User-Controlled Variable Stiffness Prosthesis to Improve Amputee Balance

 描述（由申请人提供）： 许多下肢截肢者在行走时难以保持平衡，特别是在现实世界中需要对地形或表面条件的变化做出快速反应的情况下。可以肯定的是，截肢者（和其他人）可能会因为各种原因以各种方式摔倒。在表面上意外滑动（例如，由于表面上的冰、油或其它液体）是一类福尔斯的例子，其中很难想象可能防止失去平衡的修复干预。踩在不平坦的地形是一个不同的类，我们建议一个新的假肢可能有助于平衡恢复。四分之一的户外福尔斯，在各种各样的不平坦的地形存在，发生在一个侧面（中侧）的方向。对于下肢截肢者来说，在不平坦的地形上行走时保持平衡尤其困难，因为他们缺乏补偿所需的足踝肌肉，而且他们的假肢是被动的弹性装置，其性能无法改变或适应。这项研究的目的是通过为下肢截肢者提供一种优化的假肢来改善他们的平衡，这种假肢可以响应他们的运动意图并适应地形的变化。为了解决退伍军人下肢截肢者面临的这一重要问题，我们已经开发了一个先进的计算机建模和仿真框架，我们将使用该框架来确定最佳踝关节特性，以便在不平坦的地形上行走后最大限度地恢复平衡。我们还构建了具有可变冠状面踝关节刚度的第一代假体，并在截肢者在一种新型仪器化走道上行走的帮助下对其进行了测试，该走道复制了在不平坦地形上的一步。我们的初步测试结果表明，不同的冠状面踝关节刚度可以影响截肢者如何控制他们的平衡。我们提出的研究有三个具体的目标：（1）确定地形依赖的冠状踝关节特性，最大限度地恢复平衡。我们建议开发一个三维的双足肌肉骨骼模型的人类行走在不平坦的地形，并用它来回答一个关键问题：什么是最佳的冠状面刚度，最大限度地平衡恢复后，一步不平坦的地形？(2)在踏上不平坦的地形之前识别用户的运动意图。我们建议进行一项人类受试者实验（n=20）与穿我们的第一代假体胫骨截肢者。受试者将被要求在我们的仪器化走道上行走，该走道在不平坦的地形上重复一步，同时我们测量他们的运动意图（表面肌电图）。利用实验结果，我们将开发和测试三种算法来预测不平坦地形上的步骤。我们假设这三种算法的准确性存在差异。我们将使用的结果，以指定一个控制律，最好地预测一步不平坦的地形与我们的新型假肢使用。(3)确定与截肢者的处方假肢相比，针对平衡恢复进行优化并由用户运动意图控制的新型假肢是否可以改善从不平坦地形上踏出的恢复。为了实现这一目标，我们建议构建第二代假体，该假体结合了特定目标1和2的结果，以及我们从第一代假体中吸取的经验教训。然后，我们建议进行一项人类受试者实验与经胫骨截肢者（n=20），将测量他们的平衡恢复后，一步不平坦的地形。我们假设，我们的新假肢将改善恢复平衡后，一步不平坦的地形相比，截肢者的规定假肢。扩大退伍军人截肢者可以自信地行走的地形是VA应该在的地方：在假肢技术和处方实践的最前沿，促进截肢者护理。

 DESCRIPTION (provided by applicant): Project Summary (Public Abstract) Many lower limb amputees have difficulty maintaining balance while walking, especially in real-world situations that require quick responses to changes in terrain or surface conditions. To be certain, amputees (and others) can fall in a myriad of ways for a myriad of reasons. Unexpected slipping on a surface (e.g., due to ice, oil or other liquids on the surface) is an example of a class of falls where it is difficult to imagine a prosthetic intervention that might prevent loss of balance. Stepping on uneven terrain is a different class where we suggest a novel prosthesis might aid in balance recovery. A quarter of outdoor falls, where a wide variety of uneven terrains exist, occur in a sideways (mediolateral) direction. Maintaining balance when stepping on uneven terrain can be particularly difficult for lower limb amputees because they lack the foot-ankle muscles needed to compensate and their prostheses are passive, elastic devices whose properties cannot change or adapt. The purpose of this research is to improve the balance of lower limb amputees by providing them with an optimized prosthesis that can respond to their motor intentions and adapt to changes in terrain. To address this important issue faced by Veteran lower limb amputees, we have already developed an advanced computer modeling and simulation framework, which we will use to identify the optimal ankle properties that maximize balance recovery after a step on uneven terrain. We have also built a first generation prosthesis with variable coronal plane ankle stiffness and tested it with the help of amputees walking on a novel instrumented walkway that replicates a step on uneven terrain. The results of our preliminary tests suggest that varying coronal plane ankle stiffness can influence how an amputee controls their balance. Our proposed research has three specific aims: (1) To identify terrain-dependent coronal ankle properties that maximize balance recovery. We propose to develop a three-dimensional bipedal musculoskeletal model of human walking on uneven terrain and use it to answer a key question: What is the optimal coronal plane stiffness that maximizes balance recovery after a step on uneven terrain? (2) To identify user motor intentions before a step on uneven terrain. We propose to conduct a human subject experiment (n=20) with transtibial amputees wearing our first generation prosthesis. Subjects will be asked to walk on our instrumented walkway that replicates a single step on uneven terrain while we measure their motor intentions (surface electromyography). Using the experimental results, we will develop and test three algorithms to predict the step on uneven terrain. We hypothesize that there will be a difference in accuracy among the three algorithms. We will use the results to specify a control law that best predicts a step on uneven terrain for use with our novel prosthesis. (3) Determine if a novel prosthesis optimized for balance recovery and controlled by user motor intentions can improve the recovery from a step on uneven terrain when compared to the amputee's as- prescribed prosthesis. To achieve this aim, we propose to build a second generation prosthesis that incorporates the results from Specific Aims 1 and 2, as well as the lessons learned from our first generation prosthesis. We then propose to conduct a human subject experiment with transtibial amputees (n=20) that will measure their balance recovery after a step on uneven terrain. We hypothesize that our novel prosthesis will improve the recovery of balance after a step on uneven terrain when compared to the amputee's as-prescribed prosthesis. Expanding the terrain over which Veteran amputees can confidently walk is where the VA should be: at the forefront of prosthetic technology and prescription practice that advances amputee care.