In vivo relationships between lumbar facet joint and intervertebral disc composition and diurnal deformation

• Published in: Clinical biomechanics (Bristol) Vol. 88; p. 105425
• Main Authors: Oldweiler, Alexander B., Martin, John T.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2021
• Subjects: Adult; Aged; Biomechanics; Facet joint; Humans; Imaging; Intervertebral disc; Intervertebral Disc - diagnostic imaging; Intervertebral Disc Degeneration - diagnostic imaging; Lumbar Vertebrae - diagnostic imaging; Magnetic Resonance Imaging; Physical Medicine and Rehabilitation; T1rho relaxation time; Young Adult; Zygapophyseal Joint - diagnostic imaging; Biomechanics; T1rho relaxation time; Facet joint; Intervertebral disc; Imaging
• ISSN: 0268-0033; 1879-1271; 1879-1271
• DOI: 10.1016/j.clinbiomech.2021.105425

Spinal motion is facilitated by a “three joint complex”, two facet joints and one intervertebral disc at each spinal level. Both the intervertebral discs and facet joints are subject to natural age-related degeneration, and while these processes may be linked it is not clear how. As instability in the disc could underlie facet arthritis, we evaluated the hypothesis that the discs and facet joints are mechanically coupled. We recruited young, asymptomatic volunteers (n = 10; age: mean 25, range 21–30 years; BMI: mean 23.1, range 19.1–29.0 kg/m2) and applied magnetic resonance imaging (MRI) and three-dimensional (3D) modeling to measure facet and disc composition (MRI T1rho relaxation time) and facet and disc function (diurnal changes in facet space width, disc height) in the lumbar spine. We found that facet space width was positively associated with facet T1rho relaxation time (fluid content) and negatively associated with disc T1rho, and that facets adjacent to degenerated discs were significantly thicker and had significantly higher T1rho. Furthermore, the diurnal change in wedge angle was positively associated the diurnal change in facet space width, while disc degeneration, the diurnal change in disc height, and facet T1rho were not. These data demonstrate an interdependence between disc and facet health, but not between disc and facet mechanical function. Furthermore, the weak relationship between facet cartilage composition and in vivo function suggests that other factors, like spinal curvature, determine in vivo spine mechanics. Future work in symptomatic or aged populations are warranted to confirm these findings. •Facet hypertrophy (thickening, effusion) occurs at levels with degenerated discs.•Facet compression was associated with spinal curvature, not disc compression.•Imaging findings of disc/facet degeneration were not indicative of facet dysfunction.•Mechanical coupling may not underlie parallel disc and facet degeneration processe.