佩戴假肢能够大大改善肢体缺失患者的外观，恢复肢体功能，尤其是对心理调整、心理恢复有极大好处。患者戴假肢后能够有更强的自理能力，可以更好地完成社会生活以及工作，因此，为截肢者提供良好的假肢是社会、行业、患者共同的需要。

多因素驱动行业发展

近年来，国家高度重视残疾人康复服务需求。２０１６年１０月，国务院在《关于加快发展康复辅助器具产业的若干意见》中明确提出，推动“医工结合”，支持人工智能、脑机接口、虚拟现实等新技术在康复辅助器具产品中的集成应用，支持外骨骼机器人、照护和康复机器人、仿生假肢、虚拟现实康复训练设备等产品研发。为截肢者提供反馈自然的假肢是目前我国康复事业发展的迫切要求。

国外咨询机构调查显示，２０１８年全球上肢型假肢市场规模已达１０亿美元，年复合增长率高于１１％，有望在２０２０年扩大为２３亿美元。根据第六次全国人口普查及第二次全国残疾人抽样调查，２０１０年末，我国残疾人已达到８５０２万人，其中５０００多万人有康复需求，６０％以上需要辅助器具。

目前，我国上肢功能性假肢行业需求从低端的机械型假肢向肌电型假肢过渡，高端产品需求十分强烈。２０１７年，我国上肢功能性假肢行业需求规模为３．０５亿元，上肢功能性假肢产量为２．４６万件，同比增长７．７％。预计到２０２３年，我国上肢功能性假肢需求量将增长到５．１０万件。

对于截肢者而言，虽然目前已有不少成熟的假肢手产品，但有调查显示成年假肢用户对假肢的拒绝率达４５％，其中近端截肢者、高龄截肢者对于假肢手的排斥率较高。除了假肢手存在磨损等舒适度问题之外，主要原因还是假肢手感知能力的缺乏以及假体与感知需求之间的差异。假肢手能够辅助截肢者完成一定的基本动作，但缺乏可靠的感觉反馈是这些产品较大的缺陷，极大地阻碍了它们的实用性和功能体现，也是截肢者拒绝的主要原因。真正实现假肢手的感知反馈不仅需要面对许多技术上的挑战，而且也需要解决大脑、神经方面的科学问题。

假肢反馈新兴技术

如何使机械的上肢型假肢人性化使用，高度依赖于假肢的反馈技术。过去几十年，许多研究致力于通过植入电极、感觉神经功能重建等有创方式，或通过机械反馈、振动反馈、电触觉反馈等无创方式实现假肢手的感觉反馈，在一定程度上提高了假肢手的操作能力和截肢者对假肢手的接纳度。

植入性电极

植入性电极通常包括在神经内植入纵向束内电极（Ｌｏｎｇｉｔｕｄｉｎａｌ Ｉｎｔｒａｆａｓｃｉｃｕｌａｒ Ｅｌｅｃｔｒｏｄｅ，ＬＩＦＥ）、束内电刺激阵列（Ｔｒａｎｓｖｅｒｓｅ Ｉｎｔｒａｆａｓｃｉｃｕｌａｒ Ｍｕｌｔｉｃｈａｎｎｅｌ Ｅｌｅｃｔｒｏｄｅｓ，ＴＩＭＥ）、犹他斜面刺入式电极阵列（Ｕｔａｈ Ｓｌａｎｔ Ｅｌｅｃｔｒｏｄｅ Ａｒｒａｙ，ＵＳＥＡ）及扁平束内电极（Ｆｌａｔ Ｉｎｔｒａｆａｓｃｉｃｕｌａｒ Ｎｅｒｖｅ Ｅｌｅｃｔｒｏｄｅ，ＦＩＮＥ）等植入性神经电极。

脑感知皮层微电流刺激

除了能在截肢残端植入电极生成刺激形成反馈外，目前也有不少研究致力于在大脑皮层植入电极形成脑机接口，使高位截肢者通过脑电控制假肢，提供假肢反馈。一个植入性电极阵列可以记录１００－２００个神经元的信号。记录下来的神经信号将传送给经过解码后可以识别神经元的放电模式，根据放电模式的规律将其编译为相应的运动指令，从而驱动假肢完成运动。

