Accuracy, Repeatability, and Reproducibility of a Hand-Held Structured-Light 3D Scanner across Multi-Site Settings in Lower Limb Prosthetics

The aim of this work was to assess the accuracy, repeatability, and reproducibility of a hand-held, structured-light 3D scanner (EINScan Pro 2X Plus with High Definition Prime Pack, SHINING 3D Tech. Co., Ltd., Hangzhou, China), to support its potential use in multi-site settings on lower limb prosthetics. Four limb models with different shapes were fabricated and scanned with a metrological 3D scanner (EINScan Laser FreeScan 5X, SHINING 3D Tech. Co., Ltd., Hangzhou, China) by a professional operator (OP0). Limb models were then mailed to three sites where two operators (OP1, OP2) scanned them using their own structured-light 3D scanner (same model). OP1 scanned limb models twice (OP1-A, OP1-B). OP0, OP1-A, and OP2 scans were compared for accuracy, OP1-A and OP1-B for repeatability, and OP1-A and OP2 for reproducibility. Among all comparisons, the mean radial error was <0.25 mm, mean angular error was <4°, and root mean square error of the radial distance was <1 mm. Moreover, limits of agreement were <3.5% for perimeters and volumes. By comparing these results with respect to clinically-relevant thresholds and to the literature available on other 3D scanners, we conclude that the EINScan Pro 2X Plus 3D Scanner with High Definition Prime Pack has good accuracy, repeatability, and reproducibility, supporting its use in multi-site settings.

Intuitive control of additional prosthetic joints via electro-neuromuscular constructs improves functional and disability outcomes during home use - a case study

OBJECTIVE

The advent of surgical reconstruction techniques has enabled the recreation of myoelectric controls sites that were previously lost due to amputation. This advancement is particularly beneficial for individuals with higher-level arm amputations, who were previously constrained to using a single degree of freedom (DoF) myoelectric prostheses due to the limited number of available muscles from which control signals could be extracted. In this study, we explore the use of surgically created electro-neuromuscular constructs to intuitively control multiple bionic joints during daily life with a participant who was implanted with a neuromusculoskeletal prosthetic interface. Approach: We sequentially increased the number of controlled joints, starting at a single DoF allowing to open and close the hand, subsequently adding control of the wrist (2 DoF) and elbow (3 DoF). Main Results: We found that the surgically created electro-neuromuscular constructs allow for intuitive simultaneous and proportional control of up to three degrees of freedom using direct control. Extended home-use and the additional bionic joints resulted in improved prosthesis functionality and disability outcomes. Significance: Our findings indicate that electro-neuromuscular constructs can aid in restoring lost functionality and thereby support a person who lost their arm in daily-life tasks. .

Building a Multidisciplinary Clinic Dedicated to Upper-Extremity Limb Loss

Complete care of the patient with upper limb loss mandates a long-term, multifaceted approach. Increased functionality and quality of life require collaborative efforts between the patient's surgeon, prosthetist, hand therapists, mental health professionals, and peers. An individual surgeon may find that initiating and maintaining a practice offering total integrated treatment for upper-extremity amputees is a formidable task, but with specific, actionable recommendations, the process can be demystified. The upper-extremity surgeon must be facile with operative techniques such as targeted muscle reinnervation (TMR), regenerative peripheral nerve interface (RPNI), and soft tissue reconstruction and focus on team recruitment strategy and promotion of the clinic within the community. Consistent communication and team decision-making shape each patient's preoperative and postoperative course. We aim to relay effective interventions at each step of recovery from each clinic member and describe clinic workflow designed to reinforce holistic care. We present a blueprint for creating a functional and comprehensive multidisciplinary center for patients with upper-extremity limb loss for those providers interested in providing care, but who are missing the logistical roadmap for how to do so.

Describe the population receiving orthotic/prosthetic services using telehealth in Australia, and their experience and satisfaction: a quantitative and qualitative investigation

PURPOSE

Telehealth may help meet the growing demand for orthotic/prosthetic services. Despite the resurgence of telehealth due to COVID-19, there is limited evidence to inform policy and funding decisions, nor guide practitioners.

METHODS

Participants were adult orthosis/prosthesis users or parents/guardians of child orthosis/prosthesis users. Participants were convenience sampled following an orthotic/prosthetic telehealth service. An online survey included: demographics, Telehealth Usability Questionnaire, and the Orthotic Prosthetic Users Survey - Client Satisfaction with Services. A subsample of participants took part in a semi-structured interview.

RESULTS

Most participants were tertiary educated, middle-aged, female, and lived in metropolitan or regional centres. Most telehealth services were for routine reviews. Most participants chose to use telehealth given the distance to the orthotic/prosthetic service, irrespective of whether they lived in metropolitan cities or regional areas. Participants were highly satisfied with the telehealth mode and the clinical service they received via telehealth.

While orthosis/prosthesis users were highly satisfied with the clinical service received, and the telehealth mode, technical issues affected reliability and detracted from the user experience. Interviews highlighted the importance of high-quality interpersonal communication, agency and control over the decision to use telehealth, and a degree of health literacy from a lived experience of using an orthosis/prosthesis.

Complications Following Osseointegrated Transfemoral and Transtibial Implants: A Systematic Review

Lower limb amputation is a common orthopedic surgery in the United States and can be performed either above or below the knee. Prosthetics are typically externally fitted to the patient's residual stump; however, osseointegrated implants offer a potential alternative to this process. Transcutaneous limb osseointegration involves the intramedullary anchoring of an implant that can later attach to a prosthetic via a stoma in the residual limb. There are proposed benefits to this, including decreased skin and soft tissue complications as well as an increased sense of stability. As this is a relatively new procedure, the complications and efficacy are not well supported by the literature at this time. The primary aim of this analysis was to synthesize the currently available data on transfemoral and transtibial osseointegration in order to improve our understanding of the potential complications of the procedure. A literature search was performed in the following databases: Biomedical Reference Collection, CINAHL, Cochrane Library, and PubMed/MEDLINE. Articles were screened by three independent reviewers for studies written or available in English, study design, and study outcomes, including complications. No filter was applied for publication date, publication national origin, or sample size. A total of 20 articles were selected for the final qualitative analysis. This review demonstrates an overall low or non-inferior rate of both minor and severe complications in transtibial and transfemoral osseointegration. This procedure should be considered as an option during preoperative planning in the context of above-the-knee and below-the-knee amputations. However, continued studies with larger sample sizes and extended postoperative follow-up are necessary for a greater strength of recommendation.

Finger Prosthesis Driven by DEA Pairs as Agonist-Antagonist Artificial Muscles

Loss of an upper limb exerts a negative influence on an individual's ability to perform their activities of daily living (ADLs), reducing quality of life and self-esteem. A prosthesis capable of performing basic ADLs functions has the capability of restoring independence and autonomy to amputees. However, current technologies present in robotic prostheses are based on rigid actuators with several drawbacks, such as high weight and low compliance. Recent advances in robotics have allowed for the development of flexible actuators and artificial muscles to overcome the limitations of rigid actuators. Dielectric elastomer actuators (DEAs) consist of a thin elastomer membrane arranged between two compliant electrodes capable of changing dimensions when stimulated with an electrical potential difference. In this work, we present the design and testing of a finger prosthesis driven by two DEAs arranged as agonist-antagonist pairs as artificial muscles. The soft actuators are designed as fiber-constrained dielectric elastomers (FCDE), enabling displacement in just one direction as natural muscles. The finger prosthesis was designed and modeled to show bend movement using just one pair of DEAs and was made of PLA in an FDM 3D printer to be lightweight. The experimental results show great agreement with the proposed model and indicate that the proposed finger prosthesis is promising in overcoming the limitations of the current rigid based actuators.

Gait quality in prosthesis users is reflected by force-based metrics when learning to walk on a new research-grade powered prosthesis

Introduction

Powered prosthetic feet require customized tuning to ensure comfort and long-term success for the user, but tuning in both clinical and research settings is subjective, time intensive, and the standard for tuning can vary depending on the patient's and the prosthetist's experience levels.

Methods

Therefore, we studied eight different metrics of gait quality associated with use of a research-grade powered prosthetic foot in seven individuals with transtibial amputation during treadmill walking. We compared clinically tuned and untuned conditions with the goal of identifying performance-based metrics capable of distinguishing between good (as determined by a clinician) from poor gait quality.

