Shana Lieberman Klinger

The DEKA Arm: Its features, functionality, and evolution during the Veterans Affairs Study to optimize the DEKA Arm

Background and aim: DEKA Integrated Solutions Corp. (DEKA) was charged by the Defense Advanced Research Project Agency to design a prosthetic arm system that would be a dramatic improvement compared with the existing state of the art. The purpose of this article is to describe the two DEKA Arm prototypes (Gen 2 and Gen 3) used in the Veterans Affairs Study to optimize the DEKA Arm. Technique: This article reports on the features and functionality of the Gen 2 and Gen 3 prototypes discussing weight, cosmesis, grips, powered movements Endpoint, prosthetic controls, prosthetist interface, power sources, user notifications, troubleshooting, and specialized socket features; pointing out changes made during the optimization efforts. Discussion: The DEKA Arm is available in three configurations: radial configuration, humeral configuration, and shoulder configuration. All configurations have six preprogrammed grip patterns and four wrist movements. The humeral configuration has four powered elbow movements. The shoulder configuration uses Endpoint Control to perform simultaneous multi-joint movements. Three versions of foot controls were used as inputs. The Gen 3 incorporated major design changes, including a compound wrist that combined radial deviation with wrist flexion and ulnar deviation with wrist extension, an internal battery for the humeral configuration and shoulder configuration, and embedded wrist display. Clinical relevance The DEKA Arm is an advanced upper limb prosthesis, not yet available for commercial use. It has functionality that surpasses currently available technology. This manuscript describes the features and functionality of two prototypes of the DEKA Arm, the Gen 2 and the Gen 3.

Do users want to receive a DEKA Arm and why? Overall findings from the Veterans Affairs Study to optimize the DEKA Arm

Background: The purposes of this article are (1) to report on the overall desirability of the DEKA Arm by prototype and by level of prosthesis, (2) to report on user-perceived benefits of the DEKA Arm as compared to their current prostheses, and (3) to summarize user concerns about taking the device home. Study design: Qualitative content analysis of data from a multiple case study design. Methods: This study utilized data from 24 upper-limb amputees fit with a Gen 2 DEKA Arm and 13 fit with a Gen 3 DEKA Arm. Surveys were administered after fitting the DEKA Arm and at the end of training. Subjects recorded audiotaped comments about their experiences. All study sessions were videotaped. Results: In all, 79% of Gen 2 and 85% of Gen 3 users indicated that either they wanted to receive or might want to receive a DEKA Arm. In total, 95% of Gen 2 and 91% of Gen 3 prior prosthesis users reported that they were able to perform new activities that they were unable to perform with their own device. Conclusions: A large majority of subjects wanted a DEKA Arm, although desirability varied by amputation level. Clinical relevance The majority of amputees in this study expressed a desire to receive the DEKA Arm, a device which provides multiple powered degrees of freedom and is operated predominantly by foot controls. The majority reported functional advantages of the DEKA Arm over their existing prostheses.

Controlling a multi-degree of freedom upper limb prosthesis using foot controls: user experience

Abstract Purpose: The DEKA Arm, a pre-commercial upper limb prosthesis, funded by the DARPA Revolutionizing Prosthetics Program, offers increased degrees of freedom while requiring a large number of user control inputs to operate. To address this challenge, DEKA developed prototype foot controls. Although the concept of utilizing foot controls to operate an upper limb prosthesis has been discussed for decades, only small-sized studies have been performed and no commercial product exists. The purpose of this paper is to report amputee user perspectives on using three different iterations of foot controls to operate the DEKA Arm. Method: Qualitative data was collected from 36 subjects as part of the Department of Veterans Affairs (VA) Study to Optimize the DEKA Arm through surveys, interviews, audio memos, and videotaped sessions. Three major, interrelated themes were identified using the constant comparative method: attitudes towards foot controls, psychomotor learning and physical experience of using foot controls. Results: Feedback about foot controls was generally positive for all iterations. The final version of foot controls was viewed most favorably. Conclusions: Our findings indicate that foot controls are a viable control option that can enable control of a multifunction upper limb prosthesis (the DEKA Arm). Implications for Rehabilitation Multifunction upper limb prostheses require many user control inputs to operate. Foot controls offer additional control input options for such advanced devices, yet have had minimal study. This study found that foot controls were a viable option for controlling multifunction upper limb prostheses. Most of the 36 subjects in this study were willing to adopt foot controls to control the multiple degrees of freedom of the DEKA Arm. With training and practice, all users were able to develop the psychomotor skills needed to successfully operate food controls. Some had initial difficulty, but acclimated over time.