美国加州理工学院的研究团队曾在大脑表面约３毫米厚的组织中采集脑电信号，将大脑皮层深层的神经信号传输到计算机，通过大量训练使患者逐渐掌握如何用意念控制假肢手。目前的植入电极一般可以使用５年，但仍然存在兼容性、电极偏移等问题，未来柔性电极也许会解决这一问题。虽然脑机接口的确是一项突破性技术，但离实际应用还有一段距离。 诱指感反馈 截肢后的残端部位与手指存在一定的解剖映射关系，利用这种仅存的映射关系可以刺激残端使截肢者感到其失去的手指被触摸，这种现象被研究者称为诱指感现象。利用经皮神经电刺激（Ｔｒａｎｓｃｕｔａｎｅｏｕｓ Ｅｌｅｃｔｒｉｃａｌ Ｎｅｒｖｅ Ｓｔｉｍｕｌａｔｉｏｎ，ＴＥＮＳ）可以在截肢残端实现诱指感。经皮神经电刺激的电流脉宽、幅度、频率等参数可调节，可不同程度地刺激到皮肤中的多种感受器及神经末梢，产生多种感知模式，如轻触、按压、嗡鸣、震动、麻木、疼痛等。通过调节不同程度的刺激幅度、脉冲宽度或频率，截肢者可以明显感觉到失去的手指似乎被触摸。基于诱发指感的感觉反馈因其无创、自然的特点目前成为假肢手感觉反馈中的研究热点，被认为是可能实现自然的假肢手感知反馈方法之一。

上海交通大学神经康复工程实验室团队通过电刺激并询问的方法确定截肢者的诱发指感区域，并改变电流、脉冲、频率的强度对诱发指感区域进行经皮神经电刺激。实验表明，截肢者通过ＴＥＮＳ可以获得该区域相应的诱发手指地图（Ｐｒｏｊｅｃｔｅｄ Ｆｉｎｇｅｒ Ｍａｐ，ＰＦＭ），根据刺激参数的不同确定了７种不同的感知模式及其刺激范围。在此基础上，研究团队又进一步研究了ＴＥＮＳ在截肢者残端皮肤引发的触觉现象。在改变刺激电流幅度的条件下，９名截肢者都能对触碰、压力等不同感觉模式进行准确识别，实验还表明，截肢部位越靠近手指，诱发指感区域与手指的映射关系越明显。在长达１１个月的连续观察中，截肢者的诱发指感区域并没有明显的位移。

视觉反馈

大脑对于假肢的理解，很大程度上依赖于视觉通路，因此视觉反馈对于假肢手来说同样也是很重要的反馈方式。东京大学的研究者设计了一套虚拟现实与触觉反馈结合的系统，可用于缓解截肢者的传入阻滞性疼痛。截肢者在健侧手掌佩戴数据反馈手套，头戴Ｏｃｕｌｕｓ设备，在ＶＲ环境中用健侧去抓取目标物体，同时通过Ｋｉｎｅｃｔ与数据反馈手套捕捉截肢者健侧的运动，将健侧运动在ＶＲ环境中镜像为残肢运动，即由真实健侧手肢控制虚拟患侧手肢完成抓取任务，任务完成时会有声音和振动提示。在虚拟现实和振动反馈下，截肢者能减少４１．８±１９．８％的疼痛感。

２０１６年哥德堡查尔默斯理工大学研究团队在一项研究中，利用网络摄像头对截肢者残端的识别码进行定位，随后在屏幕上将虚拟手肢与残肢对齐，通过对肌电图的分析获取残肢端的运动速度，同时显示虚拟手肢并引导截肢者完成相应康复动作。通过一年时间的训练，结果发现截肢者的幻肢疼痛感降低了４７％，四名接受药物治疗的截肢者中有两名分别减少了８１％和３３％的药物摄入量。随后在此基础上，２０１８年又通过对残端肌电图进行解码，通过侦测残端上的肌电信号判断截肢者的动作意图，然后将动作投影至在屏幕上，截肢者看着屏幕，就像对着镜子做动作，增强了假肢使用体验。

机遇与挑战并存

在假肢市场规模方面，目前我国上肢功能性假肢大型企业数量较少，Ｏｔｔｏｂｏｃｋ和Ｏｓｓｕｒ两大国外品牌占据了较高的市场份额，国内仅有科生等少数几家规模稍大的企业，其余企业规模都较小。在核心技术方面，国外假肢产品覆盖面全，假肢类型多，控制与反馈效果好，得到了众多消费者的认可；而国产假肢虽然具有成本上的优势，但使用效果与国外品牌相比仍有差距，缺乏竞争力。第一次世界大战后，假肢逐渐出现在人们生活中，随着科技的进步，不少先进技术逐渐应用于假肢研发。目前市面上已经出现多款仿生假肢，可以通过肌电信号控制，３Ｄ打印技术等方式实现，这些仿生假肢已经与真实肢体一般无二，但假肢较高的拒绝率和较低的普及率仍然是很严峻的现实问题。如何为假肢用户提供一个易于使用、感觉反馈可靠的假肢，需用通过工程师、医生从工程技术、神经科学等两大方面联合考虑。除此之外，当截肢者佩戴假肢回归社会时，我们也需要为他们提供绿色通道，使他们拥有更强的自理能力，可以更好地完成社会生活以及工作。

综上，在政策红利、科技发展的背景下，上肢型假肢行业一方面展现出方兴未艾、大有作为的发展趋势，另一方面也面临着核心技术、康复配套环境的差距，未来发展任重而道远。

来源：中国医药报

Wearing prosthetic limb can greatly improve the appearance of patients with limb loss and restore limb function, especially for psychological adjustment and psychological recovery. Patients with prosthetics can have stronger self-care ability, and can better complete social life and work. Therefore, providing good prosthesis for amputees is the common needs of society, industry and patients.