Results

Differences between the tuned and untuned conditions were reflected in ankle power, both the vertical and anterior-posterior impulse symmetry indices, limb-force alignment, and positive ankle work, with improvements seen in all metrics during use of the tuned prosthesis.

Discussion

Notably, all of these metrics relate to the timing of force generation during walking which is information not directly accessible to a prosthetist during a typical tuning process. This work indicates that relevant, real-time biomechanical data provided to the prosthetist through the future provision of wearable sensors may enhance and improve future clinical tuning procedures associated with powered prostheses as well as their long-term outcomes.

On Automated Object Grasping for Intelligent Prosthetic Hands Using Machine Learning

Prosthetic technology has witnessed remarkable advancements, yet challenges persist in achieving autonomous grasping control while ensuring the user's experience is not compromised. Current electronic prosthetics often require extensive training for users to gain fine motor control over the prosthetic fingers, hindering their usability and acceptance. To address this challenge and improve the autonomy of prosthetics, this paper proposes an automated method that leverages computer vision-based techniques and machine learning algorithms. In this study, three reinforcement learning algorithms, namely Soft Actor-Critic (SAC), Deep Q-Network (DQN), and Proximal Policy Optimization (PPO), are employed to train agents for automated grasping tasks. The results indicate that the SAC algorithm achieves the highest success rate of 99% among the three algorithms at just under 200,000 timesteps. This research also shows that an object's physical characteristics can affect the agent's ability to learn an optimal policy. Moreover, the findings highlight the potential of the SAC algorithm in developing intelligent prosthetic hands with automatic object-gripping capabilities.

Cortical Reorganization after Limb Loss: Bridging the Gap between Basic Science and Clinical Recovery

Despite the increasing incidence and prevalence of amputation across the globe, individuals with acquired limb loss continue to struggle with functional recovery and chronic pain. A more complete understanding of the motor and sensory remodeling of the peripheral and central nervous system that occurs postamputation may help advance clinical interventions to improve the quality of life for individuals with acquired limb loss. The purpose of this article is to first provide background clinical context on individuals with acquired limb loss and then to provide a comprehensive review of the known motor and sensory neural adaptations from both animal models and human clinical trials. Finally, the article bridges the gap between basic science researchers and clinicians that treat individuals with limb loss by explaining how current clinical treatments may restore function and modulate phantom limb pain using the underlying neural adaptations described above. This review should encourage the further development of novel treatments with known neurological targets to improve the recovery of individuals postamputation.Significance Statement In the United States, 1.6 million people live with limb loss; this number is expected to more than double by 2050. Improved surgical procedures enhance recovery, and new prosthetics and neural interfaces can replace missing limbs with those that communicate bidirectionally with the brain. These advances have been fairly successful, but still most patients experience persistent problems like phantom limb pain, and others discontinue prostheses instead of learning to use them daily. These problematic patient outcomes may be due in part to the lack of consensus among basic and clinical researchers regarding the plasticity mechanisms that occur in the brain after amputation injuries. Here we review results from clinical and animal model studies to bridge this clinical-basic science gap.

The Prevalence of Depression and PTSD in Adults With Surgically Managed Traumatic Upper-Extremity Amputations

BACKGROUND

Upper-extremity limb loss has been associated with serious psychological sequelae. Despite advancements in surgical procedures and prostheses for upper limb amputees, it is critical to recognize the psychosocial component of these patients' care. Although the role of psychological factors in outcomes is increasingly acknowledged, little is known about the prevalence of depression and post-traumatic stress disorder (PTSD) in the civilian population after traumatic upper-extremity amputation.

METHODS

In this retrospective observational single-center study, adult patients evaluated for traumatic upper limb amputations from 2016 to 2019 completed the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire, Visual Analogue Scale, the Center for Epidemiologic Studies Depression Scale, and the Primary Care PTSD Screen during visits. All data underwent descriptive statistical analysis.

RESULTS

Thirty-nine adult patients treated for upper-extremity traumatic amputation completed patient-reported outcomes (PROs) questionnaires. The median final follow-up time for our cohort was 17 months from amputation. Twenty patients (51%) screened positive for depression and 27 (69%) for PTSD during follow-up. The median time from amputation to first positive screening was 6.5 months for depression and 10 months for PTSD. The physical component score of Veterans RAND 12-Item Health Survey (VR-12) was significantly worse for patients with depression. The Median DASH and mental component score of VR-12 were significantly worse for patients with PTSD.

CONCLUSION

Upper-extremity limb loss has a significant impact on mental health, which in turn affects PROs. The high prevalence of depression and PTSD in traumatic upper-extremity amputees underscores the necessity for screening and multidisciplinary treatment.

Distal weight bearing in transtibial prosthesis users wearing pin suspension

Introduction

Low-level distal weight bearing in transtibial prosthesis users may help maintain perfusion and improve both proprioception and residual limb tissue health.

Methods

The primary objectives of this research were to develop a sensor to continuously measure distal weight bearing, evaluate how prosthesis design variables affected weight bearing levels, and assess fluctuations in distal weight bearing during at-home and community use.

Results

In-lab testing on a small group of participants wearing adjustable sockets demonstrated that if distal contact was present, when socket size was increased distal weight bearing increased and when socket size was reduced distal weight bearing decreased. During take-home use, participants accepted the distal weight bearing level set by the research team. It ranged between 1.1% and 6.4% BW for all days tested. The coefficient of variation (standard deviation/mean) ranged from 25% to 43% and was expected due in part to differences in walking style, speed, terrain, direction of ambulation, and bout duration. Two participants commented that they preferred presence of distal weight bearing to non-presence.

Discussion

Next steps in this research are to develop clinical practices to determine target distal weight bearing levels and ranges, and to simplify the design of the sensor and weight bearing adjustment mechanism for clinical use.

Biomimetic Random Pulse Computation or Why Do Humans Play Basketball Better than Robots?

In this work, we compare the basketball scoring performance of two imaginary (simulated) mechanical robots in conditions of erroneous information-processing circuits: Machine, whose moves are controlled by a conventional digital computer and Man, controlled by a random pulse computer composed of biologically-inspired circuits which execute basic arithmetic operations. This is the first comparative study of robustness of the digital and the random pulse computing paradigms, with respect to the error rate of the information-processing circuits (perr), for a mechanical robot. In spite of the fact that Man's computer consists of only about 100 logic gates while Machine's requires about 3500 gates, Man achieves a significantly higher scoring probability for perr in the range from 0.01% all the way to 10%, while at lower perr, both converge to the perfect score. Furthermore, Man's hits make up a smooth Gaussian distribution with a vanishing probability of making large misses even at the highest perr, while Machine is prone to spectacular misses already at perr as low as 1 part-per-million. These findings indicate that the biologically inspired computation requires less hardware for the same task, and ensures higher robustness and better behaving operation than digital computation, which are characteristics of importance for the survivability of living beings.

Arch Symmetry in Patients Without and With Cleft Lip and Palate After Orthodontic/Rehabilitative Treatment-A Stereophotogrammetry Study

To evaluate and compare the dental arch symmetry of individuals with and without cleft lip and palate after orthodontic/rehabilitation treatment.

Cross-sectional study.

Tertiary cleft center in Brazil.

Fifty-five participants aged between 18 and 30 years were divided into 3 groups according to treatment. Patients that received either a fixed partial denture (FPD) or implant-supported crown (ISC) in the cleft area or only orthodontic treatment, noncleft patients (NC).

An analysis was performed using digitized dental casts scanned by laser and software. The following linear measurements were evaluated: incisor-canine; canine-molar; incisor-molar; surface and volume of the palatal region.

Three-way ANOVA was used to compare the study factors: group (FPD/ISC/NC) and side (right/left) followed by the Tukey test to verify their interaction (α = .05).

The results showed statistically significant differences among groups for the maxillary linear measurements canine-molar and incisor-molar, but not for incisor-canine. No statistically significant differences were found regarding the side for the maxillary measurements, while the factor interaction showed similarity only for incisor-canine. The mandibular measurements showed no statistical differences among groups, sides, or factor interactions. In surface and volume, all values in patients with cleft presented lesser than in without cleft patients.

