Abstract Background Rotational osteotomy is frequently indicated to correct excessive femoral anteversion in cerebral palsy patients. Angled blade plate is the standard fixation device used when performed in the proximal femur, but extensile exposure is required for plate accommodation. The authors developed a short locked intramedullary nail to be applied percutaneously in the fixation of femoral rotational osteotomies in children with cerebral palsy and evaluated its mechanical properties. Methods The study was divided into three stages. In the first part, a prototype was designed and made based on radiographic measurements of the femoral medullary canal of ten-year-old patients. In the second, synthetic femoral models based on rapid-prototyping of 3D reconstructed images of patients with cerebral palsy were obtained and were employed to adjust the nail prototype to the morphological changes observed in this disease. In the third, rotational osteotomies were simulated using synthetic femoral models stabilized by the nail and by the AO-ASIF fixed-angle blade plate. Mechanical testing was done comparing both devices in bending-compression and torsion. Results The authors observed proper adaptation of the nail to normal and morphologically altered femoral models, and during the simulated osteotomies. Stiffness in bending-compression was significantly higher in the group fixed by the plate (388.97 ± 57.25 N/mm) than in that fixed by the nail (268.26 ± 38.51 N/mm) as torsional relative stiffness was significantly higher in the group fixed by the plate (1.07 ± 0.36 Nm/°) than by the nail (0.35 ± 0.13 Nm/°). Conclusions Although the device presented adequate design and dimension to fit into the pediatric femur, mechanical tests indicated that the nail was less stable than the blade plate in bending-compression and torsion. This may be a beneficial property, and it can be attributed to the more flexible fixation found in intramedullary devices.
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机译：摘要背景旋转截骨术常用于纠正脑瘫患者的股骨前倾过度。倾斜的刀片板是在股骨近端进行手术时使用的标准固定装置，但是板暴露需要伸展性暴露。作者开发了一种短锁髓内钉，将其经皮应用于脑瘫患儿股骨旋转截骨术的固定，并评估了其机械性能。方法研究分为三个阶段。在第一部分中，基于对十岁患者的股骨髓管进行放射线照相测量，设计并制造了原型。第二步，获得基于脑瘫患者3D重建图像快速原型的合成股骨模型，并将其用于调整指甲原型以适应这种疾病中观察到的形态变化。第三，使用由股骨和AO-ASIF固定角刀片固定的合成股骨模型模拟旋转截骨术。进行了机械测试，比较了两种设备的弯曲压缩和扭转情况。结果作者观察到指甲在正常和形态改变的股骨模型中以及在模拟截骨术中的适当适应性。钉板固定组的弯曲压缩刚度（388.97±57.25 N / mm）明显高于钉固定组的弯曲压缩刚度（268.26±38.51 N / mm），因为钉板固定组的扭转相对刚度明显更高。板（1.07±0.36 Nm /°）比用钉子（0.35±0.13 Nm /°）高。结论尽管该装置具有足够的设计和尺寸以适合小儿股骨，但机械测试表明，在弯曲压缩和扭转方面，指甲的稳定性不如刀片。这可能是有益的性质，并且可以归因于在髓内装置中发现的更灵活的固定。
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