Biomedical Services, AO Research Institute, Davos, Switzerland.
J Trauma Acute Care Surg. 2012 Apr;72(4):1098-101. doi: 10.1097/TA.0b013e318248bfa7.
Previous studies have clearly demonstrated superior biomechanical behavior of augmented proximal femoral nail antirotation (PFNA) blades compared with nonaugmented ones with respect to implant cutout. Nevertheless, there is concern about thermal bone necrosis due to exothermic curing of polymethylmethacrylate (PMMA)-based bone cements. The objective of this study was to quantify the temperatures arising around perforated titanium PFNA blades when augmenting with PMMA.
Cylindrical samples from six pairs of fresh frozen human cadaveric femoral heads implanted with a PFNA blade were placed in a 37°C water bath and augmented with 3 mL and 6 mL PMMA. During augmentation, temperatures were measured using six K-type thermocouples that were placed at controlled distances around the implant. With the help of high-resolution quantitative computed tomography images, the locations of all thermocouples with respect to the cement-bone interface were reconstructed.
No temperatures higher than 45°C were measured in the interface region and the surrounding cement-free cancellous bone. In the same regions, the longest exposure time above 41°C was 8.5 minutes and was measured in a 6-mL sample. Average maximum temperature was significantly lower for the 3-mL group compared with the 6-mL group (p = 0.017).
The results of this study suggest that augmentation of titanium PFNA blades is not associated with a risk of thermal bone necrosis when using up to 6 mL of PMMA. However, larger amounts of cement lead to higher temperatures. PMMA application should therefore be kept low to minimally alter the biological system.
先前的研究清楚地表明，与非增强型近端股骨防旋钉（PFNA）刀片相比，增强型刀片在植入物切出方面具有更好的生物力学行为。然而，由于聚甲基丙烯酸甲酯（PMMA）基骨水泥的放热固化，存在热骨坏死的担忧。本研究的目的是量化在增强型 PMMA 时穿孔钛制 PFNA 刀片周围产生的温度。
将来自六对新鲜冷冻人尸头的 PFNA 刀片的圆柱形样本放置在 37°C 的水浴中，并分别用 3 毫升和 6 毫升 PMMA 进行增强。在增强过程中，使用六个 K 型热电偶测量温度，这些热电偶放置在植入物周围的受控距离处。借助高分辨率定量计算机断层扫描图像，重建了所有热电偶相对于骨水泥-骨界面的位置。
在界面区域和周围无水泥的松质骨中，未测量到高于 45°C 的温度。在相同区域，最长的暴露时间超过 41°C 为 8.5 分钟，在 6 毫升样本中测量到。与 6 毫升组相比，3 毫升组的平均最大温度显著降低（p = 0.017）。
本研究结果表明，当使用多达 6 毫升 PMMA 增强钛制 PFNA 刀片时，不会增加热骨坏死的风险。然而，更大剂量的水泥会导致更高的温度。因此，PMMA 的应用应保持较低水平，以最小程度地改变生物系统。
