Vangsness C T, Mitchell W, Nimni M, Erlich M, Saadat V, Schmotzer H
University of Southern California School of Medicine, Department of Orthopaedics, Los Angeles, USA.
Clin Orthop Relat Res. 1997 Apr(337):267-71. doi: 10.1097/00003086-199704000-00030.
Decreasing joint laxity is a clinical goal of ligament reconstructions. This in vitro study examined the structural and histologic effects of heat shrinkage of human collagen. Two preliminary studies were performed to assess the effect of heat on fresh frozen human tendons obtained from a local tissue bank. As heat was applied to tissue in a saline solution, the percent shrinkage was plotted against temperature. A second study used a freebeam Nd:YAG laser to maximally shrink patellar tendons measuring percent shrinkage versus energy applied. Finally, the effects of 10% shrinkage of fresh frozen human patellar tendons were analyzed mechanically and histologically. Consistent tendon shrinkage curves were found with increasing temperatures in a saline solution. A sharp increase in shrinkage to approximately 70% of resting length was noted around 70 degrees C. Tendon shrinkage by laser induced heat was precise and dose related. Tensile testing of the tendons shortened 10% of their resting length showed a decrease in load to failure to approximately 1/3 compared with that of historical control specimens. Histologic sections showed a well demarcated site of diffuse denaturation and degeneration of collagenous elements. Normal collagen was present adjacent to these thermal changes. These experiments showed that collagen tissue can be shortened precisely by the application of heat. Future studies need to examine the in vivo biologic response of shortened collagen tissue with time, especially recollagenization, restoration of length, and the long term biomechanical effects.
降低关节松弛度是韧带重建的临床目标。这项体外研究考察了人胶原蛋白热收缩的结构和组织学效应。进行了两项初步研究，以评估热对从当地组织库获取的新鲜冷冻人肌腱的影响。当在盐溶液中对组织施加热量时，绘制收缩百分比与温度的关系图。第二项研究使用自由光束钕：钇铝石榴石激光使髌腱最大程度收缩，测量收缩百分比与施加能量的关系。最后，对新鲜冷冻人髌腱10%收缩的影响进行了力学和组织学分析。在盐溶液中，随着温度升高，发现了一致的肌腱收缩曲线。在约70摄氏度时，收缩率急剧增加至静息长度的约70%。激光诱导热导致的肌腱收缩精确且与剂量相关。对缩短至静息长度10%的肌腱进行拉伸测试显示，与历史对照标本相比，破坏载荷降低至约1/3。组织学切片显示胶原成分有明确界定的弥漫性变性和退化部位。在这些热变化区域附近存在正常胶原。这些实验表明，通过施加热量可以精确缩短胶原组织。未来的研究需要考察缩短的胶原组织在体内随时间的生物学反应，特别是再胶原化、长度恢复以及长期生物力学效应。
