Engineering functional partial joint replacement: a soft solution to a hard problem

关节炎是一种常见的问题，典型的治疗方法包括在关节两侧用硬金属代替关节表面，并用中间的塑料或陶瓷代替。虽然成功，但随着时间的推移，这些手术会失败，进一步的手术可能会带来难以预测的结果。在很大比例的情况下，关节炎开始于关节一侧的焦点区域，在这种情况下，可能会更换其中一个接触关节软骨表面。这是侵入性较小，并允许患者恢复日常活动更快。目前，这些治疗选择（被称为半关节成形术）包括用坚硬的金属表面代替柔软的关节软骨，并且在治疗创伤和/或关节炎继发的关节问题中很常见。目前存在用于髋关节、膝关节、踝关节和肩部的半关节置换术，但结果有些不可预测。体外研究表明，用坚硬的、金属的、轴对称的半关节置换术植入物取代相对柔韧的软骨覆盖的天然表面，与天然关节相比，可使关节接触面积减少多达三分之二，并产生更高的峰值接触应力。异常的接触力学可促进原生软骨的退化和侵蚀，导致持续疼痛、僵硬和功能丧失。毫无疑问，发生在器械-软骨界面的相互作用是植入成功的关键。在利兹大学，我们最近开发了一种新的两步方法，用于理想金属和聚合物生物材料的表面激活功能化。该研究利用软物质材料的概念来生产一种在结构和化学上与磷脂双分子层相似的材料系统。这些凝胶型层使我们能够生产相对较厚（~ 3微米）和软润滑的表面层（微< 0.01），尽管具有单一模量和有限的承载能力（有效达到~ 20 MPa的接触压力）。然而，使用这种方法，这些层的性质可以很容易地通过合成参数改变，并且很容易转化为低模量的生物材料（即PEEK）。这为未来的设备和应用提供了巨大的机会，在这些设备和应用中，植入物接口的接触需要与软骨或软组织兼容。本研究的目标包括：1。开发一个强大的多模软水性界面，能够承受在上述应用中观察到的关节反作用力，当滑向关节软骨时。这将在二维表面（PEEK和CoCrMo）上完成，并使用一系列表面敏感（FTIR， XPS, cro - sem），机械（AFM，纳米压痕）和功能评估（摩擦学，腐蚀）进行表征。2 .探讨添加治疗药物靶向治疗感染或局部关节炎的可行性（分别为硫酸庆大霉素或硫酸氨基葡萄糖）。翻译和演示所提出的技术在临床相关组件上的功能。这些设备的耐用性将使用联合模拟器套件来确定。

Arthritis is a common problem and typically treatment includes replacing the articular surfaces with hard metal on both sides of the joint with intervening plastic or ceramic. Although successful, with time these fail and further surgery is extensive with unpredictable outcomes. In a significant proportion of cases, the arthritis starts as a focal area on one side of the joint and in such cases, the replacement of one of the contacting articular cartilage surfaces is possible. This is less invasive and allows the patient to return to day to day activities quicker. Currently, these treatment options (known as hemiarthroplasty) include replacing the soft articular cartilage with a hard metallic surface, and are common in the treatment of joint problems secondary to trauma and/or arthritis. Hemiarthroplasty devices for hip, knee, ankle and shoulder currently exist but with somewhat unpredictable results. In vitro studies have shown that replacing the relatively compliant cartilage-covered native surface with a stiff, metallic, axisymmetrical hemiarthroplasty implant can reduce joint contact area by up to two thirds compared with the native joint and cause higher peak contact stress. The abnormal contact mechanics may promote degeneration and erosion of the native cartilage leading to persistent pain, stiffness, and loss of function. Without a doubt, the interactions occurring at the device-cartilage interface are key to successful implantation.At Leeds, we have recently developed a novel two step method for the surface initiated functionalisation of idealised metallic and polymer biomaterials. This exploits soft matter materials concepts to produce a materials system similar in structure and chemistry to a phospholipid bilayer. These gel-type layers have enabled us to produce a relatively thick (~ 3 micrometers) and soft lubricious surface layer (micro < 0.01), although with a single moduli and limited load bearing capacity (effective up to contact pressures of ~ 20 MPa). However with this methods, the properties of these layers can be varied easily through synthesis parameters and are easily translatable to lower moduli biomaterials (ie PEEK). This presents tremendous opportunities for future devices and application where contact of implant interfaces need to be compliant with cartilage or soft tissues. Objectives of this studentship include:1. Develop a robust multi-moduli soft - aqueous based interface capable of withstanding common joint reaction forces observed in the aforementioned applications when slid against articular cartilage. This will be completed on 2D surfaces (PEEK & CoCrMo) and characterised using a range of surface sensitive (FTIR, XPS, cryo-SEM), mechanical (AFM, Nano-indentation) and functional assessments (Tribology, Corrosion).2. Investigate the feasibility of adding therapeutic agents for the targeted treatment of infection or localised arthritis (gentamicin sulphate or glucosamine sulphate, respectively).3. Translate and demonstrate the functionality of the proposed technology on clinically relevant components. The durability of these devices will be determined using the suite of joint simulators.