Regardless of the rehabilitation, arch symmetry can be achieved in the incisor-canine dimension in the cleft area.

Patient-specific cranioplasty, by direct and indirect additive manufacturing of biopolymers and implantable materials

BACKGROUND

Autologous bones are traditionally used in surgical reconstruction of skullcap. Since patients' bones are often unavailable or cause of infections, implantable synthetic materials emerged as promising alternative. These can be shaped by different technologies, while 3D printing offers remarkable chances in terms of flexibility, accuracy, cost-saving and customizability.

METHODS

This study aims to evaluate strengths and limitations of the three main strategies that imply additive manufacturing for the implementation of cranial prosthesis: (i) direct printing of PLA (polylactic acid) skullcaps, mould casting of poly(methyl methacrylate) (PMMA) prosthesis using (ii) silicone mould manufactured from a 3D printed master, (iii) 3Dprinted TPU (thermoplastic polyurethane) mould.

RESULTS

All solutions achieved good geometric accuracy and excellent mechanical resistance. Direct printing of the PLA resulted in the fastest strategy, followed by PMMA casting in a silicone mould.

CONCLUSIONS

The use of silicone was overall more advantageous, due to lower costs and the possibility of sterilization by using autoclaving.

Functionally Adaptive Myosite Selection Using High-Density sEMG for Upper Limb Myoelectric Prostheses

OBJECTIVE

Our study defines a novel electrode placement method called Functionally Adaptive Myosite Selection (FAMS), as a tool for rapid and effective electrode placement during prosthesis fitting. We demonstrate a method for determining electrode placement that is adaptable towards individual patient anatomy and desired functional outcomes, agnostic to the type of classification model used, and provides insight into expected classifier performance without training multiple models.

METHODS

FAMS relies on a separability metric to rapidly predict classifier performance during prosthesis fitting.

RESULTS

The results show a predictable relationship between the FAMS metric and classifier accuracy (3.45%SE), allowing estimation of control performance with any given set of electrodes. Electrode configurations selected using the FAMS metric show improved control performance ( ) for target electrode counts compared to established methods when using an ANN classifier, and equivalent performance ( R2 ≥ .96) to previous top-performing methods on an LDA classifier, with faster convergence ( ). We used the FAMS method to determine electrode placement for two amputee subjects by using the heuristic to search through possible sets, and checking for saturation in performance vs electrode count. The resulting configurations that averaged 95.8% of the highest possible classification performance using a mean 25 number of electrodes (19.5% of the available sites).

SIGNIFICANCE

FAMS can be used to rapidly approximate the tradeoffs between increased electrode count and classifier performance, a useful tool during prosthesis fitting.

Unsupervised Cluster Analysis of Walking Activity Data for Healthy Individuals and Individuals with Lower Limb Amputation

This is the first investigation to perform an unsupervised cluster analysis of activities performed by individuals with lower limb amputation (ILLAs) and individuals without gait impairment, in free-living conditions. Eight individuals with no gait impairments and four ILLAs wore a thigh-based accelerometer and walked on an improvised route across a variety of terrains in the vicinity of their homes. Their physical activity data were clustered to extract 'unique' groupings in a low-dimension feature space in an unsupervised learning approach, and an algorithm was created to automatically distinguish such activities. After testing three dimensionality reduction methods-namely, principal component analysis (PCA), t-distributed stochastic neighbor embedding (tSNE), and uniform manifold approximation and projection (UMAP)-we selected tSNE due to its performance and stable outputs. Cluster formation of activities via DBSCAN only occurred after the data were reduced to two dimensions via tSNE and contained only samples for a single individual. Additionally, through analysis of the t-SNE plots, appreciable clusters in walking-based activities were only apparent with ground walking and stair ambulation. Through a combination of density-based clustering and analysis of cluster distance and density, a novel algorithm inspired by the t-SNE plots, resulting in three proposed and validated hypotheses, was able to identify cluster formations that arose from ground walking and stair ambulation. Low dimensional clustering of activities has thus been found feasible when analyzing individual sets of data and can currently recognize stair and ground walking ambulation.

A qualitative study exploring healthcare professionals' perceptions of lower limb 3D printed sockets

PURPOSE

The purpose of this study was to explore healthcare professionals' (HCPs) perceptions and experiences related to 3D scanning and 3D printing for fabricating lower limb prosthetic sockets.

MATERIALS AND METHODS

This study used a qualitative descriptive approach. Participants were recruited through HCPs' professional associations, social media posts, and snowball sampling. Purposive sampling was used to attain variation in provider type. One-on-one telephone interviews were conducted using a semi-structured interview guide. Inductive thematic analysis was performed to identify the main themes.

RESULTS

Three themes were identified: (1) 3D scanning of the residual limb for designing prosthetic sockets is perceived as clean, quick, and convenient; (2) concerns about the strength and safety of 3D printed sockets for long-term use; (3) Adoption of 3D scanning and 3D printing technology for fabricating prosthetic sockets.

CONCLUSION

We identified perceived benefits and challenges with digital technologies for fabricating prosthetic sockets. To increase adoption, more research demonstrating its efficacy compared to conventional methods, increasing 3D printing material quality, and improving software training programs are needed.Implications for Rehabilitation3D printing and 3D scanning are emerging digital technologies that can be used as alternative methods for prosthetic socket manufacturing in the field of rehabilitation.Our research identified perceived benefits of using digital technologies for fabricating prosthetics sockets (3D scanning is perceived as clean, quick, and convenient) and perceived challenges (concerns about the strength and safety of 3D printed sockets for long-term use and a prolonged learning curve).To increase adoption of these digital technologies, more training should be provided to prosthetists and support provided to integrate new processes into staff workloads.

New Insights into the Applications of 3D-Printed Biomaterial in Wound Healing and Prosthesis

Recently three-dimensional bioprinting (3D-bioP) has emerged as a revolutionary technique for numerous biomedical applications. 3D-bioP has facilitated the printing of advanced and complex human organs resulting in satisfactory therapeutic practice. One of the important biomedical applications of 3D-bioP is in tissue engineering, wound healing, and prosthetics. 3D-bioP is basically aimed to restore the natural extracellular matrix of human's damage due to wounds. The relevant search was explored using various scientific database, viz., PubMed, Web of Science, Scopus, and ScienceDirect. The objective of this review is to emphasize interpretations from the pre-executed studies and to assess the worth of employing 3D-bioP in wound healing as well as prosthetics in terms of patient compliance, clinical outcomes, and economic viability. Furthermore, the benefits of applying 3D-bioP in wound healing over traditional methods have been covered along with the biocompatible biomaterials employed as bioinks has been discussion. Additionally, the review expands about the clinical trials in 3D-bioP field, showing promise of biomedical applicability of this technique with growing advancement in recent years.

Assessment of knee flexion in young children with prosthetic knee components using dynamic time warping

Introduction

Analysis of human locomotion is challenged by limitations in traditional numerical and statistical methods as applied to continuous time-series data. This challenge particularly affects understanding of how close limb prostheses are to mimicking anatomical motion. This study was the first to apply a technique called Dynamic Time Warping to measure the biomimesis of prosthetic knee motion in young children and addressed the following research questions: Is a combined dynamic time warping/root mean square analysis feasible for analyzing pediatric lower limb kinematics? When provided at an earlier age than traditional protocols dictate, can children with limb loss utilize an articulating prosthetic knee in a biomimetic manner?

Methods

Warp costs and amplitude differences were generated for knee flexion curves in a sample of ten children five years of age and younger: five with unilateral limb loss and five age-matched typically developing children. Separate comparisons were made for stance phase flexion and swing phase flexion via two-way ANOVAs between bilateral limbs in both groups, and between prosthetic knee vs. dominant anatomical knee in age-matched pairs between groups. Greater warp costs indicated greater temporal dissimilarities, and a follow-up root mean square assessed remaining amplitude dissimilarities. Bilateral results were assessed by age using linear regression.

Results

The technique was successfully applied in this population. Young children with limb loss used a prosthetic knee biomimetically in both stance and swing, with mean warp costs of 12.7 and 3.3, respectively. In the typically developing group, knee motion became more symmetrical with age, but there was no correlation in the limb loss group. In all comparisons, warp costs were significantly greater for stance phase than swing phase. Analyses were limited by the small sample size.

