用于视网膜修复的植入系统研究

在视网膜附近植入人造芯片以恢复受损的视觉功能是视网膜修复的一个重要研究方面。本文综合讨论了目前该领域主要采用的两种方法：视网膜外植入和视网膜下植入方法,分析了各自的优缺点,并讨论了视网膜修复中的几个关键问题。     

运动神经假体康复技术回顾与展望

运动神经假体是一类帮助神经系统受损患者恢复或替代其身体运动功能的电子装置,通过功能性电刺激(FES)技术代替大脑发出神经控制命令来激励相关肌肉活动、驱动受损肢体或直接控制人工假体完成预期动作,达到恢复或替代肢体运动功能目的.另外,脑-机接口(BCI)技术也是运动神经假体系统中的关键组成部分,它通过提取与解码大脑神经活动实现人脑与神经假体之间的交互.目前,随着FES技术以及BCI技术的高速发展,运动神经假体系统已经在脊髓损伤和中风患者的康复和功能辅助方面得到了广泛的临床应用,现阶段的研究热点在于如何开发更加有效的神经译码技术,提取出更丰富的大脑指令信息,使患者可以控制神经假体完成复杂的运动功能来满足日常活动的需要.未来,运动神经假体系统将向着便携化、网络化和更加逼近自然肢体功能的方向发展.本文主要介绍运动神经假体系统的组成和应用,综述运动神经假体康复技术的发展历程与现状,以期为神经损伤患者及从事神经假体技术研究的科研人员提供参考和帮助.     

航空材料在外科植入物骨关节假体中的应用

在现代材料科学与技术的发展历程中,航空材料一直扮演着先导和基础作用.航空材料中的高温合金(主要是钴基合金)、钛合金、不锈钢、陶瓷、高耐磨非金属等材料以其轻质、高强、高抗疲劳性、高耐热、高可靠性,并且具有良好的生物相容性等优良性能,已成为临床中较为理想的植入材料,并被广泛应用于外科植入物方面.国内外人工关节得以迅猛发展很大程度上依赖于航空材料在外科植入物骨关节假体中的应用.本文旨在介绍目前航空材料在外科植入物骨关节假体应用方面的常用材料、性能及使用要求.     

人工髋关节假体材料的研究进展

阐述了人工髋关节假体材料的性能要求和金属、高分子、陶瓷以及碳质假体材料的研究新进展,分析了各种材料在实际应用中的优势和存在的问题,并对其发展趋势进行了展望.研究认为髋关节假体材料的表面改性和人体髋关节生物摩擦行为是未来研究的热点,髋关节假体材料性能评价体系的完善是亟待解决的问题.     

Mg-Li基复合材料的研究近况

Mg-Li基复合材料因具有很高的比强度和比刚度等优点,成为近年来金属基复合材料研究的热点之一.主要简述了原位合成这种新方法在Mg-Li基复合材料制备中的应用,介绍了近年来该领域出现的新的研究热点--阻尼性能;并针对Mg-Li基复合材料的界面优化、增强体表面改性等研究现状进行了概述.     

驾驶分心行为的测量方法及其应用研究进展

驾驶分心行为的研究以成为工程心理学的研究热点。本文概述了驾驶分心行为的测量方法,重点介绍了外周视觉任务检测法(PDT)的应用。外周视觉任务检测法(peripheral detection task,PDT)是一种近年来较流行的用来测量驾驶分心的方法,文章总结了使用PDT测量法的主要研究进展,PDT测量法可以应用于视觉分心和认知分心的各种研究中,并且在和其他方法的比较中,PDT测量法也显示出了较好的安全性和易用性,最后展望了驾驶分心行为的研究趋势。     

碳磷灰石的制备和性能研究

羟基磷灰石(HA)被认为是目前最有吸引力的骨组织替代材料,与纯HA相比,碳磷灰石(CHA)在化学组成上更接近于人骨和牙齿等硬组织,且具有更好的生物相容性和更高的骨传导性,因此有望成为新型的骨组织替代材料.综述了目前国内外关于碳磷灰石的研究,主要介绍了CHA中碳酸根的取代类型、机理及制备方法,碳酸根的取代对HA结构及各方面性能的影响,以及碳酸根含量的测定等,并指出仿生法合成CHA及其复合材料是最新的研究热点,也是今后骨植入材料研究中的一个重要方向.     

骨组织工程支架材料的研究进展

骨组织工程的发展,要求充分结合材料工程与生物工程相关知识,对植入材料进行分子及细胞水平的设计.细胞外基质材料(支架材料)的选择与制备是骨组织工程的一项重要而关键的任务.如何找到能促进并指导细胞黏附、增殖的支架材料是目前骨组织工程研究的热点之一.介绍了骨组织工程相关原理,并综述了几种支架材料的发展研究现状.     

