New technique to extend the useful life of a biodegradable cartilage implant.
New technique to extend the useful life of a biodegradable cartilage implant.
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延长可生物降解软骨植入物使用寿命的新技术。
DOI：
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发表时间：
1998
影响因子：
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通讯作者：
Kyriacos, Κυριάκος, Athanasiou, Αθανασίου
中科院分区：
文献类型：
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作者：
T. L. Spain;C. M. Agrawal;Kyriacos, Κυριάκος, Athanasiou, Αθανασίου
由α-羟基聚酯（如聚乳酸、聚乙醇酸或其共聚物）制成的生物可降解植入物经历本体降解，伴随着质量损失。尽管生物相容性或毒性问题（偶尔会报告这些材料的体内行为）与快速质量损失无关，但我们假设这些植入物应以更均匀的速率降解和损失质量。为此，我们设计了一种新的植入物，预期用于关节软骨修复，由三种共聚物的混合物组成，即特性粘度为0.23、0.58和1.37 dL/g的50：50聚（d，l）-丙交酯-乙交酯共聚物。混合植入物设计的目的是与先前的设计（使用特性粘度为0.58 dL/g的单一共聚物）相比，实现更慢的降解速率和质量损失。共混物的体外降解特性，并进行了比较的质量，分子量，pH值，机械性能，总形态和孔隙率方面的控制设计。我们研究的另一个目的是设计和采用一种新的测试来评估多孔支架的渗透性，在直接渗透条件下使用定制的装置。两组的时间行为存在显著差异，混合种植体保持整体结构完整性的时间长于对照样本（6周对3周）。这是一个令人惊讶的发现，因为这两组的分子量损失相似。通过该研究中描述的方法实现的结构有用性延长至6周，可以预期增强该支架在诸如软骨修复的体内应用中的活力。因此，共混共聚物植入物可能更适合于骨科应用，其中降低的降解速率将是优选的。
Biodegradable implants made of alpha-hydroxypolyesters, such as polylactic acid, polyglycolic acid, or their copolymers, undergo bulk degradation with a concomitant mass loss. Although biocompatibility or toxicity problems, which have occasionally been reported in response to these materials' in vivo behavior, have not been conclusively linked to rapid mass loss, we hypothesized that such implants should degrade and lose mass in a more uniform rate. To this end, we designed a new implant, intended to be used in articular cartilage repair, consisting of a blend of three copolymers of 50:50 poly(d,l)-lactide coglycolide with inherent viscosities of 0.23, 0.58, and 1.37 dL/g. The objective of the blend implant design was to achieve a slower rate of degradation and mass loss in comparison to a previous design, which used a single copolymer of inherent viscosity of 0.58 dL/g. The blend's in vitro degradation characteristics were obtained and compared to those of the control design in terms of mass, molecular weight, pH, mechanical properties, gross morphology, and porosity. Another objective of our study was to design and employ a novel test for assessing the permeability of porous scaffolds, using a custom apparatus under direct permeation conditions. Significant differences in the temporal behavior of the two groups were found. The blend implants maintained their overall structural integrity longer than control specimens (6 weeks versus 3 weeks). This was a surprising finding in light of the fact that losses in molecular weight were similar in the two groups. Extension of structural usefulness to 6 weeks, achieved by the method described in the study, can be expected to enhance the viability of this scaffold in an in vivo application such as cartilage repair. Thus, the blended copolymer implants may be more suitable in orthopedic applications, where a decreased degradation rate would be preferable.