人工关节假体:材料特征与物理治疗

背景:人工关节置换是应用人工生物材料替代已有明显病损的关节,从而达到缓解疼痛、纠正畸形、恢复与改善关节功能的目的。目的:探讨人工关节假体材料与关节置换后物理治疗的效果。方法:以"人工关节,关节材料,物理治疗;artificial joints,joints materials,physical therapy"为关键词,应用计算机检索2000至2014年万方数据库、清华知网数据库、Pub Med数据库,选取有关人工关节假体材料与关节置换后物理治疗的文献,同一领域文献选择权威杂志或发表时间为近期的文章,依据纳入排除标准选取15篇文献进行分析。结果与结论:对于不同人工关节假体材料有着不同的康复治疗方案。人工关节置换后的物理治疗方法包括物理因子疗法和运动疗法。物理因子疗法可以减少炎性因子的释放并促进吸收,有效缓解疼痛,低频超声干预下可促进和加快载抗生素骨水泥的药物释放。运动康复疗法应用持续被动活动机可以促进静脉淋巴回流,减轻患肢肿胀,避免静脉血栓的发生,预防和治疗关节挛缩,有利于肌力的增强,促进人工关节置换后关节功能的恢复。选择适宜的人工关节假体材料并在置换后进行科学合理的物理治疗,可以使患者达到康复速度快、关节活动度好、并发症少的目的。     

人工关节的研究现状和发展趋势

人工关节用于临床已有近百年的历史，经科研工作者们的不断努力，人工关节从材料到设计，都取得了很大的进步。随着材料制造技术及医疗技术的发展，人们已经能够应用多种金属或合金、高分子聚合物、碳质材料、陶瓷材料等对患者进行骨或关节的置换。目前，人工关节的置换包括有髋、膝、肩、肘、腕、踝等关节，但以髋关节和膝关节置换为主，     

不同生物材料假体在人工关节置换中的应用现状

背景：人工关节置换中假体材料替代原有的病损关节,可以极大改善患者的关节功能,减轻疼痛,恢复运动,提高生活质量。 目的：概述目前应用于关节置换领域的假体材料及研究进展。 方法：以biomaterials, joint prosthesis, implants为检索词,检索PubMed 数据库(2000年1月至2011年12月中有关关节置换领域假体材料的文献。 结果与结论：目前临床中常见的关节假体材料包括金属、聚合物、陶瓷等,这些材料已被学者们所接受,并广泛应用于临床中,但仍存在一些不足和亟待解决的问题,如何完善和提升金属、聚合物、陶瓷的性能,降低甚至去除可能的磨损、离子释放、骨溶解、碎裂等不良后果,是目前需要学者们共同考虑的问题。相信随着制作工艺的不断进步、研究的不断深入,牢固可靠的假体材料定将推陈出新,达到更加令人满意的疗效,为临床所用。     

用于骨移植的模拟生物材料

以往应用于骨关节置换的主要是三种金属材料,即奥氏体不锈钢、钴镍合金和钛。这些材料的性质对冶金处理的微结构很敏感,特别是疲劳强度和移植体的表面状况关系很大。由这些材料制成的全关节置换假体在体内寿命都不够长,有时需再次手术进行修理。导致移植体疲劳的主要原因是合成的与天然的关节结构配合不好以及移植材料与周围骨头变形有差异。因     

基于两种材料的髋关节假体柄疲劳性能分析

人工髋关节置换手术是利用机械性能和生物相容性良好的材料制成类似人体骨关节的假体,然后把其置换到被破坏的关节面。它可以缓解甚至消除病痛,有效地维持关节的稳定性和自由度,从而恢复关节的正常性能。利用有限元法建立人工髋关节股骨柄的三维有限元模型,以探讨不同材料股骨柄假体的疲劳性能,从而确保髋关节置换假体的安全性及可靠性。计算获得了两种不同金属材料髋关节假体的疲劳性能,包括假体的寿命、变形等结果。钛合金假体的使用寿命最小为568万次,满足ISO标准。而不锈钢材料则不适合作为假体材料。     