User and clinician perspectives on DEKA arm: results of VA study to optimize DEKA arm.

This article summarizes feedback from Department of Veterans Affairs (VA) subjects and clinicians gathered during the VA optimization study of the DEKA Arm. VA subjects and clinicians tested two DEKA Arm prototypes (second-generation [gen 2] and third-generation [gen 3]). Features of the prototypes in three configurations are described. DEKA used feedback from the VA optimization study and from their own subjects to refine the gen 2 prototype. Thirty-three unique subjects participated in the VA evaluation; 26 participated in the gen 2 evaluation (1 subject participated twice), 13 participated in the gen 3 evaluation, and 5 participated in both gen 2 and gen 3 evaluations. Subject data were gathered through structured and open-ended surveys, interviews, and audio- and videotaped sessions. Study prosthetists and therapists provided ongoing feedback and completed surveys at the end of each subjects protocol. Eleven categories of feedback were identified: weight, cosmesis, hand grips, wrist design, elbow design, end-point control, foot controls, batteries and chargers, visual notifications, tactor, and socket features. Final feedback on the gen 3 was generally positive, particularly regarding improvements in wrist design, visual notifications, foot controls, end-point control, and cosmesis. Additional refinements to make the device lighter in weight, eliminate external wires and cables, and eliminate the external battery may further enhance its perceived usability and acceptability.

Does the DEKA Arm substitute for or supplement conventional prostheses

Background: Research on home use of advanced upper limb prostheses is needed. Objectives: To describe and compare DEKA Arm usage patterns during the last 4 weeks of a home trial for participants with a personal prosthesis and those without. To compare usage patterns during home trial to those of the personal prosthesis prior to home trial. To evaluate user activity preferences for the DEKA Arm and personal prosthesis after a trial of home use. Study design: Quasi-experimental, time-series design. Methods: Data from 17 participants were analyzed. At baseline, prosthesis users reported days and hours they wore and used personal device(s). Home trial diaries documented days and hours of wear and use for the DEKA Arm and personal device(s), if applicable. Questionnaires asked prosthesis users to list activities they could do with the DEKA Arm but not with their current prosthesis and vice versa and activities they preferred doing with either devices. Results: The DEKA Arm was worn 81% and used 73% of functioning days, averaging 4.2 h worn and 2.4 h used on days worn. During home trial, prosthesis users used personal devices and any prosthesis for fewer hours/day than at baseline. Conclusion: The DEKA supplemented but did not substitute for the personal prosthesis. Clinical relevance Findings strongly suggest that given the limitations of the DEKA Arm and conventional prosthesis, persons with upper limb amputation would be best served and would be able to perform the widest range of activities if they had several types of devices.

Predictors of retention and attrition in a study of an advanced upper limb prosthesis: implications for adoption of the DEKA Arm

