Upper Limb Prosthetics

Completed Projects

Assessing and Responding to the Prosthetic Needs of Farmers and Ranchers

Co-Investigators: Stefania Fatone, PhD, Steven A. Gard, PhD, Kathryn Waldera, MS
Students/Interns: Margaret Parker, MS, Elisah Pietersma, BS
Project Director: Craig Heckathorne, MS
Collaborators: The National AgrAbility Project
Funded by: National Institute on Disability and Rehabilitation Research (NIDRR)
Status: Completed

Farming and ranching are important occupations in the United States, offering many people both valuable employment and a satisfying life style. However, these occupations also expose workers to many dangers. In 2012, the U.S. Bureau of Labor Statistics ranked farming and ranching as having the 9th highest fatality rate of U.S. occupational categories with the 2nd highest number of fatalities in that year. Generally, in occupations with many fatalities, there also are many more non-fatal injuries. The National Safety Council reported that among persons employed in agriculture "one out of every ten of these workers will suffer an amputation while on the job" (Kircher 2003). Many of these amputations will involve part or all of a finger or toe, but it is estimated that 5 to 6 percent (about 1 out of every 200 agricultural workers) will have a major limb amputation involving complete loss of a hand or foot or more of a limb (Brown 2003).

Many farmers and ranchers with major limb amputation are geographically isolated, working in remote settings far from prosthetic clinics. Farmers and ranchers have unique needs that often are not met by standard prosthetic devices. Furthermore, farmers and ranchers who use prostheses are at risk of experiencing secondary injuries due to falls, prosthetic entanglement, overuse injury to the intact limbs, and injuries to the residual limb (Wilkomm and Novak 2007). Lacking are objective data and rigorous engineering analyses of components that could explain why prosthetic devices are not meeting the needs of farmers and ranchers with amputations.

Purpose

The ultimate goals of this project are to promote appropriate application of prosthetic components for farmers and ranchers; to reduce prosthetic device failure and resultant secondary injuries; and to suggest improved prosthetic designs.

Specific Objectives

Identify activities where prosthetic devices either help or hinder farm-related activities by surveying farmers and ranchers with amputations and the prosthetists who provide services to them.
Promote appropriate clinical designs by developing educational materials and tutorials for prosthetists who work with farmers and ranchers.
Improve the design of prosthetic componentry by analyzing failed devices, identifying specific deficiencies and/or needs, and engaging in development projects.

Progress

The first objective was addressed through a two-stage process. The first stage involved a series of telephone and in-person interviews to define prosthetic issues pertinent to farmers and ranchers. The results of these interviews were reported in the journal Disability and Rehabilitation: Assistive Technology (Waldera et al. 2012. Copy and paste this link into your browser: http://www.ncbi.nlm.nih.gov/pubmed/22779443) and in a webinar, Prosthetics for Farmers and Ranchers: What Is Used and What is Needed, available on the website of the National AgrAbility Project (Heckathorne et al. 2012). Issues explored in the interviews included current and past prostheses used, prosthetic failures, and the ability to complete farm tasks using a prosthesis. Prosthetists who provide services to this population were also interviewed to gain knowledge of specific devices and practices used in their geographic region.

Interviews with 40 farmers (in 12 states) and 26 prosthetists (in 14 states) revealed several common themes related to prostheses and their use.

The interviews confirmed that farmers and ranchers with amputations have prosthetic needs distinct from the needs of the general population. Also, it was clear that post-amputation farming or ranching can be facilitated by creating more durable, affordable, and adaptable prosthetic components.

The interview results guided the second stage: the design of two surveys, one specifically for farmers and ranchers with upper-limb amputations and another for those with lower-limb amputations. The objective of these surveys was to obtain more specific information about the concerns of farmers and ranchers with limb amputations in order to establish priorities for improvements. The surveys also provided an opportunity to increase the representation of different types and levels of amputation, different farming and livestock operations, and additional geographic regions. The surveys were available online and in print format.

