Conventional leg prostheses do not convey sensory information about motion or interaction with the ground to aboveknee amputees, thereby reducing confidence and walking speed in the users that is associated with high mental and physical fatigue 1-4 . The lack of physiological feedback from the remaining extremity to the brain also contributes to the generation of phantom limb pain from the missing leg 5,6 . To determine whether neural sensory feedback restoration addresses these issues, we conducted a study with two transfemoral amputees, implanted with four intraneural stimulation electrodes 7 in the remaining tibial nerve (ClinicalTrials. gov identifier NCT03350061). Participants were evaluated while using a neuroprosthetic device consisting of a prosthetic leg equipped with foot and knee sensors. These sensors drive neural stimulation, which elicits sensations of knee motion and the sole of the foot touching the ground. We found that walking speed and self-reported confidence increased while mental and physical fatigue decreased for both participants during neural sensory feedback compared to the no stimulation trials. Furthermore, participants exhibited reduced phantom limb pain with neural sensory feedback. The results from these proof-of-concept cases provide the rationale for larger population studies investigating the clinical utility of neuroprostheses that restore sensory feedback.Despite advances in the development of lower-limb prosthetics 8 , the potential benefits of restoring sensory feedback from such devices to transfemoral (above-knee) or transtibial (below-knee) amputees has not been investigated. Most surgery techniques 9 and noninvasive methods 10-12 to restore sensory feedback have been tested only in transtibial amputations, which produce a less disabling clinical condition than transfemoral amputation 1,3 . Direct neural stimulation through transversal intrafascicular multichannel electrodes (TIMEs) 7 has enabled upper-limb amputees to feel touch sensations from the missing hand and to exploit them for long-term prosthesis control 13,14 . Only F.M.P. designed the study, developed the software and the overall system integration, performed and supervised the experiments, analyzed the data and wrote and reviewed the paper. M.B. performed the surgeries, was responsible for all the clinical aspects of the study and reviewed the manuscript. G.V. developed the software and the overall system integration, performed the experiments, analyzed the data and reviewed the manuscript. V.I. and S. Mazic collected and analyzed the metabolic measurements. P.M. and B.M. collected and analyzed the EEG measurements. P.C. and T.S. developed the TIME electrodes and delivered technical assistance during the implantation and explanation procedures. F.B. and D.B. developed the software and the overall system integration and performed the experiments. N.K. analyzed the data. D.G. and D.A. designed the hardware and embedded software (real-time control) for STIMEP. K.L. and A.A. participated in the experimental design...

Lower limb amputation (LLA) destroys the sensory communication between the brain and the external world during standing and walking. Current prostheses do not restore sensory feedback to amputees, who, relying on very limited haptic information from the stump-socket interaction, are forced to deal with serious issues: the risk of falls, decreased mobility, prosthesis being perceived as an external object (low embodiment), and increased cognitive burden. Poor mobility is one of the causes of eventual device abandonment. Restoring sensory feedback from the missing leg of above-knee (transfemoral) amputees and integrating the sensory feedback into the sensorimotor loop would markedly improve the life of patients. In this study, we developed a leg neuroprosthesis, which provided real-time tactile and emulated proprioceptive feedback to three transfemoral amputees through nerve stimulation. The feedback was exploited in active tasks, which proved that our approach promoted improved mobility, fall prevention, and agility. We also showed increased embodiment of the lower limb prosthesis (LLP), through phantom leg displacement perception and questionnaires, and ease of the cognitive effort during a dual-task paradigm, through electroencephalographic recordings. Our results demonstrate that induced sensory feedback can be integrated at supraspinal levels to restore functional abilities of the missing leg. This work paves the way for further investigations about how the brain interprets different artificial feedback strategies and for the development of fully implantable sensory-enhanced leg neuroprostheses, which could drastically ameliorate life quality in people with disability.