Discussion

This study has established that dynamic time warping with root mean square analysis can be used to compare the entirety of time-series curves generated in gait analysis. The study also provided clinically relevant insights on the development of mature knee flexion patterns during typical development, and the role of a pediatric prosthetic knee.

Sensing in Soft Robotics

Soft robotics is an exciting field of science and technology that enables robots to manipulate objects with human-like dexterity. Soft robots can handle delicate objects with care, access remote areas, and offer realistic feedback on their handling performance. However, increased dexterity and mechanical compliance of soft robots come with the need for accurate control of the position and shape of these robots. Therefore, soft robots must be equipped with sensors for better perception of their surroundings, location, force, temperature, shape, and other stimuli for effective usage. This review highlights recent progress in sensing feedback technologies for soft robotic applications. It begins with an introduction to actuation technologies and material selection in soft robotics, followed by an in-depth exploration of various types of sensors, their integration methods, and the benefits of multimodal sensing, signal processing, and control strategies. A short description of current market leaders in soft robotics is also included in the review to illustrate the growing demands of this technology. By examining the latest advancements in sensing feedback technologies for soft robots, this review aims to highlight the potential of soft robotics and inspire innovation in the field.

Qualitative needs assessment for the development of a smart thumb prosthesis

PURPOSE

To critically explore experiences following thumb amputation and delineate elements of an ideal thumb prosthesis from the end user perspective.

METHODS

A qualitative study was undertaken with end user stakeholder groups, which included persons with a thumb amputation, rehabilitation professionals, and prosthetists. Analysis proceeded in line with conventional content analysis.

RESULTS

Six patients with traumatic thumb amputation and eight healthcare providers (HCPs) were interviewed. Six themes were identified. The first theme discussed the impact of losing a thumb upon function, occupational activities, and mental wellbeing. The second theme reflected the idiosyncratic nature of thumb amputees, including their goals and nature of injury. The third theme stressed the costs associated with obtaining a thumb prosthesis. The fourth theme explored patient frustration and causes of device abandonment. Theme five summarized opinions on currently available thumb prostheses, and theme seven was the ideal design for a thumb prosthetic, including sensory elements and materials.

CONCLUSIONS

Representative data from stakeholders mapped the current status of thumb prostheses. Preferences for an ideal thumb prosthesis included a simple, durable design with the ability to oppose, grasp, and sense pressure. Affordable cost and ease of fit emerged as systemic objectives.

Repair strategies for assistive technology in low resource settings

PURPOSE

To investigate the practices of repair that exist for users of mobility assistive products in low resource settings, as well as the psychosocial impact that the repair, or non-repair, of these devices has on users' lives.

MATERIALS AND METHODS

This article collates data on repair practices and the responses from participants on the topic of repair from studies conducted by the authors across four different low resource settings in Kenya, Uganda, Sierra Leone, and Indonesia. This data was then analyzed to identify the common themes found across geographies.

RESULTS

Three major models of repair practice emerged from the data: "Individual or Informal Repair in the Community"; "Local Initiatives"; and "Specialist AT Workshop Repair". Additionally, the wider impact on the participants' lives of "Problems & Concerns with Repair"; "Experiences of Breakages & Frequencies of Repair" and the "Impact of Broken Devices" are explored.

CONCLUSIONS

The results of this analysis demonstrate the paramount importance of community-based repair of devices, and how despite this importance, repair is often overlooked in the planning and design of assistive products and services. There is a need to further incorporate and support these informal contributions as part of the formal provision systems of assistive device.IMPLICATIONS FOR REHABILITATIONA lack of available specialist repair services in low resource settings hinders the potential impact of assistive technology provision systems.Community-based repair is the major route by which assistive devices are repaired in low resource settings.Appropriate community-based repair strategies should be incorporated into and supported by the formal assistive technology provision models in order to optimise outcomes.A lack of data on outcomes across the lifecycle of assistive products hinders progress on improving focus on follow-up services - in particular repair & maintenance.By supporting community-based repair, repairs that are inappropriate for that approach could be better directed to specialist repair services.

Autoencoder-based myoelectric controller for prosthetic hands

In the past, linear dimensionality-reduction techniques, such as Principal Component Analysis, have been used to simplify the myoelectric control of high-dimensional prosthetic hands. Nonetheless, their nonlinear counterparts, such as Autoencoders, have been shown to be more effective at compressing and reconstructing complex hand kinematics data. As a result, they have a potential of being a more accurate tool for prosthetic hand control. Here, we present a novel Autoencoder-based controller, in which the user is able to control a high-dimensional (17D) virtual hand via a low-dimensional (2D) space. We assess the efficacy of the controller via a validation experiment with four unimpaired participants. All the participants were able to significantly decrease the time it took for them to match a target gesture with a virtual hand to an average of 6.9s and three out of four participants significantly improved path efficiency. Our results suggest that the Autoencoder-based controller has the potential to be used to manipulate high-dimensional hand systems via a myoelectric interface with a higher accuracy than PCA; however, more exploration needs to be done on the most effective ways of learning such a controller.

A low-power ankle-foot prosthesis for push-off enhancement

Passive ankle-foot prostheses are light-weighted and reliable, but they cannot generate net positive power, which is essential in restoring the natural gait pattern of amputees. Recent robotic prostheses addressed the problem by actively controlling the storage and release of energy generated during the stance phase through the mechanical deformation of elastic elements housed in the device. This study proposes an innovative low-power active prosthetic module that fits on off-the-shelf passive ankle-foot energy-storage-and-release (ESAR) prostheses. The module is placed parallel to the ESAR foot, actively augmenting the energy stored in the foot and controlling the energy return for an enhanced push-off. The parallel elastic actuation takes advantage of the amputee's natural loading action on the foot's elastic structure, retaining its deformation. The actuation unit is designed to additionally deform the foot and command the return of the total stored energy. The control strategy of the prosthesis adapts to changes in the user's cadence and loading conditions to return the energy at a desired stride phase. An early verification on two transtibial amputees during treadmill walking showed that the proposed mechanism could increase the subjects' dorsiflexion peak of 15.2% and 41.6% for subjects 1 and 2, respectively, and the cadence of about 2%. Moreover, an increase of 26% and 45% was observed in the energy return for subjects 1 and 2, respectively.

Stretchable and All-Directional Strain-Insensitive Electronic Glove for Robotic Skins and Human-Machine Interfacing

Electronic gloves (e-gloves), with their multifunctional sensing capability, hold a promising application in robotic skin and human-machine interfaces, endowing robots with a human sense of touch. Despite the progress in developing e-gloves by exploiting flexible or stretchable sensors, existing models have inherent rigidity in their sensing area, limiting their stretchability and sensing performance. Herein, we present an all-directional strain-insensitive stretchable e-glove that successfully extends sensing functionality such as pressure, temperature, humidity, and ECG with minimal crosstalk. A scalable and facile method is successfully demonstrated by combining low-cost CO₂ laser engraving and electrospinning technology to fabricate multimodal e-glove sensors with a vertical architecture. In comparison to other smart gloves, the proposed e-glove features a ripple-like meandering sensing area and interconnections that are designed to stretch in response to the applied deformation, without affecting the performance of the sensors offering full mechanical stretchability. Furthermore, CNT-coated laser-engraved graphene (CNT/LEG) is used as an active sensing material in which the cross-linking network of the CNT in the LEG minimizes the stress effect and maximizes the sensitivity of the sensors. The fabricated e-glove can detect hot/cold, moisture, and pain simultaneously and precisely, while also allowing for remote transmission of sensory data to the user.