The survey was conducted from February 2013 through March 2014. During that time, 27 farmers and ranchers completed the survey online and one farmer completed a paper survey. Of the 28 respondents, 20 identified themselves as farmers, 7 as ranchers, and one as an agricultural worker. Fourteen of the 28 had upper-limb amputations and fourteen had lower-limb amputations. Using photographs incorporated in the survey, respondents identified the types of prosthetic components and systems they were using. Also, using a four-point scale from "not a problem" to a "very big problem", respondents rated a variety of factors related to problems they experienced with their prostheses. These included design factors (of the prosthesis), functional factors (how the prosthesis performed in farm and ranch work), service factors (service provided by prosthetists), and cost factors (including direct costs of purchasing the prosthesis and paying for repairs and indirect costs that affected productivity).

The survey results were organized into a webinar intended to inform prosthetists about the prosthetic needs of agricultural workers with amputations. The webinar, “Prostheses for Farmers and Ranchers: What Is Used, What Is Needed” (2014), is available to view free of charge (or with a fee to receive Continuing Education Credit if desired) on the Paul E. Leimkuehler Online Learning Center. (Accessibility Option: This webinar is accessible to individuals with a hearing impairment. Downloading the PowerPoint file using the “Resource Link” at the top right corner of the streaming video enables slide views that show transcription of the narrator's oral presentation in the Notes pane.) This webinar addresses our second objective, education. Content focuses on the types of prostheses used by farmers and ranchers in their work and the problems they encountered. Topics include respondents’ specific components, device construction, durability, maintainability, ease of cleaning and decontaminating, use in adverse weather conditions, prosthetic services, and ranking in order of importance the problems they identified.

Our third objective was to develop ideas to improve prosthetic components. We planned to acquire and analyze failed components obtained from farmers and ranchers. However, collection of failed components proved to be impractical because farmers wanted to keep their parts as spares for future use; had repaired the damaged parts by themselves; or had left the failed parts with their prosthetist to make repairs.

Unable to acquire failed components, we shifted our developmental focus to a prevalent problem identified by farmers and ranchers in both the interviews and the survey, namely heat and perspiration buildup in the prosthetic socket during summer months. Agricultural workers routinely remove their prosthesis several times a day to alleviate the discomfort from heat and sweat and to dry the socket and limb, thus preventing injury to the skin of the residual limb. Having to remove their prosthesis interrupted their work and reduced their productivity.

We reviewed empirical designs for alternative frame-type sockets that could improve heat and moisture dissipation. We developed a conceptual procedure for designing and fabricating a frame-type transradial socket based on pressure measurements at the socket-limb interface and measurements of the heat dissipation characteristics of the frame.

Clinical Implications

The information gathered during this project can impact the design of prostheses for agricultural workers and the way prosthetic services may be tailored to the particular work and life requirements of this population. Areas for future work include the development of prostheses that are more durable, less costly, and more maintainable by the farmer or rancher. It was clear that far more robust and functional prostheses are needed in particular for persons with arm amputations proximal to the elbow, the majority of whom generally choose not to use prostheses while continuing to farm or ranch. Developments in these areas also may benefit persons with amputations who work in other physically demanding occupations such as construction, forestry, mining, and manufacturing. Such improvements may also serve the physical demands of soldiers with amputations who are deployed in combat situations. Furthermore, new developments that address common concerns can be transferred to all prosthesis users.

References

Bureau of Labor Statistics (2012). National Census of Fatal Occupational Injuries in 2011 (Preliminary Results). USDL-12-1888. News Release, September 20, 2012.
Brown J. (2003). Amputations: A Continuing Workplace Hazard. http://www.bls.gov/opub/mlr/cwc/amputations-a-continuing-workplace-hazard.pdf. Access Date: 03/21/12.
Kircher R. (2003). Farming with an Arm Amputation, Oklahoma AgrAbility Newsletter, 2(2):1-8.
Wilkomm T and Novak M. (2007). Assistive Technology and Secondary Injuries Experienced by Farmers, Proceedings of the RESNA Annual Conference, Phoenix, AZ, June 15-19.

