Human Movement Science Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC.
Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC.
Med Sci Sports Exerc. 2019 Apr;51(4):630-639. doi: 10.1249/MSS.0000000000001834.
Aberrant walking biomechanics after anterior cruciate ligament reconstruction (ACLR) are hypothesized to be associated with deleterious changes in knee cartilage. T1ρ magnetic resonance imaging (MRI) is sensitive to decreased proteoglycan density of cartilage. Our purpose was to determine associations between T1ρ MRI interlimb ratios (ILR) and walking biomechanics 6 months after ACLR.
Walking biomechanics (peak vertical ground reaction force (vGRF), vGRF loading rate, knee extension moment, knee abduction moment) were extracted from the first 50% of stance phase in 29 individuals with unilateral ACLR. T1ρ MRI ILR (ACLR limb/uninjured limb) was calculated for regions of interest in both medial and lateral femoral (LFC) and medial and lateral tibial condyles. Separate, stepwise linear regressions were used to determine associations between biomechanical outcomes and T1ρ MRI ILR after accounting for walking speed and meniscal/chondral injury (P ≤ 0.05).
Lesser peak vGRF in the ACLR limb was associated with greater T1ρ MRI ILR for the LFC (posterior ΔR = 0.14, P = 0.05; central ΔR = 0.15, P = 0.05) and medial femoral condyle (central ΔR = 0.24, P = 0.01). Lesser peak vGRF loading rate in the ACLR limb (ΔR = 0.21, P = 0.02) and the uninjured limb (ΔR = 0.27, P = 0.01) was associated with greater T1ρ MRI ILR for the anterior LFC. Lesser knee abduction moment for the injured limb was associated with greater T1ρ MRI ILR for the anterior LFC (ΔR = 0.16, P = 0.04) as well as the posterior medial tibial condyle (ΔR = 0.13, P = 0.04).
Associations between outcomes related to lesser mechanical loading during walking and greater T1ρ MRI ILR were found 6 months after ACLR. Although preliminary, our results suggest that underloading of the ACLR limb at 6 months after ACLR may be associated with lesser proteoglycan density in the ACLR limb compared with the uninjured limb.
前交叉韧带重建（ACLR）后异常的步行生物力学被假设与膝关节软骨的有害变化有关。T1ρ 磁共振成像（MRI）对软骨中蛋白聚糖密度的降低敏感。我们的目的是确定 ACLR 后 6 个月 T1ρ MRI 双侧肢体比值（ILR）与步行生物力学之间的关系。
从 29 名单侧 ACLR 患者的支撑相前 50%中提取步行生物力学（峰值垂直地面反作用力（vGRF）、vGRF 加载率、膝关节伸展力矩、膝关节外展力矩）。计算内侧和外侧股骨（LFC）以及内侧和外侧胫骨髁的感兴趣区域的 T1ρ MRI ILR（ACLR 肢体/未受伤肢体）。在考虑步行速度和半月板/软骨损伤后（P ≤ 0.05），使用逐步线性回归来确定生物力学结果与 T1ρ MRI ILR 之间的关系。
ACL 肢体的较小峰值 vGRF 与 LFC 的较大 T1ρ MRI ILR 相关（后 ΔR = 0.14，P = 0.05；中 ΔR = 0.15，P = 0.05）和内侧股骨髁（中 ΔR = 0.24，P = 0.01）。ACL 肢体（ΔR = 0.21，P = 0.02）和未受伤肢体（ΔR = 0.27，P = 0.01）的较小峰值 vGRF 加载率与前 LFC 的较大 T1ρ MRI ILR 相关。受伤肢体的较小膝关节外展力矩与前 LFC（ΔR = 0.16，P = 0.04）以及后内侧胫骨髁（ΔR = 0.13，P = 0.04）的较大 T1ρ MRI ILR 相关。
在 ACLR 后 6 个月，与步行时机械负荷较小相关的结果与较大的 T1ρ MRI ILR 之间存在关联。尽管初步研究结果表明，ACL 重建后 6 个月 ACLR 肢体的低负荷可能与 ACLR 肢体与未受伤肢体相比，蛋白聚糖密度较低有关。
