Inacio Jordan V, Malige Ajith, Schroeder Jake T, Nwachuku Chinenye O, Dailey Hannah L
Department of Mechanical Engineering & Mechanics, Lehigh University, Packard Laboratory, 19 Memorial Drive West, Bethlehem, PA 18015, USA.
Department of Orthopaedic Surgery, St. Luke's University Health Network, 801 Ostrum Street, Bethelehem, PA 18015, USA.
Clin Biomech (Bristol). 2019 Jul;67:20-26. doi: 10.1016/j.clinbiomech.2019.04.014. Epub 2019 Apr 24.
Mechanical testing of implant constructs designed to treat distal femur fractures has been hampered by a lack of clinical data on the biomechanical properties of the distal femur in patients who sustain these fractures. Therefore, the purpose of this study was to use quantitative computed tomography (qCT) to investigate the mechanical characteristics of fractured distal femurs to inform the selection of synthetic materials for biomechanical testing.
Distal femur fractures treated at a Level I trauma center were retrospectively reviewed and 43 cases with preoperative CT scans were identified for analysis. Scans were segmented and each bone fragment was reconstructed as a 3D model. The Young's modulus of the distal femur was determined from voxel-based radiodensity.
Median patient age was 72 years (IQR = 57-81), with 26% males and 74% females. Young's modulus in the distal femur was negatively correlated with patient age (R = 0.50, p < 0.001). The distribution of patient-specific modulus values was also compared with the compressive modulus ranges for graded polyurethane foams according to ASTM F1839. Bone quality ranged from Grade 25 in younger individuals to Grade 5 in older individuals.
No single grade of synthetic polyurethane foam can be selected to model all clinically important scenarios for biomechanical testing of distal femur fracture fixation devices. Rather, this data can be used to select an appropriate material for a given clinical scenario. A Grade 25 foam is appropriate for implant longevity, whereas for implant stability, Grades 5-15 are more appropriate.
用于治疗股骨远端骨折的植入物结构的力学测试一直受到阻碍，因为缺乏这些骨折患者股骨远端生物力学特性的临床数据。因此，本研究的目的是使用定量计算机断层扫描（qCT）来研究骨折股骨远端的力学特性，为生物力学测试中合成材料的选择提供依据。
回顾性分析在一级创伤中心治疗的股骨远端骨折病例，确定43例术前行CT扫描的病例进行分析。对扫描图像进行分割，将每个骨碎片重建为三维模型。根据基于体素的骨密度测定股骨远端的杨氏模量。
患者中位年龄为72岁（四分位间距=57-81岁），男性占26%，女性占74%。股骨远端的杨氏模量与患者年龄呈负相关（R=0.50，p<0.001）。还将患者特异性模量值的分布与根据ASTM F1839分级的聚氨酯泡沫的压缩模量范围进行了比较。骨质从年轻个体的25级到老年个体的5级不等。
不能选择单一等级的合成聚氨酯泡沫来模拟股骨远端骨折固定装置生物力学测试的所有临床重要情况。相反，这些数据可用于为特定临床情况选择合适的材料。25级泡沫适合植入物的长期使用，而对于植入物的稳定性，5-15级更合适。
