Boner Vanessa, Kuhn Philipp, Mendel Thomas, Gisep Armando
AO Development Institute, Davos, Switzerland.
J Biomed Mater Res B Appl Biomater. 2009 Aug;90(2):842-8. doi: 10.1002/jbm.b.31353.
The use of polymethylmethacrylate (PMMA) bone cement to augment hip screws reduces cut-out risk but is associated with an exothermic reaction. This in vitro investigation evaluated the risk of thermal necrosis when augmenting the implant purchase with PMMA. A pilot study analyzed the effects of different PMMA layer thicknesses on temperatures around an implant. The main study used either 3.0 or 6.0 cc PMMA for hip screw augmentation in human femoral heads. The risk of thermal necrosis was estimated according to critical values reported in literature. Highest temperatures were measured inside the PMMA with a significant drop of average maximum temperatures from the center of the PMMA to the PMMA/bone interface. Risk of thermal necrosis exists with PMMA layer thicknesses greater than 5.0 mm. In the main study, we found no risk of thermal necrosis at the PMMA/bone interface or in the surrounding bone, neither with 3.0 nor 6.0 cc PMMA. The results of the two studies were consistent regarding average peak temperatures related to associated cement layer thicknesses. The results of this in vitro study reduce objections concerning the risk of thermal necrosis when augmenting cancellous bone around hip screws with up to 6.0 cc PMMA.
使用聚甲基丙烯酸甲酯（PMMA）骨水泥增强髋螺钉可降低螺钉穿出风险，但会引发放热反应。这项体外研究评估了用PMMA增强植入物锚合力时发生热坏死的风险。一项初步研究分析了不同PMMA层厚度对植入物周围温度的影响。主要研究采用3.0或6.0立方厘米的PMMA对人体股骨头中的髋螺钉进行增强。根据文献报道的临界值估计热坏死风险。在PMMA内部测量到最高温度，从PMMA中心到PMMA/骨界面平均最高温度显著下降。当PMMA层厚度大于5.0毫米时存在热坏死风险。在主要研究中，我们发现在PMMA/骨界面或周围骨中，无论是3.0还是6.0立方厘米的PMMA都不存在热坏死风险。两项研究关于与相关骨水泥层厚度相关的平均峰值温度的结果是一致的。这项体外研究的结果减少了关于用高达6.0立方厘米的PMMA增强髋螺钉周围松质骨时热坏死风险的反对意见。