Learning to operate a high-dimensional hand via a low-dimensional controller

Dimensionality reduction techniques have proven useful in simplifying complex hand kinematics. They may allow for a low-dimensional kinematic or myoelectric interface to be used to control a high-dimensional hand. Controlling a high-dimensional hand, however, is difficult to learn since the relationship between the low-dimensional controls and the high-dimensional system can be hard to perceive. In this manuscript, we explore how training practices that make this relationship more explicit can aid learning. We outline three studies that explore different factors which affect learning of an autoencoder-based controller, in which a user is able to operate a high-dimensional virtual hand via a low-dimensional control space. We compare computer mouse and myoelectric control as one factor contributing to learning difficulty. We also compare training paradigms in which the dimensionality of the training task matched or did not match the true dimensionality of the low-dimensional controller (both 2D). The training paradigms were a) a full-dimensional task, in which the user was unaware of the underlying controller dimensionality, b) an implicit 2D training, which allowed the user to practice on a simple 2D reaching task before attempting the full-dimensional one, without establishing an explicit connection between the two, and c) an explicit 2D training, during which the user was able to observe the relationship between their 2D movements and the higher-dimensional hand. We found that operating a myoelectric interface did not pose a big challenge to learning the low-dimensional controller and was not the main reason for the poor performance. Implicit 2D training was found to be as good, but not better, as training directly on the high-dimensional hand. What truly aided the user's ability to learn the controller was the 2D training that established an explicit connection between the low-dimensional control space and the high-dimensional hand movements.

Surface profile of laminated transfemoral socket fabricated with different types of reinforcement materials

Composite materials used in the prosthetic and orthotic fields have helped improve the fabrication of sockets. Laminated sockets proved to be stronger than conventional thermoplastic sockets. The internal surface of a laminated socket plays an important role in patient comfort and is influenced by the material used to fabricate the socket. This study analyzes the internal surface profile of five different materials, that is, Dacron felt, fiberglass, Perlon stockinette, polyester stockinette, and elastic stockinette. All sockets were fabricated using an acrylic resin mix with hardener powder at a ratio of 100:3. The internal surface of the sockets was tested using the Mitutoyo SurfTest SJ-210 series for 20 trials. The overall R_a values were 2.318, 2.380, 2.682, 2.722, and 3.750 µm for fiberglass, polyester, Perlon, elastic stockinette, and Dacron felt. Dacron felt yielded the lowest R_a value, thus, producing the smoothest internal surface but requiring high skill and the correct technique during the fabrication of a laminated socket. Fiberglass is considered the best material for the internal surface despite not producing the lowest value individually but overall is the lowest and most consistent, indicating that it is easy to use to laminate prosthetic sockets.

Improving access to prosthetic services in Western Nepal: a local stakeholder perspective

PURPOSE

Evidence of effective strategies to improve access to assistive technology (AT) like prostheses is limited, especially in rural and remote areas of low- and middle-income countries where unmet needs are the greatest. This study aimed to identify barriers and facilitators to accessing prosthetic services in rural areas of western Nepal and explore strategies to improve access from the perspective of local stakeholders.

METHOD

Semi-structured interviews were conducted with 13 service providers and consumers. Barriers and facilitators of access were highlighted and potential solutions to overcome access barriers were explored using thematic analysis of transcripts.

RESULTS

Six themes concerning barriers and facilitators arose: awareness and literacy of prosthetic services, attitudes and belief systems, financial supports, geographical access, health system and referral processes, as well as service provider capacity and regulation. Six themes regarding potential solutions were also identified: awareness campaigns, procurement pathways, referral pathways, subsidised and shared costs of AT, professional support networks and development opportunities, as well as task shifting and sharing.

CONCLUSIONS

While facilitating interventions support access to prosthetic services, they remain insufficient to overcome several barriers that continue to inhibit this access. Nevertheless, real opportunities to alleviate barriers and address the unmet need exist and must be explored.Implications For RehabilitationIt is advised that rehabilitation professionals, particularly those delivering prosthetic services in rural and remote settings of Nepal, consider piloting alternative service delivery strategies which utilise resources accessible to them in order to overcome several existing barriers to AT access e.g., task shifting.Rehabilitation professionals in Nepal have the opportunity to support others working in low-resources settings to expand professional development opportunities through online and digital platforms.Gathering and sharing data on the current state of prosthetic and AT service delivery within Nepal is highly valuable to the development of the prosthetic rehabilitation profession and ultimately equity in access to appropriate AT.Proposed interventions identified within this study can potentially serve to guide stakeholders in rural and remote settings of other LMICs in developing strategies to overcome barriers to AT access suitable to their context.

Development of an item bank for measuring prosthetic mobility in people with lower limb amputation: The Prosthetic Limb Users Survey of Mobility (PLUS-M)

BACKGROUND

Achieving mobility with a prosthesis is a common post-amputation rehabilitation goal and primary outcome in prosthetic research studies. Patient-reported outcome measures (PROMs) available to measure prosthetic mobility have practical and psychometric limitations that inhibit their use in clinical care and research.

OBJECTIVE

To develop a brief, clinically meaningful, and psychometrically robust PROM to measure prosthetic mobility.

DESIGN

A cross-sectional study was conducted to administer previously developed candidate items to a national sample of lower limb prosthesis users. Items were calibrated to an item response theory model and two fixed-length short forms were created. Instruments were assessed for readability, effective range of measurement, agreement with the full item bank, ceiling and floor effects, convergent validity, and known groups validity.

SETTING

Participants were recruited using flyers posted in hospitals and prosthetics clinics across the United States, magazine advertisements, notices posted to consumer websites, and direct mailings.

PARTICIPANTS

Adult prosthesis users (N = 1091) with unilateral lower limb amputation due to traumatic or dysvascular causes.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Candidate items (N = 105) were administered along with the Patient Reported Outcome Measurement Information System Brief Profile, Prosthesis Evaluation Questionnaire - Mobility Subscale, and Activities-Specific Balance Confidence Scale, and questions created to characterize respondents.

RESULTS

A bank of 44 calibrated self-report items, termed the Prosthetic Limb Users Survey of Mobility (PLUS-M), was produced. Clinical and statistical criteria were used to select items for 7- and 12-item short forms. PLUS-M instruments had an 8th grade reading level, measured with precision across a wide range of respondents, exhibited little-to-no ceiling or floor effects, correlated expectedly with scores from existing PROMs, and differentiated between groups of respondents expected to have different levels of mobility.

CONCLUSION

The PLUS-M appears to be well suited to measuring prosthetic mobility in people with lower limb amputation. PLUS-M instruments are recommended for use in clinical and research settings.

Functionalization of 3D Printed Scaffolds Using Polydopamine and Silver Nanoparticles for Bone-Interfacing Applications

The prevention of bacterial colonization and the stimulation of osseointegration are two major requirements for bone-interfacing materials to reduce the incidence of complications and promote the restoration of the patient's health. The present investigation developed an effective, two-step functionalization of 3D printed scaffolds intended for bone-interfacing applications using a simple polydopamine (PDA) dip-coating method followed by the formation of silver nanoparticles (AgNPs) after a second coating step in silver nitrate. 3D printed polymeric substrates coated with a ∼20 nm PDA layer and 70 nm diameter AgNPs proved effective in hindering Staphylococcus aureus biofilm formation, with a 3000-8000-fold reduction in the number of bacterial colonies formed. The implementation of porous geometries significantly accelerated osteoblast-like cell growth. Microscopy characterization further elucidated homogeneity, features, and penetration of the coating inside the scaffold. A proof-of-concept coating on titanium substrates attests to the transferability of the method to other materials, broadening the range of applications both in and outside the medical sector. The antibacterial efficiency of the coating is likely to lead to a decrease in the number of bacterial infections developed after surgery in the presence of these coatings on prosthetics, thus translating to a reduction in revision surgeries and improved health outcomes.

3D Printability of Silk/Hydroxyapatite Composites for Microprosthetic Applications

Micro-prosthetics requires the fabrication of mechanically robust and personalized components with sub-millimetric feature accuracy. Three-dimensional (3D) printing technologies have had a major impact on manufacturing such miniaturized devices for biomedical applications; however, biocompatibility requirements greatly constrain the choice of usable materials. Hydroxyapatite (HA) and its composites have been widely employed to fabricate bone-like structures, especially at the macroscale. In this work, we investigate the rheology, printability, and prosthetic mechanical properties of HA and HA-silk protein composites, focusing on the roles of composition and water content. We correlate key linear and nonlinear shear rheological parameters to geometric outcomes of printing and explain how silk compensates for the inherent brittleness of printed HA components. By increasing ink ductility, the inclusion of silk improves the quality of printed items through two mechanisms: (1) reducing underextrusion by lowering the required elastic modulus and, (2) reducing slumping by increasing the ink yield stress proportional to the modulus. We demonstrate that the elastic modulus and compressive strength of parts fabricated from silk-HA inks are higher than those for rheologically comparable pure-HA inks. We construct a printing map to guide the manufacturing of HA-based inks with excellent final properties, especially for use in biomedical applications for which sub-millimetric features are required.

