was developed in this study. The biomechanical features of the NIPD were evaluated in this study. Three finite-element (FE) models of the entire lumbar spine were implemented to perform biomechanical analysis: the intact, defect (DEF), and NIPD models. The DEF model was considered for lumbar spines with bilateral laminotomies and partial discectomy at L3–L4. Range of motion (ROM), disc stress, and facet joint contact force were evaluated in flexion, extension, torsion, and lateral bending in the three FE models. The results indicated that ROM in the extension increased by 23% in the DEF model but decreased by 23% in the NIPD model. In the NIPD model, the cephalic adjacent disc stress in flexion and extension was within 5%, and negligible changes were noted in the facet joint contact force for torsion and lateral bending. Thus, the NIPD offers superior spinal stability and causes only a minor change in cephalic adjacent disc stress in flexion and extension during the bilateral laminotomy and partial discectomy of the lumbar spine. However, the NIPD has a minor influence on the ROM and facet joint force for lateral bending and torsion.

Highlights

Lumbar spines have a three-point joint, including a facet joint and spinal disc
The results of this study indicate that the Range of motion (ROM) of the laminotomies in the DEF model increased by 16% in flexion, 23% in extension, 4% in lateral bending, and 28% in rotation compared with the corresponding values in the intact lumbar spine (INT) model
The ROM in the new interspinous process device (NIPD) model was 18% and 23% lower than that in the INT model in flexion and extension, respectively; the NIPD model increased the spinal stability in flexion and extension

Summary

Introduction

Lumbar spines have a three-point joint, including a facet joint and spinal disc. Spinal stenosis in the lumbar spine is caused by a hypertrophic facet joint or bulged disc. Approaches for removing lamina for decompression include partial or total laminectomy. Laminectomy sometimes results in iatrogenic spondylolisthesis because the surgery involves the removal of excessive posterior elements and the cutting of posterior spinal ligaments, which induce spinal instability [3,4]. The spinal ligament must be retained as much as possible to maintain spinal stability. Laminectomy helps preserve the interspinous and supraspinous ligaments and assists in stabilizing spinal motion in flexion [5]. Partial removal of the lamina, such as in laminotomy, decompresses the spinal cord and allows for the achievement of spinal stability

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