Witkiewicz H, Deng M, Vidovszky T, Bolander M E, Rock M G, Morrey B F, Shalaby S W
Department of Orthopedics, Mayo Clinic, Rochester, Minnesota, USA.
J Biomed Mater Res. 1996 Summer;33(2):73-82. doi: 10.1002/(SICI)1097-4636(199622)33:2<73::AID-JBM3>3.0.CO;2-I.
Differential scanning calorimetry (DSC) was used to examine thermal and thermooxidative properties of ultrahigh molecular weight polyethylene (UHMW-PE) of five acetabular components of failed orthopedic implants retrieved at revision of total hip arthoplasty. The results were compared with controls (unimplanted acetabular cups, a 20-year-old slab of UHMW-PE, and raw material). Profiles of exothermic peaks indicated increased levels of oxidation in all retrieved cups. In three retrieved cups, DSC revealed an additional peak of endotherm that was not seen in control samples. The additional endotherm peaks were not artifacts due to oxidation during scanning, heat buildup during cutting of the samples, or the sterilization method after retrieval. The additional peak was associated with the bulk of the polymer that was extracted with hexane. It varied in relative area, depending on its original location of the sample in a cup, implicating local variability in the extent of changes in material property. The distribution of the changes suggests that, during implantation, tissue exposure and friction affected the level of oxidation and degree of crystallinity in the UHMW-PE to a greater degree than did loading alone. Overall results showed that DSC may be a useful tool in evaluating changes in the properties of UHMW-PE orthopedic components in vivo.
采用差示扫描量热法（DSC）检测了在全髋关节置换翻修术中取出的5个失败骨科植入物髋臼组件的超高分子量聚乙烯（UHMW-PE）的热性能和热氧化性能。将结果与对照组（未植入的髋臼杯、一块20年的UHMW-PE平板和原材料）进行比较。放热峰曲线表明，所有取出的髋臼杯中氧化水平均有所升高。在3个取出的髋臼杯中，DSC显示出一个额外的吸热峰，而在对照样品中未观察到该峰。额外的吸热峰并非扫描过程中氧化、样品切割过程中产生的热量积累或取出后灭菌方法所导致的假象。该额外峰与用己烷萃取的聚合物主体相关。其相对面积有所不同，这取决于样品在髋臼杯中的原始位置，这意味着材料性能变化程度存在局部差异。变化的分布表明，在植入过程中，组织暴露和摩擦对UHMW-PE中氧化水平和结晶度的影响程度大于单纯的负荷影响。总体结果表明，DSC可能是评估体内UHMW-PE骨科组件性能变化的有用工具。