An Improved Approach for Grasp Force Sensing and Control of Upper Limb Soft Robotic Prosthetics

The following research proposes a closed loop force control system, which is implemented on a soft robotic prosthetic hand. The proposed system uses a force sensing approach that does not require any sensing elements to be embedded in the prosthetic's fingers, therefore maintaining their monolithic structural integrity, and subsequently decreasing the cost and manufacturing complexity. This is achieved by embedding an aluminum test specimen with a full bridge strain gauge circuit directly inside the actuator's housing rather than in the finger. The location of the test specimen is precisely at the location of the critical section of the bending moment on the actuator housing due to the tension in the driving tendon. Therefore, the resulting loadcell can acquire a signal proportional to the prosthetic's grasping force. A PI controller is implemented and tested using this force sensing approach. The experiment design includes a flexible test object, which serves to visually demonstrate the force controller's performance through the deformation that the test object experiences. Setpoints corresponding to "light", "medium", and "hard" grasps were tested with pinch, tripod, and full grasps and the results of these tests are documented in this manuscript. The developed controller was found to have an accuracy of ±2%. Additionally, the deformation of the test object increased proportionally with the given grasp force setpoint, with almost no deformation during the light grasp test, slight deformation during the medium grasp test, and relatively large deformation of the test object during the hard grasp test.

The effects of swing assistance in a microprocessor-controlled transfemoral prosthesis on walking at varying speeds and grades

This article proposes, describes, and tests a swing-assist walking controller for a stance-controlled, swing-assisted knee prosthesis that aims to combine benefits of passive swing mechanics (e.g., quiet operation, biomimetic function, and low power requirements) with benefits of powered swing assistance (e.g., increased robustness of swing-phase motion and specifically increased toe clearance). A three-participant, multislope, multispeed treadmill walking study was performed using the swing-assist prosthesis and controller, as well as using the participants' prescribed microprocessor knee devices. The swing-assist device and approach were found to improve user minimum foot clearance during walking at slopes and speeds, and also to improve symmetry of knee motion. Hip power inputs from stance knee release to heel strike indicated that, on average, less hip power was required when using the swing-assist prosthesis, indicating that the observed benefits were likely the result of the knee device and its control methodology, rather than a result of increased hip joint effort.

Full body musculoskeletal model for simulations of gait in persons with transtibial amputation

This paper describes the development, properties, and evaluation of a musculoskeletal model that reflects the anatomical and prosthetic properties of a transtibial amputee using OpenSim. Average passive prosthesis properties were used to develop CAD models of a socket, pylon, and foot to replace the lower leg. Additional degrees of freedom (DOF) were included in each joint of the prosthesis for potential use in a range of research areas, such as socket torque and socket pistoning. The ankle has three DOFs to provide further generality to the model. Seven transtibial amputee subjects were recruited for this study. 3 D motion capture, ground reaction force, and electromyographic (EMG) data were collected while participants wore their prescribed prosthesis, and then a passive prototype prosthesis instrumented with a 6-DOF load cell in series with the pylon. The model's estimates of the ankle, knee, and hip kinematics comparable to previous studies. The load cell provided an independent experimental measure of ankle joint torque, which was compared to inverse dynamics results from the model and showed a 7.7% mean absolute error. EMG data and muscle outputs from OpenSim's Static Optimization tool were qualitatively compared and showed reasonable agreement. Further improvements to the muscle characteristics or prosthesis-specific foot models may be necessary to better characterize individual amputee gait. The model is open-source and available at (https://simtk.org/projects/biartprosthesis) for other researchers to use to advance our understanding and amputee gait and assist with the development of new lower limb prostheses.

Equivalent system based inverse dynamics analysis of transfemoral prosthetic legs: Validation and application

Inverse dynamics analysis of prosthetic legs with polycentric knees is complex due to increased number of links. The present work proposes a simple and general method called equivalent system (ES) analysis. The ES analysis provides forces and moment at hip joint as well as at the functional knee centre (FKC), the instant centre of the polycentric knee. The input to the ES analysis is the motion data. For validation of the proposed method, synthetic motion data for the swing phase of walking with prosthetic legs having different knees are generated by simulations using ADAMS. The hip kinetics evaluated by the proposed method is compared with that from ADAMS. The root mean square errors of the ES analysis are lower than 17 (10^-6) N for hip reaction forces and 2.6 (10^-6) Nm for the hip moments, thereby validating the proposed method. In order to demonstrate the application of the proposed methodology, the motion data of two transfemoral amputees using single-axis and four-bar knee prostheses are obtained during gait trials. The hip kinetics as well as kinetics at FKC are computed using ES analysis. Hip power during the swing phase is also evaluated and compared. The results are presented in this paper and discussed. The ES analysis is shown to be a versatile tool to provide insights into the human-mechanism interaction.

Interdisciplinary Care Provided in a Rural Setting to Patient with Below-Knee Amputation

As a result of severe injury, limb amputation remains a pivotal procedure to preserve residual function of an injured extremity. Complications following amputation can impact successful rehabilitation. This case report aims to highlight the clinical importance of interdisciplinary care demonstrated by a 65-year-old Caucasian male below-knee amputee (BKA) who presented to an amputee clinic with complaints of right distal tibia pain. He reported that he was seen at a small rural clinic and was told he had "deterioration of his tibia". Physical exam revealed a well-healed below-knee amputation stump with tenderness to palpation of the right lateral distal residual fibula. Upon prosthetic modifications managed by our prosthetist, the patient's symptoms persisted. Further work up by Physical Medicine and Rehabilitation (PM&R) revealed a sharp edge to the distal fibula and the need for surgical revision by plastic surgery. Conditions resulting from the initial operation left this patient with factors that significantly impacted the process of restoring function to this BKA. Management of care for amputees commonly involves a variety of healthcare provider consisting of, but not limited to, primary care, physiatrists, prosthetists, plastic surgeons, and physical and occupational therapists. The aim of this case report is to illustrate how the fundamental collaboration rooted in interdisciplinary care is paramount to ensure that comprehensive care is delivered to this complex patient population that reside in rural areas.

Analysis and Validation of Sensitivity in Torque-Sensitive Actuators

Across different fields within robotics, there is a great need for lightweight, efficient actuators with human-like performance. Linkage-based passive variable transmissions and torque-sensitive transmissions have emerged as promising solutions to meet this need by significantly increasing actuator efficiency and power density, but their modeling and analysis remain an open research topic. In this paper, we introduce the sensitivity between input displacement and output torque as a key metric to analyze the performance of these complex mechanisms in dynamic tasks. We present the analytical model of sensitivity in the context of two different torque-sensitive transmission designs, and used this sensitivity metric to analyze the differences in their performance. Experiments with these designs implemented within a powered knee prosthesis were conducted, and results validated the sensitivity model as well as its role in predicting actuators' dynamic performance. Together with other design methods, sensitivity analysis is a valuable tool for designers to systematically analyze and create transmission systems capable of human-like physical behavior.

Developing Patient-Specific Statistical Reconstructions of Healthy Anatomical Structures to Improve Patient Outcomes

There are still numerous problems with modern joint replacement prostheses, which negatively influence patient health and recovery. For example, it is especially important to avoid failures and complications following hip arthroplasty because the loss of hip joint function is commonly associated with increased demand on the healthcare system, reoperation, loss of independence, physical disability, and death. The current study uses hip arthroplasty as a model system to present a new strategy of computationally generating patient-specific statistical reconstructions of complete healthy anatomical structures from computed tomography (CT) scans of damaged anatomical structures. The 3D model morphological data were evaluated from damaged femurs repaired with prosthetic devices and the respective damaged femurs that had been restored using statistical reconstruction. The results from all morphological measurements (i.e., maximum femoral length, Hausdorff distance, femoral neck anteversion, length of rotational center divergence, and angle of inclination) indicated that the values of femurs repaired with traditional prostheses did not fall within the +/-3 standard deviations of the respective patient-specific healthy anatomical structures. These results demonstrate that there are quantitative differences in the morphology of femurs repaired with traditional prostheses and the morphology of patient-specific statistical reconstructions. This approach of generating patient-specific statistical reconstructions of healthy anatomical structures might help to inform prosthetic designs so that new prostheses more closely resemble natural healthy morphology and preserve biomechanical function. Additionally, the patient-specific statistical reconstructions of healthy anatomical structures might be valuable for surgeons in that prosthetic devices could be selected and positioned to more accurately restore natural biomechanical function. All in all, this contribution establishes the novel approach of generating patient-specific statistical reconstructions of healthy anatomical structures from the CT scans of individuals' damaged anatomical structures to improve treatments and patient outcomes.

