PRELIMINARY MECHANICAL TEST OF PROXIMAL FEMUR REINFORCEMENT WITH CEMENTED X-SHAPED PMMA

ABSTRACT Objective: To evaluate the mechanical behavior of the proximal end of the femur submitted to the X-shaped polymethylmethacrylate (PMMA) reinforcement technique. Methods: Fifteen synthetic femurs, with a Nacional® density of 10 PCF, were divided into two groups: the DX group, with 5 units that were submitted to PMMA reinforcement, and the DP group, with 10 units, which were evaluated intact. The volume of PMMA required, the maximum load, and the absorbed energy to fracture were analyzed by means of a static mechanical bending test simulating a fall on the greater trochanter. Results: A mean of 6 ml of PMMA was used to model the X-reinforcement; it was observed that the DX group presented significantly higher maximum load (median = 1553 N, p = 0.005) and absorbed energy to fracture (median = 9.7 J; p = 0.050) than the DP group (median = 905 N and 6.6 J). Conclusion: X-reinforcement of the proximal end of synthetic femurs showed a statistically significant increase in the maximum load and absorbed energy to fracture in the mechanical assay when compared to the control group. Level of Evidence III, Experimental study.摘要 目的：评估接受X形聚甲基丙烯酸甲酯（PMMA）强化技术的股骨近端的力学行为。 方法：选取15具Nacional®密度为10 PCF的合成股骨，分为两组：DX组（5具，接受PMMA强化处理）与DP组（10具，为完整未处理标本）。通过模拟大转子跌倒的静态力学弯曲试验，对所需PMMA体积、最大载荷及骨折吸收能量进行分析。 结果：X形强化所需PMMA平均用量为6ml；结果显示，DX组的最大载荷（中位数=1553 N，p=0.005）及骨折吸收能量（中位数=9.7 J；p=0.050）均显著高于DP组（中位数分别为905 N和6.6 J）。 结论：与对照组相比，合成股骨近端的X形强化处理可使力学试验中的最大载荷与骨折吸收能量出现具有统计学意义的提升。 证据等级Ⅲ级，属实验性研究。