Chatterjee Subhomoy, Roy Sandipan, Majumder Santanu, RoyChowdhury Amit
Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Howrah, West Bengal 711103, India; Materials Research Centre, Indian Institute of Science, Bangalore, Karnataka 560012, India.
Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Howrah, West Bengal 711103, India; Department of Mechanical Engineering, SRM Institute of Science & Technology, Kattankulathur, Kancheepuram, Chennai, Tamil Nadu 603203, India.
J Biomech Eng. 2020 Oct 1;142(10). doi: 10.1115/1.4046973.
Stress shielding due to difference in stiffness of bone and implant material is one among the foremost causes of loosening and failure of load-bearing implants. Thus far, femoral geometry has been given priority for the customization of total hip joint replacement (THR) implant design. This study, for the first time, demonstrates the key role of bone condition and subject-weight on the customization of stiffness and design of the femoral stem. In particular, internal hollowness was incorporated to reduce the implant stiffness and such designed structure has been customized based on subject parameters, including bone condition and bodyweight. The primary aim was to tailor these parameters to achieve close to natural strain distribution at periprosthetic bone and to reduce interfacial bone loss over time. The maintenance of interfacial bone density over time has been studied here through analysis of bone remodeling (BR). For normal bodyweight, the highest hollowness exhibited clinically relevant biomechanical response, for all bone conditions. However, for heavier subjects, consideration of bone quality was found to be essential as higher hollowness induced bone failure in weaker bones and implant failure in stronger bones. Moreover, for stronger bone, thinner medial wall was found to reduce bone resorption over time on the proximo-lateral zone of stress shielding, while lateral thinning was found advantageous for weaker bones. The findings of this study are likely to facilitate designing of femoral stems for achieving better physiological outcomes and enhancement of the quality of life of patients undergoing THR surgery.
由于骨与植入物材料刚度差异导致的应力遮挡是承重植入物松动和失效的主要原因之一。到目前为止，股骨几何形状在全髋关节置换（THR）植入物设计定制中一直占据优先地位。本研究首次证明了骨状况和受试者体重在股骨柄刚度定制和设计中的关键作用。特别是，通过引入内部中空来降低植入物刚度，并且这种设计结构已根据包括骨状况和体重在内的受试者参数进行定制。主要目的是调整这些参数，以在假体周围骨处实现接近自然的应变分布，并随着时间的推移减少界面骨丢失。在此，通过骨重塑（BR）分析研究了随时间推移界面骨密度的维持情况。对于正常体重的受试者，在所有骨状况下，最高的中空度表现出临床相关的生物力学反应。然而，对于体重较重的受试者，发现考虑骨质至关重要，因为较高的中空度会在较弱的骨中导致骨衰竭，而在较强的骨中导致植入物失效。此外，对于较强的骨，较薄的内侧壁被发现可减少应力遮挡近端外侧区域随时间的骨吸收，而外侧变薄对较弱的骨有利。本研究结果可能有助于设计股骨柄，以实现更好的生理结果并提高接受THR手术患者的生活质量。
