Kinneberg Kirsten R C, Galloway Marc T, Butler David L, Shearn Jason T
University of Cincinnati, School of Energy, Environmental, Biological and Medical Engineering, Biomedical Engineering Program, 601 Engineering Research Center, Cincinnati, OH 45220, USA.
J Biomech Eng. 2011 Sep;133(9):091002. doi: 10.1115/1.4004948.
Previous studies by our laboratory have demonstrated that implanting a stiffer tissue engineered construct at surgery is positively correlated with repair tissue stiffness at 12 weeks. The objective of this study was to test this correlation by implanting a construct that matches normal tissue biomechanical properties. To do this, we utilized a soft tissue patellar tendon autograft to repair a central-third patellar tendon defect. Patellar tendon autograft repairs were contrasted against an unfilled defect repaired by natural healing (NH). We hypothesized that after 12 weeks, patellar tendon autograft repairs would have biomechanical properties superior to NH. Bilateral defects were established in the central-third patellar tendon of skeletally mature (one year old), female New Zealand White rabbits (n = 10). In one limb, the excised tissue, the patellar tendon autograft, was sutured into the defect site. In the contralateral limb, the defect was left empty (natural healing). After 12 weeks of recovery, the animals were euthanized and their limbs were dedicated to biomechanical (n = 7) or histological (n = 3) evaluations. Only stiffness was improved by treatment with patellar tendon autograft relative to natural healing (p = 0.009). Additionally, neither the patellar tendon autograft nor natural healing repairs regenerated a normal zonal insertion site between the tendon and bone. Immunohistochemical staining for collagen type II demonstrated that fibrocartilage-like tissue was regenerated at the tendon-bone interface for both repairs. However, the tissue was disorganized. Insufficient tissue integration at the tendon-to-bone junction led to repair tissue failure at the insertion site during testing. It is important to re-establish the tendon-to-bone insertion site because it provides joint stability and enables force transmission from muscle to tendon and subsequent loading of the tendon. Without loading, tendon mechanical properties deteriorate. Future studies by our laboratory will investigate potential strategies to improve patellar tendon autograft integration into bone using this model.
我们实验室之前的研究表明，手术时植入更硬的组织工程构建体与12周时修复组织的硬度呈正相关。本研究的目的是通过植入与正常组织生物力学特性相匹配的构建体来验证这种相关性。为此，我们使用软组织髌腱自体移植物修复髌腱中央三分之一处的缺损。将髌腱自体移植修复与通过自然愈合（NH）修复的未填充缺损进行对比。我们假设12周后，髌腱自体移植修复的生物力学特性将优于自然愈合。在骨骼成熟（一岁）的雌性新西兰白兔（n = 10）的髌腱中央三分之一处建立双侧缺损。在一侧肢体中，将切除的组织即髌腱自体移植物缝合到缺损部位。在对侧肢体中，缺损处保持空置（自然愈合）。恢复12周后，对动物实施安乐死，并将其肢体用于生物力学（n = 7）或组织学（n = 3）评估。与自然愈合相比，仅髌腱自体移植治疗改善了硬度（p = 0.009）。此外，髌腱自体移植和自然愈合修复均未在肌腱与骨骼之间再生出正常的带状插入位点。II型胶原的免疫组织化学染色表明，两种修复在肌腱-骨界面均再生出了纤维软骨样组织。然而，该组织排列紊乱。肌腱与骨交界处的组织整合不足导致测试期间插入部位的修复组织失效。重新建立肌腱与骨插入位点很重要，因为它提供关节稳定性，并使力能够从肌肉传递到肌腱以及随后加载到肌腱上。没有负荷，肌腱的力学性能会恶化。我们实验室未来的研究将使用该模型研究改善髌腱自体移植物与骨整合的潜在策略。
