许多老年股骨颈骨折后医生给予了人工股骨头置换手术治疗，该手术尤其显著优点：手术快、损伤小、恢复快，患者术后即可下地活动，很快能够恢复到手术前的活动状态。但其最大的问题在于人工股骨头的材料目前都是采用了金属，包括钴铬钼合金或医用不锈钢等材料，随之而来的问题是髋关节对侧髋臼软骨的磨损。北京大学人民医院骨关节科李志昌北京大学人民医院骨关节科李志昌

美国骨科研究会官方杂志Journal of Orthopaedic Research最新的研究指出：人工股骨头置换术后髋臼软骨磨损加速是由于假体材料与骨软骨刚度不匹配所造成的。该研究利用有限元模型分析方法，尝试了多种人工股骨头材料（钴铬钼、热解炭、聚醚醚酮、高分子聚乙烯、Bionate‐55D、Bionate‐75D 和 Bionate‐80A）。同时该研究还关注了人工股骨头直径与髋臼直径的最佳配比，股骨柄安放内外翻等因素。最终发现，人工股骨头界面材料对于与髋臼软骨表面接触面积和最大接触应力都有着显著的影响。所有的材料均与原有的软骨存在差异，只有Bionate-80A在某两个角度时与原始软骨相同。只有界面弹性模量小玉Bionate-55D(288MPa）时，其对髋臼软骨的影响才显著降低，接近原始软骨。这一研究结果提示，当前使用的人工股骨头界面材料的刚度都过高。从保护对侧软骨的角度考虑，需要大大降低人工股骨头材料的刚度。

RESEARCH ARTICLE

Hemiarthroplasty implants should have very low stiffness to optimize cartilage contact stress

Carolyn Berkmortel , G. Daniel G. Langohr , Graham King , James Johnson?? First published: 03 February 2020| https://doi.org/10.1002/jor.24610 Read the full text

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Abstract

Hemiarthroplasty is often preferred to total arthroplasty as it preserves native tissue; however, accelerated wear of the opposing cartilage is problematic. This is thought to be caused by the stiffness mismatch between the implant and cartilage‐bone construct. Reducing the stiffness of the implant by changing the material has been hypothesized as a potential solution. This study employs a finite element model to study a concave‐convex hemiarthroplasty articulation for various implant materials (cobalt‐chrome, pyrolytic carbon, polyether ether ketone, ultra‐high‐molecular‐weight polyethylene, Bionate‐55D, Bionate‐75D, and Bionate‐80A). The effect of the radius of curvature and the degree of flexion‐extension was also investigated to ensure any relationships found between materials weregeneralizable. The implant material had a significant effect (P   < .001) for both contact area and maximum contact pressure on the cartilage surface. All of the materials were different from the native state except for Bionate‐80A at two of the different flexion angles. Bionate‐80A and Bionate‐75D, the materials with the lowest stiffnesses, were the closest to the native state for all flexion angles and radii of curvature. No evident difference between materials occurred unless the modulus was below that of Bionate‐55D (288 MPa), suggesting that hemiarthroplasty materials need to be less stiff than this material if they are to protect the opposing cartilage. This is clinically significant as the findings suggest that the development of new hemiarthroplasty implants should use materials with stiffnesses much lower than currently available devices.