Helgason Benedikt, Pálsson Halldór, Rúnarsson Tómas Philip, Frossard Laurent, Viceconti Marco
School of Science and Engineering, Department of Biomedical Engineering, Reykjavík University, Iceland.
Med Eng Phys. 2009 Jun;31(5):595-600. doi: 10.1016/j.medengphy.2008.11.015. Epub 2009 Jan 15.
Direct skeletal attachments for transfemoral amputees have been the subject of clinical trials since the early nineties. This method of attachment allows the amputee an unrestricted range of motion around the hip joint, better sitting comfort, improved sensory feedback through osseoperception, improved limb control and reduced soft tissue problems. However, the length of the rehabilitation period is perceived as a shortcoming by the amputees and the clinicians. The aim of the present study is to estimate the risk of failure during gait, for a patient with direct skeletal attachment of a femoral prosthesis, using finite element analysis (FEA). Material properties and loads were derived from subject-specific data and implant stability assumed secured by bone ingrowth into a porous implant surface. A simplified FEA was used to optimize the implant geometry with respect to load bearing capacity. The resulting geometry was then implemented in a subject-specific FE study. The results indicate that the risk of failure for the implant system is approximately three times greater than what can be expected for an intact femur. The main conclusion, based on the risk of failure factors calculated, is that it is likely that a porous-coated implant could be beneficial for osseointegrated fixation. It is also suggested that the proposed methodology can be used in future studies exploring the mechanical stability of osseointegrated fixation in the view of improving direct skeletal attachments for lower limb amputees.
自九十年代初以来，经股骨截肢者的直接骨骼附着一直是临床试验的主题。这种附着方法使截肢者在髋关节周围有不受限制的活动范围，坐姿更舒适，通过骨感知改善感觉反馈，改善肢体控制并减少软组织问题。然而，康复期的长度被截肢者和临床医生视为一个缺点。本研究的目的是使用有限元分析（FEA）评估股骨假体直接骨骼附着患者在步态期间的失败风险。材料特性和载荷来自特定个体数据，并且假定植入物稳定性通过骨长入多孔植入物表面来确保。使用简化的有限元分析来优化植入物几何形状的承载能力。然后将所得几何形状应用于特定个体的有限元研究中。结果表明，植入系统的失败风险大约是完整股骨预期风险的三倍。基于计算出的失败风险因素得出的主要结论是，多孔涂层植入物可能有利于骨整合固定。还建议所提出的方法可用于未来的研究，以探索骨整合固定的机械稳定性，以期改善下肢截肢者的直接骨骼附着。
