OBJECTIVE Massive weight loss leads to marked knee pain reduction in individuals with knee pain, but the reason for the reduction in pain is unknown. This study was undertaken to quantify the contribution of magnetic resonance imaging (MRI)-evidenced changes in pain-sensitive structures, bone marrow lesions (BMLs), and synovitis, and changes in pain sensitization or depressive symptoms, to knee pain improvement after substantial weight loss. METHODS Morbidly obese patients with knee pain on most days were evaluated before bariatric surgery or medical weight management and at 1-year follow-up for BMLs and synovitis seen on MRI, the pressure pain threshold (PPT) at the patella and the right wrist, depressive symptoms (using the Center for Epidemiologic Studies Depression scale [CES-D]), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain survey. Natural-effects models were used to quantify the extent that achieving a minimum clinically important difference (MCID) of ≥18% on the WOMAC pain scale could be mediated by weight loss-induced changes in BMLs, synovitis, PPT, and depressive symptoms. RESULTS Of 75 participants, 53.3% lost ≥20% of weight by 1 year. Of these, 75% attained the MCID for pain improvement, compared with 34.3% in those who had <20% weight loss. Mediation analyses suggested that, in those with at least 20% weight loss, the odds of pain improvement increased by 62%, 15%, and 22% through changes in patella PPT, wrist PPT, and CES-D, respectively, but pain improvement was not mediated by MRI changes in BMLs or synovitis. CONCLUSION Weight loss-induced knee pain improvement is partially mediated by changes in pain sensitization and depressive symptoms but is independent of MRI changes in BMLs and synovitis.

中文翻译：

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骨髓病变、滑膜炎、疼痛敏化和抑郁症状对体重大幅减轻后膝关节疼痛改善的中介作用。

目的 大量减肥可以显着减轻膝盖疼痛患者的膝盖疼痛，但疼痛减轻的原因尚不清楚。这项研究的目的是量化磁共振成像（MRI）证实的疼痛敏感结构、骨髓病变（BML）和滑膜炎的变化，以及疼痛敏感性或抑郁症状的变化对大幅度负重后膝关节疼痛改善的贡献。损失。方法 在减肥手术或药物体重管理之前以及 1 年随访时对大多数日子里膝盖疼痛的病态肥胖患者进行评估，评估 MRI 上显示的 BML 和滑膜炎、髌骨和右手腕的压痛阈值 (PPT)、抑郁症状（使用流行病学研究中心抑郁量表 [CES-D]）以及西安大略省和麦克马斯特大学骨关节炎指数 (WOMAC) 疼痛调查。使用自然效应模型来量化体重减轻引起的 BML、滑膜炎、PPT 和抑郁症状变化可介导 WOMAC 疼痛量表达到≥18% 的最小临床重要差异 (MCID) 的程度。结果 75 名参与者中，53.3% 的人在 1 年内体重减轻了 ≥20%。其中，75% 的人达到了疼痛改善的 MCID，而体重减轻 <20% 的人中只有 34.3% 达到了 MCID。中介分析表明，在体重减轻至少 20% 的患者中，通过髌骨 PPT、腕部 PPT 和 CES-D 的变化，疼痛改善的几率分别增加了 62%、15% 和 22%，但疼痛改善不是由 BML 或滑膜炎的 MRI 变化介导的。结论 体重减轻引起的膝关节疼痛改善部分是由疼痛敏感性和抑郁症状的变化介导的，但与 BML 和滑膜炎的 MRI 变化无关。