Owing to certain intrinsic advantages, a surprisingly large number of upper-extremity amputees prefer simple cable operated prostheses and split hook terminal devices for many activities. For disadvantaged amputees in the United States and in developing countries, such systems often present the only viable restorative option. ADA Technologies and its supporting network of amputees and prosthetists believe a powerful way to help these users is to create a lightweight, robust, and corrosion resistant new split hook offering two refreshing functional improvements: 1) a means to readily adjust pinch force to match task need and to minimize the muscular energy expended effecting grasp;and 2) more visually appealing gripping contours that deliver stable, quality grasp without damaging the user's possessions. Consistent with ADA's mission to develop innovative new conventional prosthetic technologies that benefit users worldwide, the Primary Objective of this SBIR program is to create a versatile next-generation split hook terminal device that delights upper-extremity amputees in the United States and abroad and that can be manufactured for low cost to facilitate global distribution. In Phase I, functional grasping contours developed through previous research were combined with an innovative pinch force adjustment mechanism in a visually appealing design. Collaboration with outside fabricators ensured this design fully leverages materials and processes to minimize manufacturing cost. Field trials of the prototype device verify it delivers excellent grasp functionality, and evaluators enthusiastically praised its adjustable pinch force capability. Because ADA's split hook is lightweight and requires on average 53% less energy to operate than benchmark units, the company's expert advisors believe the device will significantly benefit transhumeral and at-risk amputees plagued by cumulative trauma injuries and trapezius muscle pathologies arising from prosthesis usage. Moreover, the device's low manufacturing cost, robustness, and immunity to galvanic corrosion make it ideal for disadvantaged amputees in developing countries, over 82% of whom survive by agrarian occupations. Phase II comprises establishing manufacturing infrastructure and validating the performance of production hardware under strenuous conditions representative of subsistence farming and ranching. Clinical testing with transhumeral amputee subjects will examine potential benefits of the device for these users. The company will also complete tasks required by law to launch its split hook as a commercial product into the worldwide marketplace. Phase III encompasses manufacturing and supplying the split hook to clinicians and humanitarian agencies in the United States and in developing countries. In keeping with the spirit and intent of the SBIR program, this approach maximally leverages NIH funding to directly benefit men and women who must cope daily with the limitations and consequences of upper-limb deficiencies.
In the United States and developing countries, affordable upper-extremity prosthetic components are much needed as escalating costs and increasing technological sophistication have for many amputees placed most existing products out of reach. The split hook technology described here incorporates key functional innovations while leveraging new materials and manufacturing processes to benefit amputees who prefer conventional prostheses and those for whom few or no other options exist. The device is designed to delight users, improving their quality of life by helping them become or remain productive members of society through renewed self-sufficiency, sense of purpose, and personal dignity.
