Objective

Sodium concentration is responsible for (at least part of) the stiffness of articular cartilage due to the osmotic pressure it generates. Therefore, we hypothesized that we could use sodium MRI to approximate the stiffness of cartilage to assess early cartilage degeneration.

Methods

Four human tibial plateaus were retrieved from patients undergoing total knee replacement (TKR), and their cartilage stiffness mapped with indentation testing, after which samples were scanned in a 7 T MRI to determine sodium concentration. The relation of biomechanical parameters to MRI sodium and glycosaminoglycan (GAG) concentration was explored by a linear mixed model.

Results

Weak correlations of GAG concentration with apparent peak modulus (p = 0.0057) and apparent equilibrium modulus (p = 0.0181) were observed and lack of correlation of GAG concentration versus MRI sodium concentration was observed. MRI sodium concentration was not correlated with apparent peak modulus, though a moderate correlation of MRI sodium concentration with permeability was shown (p = 0.0014).

Discussion and conclusion

Although there was correlation between GAG concentration and cartilage stiffness, this was not similar with sodium concentration as measured by MRI. Thus, if the correlation between MRI sodium imaging and GAG concentration could be resolved, this strategy for assessing cartilage functional quality still holds promise.

中文翻译：

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钠 MRI 可以用作绘制软骨硬度的方法吗？

客观的

由于其产生的渗透压，钠浓度是造成（至少部分）关节软骨僵硬的原因。因此，我们假设我们可以使用钠 MRI 来近似软骨的刚度来评估早期的软骨退化。

方法

从接受全膝关节置换术 (TKR) 的患者中取出四个人类胫骨平台，并通过压痕测试绘制软骨硬度，然后在 7 T MRI 中扫描样本以确定钠浓度。通过线性混合模型探索生物力学参数与 MRI 钠和糖胺聚糖 (GAG) 浓度的关系。

结果

具有明显的峰模量（GAG浓度的弱相关p  = 0.0057）和表观平衡模量（p 观察= 0.0181）和与观察MRI钠浓度缺乏GAG浓度的相关性。MRI 钠浓度与表观峰值模量无关，但显示 MRI 钠浓度与渗透性有中度相关性（p  = 0.0014）。

讨论与结论

尽管 GAG 浓度与软骨硬度之间存在相关性，但这与 MRI 测量的钠浓度不相似。因此，如果可以解决 MRI 钠成像和 GAG 浓度之间的相关性，这种评估软骨功能质量的策略仍然有希望。