Abstract Purpose: The purpose was to identify factors associated with completion of the VA home study of the DEKA Arm. Design and methodological procedures used: Differences between groups were examined using chi-square and t-tests. A multivariable logistic regression model predicting completion was generated and odds ratios (OR) for significant variables calculated. Post-hoc analysis was performed to plot the receiver operating characteristics (ROC) curve. Results: Participants who completed were more likely to be prosthesis users at study onset (p = .03), and less likely to have a history of musculoskeletal problems (p = .047). There were no statistically significant differences between groups who completed and those who did not in gender, race, veteran status, age, body mass index (BMI), weight, height, musculoskeletal pain at baseline, satisfaction with current prosthesis, type of prosthesis, or months of prosthesis use. Two variables, prosthesis use and history of musculoskeletal problems were significant at p < .10. The area under the curve (AUC) accuracy index was 0.78. Conclusions: We considered completion of the home use study a reasonable proxy for participant willingness to adopt the device; and believe that findings can be extrapolated to guide DEKA Arm prescription recommendations. Participants most likely to complete the study were already using a personal prosthesis, and without pre-existing musculoskeletal problems. Implications for rehabilitation Data from the VA Study of the DEKA Arm were analysed to determine which factors were associated with likely successful adoption of the DEKA Arm. Participants most likely to complete the study were those who already using a personal prosthesis, and those without pre-existing chronic or re-occurring musculoskeletal problems. This information may be useful when attempting to identify and target the most appropriate candidates for DEKA Arm prescription.

User experience of controlling the DEKA Arm with EMG pattern recognition

Introduction A commercially available EMG Pattern Recognition (EMG-PR) control system was adapted to interface with the multi-degree of freedom (DOF) DEKA Arm. Purpose To describe users’ experience of controlling the DEKA Arm using EMG-PR. Methods Sample: Twelve persons with upper limb amputation participated, 10 with transradial (TR), 2 with transhumeral (TH) level amputation. Ten were male, and 11 were users of a prosthesis at baselines. Design: This was a two-part study consisting of in-laboratory prosthetic training (Part A) and up to 12 weeks of home use of the prosthesis (Part B). Data collection: Qualitative data were collected through open-ended survey questions and semi-structured interviews. Data Analysis: The study used a qualitative case series design with a constant comparative approach to identify common categories of experience. Coding categories were iteratively refined until saturation of categories was achieved. The data were organized in a primary category, major categories of experience, factors impacting experience, and broader contextual factors. Results Users had mixed perspectives on the desirability of the EMG-PR control system in combination with the DEKA Arm. Major aspects of user experience related to the system complexity, process of calibrating, and functional benefits. Factors influencing user experience included training and acclimation, fatigue, prosthesis design, technical issues and control changes. Broader contextual factors, both personal and environmental, also impacted users’ experience. Discussion/Conclusion This study provided an in-depth description of user experience operating the DEKA Arm using EMG-PR control. The majority of participants expressed a preference for the controls of their personal prosthesis and controls rather than the iteration of EMG-PR controlled DEKA Arm used in this study. Most were positive about the future potential of EMG-PR as a control method. An understanding of patient experience will assist clinicians and patients choosing prosthetic options.

Feminine identity and functional benefits are key factors in women’s decision making about upper limb prostheses: a case series

Abstract Purpose: Although the DEKA Arm promises new abilities, it is unclear if women with upper limb amputation are willing to avail themselves of this new technology. The study purpose was to understand key factors and tradeoffs that shape women’s attitudes towards the DEKA Arm. Methods: This case series includes three women with transradial amputation. Structured surveys and semi-guided interviews were administered after completion of in-laboratory training and a home trial of the DEKA Arm. A constant comparative method with a grounded theory approach was used to generate a model describing women’s decision-making related to the DEKA Arm. Quantitative data on prosthetic satisfaction was used to triangulate findings. Results: Factors that enhanced desirability of the DEKA Arm were improved functionality, increased abilities and the availability of someone to service the prosthesis. Factors that detracted from desirability of the device were its appearance, conspicuousness, lifestyle incompatibility, weight, need for service and difficulty of use. Each woman weighted these factors within the larger context of the capabilities of and satisfaction with her personal prostheses, her self-concept and lifestyle needs. Situational demands, particularly the desire to appear feminine and professional or need to perform certain activities, also altered the valuation of these priorities. Conclusion: Findings strongly suggest that advanced upper limb prosthetic technologies, like the DEKA Arm, will be better accepted by women if appropriately gendered in appearance and designed with women’s priorities in mind. Implications for Rehabilitation Women should be able to derive the functional benefits of advances in upper limb technology without needing to compromise their feminine identity and lifestyle preferences. Advanced upper limb prosthetic technologies will be better accepted by women if they are appropriately gendered.