We show that state-of-the-art advanced artificial intelligence algorithms based on “deep neural networks” achieve superior performance compared to two common algorithms for decoding movement intent for prosthetic control. We performed a rigorous analysis to explain why the state-of-the-art algorithms perform better based on an analysis of 11 able-bodied subjects and 4 prosthesis users. This work shows and explains why state-of-the-art algorithms are better which is important since it has been a challenge to demonstrate that new algorithms are better due to external disturbances.
Contrary to previous claims, skin temperature is not a biomarker for ownership. We induced the Rubber Hand Illusion (RHI), the gold standard experiment to study the sense of ownership, while monitoring the participants skin temperature with a precise thermal camera. We found that temperature change does not correlate with the ownership score in the RHI paradigm and thus suggest caution in drawing strong inferences of ownership based on the skin temperature.
Mathematical models are one possible avenue for studying the working mechanisms of pain. This is a systematic review of mathematical and computational models for pain. 31 articles were identified and sorted based on their classification algorithm, data collection method, or proposal of a mathematical model.
Not everyone is susceptible to illusions. We showed that the Rubber Hand Illusion (RHI) can be induced with different types of tactile stimulation but about 30% of people are immune to it. This includes four people implanted with neuromusculoskeletal prostheses who otherwise perceive their prostheses as part of their own body when using it in daily life, thus highlighting limitations to the RHI as an experimental paradigm.
This article discusses several existing hypotheses for the origin of phantom limb pain (PLP) and speculates on their respective implications for treatments. While seemingly contradicting, these neurophysiological models of PLP might not be mutually exclusive. All of them involve mechanisms by which an artificial limb could counteract PLP.
After long-term use of a neuromusculoskeletal prosthesis where the location of a force sensor on a prosthetic hand and the location that electrical nerve stimulation corresponding to grasping force was felt did not originally match, we show that the perceived location of the touch does not change to match the sensor location. Our results with three neuromusculoskeletal prosthesis users conform to previous studies that suggest sensory maps in the brain are stable in adulthood and cannot be modified. Although the sensation and prosthesis sensor locations did not match, participants still indicated greater confidence in their prosthesis control and greater embodiment of the bionic limb. Although congruent sensory location is not required for the benefits of sensory feedback to arise, it may still be preferable for prosthesis users and thus other methods of changing sensory locations remains a future area of development.
Phantom motor execution (PME) facilitated by augmented/virtual reality (AR/VR) and serious gaming (SG) has been proposed as a treatment for phantom limb pain (PLP). Evidence of the efficacy of this approach was obtained through a clinical trial involving individuals with chronic intractable PLP affecting the upper limb, and further evidence is currently being sought with a multi-sited, international, double blind, randomized, controlled clinical trial in upper and lower limb amputees. All experiments have been conducted in a clinical setting supervised by a therapist. Here, we present a series of case studies (two upper and two lower limb amputees) on the use of PME as a self-treatment. We explore the benefits and the challenges encountered in translation from clinic to home use with a holistic, mixed-methods approach, employing both quantitative and qualitative methods from engineering, medical anthropology, and user interface design. All patients were provided with and trained to use a myoelectric pattern recognition and AR/VR device for PME. Patients took these devices home and used them independently over 12 months. We found that patients were capable of conducting PME as a self-treatment and incorporated the device into their daily life routines. Use patterns and adherence to PME practice were not only driven by the presence of PLP but also influenced by patients’ perceived need and social context. The main barriers to therapy adherence were time and availability of single-use electrodes, both of which could be resolved, or attenuated, by informed design considerations. Our findings suggest that adherence to treatment, and thus related outcomes, could be further improved by considering disparate user types and their utilization patterns. Our study highlights the importance of understanding, from multiple disciplinary angles, the tight coupling and interplay between pain, perceived need, and use of medical devices in patient-initiated therapy.
How is it like to live with a permanently implanted prosthetic limb? Three people with an implanted prostheses were interviewed about their experiences of living with a prostheses in their daily lives. The participants expressed positive effects on self-esteem, self-image, and social relations. Besides that, the participants indicated enhanced prosthetic function, increased and more diverse prosthesis use in tasks of daily living, and improved relationships between their prosthesis and phantom limb.
We show that tactile feedback is necessary for dexterous grasping with a prosthetic hand, and that the effectiveness of this feedback can be influenced by how the tactile information is encoded in the feedback. Three participants with a neuromusculoskeletal prosthesis repeatedly lifted an object which measured their grasping force and could randomly change weight, and we found that tactile feedback becomes more relevant when the expected wieght was more uncertain. Differences in participant preferences and performance also suggest that the effectiveness of sensory feedback may be partially dependent on their prior experiences. These insights into tactile sensory feedback may lead to improved control over prosthetic arms and reduce the need to closely watch the prosthesis while grasping objects.
Bone-anchored attachment of amputation limb prostheses is increasingly becoming a clinically accepted alternative to conventional socket suspension. The direct transfer of loads demands that the percutaneous implant system and the residual bone withstand all forces and moments transferred from the prosthesis. This study presents load measurements recorded at the bone-anchored attachment in 20 individuals with unilateral transfemoral amputation performing the everyday ambulatory activities: level ground walking, stairs ascent/descent and slope ascent/descent. Mean peak values for the sample populations across activities ranged from 498–684 N for the resultant force, 26.5–39.8 Nm for the bending moment, and 3.1–5.5 Nm for the longitudinal moment. Significant differences with respect to level walking were found for the resultant force during stairs ascent, (higher, p = 0.002), and stairs descent, (lower, p = 0.005). Using a crutch reduced the peak resultant forces and the peak bending moments with averages ranging from 5.5–12.6 % and 13.2–15.6 %, respectively. Large inter-participant variations were observed and no single activity resulted in consistently higher loading of the bone-anchored attachment across the participants. Results from this study can guide future development of percutaneous osseointegrated implant systems for limb prostheses and their rehabilitation protocols.