機遇挑戰(zhàn)并存！上肢型假肢新技術(shù)及行業(yè)發(fā)展趨勢

佩戴假肢能夠大大改善肢體缺失患者的外觀，恢復(fù)肢體功能，尤其是對心理調(diào)整、心理恢復(fù)有極大好處。患者戴假肢后能夠有更強的自理能力，可以更好地完成社會生活以及工作，因此，為截肢者提供良好的假肢是社會、行業(yè)、患者共同的需要。

多因素驅(qū)動行業(yè)發(fā)展

近年來，國家高度重視殘疾人康復(fù)服務(wù)需求。２０１６年１０月，國務(wù)院在《關(guān)于加快發(fā)展康復(fù)輔助器具產(chǎn)業(yè)的若干意見》中明確提出，推動“醫(yī)工結(jié)合”，支持人工智能、腦機接口、虛擬現(xiàn)實等新技術(shù)在康復(fù)輔助器具產(chǎn)品中的集成應(yīng)用，支持外骨骼機器人、照護和康復(fù)機器人、仿生假肢、虛擬現(xiàn)實康復(fù)訓練設(shè)備等產(chǎn)品研發(fā)。為截肢者提供反饋自然的假肢是目前我國康復(fù)事業(yè)發(fā)展的迫切要求。

國外咨詢機構(gòu)調(diào)查顯示，２０１８年全球上肢型假肢市場規(guī)模已達１０億美元，年復(fù)合增長率高于１１％，有望在２０２０年擴大為２３億美元。根據(jù)第六次全國人口普查及第二次全國殘疾人抽樣調(diào)查，２０１０年末，我國殘疾人已達到８５０２萬人，其中５０００多萬人有康復(fù)需求，６０％以上需要輔助器具。

目前，我國上肢功能性假肢行業(yè)需求從低端的機械型假肢向肌電型假肢過渡，高端產(chǎn)品需求十分強烈。２０１７年，我國上肢功能性假肢行業(yè)需求規(guī)模為３．０５億元，上肢功能性假肢產(chǎn)量為２．４６萬件，同比增長７．７％。預(yù)計到２０２３年，我國上肢功能性假肢需求量將增長到５．１０萬件。

對于截肢者而言，雖然目前已有不少成熟的假肢手產(chǎn)品，但有調(diào)查顯示成年假肢用戶對假肢的拒絕率達４５％，其中近端截肢者、高齡截肢者對于假肢手的排斥率較高。除了假肢手存在磨損等舒適度問題之外，主要原因還是假肢手感知能力的缺乏以及假體與感知需求之間的差異。假肢手能夠輔助截肢者完成一定的基本動作，但缺乏可靠的感覺反饋是這些產(chǎn)品較大的缺陷，極大地阻礙了它們的實用性和功能體現(xiàn)，也是截肢者拒絕的主要原因。真正實現(xiàn)假肢手的感知反饋不僅需要面對許多技術(shù)上的挑戰(zhàn)，而且也需要解決大腦、神經(jīng)方面的科學問題。

假肢反饋新興技術(shù)

如何使機械的上肢型假肢人性化使用，高度依賴于假肢的反饋技術(shù)。過去幾十年，許多研究致力于通過植入電極、感覺神經(jīng)功能重建等有創(chuàng)方式，或通過機械反饋、振動反饋、電觸覺反饋等無創(chuàng)方式實現(xiàn)假肢手的感覺反饋，在一定程度上提高了假肢手的操作能力和截肢者對假肢手的接納度。

植入性電極

植入性電極通常包括在神經(jīng)內(nèi)植入縱向束內(nèi)電極（Ｌｏｎｇｉｔｕｄｉｎａｌ Ｉｎｔｒａｆａｓｃｉｃｕｌａｒ Ｅｌｅｃｔｒｏｄｅ，ＬＩＦＥ）、束內(nèi)電刺激陣列（Ｔｒａｎｓｖｅｒｓｅ Ｉｎｔｒａｆａｓｃｉｃｕｌａｒ Ｍｕｌｔｉｃｈａｎｎｅｌ Ｅｌｅｃｔｒｏｄｅｓ，ＴＩＭＥ）、猶他斜面刺入式電極陣列（Ｕｔａｈ Ｓｌａｎｔ Ｅｌｅｃｔｒｏｄｅ Ａｒｒａｙ，ＵＳＥＡ）及扁平束內(nèi)電極（Ｆｌａｔ Ｉｎｔｒａｆａｓｃｉｃｕｌａｒ Ｎｅｒｖｅ Ｅｌｅｃｔｒｏｄｅ，ＦＩＮＥ）等植入性神經(jīng)電極。

