Biomechanical Evaluation of Different Surgical Approaches for the Treatment of Adjacent Segment Diseases After Primary Anterior Cervical Discectomy and Fusion: A Finite Element Analysis.

Wencan Ke,Zhiwei Liao,Cao Yang,Yukun Zhang,Xinghuo Wu,Shuai Li,Kun Wang,Rongjin Luo,Wenbin Hua,Saideng Lu,Gaocai Li,Chao Chen,Liang Ma,Yu Song,Yunsong Shi,Bingjin Wang

doi:10.3389/fbioe.2021.718996

Abstract

Symptomatic adjacent segment disease (ASD) is a common challenge after anterior cervical discectomy and fusion (ACDF). The objective of this study was to compare the biomechanical effects of a second ACDF and laminoplasty for the treatment of ASD after primary ACDF. We developed a finite element (FE) model of the C2-T1 based on computed tomography images. The FE models of revision surgeries of ACDF and laminoplasty were simulated to treat one-level and two-level ASD after primary ACDF. The range of motion (ROM) and intradiscal pressure (IDP) of the adjacent segments, and stress in the cord were analyzed to investigate the biomechanical effects of the second ACDF and laminoplasty. The results indicated that revision surgery of one-level ACDF increased the ROM and IDP at the C2–C3 segment, whereas two-level ACDF significantly increased the ROM and IDP at the C2–C3 and C7-T1 segments. Furthermore, no significant changes in the ROM and IDP of the laminoplasty models were observed. The stress in the cord of the re-laminoplasty model decreased to some extent, which was higher than that of the re-ACDF model. In conclusion, both ACDF and laminoplasty can relieve the high level of stress in the spinal cord caused by ASD after primary ACDF, whereas ACDF can achieve better decompression effect. Revision surgery of the superior ACDF or the superior and inferior ACDF after the primary ACDF increased the ROM and IDP at the adjacent segments, which may be the reason for the high incidence of recurrent ASD after second ACDF.

Highlights

Anterior cervical discectomy and fusion (ACDF) is generally accepted as the standard surgical treatment for cervical degenerative diseases (Oglesby et al, 2013; Kelly et al, 2018)
The biomechanical results indicated that both ACDF and laminoplasty can relieve the increased stress in the spinal cord caused by adjacent segment disease (ASD) after primary ACDF, whereas ACDF can achieve a better decompression effect than laminoplasty regardless of the level of ASD
The biomechanical results indicated that both ACDF and laminoplasty can decrease the stress in the spinal cord caused by ASD after primary ACDF, but ACDF can achieve a better decompression effect than laminoplasty regardless of the level of ASD

Summary

Introduction

Anterior cervical discectomy and fusion (ACDF) is generally accepted as the standard surgical treatment for cervical degenerative diseases (Oglesby et al, 2013; Kelly et al, 2018). Adjacent segment disease (ASD), defined as new symptoms at nerve roots or myelopathy and Biomechanical Evaluation of Revision Surgery. In a retrospective study of 177 patients who underwent ACDF, radiographic and clinical ASD were found in 92.1 and 19.2% of patients, respectively; approximately 7% of the patients required revision surgery (Chung et al, 2014). Another study reported an incidence of 2.4% per year of revision surgery at adjacent segments after primary surgery, and the authors estimated that 22% of patients would require second surgery due to symptomatic ASD within a decade (Lee et al, 2015). ACDF decompresses the nerve roots and myelopathy by removing the herniated disc and posterior osteophytes, followed by Materials

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