Department of Orthopaedics and Rehabilitation, The University of Iowa, Carver College of Medicine, Iowa City, IA 52242-1088, USA.
Osteoarthritis Cartilage. 2012 Oct;20(10):1120-6. doi: 10.1016/j.joca.2012.05.013. Epub 2012 Jun 12.
As cartilage loss and bone marrow lesions (BMLs) are associated with knee joint pain and structural worsening, this study assessed whether non-invasive estimates of articular contact stress may longitudinally predict risk for worsening of knee cartilage morphology and BMLs.
This was a longitudinal cohort study of adults aged 50-79 years with risk factors for knee osteoarthritis. Baseline and follow-up measures included whole-organ magnetic resonance imaging score (WORMS) classification of knee cartilage morphology and BMLs. Tibiofemoral geometry was manually segmented on baseline magnetic resonance imaging (MRI), and three-dimensional (3D) tibiofemoral point clouds were registered into subject-specific loaded apposition using fixed-flexion knee radiographs. Discrete element analysis (DEA) was used to estimate mean and peak contact stresses for the medial and lateral compartments. The association of baseline contact stress with worsening cartilage and BMLs in the same subregion over 30 months was assessed using conditional logistic regression.
Subjects (N = 38, 60.5% female) had a mean ± standard deviation (SD) age and body mass index (BMI) of 63.5 ± 8.4 years and 30.5 ± 3.7 kg/m2 respectively. Elevated mean articular contact stress at baseline was associated with worsening cartilage morphology and worsening BMLs by 30 months, with odds ratio (OR) [95% confidence interval (CI)] of 4.0 (2.5, 6.4) and 6.6 (2.7, 16.5) respectively. Peak contact stress also was significantly associated with worsening cartilage morphology and BMLs {1.9 (1.5, 2.3) and 2.3 (1.5, 3.6)}(all P < 0.0001).
Detection of higher contact stress 30 months prior to structural worsening suggests an etiological role for mechanical loading. Estimation of articular contact stress with DEA is an efficient and accurate means of predicting subregion-specific knee joint worsening and may be useful in guiding prognosis and treatment.
由于软骨损失和骨髓病变（BML）与膝关节疼痛和结构恶化有关，本研究评估了关节接触压力的非侵入性估计值是否可以纵向预测膝关节软骨形态和 BML 恶化的风险。
这是一项针对 50-79 岁有膝关节骨关节炎危险因素的成年人的纵向队列研究。基线和随访测量包括膝关节软骨形态和 BML 的全器官磁共振成像评分（WORMS）分类。在基线磁共振成像（MRI）上手动分割胫股几何形状，并用固定-屈曲膝关节射线照相将三维（3D）胫股点云注册到受试者特定的加载贴合中。离散元分析（DEA）用于估计内侧和外侧隔间的平均和峰值接触压力。使用条件逻辑回归评估基线接触压力与 30 个月内同一亚区软骨和 BML 恶化之间的关联。
受试者（N=38，60.5%女性）的平均±标准偏差（SD）年龄和体重指数（BMI）分别为 63.5±8.4 岁和 30.5±3.7kg/m2。基线时升高的平均关节接触压力与 30 个月时软骨形态恶化和 BML 恶化相关，优势比（OR）[95%置信区间（CI）]分别为 4.0（2.5，6.4）和 6.6（2.7，16.5）。峰值接触压力也与软骨形态恶化和 BML 恶化显著相关{1.9（1.5，2.3）和 2.3（1.5，3.6）}（均 P<0.0001）。
在结构恶化前 30 个月检测到更高的接触压力提示机械负荷的病因作用。使用 DEA 估计关节接触压力是一种有效且准确的预测膝关节亚区恶化的方法，可能有助于指导预后和治疗。