A gait phase prediction model trained on benchmark datasets for evaluating a controller for prosthetic legs

Powered lower-limb assistive devices, such as prostheses and exoskeletons, are a promising option for helping mobility-impaired individuals regain functional gait. Gait phase prediction plays an important role in controlling these devices and evaluating whether the device generates a gait similar to that of individuals with intact limbs. This study proposes a gait phase prediction method based on a deep neural network (DNN). The long short-term memory (LSTM)-based model predicts a continuous gait phase from the 250 ms history of the vertical load, thigh angle, knee angle, and ankle angle, commonly available on powered lower-limb assistive devices. One unified model was trained using publicly available benchmark datasets containing intact limb gaits for level-ground walking (LGW) and ascending stairs (SA). A phase prediction error of 1.28% for all benchmark datasets was obtained. The model was subsequently applied to a state machine-controlled powered prosthetic leg dataset collected from four individuals with unilateral transfemoral amputation. The gait phase prediction results (a phase prediction error of 5.70%) indicate that the model trained on benchmark data can be used for a system not included in the training dataset with no post-processing, such as model adaptation. Furthermore, it provided information regarding evaluation of the controller: whether the prosthetic leg generated normal gait. In conclusion, the proposed gait phase prediction model will facilitate efficient gait prediction and evaluation of controllers for powered lower-limb assistive devices.

Recalibration of myoelectric control with active learning

Introduction

Improving the robustness of myoelectric control to work over many months without the need for recalibration could reduce prosthesis abandonment. Current approaches rely on post-hoc error detection to verify the certainty of a decoder's prediction using predefined threshold value. Since the decoder is fixed, the performance decline over time is inevitable. Other approaches such as supervised recalibration and unsupervised self-recalibration entail limitations in scaling up and computational resources. The objective of this paper is to study active learning as a scalable, human-in-the-loop framework, to improve the robustness of myoelectric control.

Method

Active learning and linear discriminate analysis methods were used to create an iterative learning process, to modify decision boundaries based on changes in the data. We simulated a real-time scenario. We exploited least confidence, smallest margin and entropy reduction sampling strategies in single and batch-mode sample selection. Optimal batch-mode sampling was considered using ranked batch-mode active learning.

Results

With only 3.2 min of data carefully selected by the active learner, the decoder outperforms random sampling by 4-5 and ~2% for able-bodied and people with limb difference, respectively. We observed active learning strategies to systematically and significantly enhance the decoders adaptation while optimizing the amount of training data on a class-specific basis. Smallest margin and least confidence uncertainty were shown to be the most supreme.

Discussion

We introduce for the first time active learning framework for long term adaptation in myoelectric control. This study simulates closed-loop environment in an offline manner and proposes a pipeline for future real-time deployment.

Towards Co-Design in Delivering Assistive Technology Interventions: Reconsidering Roles for Consumers, Allied Health Practitioners, and the Support Workforce

A complexity of factors, from health and technology innovations to policy redesign to achieve consumer-directed care, are impacting traditional roles for Australian allied health practitioners (AHPs). This pilot study considers roles for AHPs in relation to assistive technology (AT) interventions. Articulating 'who does what' may serve a number of purposes including de-professionalization of the discourse; better utilization of support networks and workforces; and alignment with contemporary policy. Yet, a suitable framework to assist with collaborative AT implementation between relevant stakeholders was not identified within the existing literature. This research aimed to develop and pilot an AT collaboration tool which enables AHPs, consumers, their support networks and the support workforce, to navigate policy redesign toward ethical consumer-directed implementation of AT interventions. An AT collaboration tool was developed based upon practice-based knowledge, relevant regulatory and practice evidence and identifies relevant stakeholders, AT service steps and roles, and quality indicators to support competent practice. The tool was piloted in four separate and diverse practice analyses of AT interventions (custom prosthetics, home enteral nutrition, communication devices, and vehicle modifications) considering four allied health professions (prosthetics and orthotics, dietetics, speech pathology, occupational therapy). Pilot testing of the tool supports the feasibility of re-framing AT provision using competency-based and risk-informed approaches and enabling more inclusive roles for consumers and the support workforce. Further testing of the tool is indicated, followed by strategic actions for uptake by individuals, professions and policymakers. The AT collaboration tool has potential to enable AHPs to fulfil ethical obligations for consumer-centered practice, and to facilitate consumer choice, both in Australia and internationally.

Fatigue and Fracture Resistance Testing of Polyether Ether Ketone (PEEK) Implant Abutments in an Ex Vivo Chewing Simulator Model

Polyether ether ketone (PEEK) has been introduced into implant dentistry as a viable alternative to current implant abutment materials. However, data on its physico-mechanical properties are still scarce. The present study sought to shed light on this topic utilizing an ex vivo chewing simulator model. A total of 48 titanium two-piece implants were allocated into three groups (n = 16 per group): (1) implants with PEEK abutments and an internal butt-joint connection (PBJ), (2) implants with PEEK abutments and an internal conical implant-abutment connection (PC), and (3) implants with zirconia abutments and an internal butt-joint connection (ZA). All abutments were restored with a non-precious metal alloy crown mimicking the upper right central incisor. A dynamic chewing simulation of half (n = 8) of the specimens per group was performed with 5 × 106 cycles and a load of 49 N at a frequency of 1.7 Hz with thermocycling between 5 and 55 °C. The other eight specimens served as unloaded controls. Surface roughness, implant-abutment connection microgaps (IACMs), and the titanium base-abutment interface microgaps (TAIMs) in the loaded groups were evaluated. Finally, a quasi-static loading test was performed in a universal testing machine with all samples to evaluate fracture resistance. Overall, 23 samples survived the artificial chewing process. One abutment screw fracture was observed in the PC group. The ZA group showed higher surface roughness values than PEEK abutments. Furthermore, ZA revealed lower TAIM values compared to PEEK abutments. Similarly, ZA was associated with lower IACM values compared to PBJ. Fracture loads/bending moments were 1018 N/704 N cm for PBJ, 966 N/676 N cm for PC, and 738 N/508 N cm for ZA, with no significant differences compared to the unloaded references. Artificial loading did not significantly affect fracture resistance of the examined materials. PEEK abutments were associated with better load-bearing properties than zirconia abutments, although they showed higher microgap values. PEEK abutments could, therefore, be feasible alternatives to zirconia abutments based on the present ex vivo findings resembling 20 years of clinical service.

Early marginal bone loss around dental implants to define success in implant dentistry: A retrospective study

PURPOSE

The aim of this study was to establish an objective criterion in terms of marginal bone level (MBL) to know the prognosis of an implant.

MATERIALS AND METHODS

A group of 176 patients in whom 590 implants were placed were included in this retrospective study. Patients older than 18 years, presenting either Kennedy class I or II edentulous section, or totally edentulous at least in one of the dental arches were included in this study. Those with any type of disturbance able to alter bone metabolism or with nontreated periodontal disease were excluded. Data on radiographic MBL at loading, 6 and 18 months later, age, gender, smoking habits, history of periodontitis, bone substratum, implant, and prosthetic features were recorded. Nonparametric receiver operating curves (ROC) were constructed for the MBL at 18 months in order to establish a distinction among high bone loser (HBL) and low bone loser (LBL) implants. Differences as a function of main variables were also determined, particularly abutment height and periodontal disease.

RESULTS

HBL implants lost at least 0.48 mm of MBL 6 months after loading; they reached at least 2 mm of MBL 18 months after loading. MBL rate followed a nonlinear trend, except in implants restored over long prosthetic abutments and in patients with history of severe periodontitis; in whom the rate of MBL over the time was nearly zero.

