Virtual Integration Environment Research Articles

Modular Prosthetic Limb Control by an Individual with Congenital Upper-Limb Amputation: A Case Report

ABSTRACT Introduction This article presents a unique case study of an individual with congenital limb loss and long-time (>56 years) body-powered prosthesis use, who was able to control a sophisticated robotic upper-limb prosthesis using surface electromyography signals and pattern recognition (PR) algorithms. This case demonstrates that individuals with congenital limb amputation are able to learn unique strategies to intuitively control a dexterous prosthetic limb. Materials and Methods After completing four training sessions using a virtual integration environment, a single subject participated in 12 in-laboratory clinical training sessions using the modular prosthetic limb (MPL)—a novel multiple–degree-of-freedom dexterous upper-limb prosthesis prototype. Baseline assessments were made with her body-powered prosthesis, as well as a two-site direct-control myoelectric Bebionic she had recently received. Functional assessments with the MPL were conducted during sessions 6 and 12. Outcome measures included timed box and blocks (BB) test, Assessment of Capacity for Myoelectric Control (ACMC), Jebsen-Taylor Hand Function Test (JTHFT), Trinity Amputation and Prosthesis Experience Scale, Upper Extremity Functional Scale (UEFS), and NASA Task Load Index. Results The subject was able to control two independent wrist degrees of freedom and up to three independent hand grasps of the MPL, using an array of surface electrodes. Improvements in the BB and ACMC were observed, although the total time to complete the JTHFT stayed relatively the same from weeks 6 to 12, using the MPL. While her enpoint perceived funcitonal ability with the MPL was 58% compared with 83% with her personal myoelectric prosthesis (12 hours of use vs 4–5 weeks of use as denoted on the UEFS); the subject reported short length of training, a long-term body-powered prosthetic user with congenital limb loss was able to demonstrate objective improvements in control of a dexterous prosthetic hand over a 12-week period of in-laboratory training, achieving intuitive independent control of a variety of simultaneous individual wrist motions and grasp patterns using PR. Conclusions This case demonstrates that even individuals with congenital amputation may be considered as candidates for upper-limb PR-controlled myoelectric prosthetic devices using surface electrodes.

Virtual Integration Environment as an Advanced Prosthetic Limb Training Platform.

Background: Despite advances in prosthetic development and neurorehabilitation, individuals with upper extremity (UE) loss continue to face functional and psychosocial challenges following amputation. Recent advanced myoelectric prostheses offer intuitive control over multiple, simultaneous degrees of motion and promise sensory feedback integration, but require complex training to effectively manipulate. We explored whether a virtual reality simulator could be used to teach dexterous prosthetic control paradigms to individuals with UE loss.Methods: Thirteen active-duty military personnel with UE loss (14 limbs) completed twenty, 30-min passive motor training sessions over 1–2 months. Participants were asked to follow the motions of a virtual avatar using residual and phantom limbs, and electrical activity from the residual limb was recorded using surface electromyography. Eight participants (nine limbs), also completed twenty, 30-min active motor training sessions. Participants controlled a virtual avatar through three motion sets of increasing complexity (Basic, Advanced, and Digit) and were scored on how accurately they performed requested motions. Score trajectory was assessed as a function of time using longitudinal mixed effects linear regression.Results: Mean classification accuracy for passive motor training was 43.8 ± 10.7% (14 limbs, 277 passive sessions). In active motor sessions, >95% classification accuracy (which we used as the threshold for prosthetic acceptance) was achieved by all participants for Basic sets and by 50% of participants in Advanced and Digit sets. Significant improvement in active motor scores over time was observed in Basic and Advanced sets (per additional session: β-coefficient 0.125, p = 0.022; β-coefficient 0.45, p = 0.001, respectively), and trended toward significance for Digit sets (β-coefficient 0.594, p = 0.077).Conclusions: These results offer robust evidence that a virtual reality training platform can be used to quickly and efficiently train individuals with UE loss to operate advanced prosthetic control paradigms. Participants can be trained to generate muscle contraction patterns in residual limbs that are interpreted with high accuracy by computer software as distinct active motion commands. These results support the potential viability of advanced myoelectric prostheses relying on pattern recognition feedback or similar controls systems.

Clinical Trial of the Virtual Integration Environment to Treat Phantom Limb Pain With Upper Extremity Amputation.

Background: Phantom limb pain (PLP) is commonly seen following upper extremity (UE) amputation. Use of both mirror therapy, which utilizes limb reflection in a mirror, and virtual reality therapy, which utilizes computer limb simulation, has been used to relieve PLP. We explored whether the Virtual Integration Environment (VIE), a virtual reality UE simulator, could be used as a therapy device to effectively treat PLP in individuals with UE amputation.Methods: Participants with UE amputation and PLP were recruited at Walter Reed National Military Medical Center (WRNMMC) and instructed to follow the limb movements of a virtual avatar within the VIE system across a series of study sessions. At the end of each session, participants drove virtual avatar limb movements during a period of “free-play” utilizing surface electromyography recordings collected from their residual limbs. PLP and phantom limb sensations were assessed at baseline and following each session using the Visual Analog Scale (VAS) and Short Form McGill Pain Questionnaire (SF-MPQ), respectively. In addition, both measures were used to assess residual limb pain (RLP) at baseline and at each study session. In total, 14 male, active duty military personnel were recruited for the study.Results: Of the 14 individuals recruited to the study, nine reported PLP at the time of screening. Eight of these individuals completed the study, while one withdrew after three sessions and thus is not included in the final analysis. Five of these eight individuals noted RLP at baseline. Participants completed an average of 18, 30-min sessions with the VIE leading to a significant reduction in PLP in seven of the eight (88%) affected limbs and a reduction in RLP in four of the five (80%) affected limbs. The same user reported an increase in PLP and RLP across sessions. All participants who denied RLP at baseline (n = 3) continued to deny RLP at each study session.Conclusions: Success with the VIE system confirms its application as a non-invasive and low-cost therapy option for PLP and phantom limb symptoms for individuals with upper limb loss.

Using a virtual integration environment in treating phantom limb pain.

The Revolutionizing Prosthetics 2009 program conducted by the Defense Advanced Research Projects Agency (DARPA) has resulted in a Virtual Integration Environment (VIE) that provides a common development platform for researchers and clinicians that design, model and build prosthetic limbs and then integrate and test them with patients. One clinical need that arose during the VIE development was a feature to easily create and model animations that represent patient activities of daily living (ADLs) and simultaneously capture real-time surface EMG activity from the residual limb corresponding to the ADLs. An application of this feature is being made by the Walter Reed Military Amputee Research Program (MARP) where they are utilizing the VIE to investigate methods of reducing upper extremity amputee phantom limb pain (PLP).