2011年CRTER杂志“骨关节植入物”“数字化骨科”栏目组稿热点

<正>人工假体研究人工髋关节假体置换人工膝关节假体置换人工肩关节假体置换骨肿瘤与人工假体置换磨损微粒与假体松动假体材料与人体的反应人工关节翻修关节置换术后镇痛与血栓     

人工关节材料的仿生性能及临床应用

目的:通过分析国内外常用的金属材料、高分子材料、陶瓷材料和碳质材料人工关节的研究现状,探讨各种假体材料的优势及存在的问题,结合人工关节置换的仿生性原理,对开发新型下肢关节假体材料,提高置换关节使用寿命等重要的现实问题提出发展思路。方法:以"人工关节,假体材料,仿生性能"为关键词,采用计算机检索万方数据库(http://www.wanfangdata.com.cn/)中1993-01/2009-10有关仿生性人工关节材料实验研究与临床应用的文章,排除重复研究或Meta分析类文章。以22篇文献为主,重点对以下3个问题进行讨论:①人工关节的仿生性原理。②人工关节材料的研究现状。③人工关节的仿生性能及其临床应用。结果:目前应用于临床的人工关节材料主要是金属材料、高分子材料和陶瓷材料,科研人员正努力探索耐磨损、无毒害的新型材料,尤其是复合型涂层材料和仿生软骨材料,来加速推进接近或实现人体关节性能的假体关节。结论:人工关节仿生性能的实现是一个多学科交叉研究的系统工程,人工关节仿生需要进一步研究和开发人工关节制作材料,同时要结合结构、功能等特性,深入研究人工关节置换后关节运动的受力合理性,减少对人工关节的磨损速度。临床决策应从人体的整体出发,在经济条件允许情况下,可以考虑人工关节的个性化匹配,量身定做,使之更贴近每个患者的身体结构、关节形状和大小、功能特点以及体质状况。     

人工关节的研究现状和发展趋势

人工关节用于临床已有近百年的历史,经科研工作者们的不断努力,人工关节从材料到设计,都取得了很大的进步.随着材料制造技术及医疗技术的发展,人们已经能够应用多种金属或合金、高分子聚合物、碳质材料、陶瓷材料等对患者进行骨或关节的置换.目前,人工关节的置换包括有髋、膝、肩、肘、腕、踝等关节,但以髋关节和膝关节置换为主,因为髋关节和膝关节是人体主要的受力和磨损部位,损坏率高.在我国,大约有3000万人需要进行人工关节植入,但目前只有3万套,市场潜力很大.     

关节假体的某些工程原理

用全关节置换术治疗关节炎,二十多年来已经越来越常见。经验证明,已经有很多的假体对髋部和膝关节置换有效,而且这种方法可能很快会运用于身体大部分其它关节。所有关节置换术的目的是为劳动、生活提供满意的功能。为此,假体必须首先要使关节有适当的活动范围。第二,修复过的关节要具有稳固性,不易断裂、磨损、侵蚀或退化。此外,任何磨损、侵蚀和退化的产物必须为机体所相容。材料表1列出一些在全关节置换术中使用的材料的机械特性,还列举了聚甲基丙烯酸甲酯粘固剂和皮质骨加以对比。     

全膝置换后早期持续主动功能锻炼有利于关节功能的恢复

背景：人工全膝关节置换后早期进行康复功能锻炼,可以最大限度改善膝关节功能。 目的：观察主动和被动功能锻炼对全膝置换后早期关节功能恢复的影响。 方法：将226例全膝关节置换患者随机分为2组,置换后分别使用可控主动运动夹板和持续性被动运动器进行关节功能康复,置换后1.5,3,6个月记录两组关节活动度、术后疼痛目测类比VAS评分及KSS功能评分。 结果与结论：置换后3个月可控主动运动组KSS功能评分优于持续性被动运动组,置换后6个月两组间KSS功能评分差异无显著性意义;置换后1.5,3个月可控主动运动组关节活动度优于持续性被动运动组,置换后6个月两组间差异无显著性意义。提示全膝关节置换后使用可控主动运动夹板进行功能训练,可以促进膝关节功能早期恢复。     

Isolation and characterization of UHMWPE wear particles down to ten nanometers in size from in vitro hip and knee joint simulators

