Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, San Francisco, CA, USA.
J Orthop Sports Phys Ther. 2012 Jun;42(6):511-20. doi: 10.2519/jospt.2012.3975. Epub 2012 Mar 8.
Case series.
It has been shown in rodent and canine models that cartilage composition is significantly altered in response to long-term unloading. To date, however, no in vivo human studies have investigated this topic. The objective of this case series was to determine the influence of unloading and reloading on T1rho and T2 relaxation times of articular cartilage in healthy young joints.
Ten patients who required 6 to 8 weeks of non-weight bearing (NWB) for injuries affecting the distal lower extremity participated in the study. Quantitative T1rho and T2 imaging of the ipsilateral knee joint was performed at 3 time points: (1) prior to surgery (baseline), (2) immediately after a period of NWB (post-NWB), and (3) after 4 weeks of full weight bearing (post-FWB). Cartilage regions of interest were segmented and overlaid on T1rho and T2 relaxation time maps for quantification. Descriptive statistics are provided for all changes.
Increases of 5% to 10% in T1rho times of all femoral and tibial compartments were noted post-NWB. All values returned to near-baseline levels post-FWB. Increases in medial tibia T2 times were noted post-NWB and remained elevated post-FWB. The load-bearing regions showed the most significant changes in response to unloading, with increases of up to 12%.
The observation of a transient shift in relaxation times confirms that cartilage composition is subject to alterations based on loading conditions. These changes appear to be mostly related to proteoglycan content and more localized to the load-bearing regions. However, following 4 weeks of full weight bearing, relaxation times of nearly all regions had returned to baseline levels, demonstrating reversibility in compositional fluctuations.
Therapy, level 4.
病例系列。
在啮齿动物和犬类模型中已经表明，软骨成分在长期卸载时会发生显著改变。然而，迄今为止，尚无关于该主题的人体体内研究。本病例系列的目的是确定在健康年轻关节中，卸载和再加载对关节软骨 T1rho 和 T2 弛豫时间的影响。
10 名患者因影响下肢远端的损伤需要 6 至 8 周的非负重（NWB），参与了这项研究。对同侧膝关节进行了定量 T1rho 和 T2 成像，在 3 个时间点进行：（1）手术前（基线），（2）NWB 后立即（NWB 后），（3）完全负重 4 周后（负重后）。对 T1rho 和 T2 弛豫时间图进行了感兴趣区分割和叠加，以进行定量分析。提供了所有变化的描述性统计信息。
NWB 后，所有股骨和胫骨节段的 T1rho 时间增加了 5%至 10%。所有值在负重后均恢复到接近基线水平。NWB 后内侧胫骨 T2 时间增加，负重后仍升高。负荷区的变化最显著，增加了 12%。
弛豫时间的短暂变化表明，软骨成分会根据加载条件发生改变。这些变化似乎主要与蛋白聚糖含量有关，且更局限于负荷区。然而，在完全负重 4 周后，几乎所有区域的弛豫时间都恢复到基线水平，表明组成波动具有可逆性。
治疗，4 级。
