Comparative Analysis of the Biomechanical Characteristics After Different Minimally Invasive Surgeries for Cervical Spondylopathy: A Finite Element Analysis

Tao He,Rui Liu,Zhihe Yun,Tong Yu,Le Qi,Junyan An,Tianyang Yuan,Jiuping Wu,Xinyu Nie,Jun Zhang,Wu Xue,Haorui Du,Qinyi Liu

doi:10.3389/fbioe.2021.772853

Abstract

Minimally invasive surgeries, including posterior endoscopic cervical foraminotomy (PECF), microsurgical anterior cervical foraminotomy (MACF), anterior transdiscal approach of endoscopic cervical discectomy (ATd-ECD), and anterior transcorporeal approach of endoscopic cervical discectomy (ATc-ECD), have obtained positive results for cervical spondylotic radiculopathy. Nonetheless, there is a lack of comparison among them regarding their biomechanical performance. The purpose of this study is to investigate the biomechanical changes of operated and adjacent segments after minimally invasive surgeries compared to a normal cervical spine. A three-dimensional model of normal cervical vertebrae C3–C7 was established using finite element analysis. Afterwards, four surgical models (PECF, MACF, ATd-ECD, and ATc-ECD) were constructed on the basis of the normal model. Identical load conditions were applied to simulate flexion, extension, lateral bending, and axial rotation of the cervical spine. We calculated the range of motion (ROM), intradiscal pressure (IDP), annulus fibrosus pressure (AFP), uncovertebral joints contact pressure (CPRESS), and facet joints CPRESS under different motions. For all circumstances, ATc-ECD was close to the normal cervical spine model, whereas ATd-ECD significantly increased ROM and joints CPRESS and decreased IDP in the operated segment. PECF increased more the operated segment ROM than did the MACF, but the MACF obtained maximum IDP and AFP. Except for ATc-ECD, the other models increased joints CPRESS of the operated segment. For adjacent segments, ROM, IDP, and joints CPRESS showed a downward trend in all models. All models showed good biomechanical stability. With their combination biomechanics, safety, and conditions of application, PECF and ATc-ECD could be appropriate choices for cervical spondylotic radiculopathy.

Highlights

Cervical spondylotic radiculopathy is usually characterized by pain and numbness of the neck, shoulders, and arms as well as restriction of cervical movement, which significantly decreases quality of life for patients (Yuchi et al, 2019; Chen et al, 2020)
The most significant increase of the operated segment rang of motion (ROM) occurred in the anterior transdiscal approach of endoscopic cervical discectomy (ATd-ECD), and the ROM increased by 11.07%, 12.77%, 11.56%, and 10.51% during flexion, extension, right lateral bending, and right axial rotation, respectively
For the posterior endoscopic cervical foraminotomy (PECF) model, we found that the ROM of the operated segment increased obviously during extension–flexion and axial rotation by 8.46% and 10.74%, respectively

Summary

Introduction

Cervical spondylotic radiculopathy is usually characterized by pain and numbness of the neck, shoulders, and arms as well as restriction of cervical movement, which significantly decreases quality of life for patients (Yuchi et al, 2019; Chen et al, 2020). Anterior cervical discectomy and fusion has turned into a standard procedure for cervical spondylotic radiculopathy because of its safety, effectiveness, and high fusion rate since the 1950s (Ruetten et al, 2009; Yang et al, 2014; Ren et al, 2019), notwithstanding that it may cause some problems such as degeneration of adjacent segments, loss of intervertebral disc height, and pseudarthrosis formation (Ruetten et al, 2009; Yang et al, 2014; Yuchi et al, 2019; Chen et al, 2020). PECF and ATd-ECD have gradually become alternative options for spine surgeons in treatment of cervical disc herniation because of their good postoperative stability and high clinical success rate (Ruetten et al, 2008; Yang et al, 2014)

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