腦感知皮層微電流刺激

除了能在截肢殘端植入電極生成刺激形成反饋外，目前也有不少研究致力于在大腦皮層植入電極形成腦機接口，使高位截肢者通過腦電控制假肢，提供假肢反饋。一個植入性電極陣列可以記錄１００－２００個神經(jīng)元的信號。記錄下來的神經(jīng)信號將傳送給經(jīng)過解碼后可以識別神經(jīng)元的放電模式，根據(jù)放電模式的規(guī)律將其編譯為相應(yīng)的運動指令，從而驅(qū)動假肢完成運動。

美國加州理工學院的研究團隊曾在大腦表面約３毫米厚的組織中采集腦電信號，將大腦皮層深層的神經(jīng)信號傳輸?shù)接嬎銠C，通過大量訓練使患者逐漸掌握如何用意念控制假肢手。目前的植入電極一般可以使用５年，但仍然存在兼容性、電極偏移等問題，未來柔性電極也許會解決這一問題。雖然腦機接口的確是一項突破性技術(shù)，但離實際應(yīng)用還有一段距離。 誘指感反饋 截肢后的殘端部位與手指存在一定的解剖映射關(guān)系，利用這種僅存的映射關(guān)系可以刺激殘端使截肢者感到其失去的手指被觸摸，這種現(xiàn)象被研究者稱為誘指感現(xiàn)象。利用經(jīng)皮神經(jīng)電刺激（Ｔｒａｎｓｃｕｔａｎｅｏｕｓ Ｅｌｅｃｔｒｉｃａｌ Ｎｅｒｖｅ Ｓｔｉｍｕｌａｔｉｏｎ，ＴＥＮＳ）可以在截肢殘端實現(xiàn)誘指感。經(jīng)皮神經(jīng)電刺激的電流脈寬、幅度、頻率等參數(shù)可調(diào)節(jié)，可不同程度地刺激到皮膚中的多種感受器及神經(jīng)末梢，產(chǎn)生多種感知模式，如輕觸、按壓、嗡鳴、震動、麻木、疼痛等。通過調(diào)節(jié)不同程度的刺激幅度、脈沖寬度或頻率，截肢者可以明顯感覺到失去的手指似乎被觸摸?；谡T發(fā)指感的感覺反饋因其無創(chuàng)、自然的特點目前成為假肢手感覺反饋中的研究熱點，被認為是可能實現(xiàn)自然的假肢手感知反饋方法之一。

上海交通大學神經(jīng)康復(fù)工程實驗室團隊通過電刺激并詢問的方法確定截肢者的誘發(fā)指感區(qū)域，并改變電流、脈沖、頻率的強度對誘發(fā)指感區(qū)域進行經(jīng)皮神經(jīng)電刺激。實驗表明，截肢者通過ＴＥＮＳ可以獲得該區(qū)域相應(yīng)的誘發(fā)手指地圖（Ｐｒｏｊｅｃｔｅｄ Ｆｉｎｇｅｒ Ｍａｐ，ＰＦＭ），根據(jù)刺激參數(shù)的不同確定了７種不同的感知模式及其刺激范圍。在此基礎(chǔ)上，研究團隊又進一步研究了ＴＥＮＳ在截肢者殘端皮膚引發(fā)的觸覺現(xiàn)象。在改變刺激電流幅度的條件下，９名截肢者都能對觸碰、壓力等不同感覺模式進行準確識別，實驗還表明，截肢部位越靠近手指，誘發(fā)指感區(qū)域與手指的映射關(guān)系越明顯。在長達１１個月的連續(xù)觀察中，截肢者的誘發(fā)指感區(qū)域并沒有明顯的位移。

