Thornton G M, Oliynyk A, Frank C B, Shrive N G
McCaig Centre for Joint Injury and Arthritis Research, University of Calgary, Alberta, Canada.
J Orthop Res. 1997 Sep;15(5):652-6. doi: 10.1002/jor.1100150504.
In normal daily activity, ligaments are probably subjected to repeated loading rather than to repeated deformation. The viscoelastic response to repeated loading is creep; this effect has significance for ligament reconstructions, which potentially "stretch out" over time. However, most experimental studies have examined the viscoelastic response to repeated deformation, stress relaxation. We hypothesized that the creep of a ligament could be predicted from its stress-relaxation behaviour. Left and right medial collateral ligaments of eight skeletally mature rabbits were subjected to either creep or stress-relaxation testing under comparable conditions. The time-dependent increase in strain (creep) and reduction in load (relaxation) from the tests were modelled with use of the quasilinear viscoelastic theory and generalized standard linear solid modelling. Ligaments were found to creep distinctly less than would be predicted from relaxation tests. Although the reason for this behaviour remains unknown, we speculate that it is due to the progressive recruitment of collagen fibres during creep.
在日常正常活动中，韧带可能承受反复加载而非反复变形。对反复加载的粘弹性响应是蠕变；这种效应对于韧带重建具有重要意义，因为韧带重建可能会随着时间“拉长”。然而，大多数实验研究考察的是对反复变形的粘弹性响应，即应力松弛。我们假设韧带的蠕变可以从其应力松弛行为预测。对八只骨骼成熟兔子的左右内侧副韧带在可比条件下进行蠕变或应力松弛测试。利用准线性粘弹性理论和广义标准线性固体模型对测试中应变随时间的增加（蠕变）和负荷的降低（松弛）进行建模。结果发现韧带的蠕变明显小于根据松弛测试所预测的程度。尽管这种行为的原因尚不清楚，但我们推测这是由于蠕变过程中胶原纤维的逐步募集所致。