Background:Prosthetic services are inaccessible to people living in rural areas. Systems like the modular socket system have the potential to be fabricated outside of the prosthetic workshop.Objectives:This study aimed to evaluate the patient’s performance and satisfaction with the use of the modular socket system, and the technical feasibility of its implementation in a rural setting.Study design:A quantitative longitudinal descriptive study design was followed.Methods:A total of 15 persons with a lower limb amputation were fitted with the modular socket system and followed over 4–6 months. Performance was measured using a 2-min walk test, 10-m walk test and mobility and function questionnaire. Satisfaction was measured by the Socket Fit Comfort Score, Prosthesis Evaluation Questionnaire and EuroQoL 5 Dimensions 5 Levels. Notes on technical feasibility were taken at the moment of fitting (t0), at 1–3 months post fitting (t1) and at the end evaluation at 4–6 months post fitting (t2).Results:Performance did not change between t0 and t2. The comfort of the socket fit reduced between t0 and t2. Satisfaction with prosthesis and general health status stayed constant over time. The average fitting-time for the modular socket system was 6.4 h.Conclusion:The modular socket system can be considered a useful alternative for use in rural settings.Clinical relevanceThe use of the modular socket system is feasible and can improve accessibility to prosthetic technology in rural areas. Experienced prosthetic users were satisfied with the performance and the device. The shorter manufacturing time and use of only hand-held tools makes it an ideal alternative for use in remote and rural settings.

ObjectiveUnilateral trans-tibial amputation signifies a challenge to locomotion. Prosthetic ankle-foot units are developed to mimic the missing biological system which adapts push-off power to walking speed in some new prosthetic ankle-foot designs. The first systematic review including the two factors aims to investigate push-off power differences among Solid Ankle Cushion Heel (SACH), Energy Storage And Return (ESAR) and Powered ankle-foot units (PWR) and their relation to walking speed. Data sourcesA literature search was undertaken in the Web of Science, PubMed, IEEE xplore, and Google Scholar databases. The search term included: ampu* AND prosth* AND ankle-power AND push-off AND walking. Study appraisal and synthesis methodsStudies were included if they met the following criteria: unilateral trans-tibial amputees, lower limb prosthesis, reported analysis of ankle power during walking. Data extracted from the included studies were clinical population, type of the prosthetic ankle-foot units (SACH, ESAR, PWR), walking speed, and peak ankle power. Linear regression was used to determine whether the push-off power of different prosthetic ankle-foot units varied regarding walking speed. Push-off power of the different prosthetic ankle-foot units were compared using one-way between subjects' ANOVAs with post hoc analysis, separately for slower and faster walking speeds. Results474 publications were retrieved, 28 of which were eligible for inclusion. Correlations between walking speed and peak push-off power were found for ESAR (r = 0.568, p = 0.006) and PWR (r = 0.820, p = 0.000) but not for SACH (r = 0.267, p = 0.522). ESAR and PLOS ONE | https://doi.org/10.1371/journal.pone. Funding:The funders, Klinikum Bayreuth GmbH (https://klinikum-bayreuth.de/) and Ossur hf. (https://www.ossur.com/?select-default-destination=1), provided support in the form of salaries for authors R.M., L.M., R.A. and K.L., but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of PWR demonstrated significant differences in push-off power for slower and faster walking speeds (ESAR (p = 0.01) and PWR (p = 0.02)). ConclusionPush-off power can be used as a selection criterion to differentiate ankle-foot units for prosthetic users and their bandwidth of walking speeds.Prosthetic push-off power in trans-tibial amputee walking PLOS ONE | https://doi.org/10.

Background: This study presented the load profile applied on transfemoral osseointegrated implants by boneanchored prostheses fitted with state-of-the-art Ö SSUR microprocessor-controlled Rheo Knee XC and energystoring-and-returning Pro-Flex XC or LP feet during five standardized daily activities. Methods: This cross-sectional cohort study included 13 participants fitted with a press-fit transfemoral osseointegrated implant. Loading data were directly measured with the tri-axial transducer of an iPecsLab (RTC Electronics, USA) fitted between the implant and knee unit. The loading profile was characterized by spatio-temporal gaits variables, magnitude of loading boundaries as well as onset and magnitude of loading extrema during walking, ascending and descending ramp and stairs. Findings: A total of 2127 steps was analysed. The cadence ranged between 36 ± 7 and 47 ± 6 strides/min. The absolute maximum force and moments applied across all activities was 1322 N, 388 N and 133 N as well as 22 Nm, 52 Nm and 88 Nm on and around the long, anteroposterior and mediolateral axes of the implant, respectively. Interpretation: This study provided new benchmark loading data applied by transfemoral bone-anchored prostheses fitted with selected Ö SSUR state-of-the-art components. Outcomes suggested that such prostheses can generate relevant loads at the interface with the osseointegrated implant to restore ambulation effectively. This study is a worthwhile contribution toward a systematic recording, analysis, and reporting of ecological prosthetic loading profiles as well as closing the evidence gaps between prescription and biomechanical benefits of state-ofthe-art components. Hopefully, this will contribute to improve outcomes for growing number of individuals with limb loss opting for bionic solutions.