視覺反饋

大腦對于假肢的理解，很大程度上依賴于視覺通路，因此視覺反饋對于假肢手來說同樣也是很重要的反饋方式。東京大學的研究者設(shè)計了一套虛擬現(xiàn)實與觸覺反饋結(jié)合的系統(tǒng)，可用于緩解截肢者的傳入阻滯性疼痛。截肢者在健側(cè)手掌佩戴數(shù)據(jù)反饋手套，頭戴Ｏｃｕｌｕｓ設(shè)備，在ＶＲ環(huán)境中用健側(cè)去抓取目標物體，同時通過Ｋｉｎｅｃｔ與數(shù)據(jù)反饋手套捕捉截肢者健側(cè)的運動，將健側(cè)運動在ＶＲ環(huán)境中鏡像為殘肢運動，即由真實健側(cè)手肢控制虛擬患側(cè)手肢完成抓取任務(wù)，任務(wù)完成時會有聲音和振動提示。在虛擬現(xiàn)實和振動反饋下，截肢者能減少４１．８±１９．８％的疼痛感。

２０１６年哥德堡查爾默斯理工大學研究團隊在一項研究中，利用網(wǎng)絡(luò)攝像頭對截肢者殘端的識別碼進行定位，隨后在屏幕上將虛擬手肢與殘肢對齊，通過對肌電圖的分析獲取殘肢端的運動速度，同時顯示虛擬手肢并引導(dǎo)截肢者完成相應(yīng)康復(fù)動作。通過一年時間的訓練，結(jié)果發(fā)現(xiàn)截肢者的幻肢疼痛感降低了４７％，四名接受藥物治療的截肢者中有兩名分別減少了８１％和３３％的藥物攝入量。隨后在此基礎(chǔ)上，２０１８年又通過對殘端肌電圖進行解碼，通過偵測殘端上的肌電信號判斷截肢者的動作意圖，然后將動作投影至在屏幕上，截肢者看著屏幕，就像對著鏡子做動作，增強了假肢使用體驗。

機遇與挑戰(zhàn)并存

在假肢市場規(guī)模方面，目前我國上肢功能性假肢大型企業(yè)數(shù)量較少，Ｏｔｔｏｂｏｃｋ和Ｏｓｓｕｒ兩大國外品牌占據(jù)了較高的市場份額，國內(nèi)僅有科生等少數(shù)幾家規(guī)模稍大的企業(yè)，其余企業(yè)規(guī)模都較小。在核心技術(shù)方面，國外假肢產(chǎn)品覆蓋面全，假肢類型多，控制與反饋效果好，得到了眾多消費者的認可；而國產(chǎn)假肢雖然具有成本上的優(yōu)勢，但使用效果與國外品牌相比仍有差距，缺乏競爭力。第一次世界大戰(zhàn)后，假肢逐漸出現(xiàn)在人們生活中，隨著科技的進步，不少先進技術(shù)逐漸應(yīng)用于假肢研發(fā)。目前市面上已經(jīng)出現(xiàn)多款仿生假肢，可以通過肌電信號控制，３Ｄ打印技術(shù)等方式實現(xiàn)，這些仿生假肢已經(jīng)與真實肢體一般無二，但假肢較高的拒絕率和較低的普及率仍然是很嚴峻的現(xiàn)實問題。如何為假肢用戶提供一個易于使用、感覺反饋可靠的假肢，需用通過工程師、醫(yī)生從工程技術(shù)、神經(jīng)科學等兩大方面聯(lián)合考慮。除此之外，當截肢者佩戴假肢回歸社會時，我們也需要為他們提供綠色通道，使他們擁有更強的自理能力，可以更好地完成社會生活以及工作。

綜上，在政策紅利、科技發(fā)展的背景下，上肢型假肢行業(yè)一方面展現(xiàn)出方興未艾、大有作為的發(fā)展趨勢，另一方面也面臨著核心技術(shù)、康復(fù)配套環(huán)境的差距，未來發(fā)展任重而道遠。

來源：中國醫(yī)藥報

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