Division of Physical Therapy Education, University of Nebraska Medical Center, Omaha, Nebraska, USA.
Department of Orthopedic Surgery and Rehabilitation, University of Nebraska Medical Center, Omaha, Nebraska, USA.
J Orthop Res. 2022 Jan;40(1):138-149. doi: 10.1002/jor.25034. Epub 2021 Mar 29.
Osteoarthritis (OA) is prevalent after anterior cruciate ligament (ACL) injury, but mechanismsunderlying its development are poorly understood. The purpose of this study was to determine if gait biomechanics and daily physical activity (PA) associate with cartilage T2 relaxation times, a marker of collagen organization and water content, 1 month after ACL injury. Twenty-seven participants (15-35 years old) without chondral lesions completed magnetic resonance imaging, three-dimensional gait analysis, and 1 week of PA accelerometry. Interlimb differences and ratios were calculated for gait biomechanics and T2 relaxation times, respectively. Multiple linear regression models adjusted for age, sex, and concomitant meniscus injury were used to determine the association between gait biomechanics and PA with T2 relaxation times, respectively. Altered knee adduction moment (KAM) impulse, less knee flexion excursion (kEXC) and higher daily step counts accounted for 35.8%-65.8% of T2 relaxation time variation in the weightbearing and posterior cartilage of the medial and lateral compartment (all p ≤ .011). KAM impulse was the strongest factor for T2 relaxation times in all models (all p ≤ .001). Lower KAM impulse associated with longer T2 relaxation times in the injured medial compartment (β = -.720 to -.901) and shorter T2 relaxation in the lateral compartment (β = .713 to .956). At 1 month after ACL injury, altered KAM impulse, less kEXC, and higher PA associated with longer T2 relaxation times, which may indicate poorer cartilage health. Statement of Clinical Significance: Gait biomechanics and daily PA are modifiable targets that may improve cartilage health acutely after ACL injury and slow progression to OA.
骨关节炎（OA）在前交叉韧带（ACL）损伤后很常见，但其发病机制尚不清楚。本研究旨在确定步态生物力学和日常体力活动（PA）是否与软骨 T2 弛豫时间相关，T2 弛豫时间是胶原组织和含水量的标志物，在 ACL 损伤后 1 个月进行测量。27 名（15-35 岁）无软骨损伤的参与者完成了磁共振成像、三维步态分析和 1 周的 PA 加速度计测量。分别计算了步态生物力学和 T2 弛豫时间的肢体间差异和比值。使用多元线性回归模型，调整年龄、性别和伴发半月板损伤，分别确定步态生物力学和 PA 与 T2 弛豫时间之间的关系。膝关节内收力矩（KAM）冲量的改变、膝关节屈曲范围（kEXC）较小和每日步数较高，分别解释了负重和内侧和外侧间室后软骨 T2 弛豫时间变化的 35.8%-65.8%（均 p≤.011）。在所有模型中，KAM 冲量都是 T2 弛豫时间的最强因素（均 p≤.001）。受伤内侧间室的 KAM 冲量较低与 T2 弛豫时间较长相关（β=-.720 至-.901），而外侧间室的 T2 弛豫时间较短（β=-.713 至.956）。在 ACL 损伤后 1 个月，KAM 冲量改变、膝关节屈曲范围较小和日常 PA 较高与 T2 弛豫时间较长相关，这可能表明软骨健康状况较差。临床意义声明：步态生物力学和日常 PA 是可改变的靶点，可能会改善 ACL 损伤后急性的软骨健康，并减缓向 OA 的进展。