There is currently considerable interest in the wear debris and osteolytic potential of different types of bearings used in total joint replacements. The biological activity of the wear debris is dependent on the size and volume of the particles produced. Wear volume also plays an important role in the functional biological activity of a joint replacement. In vitro studies have shown that crosslinking of ultra high molecular weight polyethylene (UHMWPE) acetabular cups and tibial trays produces a reduction in wear volume, and crosslinking has now been introduced clinically for both types of prostheses. Previous studies have identified both micron and submicron-sized polyethylene wear particles. The aim of this study was to characterize the wear and wear particles generated from moderately crosslinked GUR 1,020 GVF UHMWPE acetabular cups and tibial trays in hip and knee joint wear simulators down to 10 nanometers in size. The wear rates of the two prosthesis types were very similar at 25.6 +/- 5.3 mm(3) per million cycles for the hip prostheses and 22.75 +/- 5.95 mm(3) per million cycles for the knee prostheses. Nanometer-sized wear particles were isolated and characterized from both hip and knee simulator lubricants for the first time. Significantly higher numbers (p < 0.05) of particles in the nanometer (<0.1 microm) size range were produced by the hip prostheses compared to the knee prostheses. The knee prostheses produced larger particles, with the mode of particle size in the 0.1-1.0 microm size range, compared to <0.1 microm size range for the hip prostheses. In addition, the knee prostheses produced a greater volumetric concentration of wear particles in the 1.0-10 microm size range, and consequently lower specific biological activity and functional biological activity indices. These results indicated that the knee prostheses had a lower osteolytic potential compared to the hip prostheses.     

陶瓷对陶瓷人工髋关节的磨擦界面特征

背景：陶瓷对陶瓷人工髋关节假体在临床上已有一定的应用,在表面磨擦、磨损和润滑方面占有优势,具有很大的研发潜力。 目的：评价陶瓷对陶瓷人工髋关节表面磨擦、磨损和润滑特性。 方法：将金属对超高分子量聚乙烯、金属对金属以及陶瓷对陶瓷人工髋关节假体的磨损界面研究进行分析,了解氧化铝陶瓷材料的结构特点、制备工艺以及磨损参数,并分析陶瓷对陶瓷人工髋关节置换治疗的效果,与其它假体材料进行对比。 结果与结论：①金属对超高分子量聚乙烯人工髋关节抗磨损性能差,使磨损颗粒进入关节和周围组织,造成骨溶解和松动。②金属对金属人工髋关节的磨损性能较金属对超高分子量聚乙烯假体有很大改善,骨溶解的发生率非常少,但由于磨损颗粒可散布于体内各脏器和体液中,使用时要注意避免发生过敏反应和毒性。③体外试验和体内试验证明陶瓷对陶瓷人工髋关节具有良好的摩擦、磨损、润滑性能,临床治疗长期随访结果显示陶瓷对陶瓷人工髋关节假体置换后无磨损颗粒,不会发生骨溶解。对于年龄较小,并且对髋关节活动度有较高要求的患者,陶瓷对陶瓷人工髋关节是治疗的首选。随着陶瓷对陶瓷人工髋关节假体设计和材料学的发展,通过改进假体的机械学特性,提高摩擦界面的耐磨性能和润滑机制,陶瓷对陶瓷人工髋关节假体的远期临床疗效将更加满意。     

Tensile and tribological properties of high-crystallinity radiation crosslinked UHMWPE

Osteolysis due to particulate wear debris associated with ultrahigh molecular weight polyethylene (UHMWPE) components of total joint replacement prostheses has been a major factor determining their in vivo lifetime. In recent years, radiation crosslinking has been employed to decrease wear rates in PE components, especially in acetabular cups of total hip replacement prostheses. A drawback of radiation crosslinking is that it leads to a crosslinked PE (or XPE) with lower mechanical properties compared with uncrosslinked PE. In contrast, high-crystallinity PEs are known to have several mechanical properties higher than conventional PE. In this study, we hypothesized that increasing the crystallinity of radiation crosslinked and remelted XPE would result in an increase in tensile properties without compromising wear resistance. High-pressure crystallization was performed on PE and XPE and analyzed for the resulting morphological alterations using differential scanning calorimeter, low voltage scanning electron microscopy, and ultrasmall angle X-ray scattering. Uniaxial tensile tests showed that high-pressure crystallization increased the tensile modulus and yield stress in both PE and XPE, decreased the ultimate strain and ultimate stress in PE but had no significant effect on ultimate strain or ultimate stress in XPE. Multidirectional wear tests demonstrated that high-pressure crystallization decreased the wear resistance of PE but had no effect on the wear resistance of XPE. In conclusion, this study shows that high-pressure crystallization can be effectively used to increase the crystallinity and modulus of XPE without compromising its superior wear resistance compared with PE.     

