Comparison of biomechanical performance of single-level triangular and quadrilateral profile anterior cervical plates.

Dean Chou,Fu Cao,Wenyuan Wang,Rongchang Fu

doi:10.1371/journal.pone.0250270

Dean Chou, Fu Cao + Show 2 more

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https://doi.org/10.1371/journal.pone.0250270

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Journal: PloS one	Publication Date: Apr 15, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: Xinjiang University

Abstract

The quadrilateral anterior cervical plate (ACP) is used extensively in anterior cervical discectomy and fusion (ACDF) to reconstruct the stability of the cervical spine and prevent cage subsidence. However, there have been no comparison studies on the biomechanical performance of quadrilateral ACP and triangular ACP. The objective of this study is to investigate the functional outcomes of quadrilateral ACP and triangular ACP usage in ACDF surgery. In this study, a finite element model of intact C1-C7 segments was established and verified. Additionally, two implant systems were built; one using triangle anterior cervical plates (TACP) and another using quadrilateral orion anterior cervical plate (QACP). Both models were then compared in terms of their postoperative biomechanical performance, under normal and excessive motion. Compared to QACP, the peak stress of the TACP screws and plates occurred at 359.2 MPa and 97.2 MPa respectively and were the highest during over extension exercises. Alternately, compared to TACP, the endplate peak stress and the cage displacement of QACP were the largest at over extension, with values of 7.5 MPa and 1.2 mm, respectively. Finally, the average stress ratio of bone grafts in TACP was relatively high at 31.6%. In terms of biomechanical performance, TACP can share the load more flexibly and reduce the risks of cage subsidence and slippage but the screws have high peak stress value, thereby increasing the risk of screw slippage and fracture. This disadvantage must be considered when designing a TACP based implant for a potential patient.

Highlights

Since the 1980s, anterior cervical discectomy and fusion (ACDF), using a bone graft-intervertebral cage, was the gold standard in the treatment of cervical spondylotic radiculopathy, myelopathy, trauma, and other cervical spondylopathy [1,2,3]
In the work done by Panjabi et al [22], all modes of motions generated expected results in terms of range of motions (ROM) movement, expect for the LB motion mode, which generated a large deviation in data
In Yu et al [24], the ROM analysis of the C3-C7 segment finite element model showed some discrepancies in the axial motion

Summary

Introduction

Since the 1980s, anterior cervical discectomy and fusion (ACDF), using a bone graft-intervertebral cage, was the gold standard in the treatment of cervical spondylotic radiculopathy, myelopathy, trauma, and other cervical spondylopathy [1,2,3]. Multiple reports have demonstrated loose screws and fracture, cervical plate fracture and displacement, cage subsidence, and bone graft nonunion caused by stress shielding [5, 6]. In a single level ACDF surgery, a quadrilateral cervical plate needs to be equipped with at least four screws for fixation and four threaded holes for proper fixation. In order to evaluate the triangle fixation system biomechanics performance, this study designed the triangle anterior cervical plate (TACP) and quadrilateral Orion anterior cervical plate (QACP) to compare the surgical outcomes of both ACP systems in terms of slippage and fracture of the plates and screws, the slippage and subsidence of the cage, and the stress ratio of the bone grafts

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