CONCLUSION

Implants that lose more than 0.5 mm of marginal bone 6 months after loading are at great risk of not being radiographically successful anymore. Therefore, 0.5 mm of MBL is proposed as a distinctive and objective criterion of success in Implant Dentistry within a 6-month follow-up period. A prosthetic abutment height ≥2 mm resulted the most protective factor in the peri-implant bone maintenance.

Evaluating the Reliability of a Shape Capturing Process for Transradial Residual Limb Using a Non-Contact Scanner

Advancements in digital imaging technologies hold the potential to transform prosthetic and orthotic practices. Non-contact optical scanners can capture the shape of the residual limb quickly, accurately, and reliably. However, their suitability in clinical practice, particularly for the transradial (below-elbow) residual limb, is unknown. This project aimed to evaluate the reliability of an optical scanner-based shape capture process for transradial residual limbs related to volumetric measurements and shape assessment in a clinical setting. A dedicated setup for digitally shape capturing transradial residual limbs was developed, addressing challenges with scanning of small residual limb size and aspects such as positioning and patient movement. Two observers performed three measurements each on 15 participants with transradial-level limb absence. Overall, the developed shape capture process was found to be highly repeatable, with excellent intra- and inter-rater reliability that was comparable to the scanning of residual limb cast models. Future work in this area should compare the differences between residual limb shapes captured through digital and manual methods.

The Impact of Sintering Technology and Milling Technology on Fitting Titanium Crowns to Abutment Teeth-In Vitro Studies

INTRODUCTION

The aim of the study is to evaluate the marginal and internal fit of titanium alloy (Ti6Al4V) crowns using the Selective Laser Melting (SLM) method and CAD/CAM milling.

MATERIALS AND METHODS

The research materials are abutment teeth and prosthetic crowns. The method is based on scanning the abutments and the interior of the substructures, creating their 3D models, using the program for comparison, and determining error maps of fitting crowns to the reference models, in the form of positive and negative deviations. Adding the deviations gives information about the tightness of the crowns. The Shapiro-Wilk test and the one-way ANOVA analysis were performed. The level of significance was p = 0.05.

RESULTS

The crowns made in SLM, a slightly better internal fit was found than for milled crowns, as well as a comparable marginal fit. The mean deviations for the sintering were the values [mm]: -0.039 and +0.107 for tooth 15 and -0.033 and +0.091 for tooth 36, and for the milling -0.048 and +0.110 for tooth 15 and -0.038 and +0.096 and for tooth 36.

CONCLUSION

Based on the research conducted and the experience in therapeutic procedures, it can be indicated that the fitting of titanium alloy crowns in SLM and milling meets the clinical requirements. To evaluate the technology, a method was developed that determines the accuracy of mapping the shape of the tooth abutments in the crown substructures for the individual conditions of the patient.

A Multi-User Transradial Functional-Test Socket for Validation of New Myoelectric Prosthetic Control Strategies

The validation of myoelectric prosthetic control strategies for individuals experiencing upper-limb loss is hindered by the time and cost affiliated with traditional custom-fabricated sockets. Consequently, researchers often rely upon virtual reality or robotic arms to validate novel control strategies, which limits end-user involvement. Prosthetists fabricate diagnostic check sockets to assess and refine socket fit, but these clinical techniques are not readily available to researchers and are not intended to assess functionality for control strategies. Here we present a multi-user, low-cost, transradial, functional-test socket for short-term research use that can be custom-fit and donned rapidly, used in conjunction with various electromyography configurations, and adapted for use with various residual limbs and terminal devices. In this study, participants with upper-limb amputation completed functional tasks in physical and virtual environments both with and without the socket, and they reported on their perceived comfort level over time. The functional-test socket was fabricated prior to participants' arrival, iteratively fitted by the researchers within 10 mins, and donned in under 1 min (excluding electrode placement, which will vary for different use cases). It accommodated multiple individuals and terminal devices and had a total cost of materials under $10 USD. Across all participants, the socket did not significantly impede functional task performance or reduce the electromyography signal-to-noise ratio. The socket was rated as comfortable enough for at least 2 h of use, though it was expectedly perceived as less comfortable than a clinically-prescribed daily-use socket. The development of this multi-user, transradial, functional-test socket constitutes an important step toward increased end-user participation in advanced myoelectric prosthetic research. The socket design has been open-sourced and is available for other researchers.

Walking with increasing acceleration is achieved by tuning ankle torque onset timing and rate of torque development

Understanding the mechanics of torque production about the ankle during accelerative gait is key to designing effective clinical and rehabilitation practices, along with developing functional robotics and wearable assistive technologies. We aimed to explore how torque and work about the ankle is produced as walking acceleration increases from 0 to 100% maximal acceleration. We hypothesized that as acceleration increased, greater work about the ankle would not be solely due to ramping up plantar flexor torque, and instead would be a product of adjustments to relative timing of ankle torque and angular displacement. Fifteen healthy participants performed walking without acceleration (constant speed), as well as low, moderate and maximal accelerations, while motion capture and ground reaction force data were recorded. We employed vector coding in a novel application to overcome limitations of previously employed evaluation methods. As walking acceleration increased, there was reduced negative work and increased positive work about the ankle. Furthermore, early stance dorsiflexion had reducing plantar flexor torque due to delayed plantar flexor torque onset as acceleration increased, while mid-stance ankle plantar flexor torque was substantially increased with minimal ankle dorsiflexion, irrespective of acceleration magnitude. Assistive devices need to account for these changes during accelerative walking to facilitate functional gait.

The myokinetic stimulation interface: activation of proprioceptive neural responses with remotely actuated magnets implanted in rodent forelimb muscles

OBJECTIVE

Proprioception is the sense of one's position, orientation, and movement in space, and it is of fundamental importance for motor control. When proprioception is impaired or absent, motor execution becomes error-prone, leading to poorly coordinated movements. The kinaesthetic illusion, which creates perceptions of limb movement in humans through non-invasively applying vibrations to muscles or tendons, provides an avenue for studying and restoring the sense of joint movement (kinaesthesia). This technique, however, leaves ambiguity between proprioceptive percepts that arise from muscles versus those that arise from skin receptors. Here we propose the concept of a stimulation system to activate kinaesthesia through the untethered application of localized vibration through implanted magnets.

APPROACH

In this proof-of-concept study, we use two simplified 1-DoF systems to show the feasibility of eliciting muscle-sensory responses in an animal model across multiple frequencies, including those that activate the kinaesthetic illusion (70 - 115 Hz). Furthermore, we generalized the concept by developing a 5-DoF prototype system capable of generating directional, frequency-selective vibrations with desired displacement profiles.

MAIN RESULTS

In-vivo tests with the 1-DoF systems demonstrated the feasibility to elicit muscle sensory neural responses in the median nerve of an animal model. Instead, in-vitro tests with the 5-DoF prototype demonstrated high accuracy in producing directional and frequency selective vibrations along different magnet axes.

SIGNIFICANCE

These results provide evidence for a new technique that interacts with the native neuro-muscular anatomy to study proprioception and eventually pave the way towards the development of advanced limb prostheses or assistive devices for the sensory impaired.

Flexible Electronics and Devices as Human-Machine Interfaces for Medical Robotics

Medical robots are invaluable players in non-pharmaceutical treatment of disabilities. Particularly, using prosthetic and rehabilitation devices with human-machine interfaces can greatly improve the quality of life for impaired patients. In recent years, flexible electronic interfaces and soft robotics have attracted tremendous attention in this field due to their high biocompatibility, functionality, conformability, and low-cost. Flexible human-machine interfaces on soft robotics will make a promising alternative to conventional rigid devices, which can potentially revolutionize the paradigm and future direction of medical robotics in terms of rehabilitation feedback and user experience. In this review, the fundamental components of the materials, structures, and mechanisms in flexible human-machine interfaces are summarized by recent and renowned applications in five primary areas: physical and chemical sensing, physiological recording, information processing and communication, soft robotic actuation, and feedback stimulation. This review further concludes by discussing the outlook and current challenges of these technologies as a human-machine interface in medical robotics.