Multi factor driving industry development

In recent years, the state attaches great importance to the needs of rehabilitation services for the disabled. In October 2016, the State Council clearly proposed in the "several opinions on accelerating the development of rehabilitation assistive devices industry" to promote the "combination of medical and industrial", support the integrated application of new technologies such as artificial intelligence, brain computer interface and virtual reality in rehabilitation assistive device products, and support the external iliac robot, care and rehabilitation robot, bionic prosthesis and virtual reality rehabilitation training Research and development of equipment and other products. It is an urgent requirement for the development of rehabilitation in China to provide feedback for amputees.

According to the survey of foreign consulting agencies, the global market for upper limb prostheses has reached US $1 billion in 2018, with an annual compound growth rate of more than 11%, and is expected to expand to $2.3 billion in 2020. According to the Sixth National Census and the second national sampling survey of disabled people, by the end of 2010, there were 85.02 million disabled people in China, of whom 50 million had rehabilitation needs and more than 60% needed assistive devices.

At present, China's upper limb functional prosthesis industry demand from the low-end mechanical prosthesis to the electromyographic prosthesis, and the demand for high-end products is very strong. In 2017, the demand scale of China's upper limb functional prosthesis industry was 305 million yuan, and the output of upper limb functional prosthesis was 24600 pieces, with a year-on-year increase of 7.7%. It is estimated that the demand for functional upper limb prostheses will increase to 51000 by 2023.

For amputees, although there are many mature prosthetic hand products, some surveys show that the rejection rate of adult prosthetic users is 45%, and the rejection rate of proximal amputees and elderly amputees is higher. In addition to the comfort problems of prosthetic hand such as wear, the main reason is the lack of perception ability of prosthetic hand and the difference between prosthesis and perception demand. Prosthetic hand can assist amputees to complete certain basic movements, but the lack of reliable sensory feedback is the biggest defect of these products, which greatly hinders their practicability and function, and is also the main reason for amputees to refuse. In order to realize the sensory feedback of prosthetic hand, we need to face many technical challenges, and also need to solve the scientific problems of brain and nerve.

New technology of prosthetic feedback

How to make the mechanical upper limb prosthesis humanized depends on the feedback technology of the prosthesis. In the past few decades, many researches have been devoted to the realization of sensory feedback of prosthetic hand by implanting electrodes, reconstructing sensory nerve function, or non-invasive methods such as mechanical feedback, vibration feedback and electro tactile feedback, which has improved the operation ability of prosthetic hand and the acceptance of amputees to a certain extent.

Implantable electrode

Implantable electrodes usually include longitudinal intrafascicular electrode (life) and transverse intrafascicular multichannel The implanted nerve electrodes included electrodes (time), Utah slant electrode array (usea) and flat intrafascicular nerve electrode (fine).

Researchers from the Federal Institute of technology in Lausanne have found that intrafascicular multi-channel electrodes can be implanted into the ulnar nerve and median nerve of the amputee stump to achieve intraneural stimulation. The accuracy rate of recognizing the size and height of an object by using artificial limbs after electrode implantation is 75.5%. Although nerve implanted electrodes can give amputees the sensory feedback effect of prosthetic hand, this method will bring certain risks, because it needs a lot of autologous nerve tissue and has certain damage. For the nerve implanted electrode, firstly, the electrode may not be placed in the required position within the nerve as desired. Secondly, it is not easy to fix the electrode body after transplantation, and the electrode position is easy to move by external force, so it is not conducive to long-term transplantation.

Cerebral sensory cortical microcurrent stimulation

In addition to the stimulation and feedback generated by implanting electrodes in the amputation stump, many researches have been devoted to the formation of brain computer interface by implanting electrodes in the cerebral cortex, so that high amputees can control the prosthesis through EEG and provide feedback. An implantable electrode array can record the signals of 100-200 neurons. The recorded neural signals will be transmitted to decoded neurons to identify the firing patterns of neurons. According to the rules of discharge patterns, the neural signals are compiled into corresponding motion instructions to drive the prosthetic limb to complete the movement.

The research team of California Institute of technology once collected EEG signals from the tissue about 3 mm thick on the surface of the brain, and transmitted the nerve signals from the deep layer of the cerebral cortex to the computer. Through a lot of training, the patients gradually mastered how to control the prosthetic hand with their ideas. At present, the implanted electrode can