Foreign body reactions in lymph nodes of oncology patients with joint prostheses--light-, electron microscopic and immunohistological investigations

Foreign body reactions in lymph nodes caused by wear particles from joint prostheses can mimic different lymphadenopathies, including metastatic cancer. The knowledge of these alterations is particularly important for pathologists performing frozen section diagnosis for oncology patients. As recent investigations of pseudocapsules have revealed that most of the wear particles are submicron-sized, transmission electron microscopic investigations were additionally performed. The histological investigation of the pelvic lymph nodes of 22 oncology patients with joint prostheses showed that the bone cement wear prevailed. At least small amounts of polyethylene wear particles were also found in all cases. Metallic wear particles were detected in 90% of the cases. The wear particles induce a macrophage-rich foreign body reaction that can cause an architectural effacement of the lymph nodes. The electron microscopic investigations showed that submicron-sized wear particles prevail. Some of them form conglomerates in size ranges detectable by light microscopy. The immunohistochemical studies showed that the foreign body reactions comprised mature CD163- and PGM1-positive macrophages and few lymphocytes, predominantly T-lymphocytes. The knowledge of the characteristic alterations of regional lymph nodes seems important in order to avoid misinterpretations. Therefore, in particular the detection of intracytoplasmatic wear particles is helpful in this respect.     

Wear properties of alumina/zirconia composite ceramics for joint prostheses measured with an end-face apparatus

While only alumina is applied to all-ceramic joint prostheses at present, a stronger ceramic is required to prevent fracture and chipping due to impingement and stress concentration. Zirconia could be a potential substitute for alumina because it has high strength and fracture toughness. However, the wear of zirconia/zirconia combination is too high for clinical use. Although some investigations on composite ceramics revealed that mixing of different ceramics was able to improve the mechanical properties of ceramics, there are few reports about wear properties of composite ceramics for joint prosthesis. Since acetabular cup and femoral head of artificial hip joint are finished precisely, they indicate high geometric conformity. Therefore, wear test under flat contact was carried out with an end-face wear testing apparatus for four kinds of ceramics: alumina monolith, zirconia monolith, alumina-based composite ceramic, and zirconia based composite ceramic. Mean contact pressure was 10 MPa and sliding velocity was 40 mm/s. The wear test continued for 72 hours and total sliding distance was 10 km. After the test, the wear factor was calculated. Worn surfaces were observed with a scanning electron micrograph (SEM). The results of this wear test show that the wear factors of the both composite ceramics are similarly low and their mechanical properties are much better than those of the alumina monolith and the zirconia monolith. According to these results, it is predicted that joint prostheses of the composite ceramics are safer against break down and have longer lifetime compared with alumina/alumina joint prostheses.     

The relative effects of radiation crosslinking and type of counterface on the wear resistance of ultrahigh-molecular-weight polyethylene

The lifetime of total joint replacement prostheses utilizing ultrahigh-molecular-weight polyethylene (UHMWPE) components has historically been determined by their wear resistance. It has been discovered that radiation crosslinking of UHMWPE can substantially increase its wear resistance. However, it is also well recognized that there is a radiation-dose-dependent decrease in several important mechanical properties of UHMWPE, such as fracture toughness and resistance to fatigue crack propagation. In this study, the effect of radiation crosslinking (followed by remelting) on the morphology, tensile properties and wear resistance of UHMWPE was investigated. Wear tests were conducted against both the commonly used cobalt-chromium counterface polished to implant grade smoothness as well as a smoother ceramic (alumina) counterface. The results showed that 50kGy dose radiation crosslinking increased the wear resistance of UHMWPE against the cobalt-chromium counterface 7-fold, but the coupling of remelted, crosslinked UHMWPE against the smoother alumina counterface led to a 20-fold increase in wear resistance. This study shows that the use of an alumina counterface would circumvent the need to use a high radiation dose in crosslinking UHMWPE, associated with poor mechanical properties, without compromising wear resistance.     