Assessing Performance Claims for Multi-Degree-of-Freedom Articulated Hands

Principal Investigator: Steven A. Gard, PhD
Co-Investigators: Edward Grahn, BSME; Matthew Major, PhD; Rebecca Stine, MS; Stefania Fatone, PhD
Project Director: Craig Heckathorne, MS
Funded by: National Institute on Disability and Rehabilitation Research (NIDRR)
Status: Completed

Before 2007, all commercially available electric-powered prosthetic hands utilized a single-degree-of-freedom (single-DOF) actuator design to open and close the fingers and thumb. The digits were configured in the pattern of palmar prehension with the distal palmar pad of the thumb opposing the distal palmar pads of the index and middle fingers, the most common grasp pattern of the human hand. This arrangement also offered cylindrical prehension for wider objects and hook prehension for rods or handles. Although this type of hand has been useful for many activities, designers of prosthetic hands have long sought to develop articulated hands with multiple degrees-of-freedom (multi-DOF) that are able to assume a greater variety of grasp patterns. It was believed that such hands would, in form and action, be more akin to the physiological hand and would, as a consequence, improve manipulative function.

Many designs have been proposed for articulated prosthetic hands. The first electric-powered articulated hand to reach commercialization was the i-limb hand by Touch Bionics (Livingston, United Kingdom), introduced in 2007. The i-limb hand has a set of individual motorized fingers and thumb that can conform to the shape of an object being held. The thumb can be positioned so that it opposes the index and middle fingers (palmar prehension or tripod grip) or the lateral surface of the index finger (lateral prehension or key grip). Positioning of the thumb is done manually for the original i-limb, the i-limb pulse, and the i-limb ultra hands, and is positioned with a motor for the i-limb ultra revolution hand. Users of the i-limb hand comment on its "natural movement", its ability to hold securely a greater variety of objects, reduced mental loading when grasping an object, reduced compensatory arm movements to orient the hand for grasping, everyday activities being "much easier", and being able to hold objects "in the normal way". These claims, based on personal user assessment, are compelling but have not been tested with controlled performance studies.

Specific Objectives

We are conducting two quantitative studies to investigate the qualitative claims made for the Touch Bionics' hands. The first study will determine if a quantitative difference exists in the ability of users of single-DOF and of multi-DOF prosthetic hands when handling a variety of objects in different manipulative tasks.

This study includes three subject groups. The first two groups are persons with unilateral transradial amputations who customarily use a myoelectrically-controlled electric-powered hand. One group will be users of single-DOF hands; the second group will be users of the multi-DOF i-limb hand. The third group, a control group, will be persons with intact upper-limbs.

Manipulative performance will be examined in three ways. The first method will use a standardized, self-administered, functional performance questionnaire involving self-care and upper-limb daily living skills. The second method will have the subjects perform a set of timed pick-and-place and activity tasks using standardized objects while their arm and body positions and movements are tracked and recorded by a motion analysis system. The third method will have the subjects perform a common daily activity at their own pace, again with motion tracking of arm and body movements. Results from the three methods will be compared to determine if significant performance differences exist between users of the two types of electric hands and between each of these groups and the control group.

The second study will compare the grip efficiency, calculated as the ratio of the force required to dislodge a grasped object to the grip force applied by the prosthetic hand, for a single-DOF hand and the i-limb hand using a variety of simple, geometrically shaped objects.

Clinical Implications

Quantitative evidence to support a functional benefit of an articulated (multi-DOF) hand over a single-DOF hand could be used to justify prescribing an articulated hand, even if the hand were more expensive and/or less durable than a single-DOF hand. Such evidence could also encourage further development of articulated hands. Furthermore, an independent, objective study of prosthetic hand function offers clinicians additional knowledge in exercising their professional judgment during clinical assessment and decision making.

Upper Limb Prosthetics

Completed Projects

Assessing and Responding to the Prosthetic Needs of Farmers and Ranchers

Purpose

Specific Objectives

Progress

Clinical Implications

References

Related Presentations and Publications

Assessing Performance Claims for Multi-Degree-of-Freedom Articulated Hands

Specific Objectives

Clinical Implications

Related Presentations and Publications