Biomechanical comparison of a two-level anterior discectomy and a one-level corpectomy, combined with fusion and anterior plate reconstruction in the cervical spine.
BACKGROUND
Common fusion techniques for cervical degenerative diseases include two-level anterior discectomy and fusion and one-level corpectomy and fusion. The aim of the study was to compare via in-vitro biomechanical testing the effects of a two-level anterior discectomy and fusion and a one-level corpectomy and fusion, with anterior plate reconstruction.


METHODS
Seven fresh frozen human cadaveric spines (C3-T1) were dissected from posterior musculature, preserving the integrity of ligaments and intervertebral discs. Initial biomechanical testing consisted of no-axial preload and 2Nm in flexion-extension, lateral bending and axial rotation. Thereafter, discectomies were performed at C4-5 and C5-6 levels, then two interbody cages and an anterior C4-C5-C6 plate was implanted. The flexibility tests were repeated and followed by C5 corpectomy and C4-C6 plate reconstruction. Biomechanical testing was performed again and statistical comparisons among the means of range of motion and axial rotation energy loss were investigated.


RESULTS
The two-level cage-plate construct had significantly lower range of motion than the one-level corpectomy-plate construct (P≤0.03). Axial rotation energy loss was significantly (P≤0.03) greater for the corpectomy-plate construct than for the two-level cage-plate construct and the intact condition.


CONCLUSIONS
A two-level cage-plate construct provides greater stability in flexion, extension and lateral bending motions when compared to a one-level corpectomy-plate construct. A two-level cage-plate is more likely to maintain axial balance by reducing the energy lost in axial rotation.
H. Lee Moffitt Cancer Center & Research Institute, NeuroOncology Program, Tampa, FL 33612, USA; Department of Neurosurgery and Orthopedics, College of Medicine, University of South Florida, Tampa, FL 33612, USA.
Kamran
K
Aghayev
H. Lee Moffitt Cancer Center & Research Institute, NeuroOncology Program, Tampa, FL 33612, USA; Dept. of Mechanical Engineering, University of South Florida, Tampa, FL 33612, USA.
James J
JJ
Doulgeris
H. Lee Moffitt Cancer Center & Research Institute, NeuroOncology Program, Tampa, FL 33612, USA. Electronic address: sabrina.gonzalezblohm@moffitt.org.
Sabrina A
SA
Gonzalez-Blohm
H. Lee Moffitt Cancer Center & Research Institute, NeuroOncology Program, Tampa, FL 33612, USA; Department of Neurosurgery and Orthopedics, College of Medicine, University of South Florida, Tampa, FL 33612, USA.
Mohammed
M
Eleraky
Dept. of Chemical & Biomedical Engineering, University of South Florida, Tampa, FL 33612, USA.
William E
WE
Lee
H. Lee Moffitt Cancer Center & Research Institute, NeuroOncology Program, Tampa, FL 33612, USA; Department of Neurosurgery and Orthopedics, College of Medicine, University of South Florida, Tampa, FL 33612, USA.
Frank D
FD
Vrionis
D001696:Biomechanical Phenomena / Q000502:physiology; D001703:Biophysics / Q000295:instrumentation; D001860:Bone Plates; D002102:Cadaver; D002574:Cervical Vertebrae / Q000601:surgery*; D017586:Diskectomy / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D016268:Internal Fixators; D007403:Intervertebral Disc; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D013123:Spinal Fusion / Q000379:methods*
Anterior cervical corpectomy and fusion (ACCF); Anterior cervical discectomy and fusion (ACDF); Energy loss; Range of motion (RoM)