Artificial encapsulation of joint prostheses

The great success of total joint replacement in surgery has been disturbed mainly by later loosening and wear-out of the plastic components. In an attempt to improve long term performance of joint prostheses and eliminate the adverse effects of wear debris, polymeric encapsulation as a main design feature has been proposed. The benefits of having an encapsulated and artificially lubricated joint prosthesis have been evaluated in tribological terms with particular reference to the UMIST shoulder joint. The selection of a number of biopolymers involved in this research project described. The possible interactions arising from the coexistence of these materials have been mechanically investigated. Much attention and a great deal of practical work has been focussed on the sealing of the capsule and on the relevant liquid permeability.     

Histological patterns of bone and articular tissues after orthopaedic reconstructive surgery (artificial joint implants).

Revision surgery after failures of joint replacements leads to histological studies on joint and bone tissues close to the implanted material. Aspectic loosening is the main complication. The surgical pathologist has to identify wear debris (metal, polyethylene, polymethylmethacrylate, chiefly) which promotes a histiocytic granuloma. Some surgical procedures such as cup or resurfacing arthroplasties create a new articular surface and a bone remodeling or necrosis. Cemented joint prostheses show various membrane structures between bone and the cement mantle while there is an association of bone resorption and formation. Non-cemented, porous-coated joint prostheses induce little bone ingrowth, even in satisfactory clinical results. Mechanical factors are predominant in massive limb prostheses. For silicone elastomer implants or artificial ligaments, wear of material promotes many tissular reactions. Often used bone grafts show little creeping substitution process in case of homografts, even well-incorporated on X-rays. More retrieval specimen studies are necessary to delineate precise topographical histological lesions, including non-loosened joint implants.     

Tissue reactions to wear products from polyacetal (Delrin) and UHMW polyethylene in total hip replacement

The tissue reaction to implanted materials and their wear products is important for the long-term fixation of a total hip replacement (THR). Recent reports indicate a relatively high incidence of aseptic loosening with Christiansen total hip prostheses. We examined tissue reactions to wear products in two groups of prostheses: 16 Christiansen prostheses with polyacetal (Delrin) sockets, and 18 Charnley-Müller total hip prostheses with ultrahigh-molecular-weight polyethylene (UHMWP) sockets. Specimens from these 34 patients were compared in a combined qualitative and semiquantitative morphological study. We saw similar histological changes in specimens of both groups, but specimens from the bone-cement interfaces of the acetabulum and femur shaft in the polyacetal group showed more inflammation and necrosis.     

Microseparation and stripe wear in alumina-on-alumina hip implants

The combination of materials that still has highest wear resistance for total hip replacement is ceramic-on-ceramic. However, brittleness is a major concern for ceramics: in vivo and in vitro studies on ceramic hip prostheses correlate microseparation with hip noise, ceramic wear, or ceramic liner damage. Ceramic microseparation can lead to edge load, ceramic head wear, and squeaking. The aim of this in vitro study was to investigate whether different angles of inclination influence the wear pattern of alumina-on-alumina hip joints with micro-separation during the swing phase. We also evaluated the wear rate obtained from this in vitro investigation with retrieval specimens obtained at 13 years' mean follow-up. The study was performed using a 12-station hip joint wear simulator (Shore Western, Monrovia, CA, USA) under bovine calf serum used as lubricant. Wear was evaluated by the gravimetric method and the test length was set at two million cycles. After two million cycles, a volumetric loss of 0.11 ±0.03 mm3 and 0.12 ±0.06 mm3 was observed, respectively, for 23° and 63° angles of inclination. In particular, the results obtained in this work revealed an increase of about 12-fold compared to previous results without microseparation conditions. No significant differences were observed between the two different inclinations on the wear patterns of the acetabular cups with a level of significance of a = 0.5. The location and general shape of the stripes wear were similar for the retrieved and simulator balls.