人工椎间盘关节材料表面耐磨改性研究进展

钛合金和超高分子量聚乙烯(UHMWPE)在人工椎间盘关节材料配对中一般是软体材料,其表面改性对提高假体耐磨性能及长期稳定性有重要意义。主要介绍了采用热处理、微弧氧化、表面渗元素、表面镀DLC膜、激光表面改性、离子注入技术提高钛合金表面硬度和耐磨性的研究进展,以及采用表面镀DLC膜等提高UHMWPE表面硬度和耐磨性的研究现状,展望了人工椎间盘假体耐磨性研究的发展趋势。     

假体植入偏差对TKA后膝关节面间力学特性的影响

该文基于含假体膝关节的实体模型,构建包含股骨假体植入偏差的直立位TKA后膝关节模型,通过有限元仿真,分析了TKA术的假体植入偏差:股骨假体的内/外移偏差、前/后移偏差、内/外旋偏差及内/外翻偏差对含假体关节面间的力学特性的影响。分析结果表明:股骨假体相对胫骨的内翻偏差对胫骨假体衬垫的最大等效应力和接触应力分布的影响最显著。因此,在全膝关节置换手术中,应尽量减小股骨假体与胫骨间的内/外翻偏差,以控制假体关节面间的应力变化及应力分布变化,来降低胫骨假体衬垫的磨损,该文的分析结果能够为膝关节假体磨损及抗磨损膝假体形面设计提供参考。     

Visual Prostheses: Technological and Socioeconomic Challenges

Visual prostheses are now entering the clinical marketplace. Such prostheses were originally targeted for patients suff ering from blindness through retinitis pigmentosa(RP). However, in late July of this year, for the first time a patient was given a retinal implant in order to treat dry agerelated macular degeneration. Retinal implants are suitable solutions for diseases that attack photoreceptors but spare most of the remaining retinal neurons. For eye diseases that result in loss of retinal output, implants that interface with more central structures in the visual system are needed. The standard site for central visual prostheses under development is the visual cortex. This perspective discusses the technical and socioeconomic challenges faced by visual prostheses.     

Interfacing Sensors With the Nervous System: Lessons From the Development and Success of the Cochlear Implant

The cochlear implant is the most successful neural prosthesis to date and may serve as a paradigm for the development or further development of other systems to interface sensors with the nervous system, e.g., visual or vestibular prostheses. This paper traces the history of cochlear implants and describes how the current levels of performance have been achieved. Lessons and insights from this experience are presented in concluding sections.     

Improved mechanical long-term reliability of hip resurfacing prostheses by using silicon nitride

Although ceramic prostheses have been successfully used in conventional total hip arthroplasty (THA) for many decades, ceramic materials have not yet been applied for hip resurfacing (HR) surgeries. The objective of this study is to investigate the mechanical reliability of silicon nitride as a new ceramic material in HR prostheses. A finite element analysis (FEA) was performed to study the effects of two different designs of prostheses on the stress distribution in the femur–neck area. A metallic (cobalt–chromium-alloy) Birmingham hip resurfacing (BHR) prosthesis and our newly designed ceramic (silicon nitride) HR prosthesis were hereby compared. The stresses induced by physiologically loading the femur bone with an implant were calculated and compared with the corresponding stresses for the healthy, intact femur bone. Here, we found stress distributions in the femur bone with the implanted silicon nitride HR prosthesis which were similar to those of healthy, intact femur bone. The lifetime predictions showed that silicon nitride is indeed mechanically reliable and, thus, is ideal for HR prostheses. Moreover, we conclude that the FEA and corresponded post-processing can help us to evaluate a new ceramic material and a specific new implant design with respect to the mechanical reliability before clinical application.     

Analysis and prediction of total hip replacement performance

The survival of total hip replacement in patients operated on at the Royal National Orthopaedic Hospital was analysed for two types of Stanmore prostheses: (a) metal-on-metal prostheses of various development designs inserted between 1963–72 (173), and (b) metal-on-plastic prostheses of one design inserted between 1969–72 (248). The survival criterion was taken to be non-removal of the prosthesis and all cases not removed were regarded as survivors. The results indicated that for metal-on-metal prostheses the overall probability of survival was only 53% after 11 years and the average annual probability of removal irrespective of cause was 5.5%. As expected, for metal-on-plastic prostheses the results were considerably better, the figures being 88% after eight years and 1.5% respectively. For both prosthesis types the predominant failure mode was loosening and for this failure mode the annual rate of removal increased as the follow-up time increased, suggesting that loosening is a wearing-out process. Femoral component fracture occurred less frequently, but also appeared to be a wearing-out process. Finally, it is demonstrated how the analysis can be used to predict the probability of survival at some time in the future.     

