Dynamic foraminal dimensions during neck motion 6.5 years after fusion and artificial disc replacement

PLoS One. 2020 Aug 11;15(8):e0237350. doi: 10.1371/journal.pone.0237350. eCollection 2020.

Abstract

Objective: To compare changes in foraminal motion at two time points post-surgery between artificial disc replacement (ADR) and anterior cervical discectomy and fusion (ACDF).

Methods: Eight ACDF and 6 ADR patients (all single-level C5-6) were tested at 2 years (T1) and 6.5 years (T2) post-surgery. The minimum foraminal height (FH.Min) and width (FW.Min) achieved during neck axial rotation and extension, and the range of these dimensions during motion (FH.Rn and FW.Rn, respectively) were measured using a biplane dynamic x-ray system, CT imaging and model-based tracking while patients performed neck axial rotation and extension tasks. Two-way mixed ANOVA was employed for analysis.

Results: In neck extension, significant interactions were found between year post-surgery and type of surgery for FW.Rn at C5-6 (p<0.006) and C6-7 (p<0.005), and for FH.Rn at C6-7 (p<0.01). Post-hoc analysis indicated decreases over time in FW.Rn for ACDF (p<0.01) and increases in FH.Rn for ADR (p<0.03) at the C6-7 adjacent level. At index level, FW.Rn was comparable between ACDF and ADR at T1, but was smaller for ACDF than for ADR at T2 (p<0.002). In axial rotation, differences were found between T1 and T2 but did not depend on type of surgery (p>0.7).

Conclusions: Changes were observed in the range of foraminal geometry at adjacent levels from 2 years to 6.5 years post-surgery that were different between ACDF and ADR for neck extension. These changes are contrary to the notion that motion at adjacent levels continue to increase following ACDF as compared to ADR over the long term.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Biomechanical Phenomena
  • Cervical Vertebrae / diagnostic imaging
  • Cervical Vertebrae / physiopathology*
  • Cervical Vertebrae / surgery
  • Diskectomy / adverse effects*
  • Female
  • Follow-Up Studies
  • Humans
  • Imaging, Three-Dimensional
  • Intervertebral Disc Degeneration / surgery*
  • Male
  • Middle Aged
  • Postoperative Period
  • Range of Motion, Articular*
  • Spinal Fusion / adverse effects*
  • Tomography, X-Ray Computed
  • Total Disc Replacement / adverse effects*
  • Total Disc Replacement / instrumentation
  • Treatment Outcome

Grants and funding

Parts of this work was supported by a Fellowship Award in Spine (VC) from Congress of Neurological Surgeons (CNS). The sponsor had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. All authors are employees or unpaid research volunteers of the Henry Ford Health System (HFHS), a private, non-profit healthcare organization. The funder provided support in the form of salaries for authors (DO, TB, AB, MJB, SWB, VC, YNY), but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.