Design and evaluation of a new short stemmed hip implant using porous titanium material to diminish stress shielding

髋关节炎的标准治疗是全髋关节置换术(THA)。尽管全髋关节置换术是一种成功的手术治疗，但年轻患者的失败促使人们寻找替代的解决方案，这些方案可能更耐用，并可能保留股骨储备，以供未来翻修。随着微创手术的日益普及，保守性植入物应运而生。短柄具有保留股骨骨块以备将来翻修的优点。众所周知，在股骨内植入金属装置可以改变向周围骨骼的负荷转移。较短的股骨柄可能会以一种更生理的方式加载股骨，从而降低应力屏蔽的风险。这种现象是由于金属和骨之间的硬度不同而引起的，导致骨吸收或骨密度下降。随着快速制造工艺的进步，现在可以设计出多孔微结构等复杂的结构材料。多孔金属材料促进骨细胞在结构内生长，导致更好的骨整合，从而更好地固定植入物与周围骨。本研究的目的是利用生物力学建模和有限元分析的方法，设计和评价一种新型仿生材料制成的短柄人工髋关节假体，以提高假体的长期存活率。该项目包括两个部分。第一部分是通过研究假体长度对假体稳定性和股骨应力的影响来评价一种新的短柄假体。第二部分是对多孔钛材料的微观结构进行优化，以获得与股骨松质骨性能相似的力学性能，并研究用该材料制作的短柄种植体的骨应力分布和应力屏蔽。拟议的方案将基于候选人所在小组之前的建模工作。

Standard treatment of hip arthritis is Total Hip Arthroplasty (THA). Although THA is a successful surgical intervention, failures in younger patients have led to search for alternative solutions which may be more durable and may conserve femoral bone stock for future revision. The increasing popularity of minimally invasive surgery had led to the development of conservative implants. Short stem has the advantage of preserving femoral bone stock for future revision. It is well known that the implantation of a metallic device inside the femur modifies the load transfer to the surrounding bone. Shorter femoral stem may load the femoral bone in a more physiological way and so reduce the risk of stress shielding. This phenomenon, caused by the difference in rigidity between the metal and the bone, leads to bone resorption or decrease of bone density. With the advancement of rapid manufacturing processes, complex structural materials can now be designed such as porous microstructures. Porous metallic materials promote bone cells to grow inside the structure, leading to better osseointegration, consequently better fixation of the implant to the surrounding bone. The aim of this research project is to design and evaluate a short stemmed hip implant made of a new biomimetic material to improve long-term survivorship of the arthroplasty, using biomechanical modeling and finite element analysis. The project foresees two parts. Part 1 consists in evaluating a new short stem implant by investigating the effect of stem length on primary stability and the femoral stresses. Part 2 consists in optimizing the microstructure of the porous titanium material to obtain mechanical properties similar to femoral cancellous bone properties, and investigate bone stress distribution and stress shielding of the short stemmed implant proposed with this material. The proposed program will be based on the previous modeling works of the candidate's group.