Background

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.

Methods

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.

Findings

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.

Interpretation

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.

中文翻译：

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腰椎小关节与椎间盘成分和昼夜变形的体内关系

背景

每个脊柱水平的“三关节复合体”、两个小关节和一个椎间盘促进了脊柱运动。椎间盘和小关节都受到与年龄相关的自然退化，虽然这些过程可能相关，但不清楚如何。由于椎间盘的不稳定性可能是关节突关节炎的基础，我们评估了椎间盘和关节突关节机械耦合的假设。

方法

我们招募了年轻、无症状的志愿者（n  = 10；年龄：平均 25 岁，范围 21-30 岁；BMI：平均 23.1，范围 19.1-29.0 kg/m ²）并应用磁共振成像（MRI）和三维（3D ) 建模以测量腰椎的小关节和椎间盘成分（MRI T1rho 弛豫时间）以及小关节和椎间盘功能（小关节间隙宽度、椎间盘高度的昼夜变化）。

发现

我们发现，小面空间宽度与小面 T1rho 弛豫时间（流体含量）呈正相关，与椎间盘 T1rho 呈负相关，并且与退化椎间盘相邻的小面明显更厚且 T1rho 显着更高。此外，楔角的日变化与小平面间隙宽度的日变化呈正相关，而椎间盘退变、椎间盘高度的日变化和小面 T1rho 则不相关。

解释

这些数据表明椎间盘和关节面健康之间存在相互依赖关系，但椎间盘和关节面机械功能之间没有相关性。此外，小关节软骨成分与体内功能之间的弱关系表明其他因素，如脊柱曲率，决定了体内脊柱力学。有必要在有症状或老年人群中进行未来的工作以证实这些发现。