Objective

Knee osteoarthritis (OA) is predominantly characterized by pain with weight-bearing activities. Pain at rest also occurs but the mechanisms for this are not clear. We evaluated the relations of nociceptive signal alterations to weight-bearing and non-weight-bearing pain in knee OA.

Design

We used data from a NIH–funded longitudinal cohort of older adults with or at risk of knee OA. We evaluated quantitative sensory testing (QST) measures (pressure pain threshold (PPT) at patellae and the wrist; mechanical temporal summation (TS); conditioned pain modulation (CPM)). Each WOMAC pain question was dichotomized as having at least moderate pain, and we further categorized them as weight-bearing pain and non-weight-bearing pain. We evaluated the relation of QST measures to each pain outcome using logistic regression, adjusting for potential confounders.

Results

2,749 participants (5,479 knees) were included (mean age 64 ± 11, 57% female). Each SD unit decrease in patellar PPT was associated with greater odds of both weight-bearing pain (OR 1.51 (95% CI 1.27, 1.79)) and non-weight-bearing pain (OR 1.46 (1.20–1.77)), while wrist PPT was associated with greater odds of weight-bearing pain (OR 1.27 (1.15, 1.39)) but only with pain during sitting/lying (OR 1.20 (1.01, 1.43)). TS was significantly associated with greater odds of pain with walking and stairs (OR 1.11 (1.01, 1.23), 1.11 (1.03, 1.20), respectively). CPM was not associated with any pain outcomes.

Conclusions

Our findings challenge the hypothesis that non-weight-bearing pain may reflect greater pain sensitization and/or inefficient CPM than weight-bearing pain in knee OA, suggesting other mechanisms are likely responsible.

中文翻译：

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负重与非负重疼痛是否反映了膝骨关节炎的不同疼痛机制？：多中心骨关节炎研究（MOST）

 客观的

膝骨关节炎（OA）的主要特征是负重活动时疼痛。休息时疼痛也会发生，但其机制尚不清楚。我们评估了膝骨关节炎中伤害性信号改变与负重和非负重疼痛的关系。

 设计

我们使用的数据来自 NIH 资助的患有或有膝骨关节炎风险的老年人纵向队列。我们评估了定量感觉测试（QST）测量（髌骨和手腕处的压痛阈值（PPT）；机械时间总和（TS）；条件性疼痛调节（CPM））。每个 WOMAC 疼痛问题都被分为至少中度疼痛，我们进一步将它们分类为负重疼痛和非负重疼痛。我们使用逻辑回归评估了 QST 测量值与每种疼痛结果的关系，并调整了潜在的混杂因素。

 结果

包括 2,749 名参与者（5,479 个膝盖）（平均年龄 64 ± 11，57% 为女性）。髌骨 PPT 每减少一个 SD 单位，与负重疼痛 (OR 1.51 (95% CI 1.27, 1.79)) 和非负重疼痛 (OR 1.46 (1.20–1.77)) 的发生率增加相关，而手腕 PPT与较大的负重疼痛相关（OR 1.27 (1.15, 1.39)），但仅与坐/躺时的疼痛相关（OR 1.20 (1.01, 1.43)）。 TS 与步行和爬楼梯时疼痛的发生率显着相关（OR 分别为 1.11 (1.01, 1.23)、1.11 (1.03, 1.20)）。 CPM 与任何疼痛结果无关。

 结论

我们的研究结果挑战了这样的假设，即膝关节 OA 中非负重疼痛可能比负重疼痛反映了更大的疼痛敏感性和/或低效 CPM，这表明其他机制可能是造成这种情况的原因。