Vibration analysis methods have been studied to evaluate bone stiffness as a quantifiable mechanical parameter that associates with the degree of fracture healing. However, the effects of soft tissue on the bone frequency response still remain as significant challenges in successfully implementing vibration analysis-based methods as an effective clinical assessment tool. This study presents a computational investigation on the mass-loading effect of soft tissue on a fractured femur bone fixated with an intramedullary nail. An oblique fracture is modelled by a 3 mm osteotomised region, where its elastic modulus is varied from 0% to 100% of the pristine bone elastic modulus to simulate the stages of fracture bone healing. The findings indicate that the first-order torsional and second-order bending modal frequencies change significantly as the fracture region regains stiffness and the significant increase in third-order bending mode amplitude suggests the fracture stiffness has recovered over 1% of the pristine bone stiffness. Furthermore, mass-loading soft tissue does not affect the torsional mode and has negligible effects on the second-order bending modes. An additional inertia strategy is employed to determine a bone healing parameter relating to the femur stiffness by utilising the torsional modal frequency. A normalised torsional flexibility scoring procedure is then devised to evaluate the healing stages of an internally fixated femur. The subsequent results serve as an important pre-requisite to develop a quantifiable bone union measure and for future efficacy testing.

已经研究了振动分析方法，以评估骨刚度作为与骨折愈合程度相关的可量化机械参数。然而，在成功实施基于振动分析的方法作为有效的临床评估工具时，软组织对骨频率响应的影响仍然是重大挑战。这项研究提出了关于用髓内钉固定股骨骨折的软组织的质量负荷效应的计算研究。斜形骨折由3毫米的截骨区域建模，其弹性模量在原始骨弹性模量的0％到100％之间变化，以模拟骨折愈合的阶段。研究结果表明，随着骨折区域恢复刚度，一阶扭转模态频率和二阶弯曲模态频率发生了显着变化，三阶弯曲模态振幅的显着增加表明断裂刚度恢复了原始骨刚度的1％以上。此外，大量加载软组织不会影响扭转模式，并且对二阶弯曲模式的影响可忽略不计。通过利用扭转模态频率，采用附加的惯性策略来确定与股骨硬度有关的骨愈合参数。然后设计标准化的扭转柔韧性评分程序，以评估内固定股骨的愈合阶段。