Biomechanical effects of hybrid constructions in the treatment of noncontinuous cervical spondylopathy: a finite element analysis

Abstract

Background Hybrid construction (HC) may be an ideal surgical strategy than noncontinuous total disc replacement (TDR) and noncontinuous anterior cervical discectomy and fusion (ACDF) in the treatment of noncontinuous cervical spondylopathy. However, there is still no consensus on the segmental selection for ACDF or TDR in HC. The study aims to analyse the effects of different segment selection of TDR and ACDF on cervical biomechanical characteristics after HC surgery. Methods Twelve FEMs of C2–C7 were constructed based on CT images of 12 mild cervical spondylopathy volunteers. Two kinds of HC were introduced in our study: Fusion-arthroplasty group (Group 1), upper-level (C3/4) ACDF, and lower-level TDR (C5/6); Arthroplasty-fusion group (Group 2), upper-level (C3/4) TDR and lower-level ACDF (C5/6). The follow-load technique was simulated by applying an axial initial load of 73.6 N through the motion centre of FEM. A bending moment of 1.0 Nm was applied to the centre of C2 in all FEMs. Statistical analysis was carried out by SPSS 26.0. The significance threshold was 5% (P < 0.05). Results In the comparison of ROMs between Group 1 and Group 2, the ROM in extension (P = 0.016), and lateral bending (P = 0.038) of C4/5 were significantly higher in Group 1 group. The average intervertebral disc pressures at C2/3 in all directions were significantly higher in Group 1 than those in Group 2 (P < 0.005). The average contact forces in facet joints of C2/3 (P = 0.007) were significantly more than that in Group 2; however, the average contact forces in facet joints of C6/7 (P < 0.001) in Group 1 group were significantly less than that in Group 2. Conclusions Arthroplasty-fusion is preferred for intervertebral disc degeneration in adjacent upper segments. Fusion-arthroplasty is preferred for patients with lower intervertebral disc degeneration or lower posterior column degeneration. Trial registration: This research was registered in Chinese Clinical Trial Registry (ChiCTR1900020513).

The Kinematics and Biomechanics for Non-Contiguous Anterior Cervical Discectomy and Fusion, Cervical Disc Arthroplasty, and Hybrid Cervical Surgery: A Systematic Review

“…Non-contiguous ACDF (CoRoent Contour) and non-contiguous CDA (Prodisc-C) were performed at C3-C4 and C5-C6 with ROM testing in flexion, extension, bilateral side bend, and bilateral axial rotation [7]. Sun et al (2023) utilized twelve FEMs constructed from CT images of six males and six females (total of twelve patients) with mild cervical spondylopathy [8]. For the hybrid cervical surgery in Sun et al ( 2023), the ACDF used NuVasive Helix ACP and CoRoent Contour, whereas the CDA used Prodisc-C [8].…”

“…For the purposes of this study, "initial non-operative cervical spine" refers to a cadaver spine prior to any cervical surgery procedure, as seen in the study by Finn et al (2011), or a finite element model (FEM) prior to any operative procedures, as seen in the other four included articles [7][8][9][10][11]. For the purposes of this study, "cephalad non-operative segment", "intermediate non-operative segment", and "caudal non-operative segment" refer to the cervical segment levels that did not receive surgical intervention and are above, between, and below the operative levels, respectively.…”

“…A total of 5 articles on the biomechanics of non-contiguous cervical fusion surgeries were included in this systematic review from a total of 523 articles found on initial search [7][8][9][10][11]. See Figure 1 for more information on the article selection process for this study.…”

“…Estimates of the prevalence of CDDD in the literature range from 37% to 96%, depending on patient age [6]. Numerous cervical surgical procedures exist for the treatment of CDDD, including anterior cervical discectomy and fusion (ACDF), cervical disc arthroplasty (CDA), and a combination of both of those procedures called hybrid cervical surgery (HCS) [1][2][3][4][5][7][8][9][10][11][12][13]. Patients can develop CDDD in a multi-level contiguous manner, in which adjacent levels of the cervical spine are affected, or in a non-contiguous manner, in which there is "skip-level" CDDD or level(s) of diseased cervical segments between level(s) of healthy cervical segments [1,[3][4][5]14,15].…”

“…To date, no systematic review in the literature examines the biomechanical properties and outcomes of these three cervical surgeries when performed in a non-contiguous manner, despite the publication of multiple individual biomechanical studies in the past five years using previously described methods of cadaveric or finite element analysis [7][8][9][10]. The purpose of this systematic review is to examine the biomechanical outcomes associated with three types of non-contiguous cervical surgeries-ACDF, CDA, and HCS-to provide a benchmark for comparison to contiguous cervical surgeries to guide surgeon decisionmaking and to advance the current understanding of ideal treatment for non-contiguous cervical pathologies.…”