Clinical Objectives and Rationale for the Project: The prosthetic components available for high-level and bilateral amputees are far from replacing the natural functions these individuals have lost. The electric hands seen in the media, with multiple functions and natural-like movements, are typically too heavy and too complex to allow the functions this clientele requires. This project will balance the simple, but very effective function of body-powered hook-type TDs, with the range of motion and higher pinch force, which can be provided by a multiple degree of freedom (DOF) wrist, and a myoelectric hook-type terminal device (TD). The example of the present Electric Terminal Device (ETD) is a good one -- combine the innate tool-like function of a hook with the high force and greater work envelope provided by myoelectric devices. It has become a very popular choice of the current service-connected amputees, and the second-generation device in process (ETD2) is shorter and even more functional.

Wrists, both motorized and passive, are key to enhancing the performance of even the most functional TD, because they allow the TD to be positioned at the optimal position, even though the TD may have only one DOF. Powered wrist rotation and flexion will be developed, as well as a unique passive Ball Wrist, which can move in 3 DOF passively, but then lock in position under the control of the wearer, creating the Ultimate Vice Grip.

Applicability of the Clinical Research:

What types of patients will it help? All levels of prosthetic fitting will be aided, since the shorter ETD2 will allow more wrist function to be added to longer-length prostheses. The highest level prostheses will have up to 4 DOF of TD and Wrist function, allowing a much wider range of manipulation than has been available in the past.

What are the clinical applications, benefits, and risks? Individuals suffering upper extremity (UE) limb loss from the hand level, or higher, who are candidates for work-type prostheses. The rugged construction and water resistance will allow outdoor activities using the ETD2+Wrist options, as well as rugged work type activities. The hook shape allows much better visibility as well as the ability to reach into pockets and/or narrow spaces. The ETD2 improves gripping surfaces for flat objects, such as papers, books, and many tools, and the ETD has sculpted cylindrical gripping shapes, which hold bottles, cans, and cylindrical tool handles very securely as well. Nearly all hand prosthesis are very limited in manual work activities, because of their more complex construction, as well as the flesh-colored coverings, which are easily stained or ripped, when using tools or machinery. The limitations of an electric hook-type TD are often aesthetic -- a person working with the public might attract unwanted attention to their prosthesis, rather than the work they are performing.

Risks: The highly complex mechanism of the 3-DOF wrist might have a long development period and be heavier than many individuals are willing to wear on their prosthesis day-in and day-out. However, in this project, alternatives will be developed that are less complex and lighter in weight.

What is the projected time it may take to achieve a clinically relevant outcome? The lower DOF versions of the ETD2 with the new Q/D may be field trialed in the second year of the project, and if successful, could be released as a product by the end of that year since the technical risk is low. Release of other components, such as the new MC Wrist Rotator, and Powered Flexion could be field trialed at the end of the second year, and field trials of the 3-DOF Powered Wrist could begin as early as the third year.

What are the advantages of the proposed technology over existing upper extremity prosthetic devices? The greatest competitor to the ETD2 will be the ETD1, over which it has advantages of shorter length, superior gripping surfaces, and better aesthetics. The wrist components will be shorter and lighter than the rotation devices currently available, and the 3-DOF wrist will provide function, which is at present unavailable in the prosthetics armamentarium.

What are the likely contributions of this study to advancing the field of research? The 4-DOF ETD2+Wrist and its subsets will be immediately useful in the M-DOF research being conducted using Targeted Muscle Reinervation, as well as implanted EMG sensors, etc. The integrated combination will communicate via the CANbus system with the entire system of components and interchange with any other choice of components.