Lipid uptake in ePTFE arterial prostheses implanted in humans

Lipid uptake in 104 ePTFE microporous vascular prostheses implanted in humans was investigated using Fourier transform infrared (FTIR) spectroscopy. The assignment of the infrared features observed in the spectra of explanted ePTFE microporous vascular prostheses shows unambiguously the presence of fatty acids in the structure of the arterial prosthesis wall. In addition, higher lipid concentration is found on the external side of the prostheses before 500 days of implantation, after which this behaviour is reversed. Finally, it seems that a greater amount of lipids are present on the surfaces of prostheses implanted in extra-anatomical sites as compared to those implanted in anatomical sites.     

Design and manufacturing of a human standardised hip cup out of titanium

Background: In recent years, the use of hip prostheses has become a routine procedure. Despite this experience and good clinical results different complications arise which have a negative influence on the lifetime of prostheses. Especially the migration or loosening of the hip cup prosthesis due to strain adaptive bone remodelling is still a problem. Patient‐individual prostheses represent a possible solution to this problem. Individual hip cups, however, are just implanted for the treatment of massive deformities or tumours. This study aimed at developing an innovative concept for the production of patient‐specific human hip prostheses made of titanium plates by sheet metal forming. Methods: For the realisation of this innovative concept, a reproducible design method for the generation of standardised human hip cup prosthesis was generated based on 13 original human geometries. By means of this methodology a hip cup was designed. Based on this design a human hip cup was produced by a developed high‐pressure sheet metal forming process. The development of the process was accompanied by a numerical preliminary design. Results: A comparison between the simulation and the fabricated hip cup leads to a standard deviation of 0.404 mm. Furthermore, an implantation of the prosthesis in a synthetic bone model shows a satisfactory fit accuracy at the edge of the prosthesis. Conclusion: The high‐pressure sheet metal forming process is suitable to manufacture the designed standardised hip cup. However, further optimisation is necessary.     

Fertigung einer universellen Hüftprothesenpfanne mittels Hochdruckblechumformung

In recent years, the use of hip prostheses has become a routine procedure. The use of total hip replacement has evolved in recent years to a routine procedure. Despite this experience, it always comes back to complications. Especially the migration or loosening of the acetabular component because of the artificial load adaptive bone remodeling is still a current problem. This is due to the changing mechanical situation after the implantation of the prosthesis. Another problem is the high bone loss during implantation, which complicates a revision of the prosthesis. One solution is the use of patient‐specific prostheses. So far, the use of these prostheses is limited due to the time‐consuming and cost‐intensive production. The overall objective of the presented project in this publication is the development and establishment of an innovative concept for the production of patient‐specific hip prosthesis made of titanium plates by sheet metal forming. The idea of this concept involves the development of a two‐stage process. First of all a standardized hip prosthesis is made by high‐pressure sheet metal forming and then individually in the second step. This publication contains the derivation of the standard prosthesis. For this purpose, a design methodology was generated, based on the so‐called agglomerative clustering. In addition, presents the results of the numerical preliminary design of the first stage of the process and the tool developed concept in the course of this paper.     

A Neuromorphic Chip That Imitates the ON Brisk Transient Ganglion Cell Set in the Retinas of Rabbits

In this paper, a new CMOS design methodology is proposed to implement CMOS neuromorphic chips which imitate the ON brisk transient ganglion cell (GC) set of rabbits' retinas. The measurement results on the fabricated CMOS neuromorphic chip are consistent with the biological measurement results. Thus, the biological functions of the chip have been successfully verified. It can be used to understand more biological behaviors and visual language of retinas under different input optical images which have not yet been tested in biological experiments. Based on the results, the full GC sets of retina can be designed. Thus, many potential applications of retinal chips on motion sensors, computer vision, retinal prosthesis, and biomedical devices are feasible.     

Low-Invasive Diagnosis of Metallic Prosthesis Osseointegration by Electrical Impedance Spectroscopy

In this paper, a digital-measurement method for low-invasive clinical diagnosis of metallic prosthesis osseointegration is proposed. Electrical impedance spectroscopy is exploited to characterize the quality of the tissue at the interface between the bone and the prosthesis. The method overcomes current resolution limits of biological electrical-impedance analysis by means of several polarization levels. Electrical modeling through an equivalent circuit is used to define a quantitative index of osseointegration. In vitro experimental results of the proposed method validation show its sensitivity and its effectiveness in low-depth prostheses, such as in dentistry applications