The Effect of Axial Compression and Distraction on Cervical Facet Cartilage Apposition During Shear and Bending Motions

Ryan D Quarrington,Claire F Jones,Darcy W Thompson-Bagshaw

doi:10.1007/s10439-022-02940-1

Abstract

During cervical spine trauma, complex intervertebral motions can cause a reduction in facet joint cartilage apposition area (CAA), leading to cervical facet dislocation (CFD). Intervertebral compression and distraction likely alter the magnitude and location of CAA, and may influence the risk of facet fracture. The aim of this study was to investigate facet joint CAA resulting from intervertebral distraction (2.5 mm) or compression (50, 300 N) superimposed on shear and bending motions. Intervertebral and facet joint kinematics were applied to multi rigid-body kinematic models of twelve C6/C7 motion segments (70 ± 13 year, nine male) with specimen-specific cartilage profiles. CAA was qualitatively and quantitatively compared between distraction and compression conditions for each motion; linear mixed-effects models (α = 0.05) were applied. Distraction significantly decreased CAA throughout all motions, compared to the compressed conditions (p < 0.001), and shifted the apposition region towards the facet tip. These observations were consistent bilaterally for both asymmetric and symmetric motions. The results indicate that axial neck loads, which are altered by muscle activation and head loading, influences facet apposition. Investigating CAA in longer cervical spine segments subjected to quasistatic or dynamic loading may provide insight into dislocation and fracture mechanisms.

Highlights

The bilateral facet joints of the subaxial cervical spine play an important role in load-bearing and kinematics of the neck
A reduction in facet joint apposition area likely increases the risk of cervical facet dislocation (CFD), while the anatomical region of contact dictates the presence and type of concomitant posterior element fractures
This study used computational reconstructions of experimental data to show that superimposed intervertebral compression significantly increased apposition area and moved the region of contact towards the pedicles, whereas superimposed distraction caused the smaller area of apposition to be closer to the facet tip

Summary

Introduction

The bilateral facet joints of the subaxial cervical spine play an important role in load-bearing and kinematics of the neck. They bear over 64% of axial load in the cervical spine[20,22] and are responsible for coupled intervertebral motions in axial rotation and lateral bending.[4,19]. Facet joint apposition area and region are dictated by bone and cartilage geometry,[30,36] posterior element deflection,[26,30] and the local instantaneous intervertebral loads and motions. Superimposed intervertebral distraction, such as that observed during inertially-produced CFD,[11,21] likely reduces facet joint apposition, which may reduce the likelihood of concomitant posterior element fracture. The effect of axial compression, versus distraction, on the magnitude and region of facet joint apposition during intervertebral motion has not previously been reported

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