PURPOSE Less physical activity has been associated with systemic biomarkers of cartilage breakdown following anterior cruciate ligament reconstruction (ACLR). Yet, previous research lacks analysis of deleterious cartilage compositional changes and objective physical activity following ACLR. The purpose of this study was to determine the association between physical activity quantified via accelerometer-based measures of daily steps and time in moderate-to-vigorous physical activity (MVPA), and T1rho magnetic resonance imaging (MRI) of the femoral articular cartilage, a marker of proteoglycan density in individuals with ACLR. METHODS Daily steps and MVPA were assessed over 7 days using an accelerometer worn on the hip in 26 individuals between 6-12 months following primary unilateral ACLR. Resting T1rho MRI were collected bilaterally, and T1rho MRI inter-limb ratios (ILR: ACLR limb/contralateral limb) were calculated for lateral and medial femoral condyle regions of interest. We conducted univariate linear regression analyses to determine associations between T1rho MRI ILRs and daily steps and MVPA with and without controlling for sex. RESULTS Greater T1rho MRI ILR of the central lateral femoral condyle, indicative of less proteoglycan density in the ACLR limb, was associated with greater time in MVPA (R2 = 0.178, P = 0.032). Sex-adjusted models showed significant interaction terms between daily steps and sex in the anterior (P = 0.025), central (P = 0.002), and posterior (P = 0.002) medial femoral condyle. CONCLUSIONS Lesser physical activity may be a risk factor for maintaining cartilage health following ACLR; additionally, the relationship between physical activity and cartilage health may be different between males and females.

中文翻译：

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体力活动与前十字韧带重建后股骨软骨的 T1rho MRI 相关。

目的 前交叉韧带重建 (ACLR) 后体力活动减少与软骨破坏的全身生物标志物相关。然而，之前的研究缺乏对 ACLR 后有害软骨成分变化和客观身体活动的分析。本研究的目的是确定通过基于加速度计的中度至剧烈体力活动 (MVPA) 中的每日步数和时间测量来量化的体力活动与股骨关节软骨的 T1rho 磁共振成像 (MRI) 之间的关联。 ACLR 个体中蛋白多糖密度的标志物。方法 在原发性单侧 ACLR 后 6-12 个月内，使用佩戴在臀部的加速度计对 26 名个体进行了 7 天的每日步数和 MVPA 评估。收集双侧静息 T1rho MRI，并计算感兴趣的外侧和内侧股骨髁区域的 T1rho MRI 四肢间比率（ILR：ACLR 肢体/对侧肢体）。我们进行了单变量线性回归分析，以确定 T1rho MRI ILR 与每日步数和 MVPA 之间的关联，无论是否控制性别。结果 中央外侧股骨髁的 T1rho MRI ILR 较高，表明 ACLR 肢体中蛋白聚糖密度较低，与 MVPA 时间较长相关（R2 = 0.178，P = 0.032）。性别调整模型显示，在股骨内侧髁前部（P = 0.025）、中央（P = 0.002）和后部（P = 0.002）中，每日步数与性别之间存在显着的交互作用。结论 较少的体力活动可能是 ACLR 后维持软骨健康的一个危险因素；此外，男性和女性之间的体力活动和软骨健康之间的关系可能有所不同。