Division of Physical Therapy Education, University of Nebraska Medical Center, 984420 Nebraska Medical Center, Omaha, NE 98198-4420, United States; Department of Orthopaedic Surgery and Rehabilitation, University of Nebraska Medical Center, 985640 Nebraska Medical Center, Omaha, NE 68198-5640, United States.
College of Medicine, University of Nebraska Medical Center, 985520 Nebraska Medical Center, Omaha, NE 68198-5520, United States.
Knee. 2021 Oct;32:19-29. doi: 10.1016/j.knee.2021.07.004. Epub 2021 Aug 6.
Articular cartilage structure and chondrocyte health are sensitive and reliant on dynamic joint loading during activities. The purpose of this pilot study was to determine the association between measures of individual and cumulative knee joint loading with T2 relaxation times in the knee cartilage of young individuals without knee injury.
Twelve participants (17-30 years old) without history of knee injury or surgery completed MRI, physical activity (PA), and biomechanical gait testing. T2 relaxation times were calculated in the cartilage within the patella and lateral and medial compartments. Accelerometry was used to measure mean daily step counts, minutes of PA, and % sedentary time over 7 days. Vertical ground reaction force, external knee joint moments and peak knee flexion angle were measured during stance phase of gait using three-dimensional motion capture. Cumulative knee joint loading was calculated as daily step count by external knee joint moment impulse. The relationship between measures of knee joint loading and T2 relaxation times was assessed using Pearson correlations.
Higher T2 relaxation times in the femoral and tibial cartilage were consistently correlated to greater body mass, daily step counts, moderate and vigorous PA, and peak knee joint moments (r = 0.10-0.84). Greater cumulative knee flexion and adduction loading was associated with higher T2 relaxation times in the femoral and tibial cartilage (r = 0.16-0.65).
Preliminary findings suggest that individual loading factors and cumulative knee joint loading are associated with higher T2 relaxation times in the articular cartilage of young, healthy knees.
关节软骨的结构和软骨细胞的健康对活动中关节的动态负荷敏感且依赖。本初步研究的目的是确定个体和累积膝关节负荷与无膝关节损伤的年轻个体膝关节软骨 T2 弛豫时间之间的关系。
12 名参与者（17-30 岁）无膝关节损伤或手术史，完成了 MRI、身体活动（PA）和生物力学步态测试。在髌骨和外侧和内侧关节腔的软骨中计算 T2 弛豫时间。加速度计用于测量 7 天内的平均日常步数、PA 分钟数和久坐时间百分比。使用三维运动捕捉在步态的站立阶段测量垂直地面反作用力、膝关节外部力矩和最大膝关节屈曲角度。累积膝关节负荷计算为每日膝关节外部力矩冲量的步数。使用 Pearson 相关评估膝关节负荷测量值与 T2 弛豫时间之间的关系。
股骨和胫骨软骨中较高的 T2 弛豫时间与较大的体重、每日步数、中等强度和剧烈 PA 以及最大膝关节力矩呈一致相关（r=0.10-0.84）。更大的累积膝关节屈曲和内收负荷与股骨和胫骨软骨中更高的 T2 弛豫时间相关（r=0.16-0.65）。
初步发现表明，个体负荷因素和累积膝关节负荷与年轻健康膝关节关节软骨中的 T2 弛豫时间升高有关。
