Advances in Lower-limb Prosthetic Technology

Improvement in quality of life of transfemoral amputees: Comparison between 2 types of transfemoral sockets and their influence on functionality and user comfort - A case report

Among the components of lower limb prostheses, a perfectly adapted prosthetic socket is crucial to a successful rehabilitation process. Thus, developing a more comfortable socket could improve the quality of life for transfemoral (TF) amputees. The objective of this case report was to compare 2 TF sockets by evaluating the relationship between socket stiffness and user comfort and their influence on functionality to improve the quality of life of TF amputees. The participant received 2 different sockets: (A) flexible Flixt® socket; (B) conventional socket. He used each socket for 90 days, and after that was submitted to an evaluation at the Gait Laboratory (kinematic and dynamic analyses), completed the Prosthesis Evaluation Questionnaire, and performed Timed Up and Go test, 6-Minute March Test (6MWT), 10-Meter Walk Test, and Amputee Mobility Predictor test. After results were analyzed, the socket that obtained the best degree of satisfaction was assigned to the amputee participant. Combined measures showed that socket B does not considerably change the kinematic parameters neither dynamics parameters namely at stance phase. At Prosthesis Evaluation Questionnaire results, socket A had a better rating than socket B. The results of the Timed Up and Go test, 6MWT, 10-Meter Walk Test, and Amputee Mobility Predictor test obtained identical values, except for the 6MWT. This case report shows evidence of participant satisfaction improvement when using the flexible socket. The study also demonstrates that both sockets are quite effective.

Running-specific prosthesis' performance characterization by dynamic finite element approach

INTRODUCTION

Composite running-specific prostheses (RSP) are widely used by athletes with lower limb amputations to simulate the spring-like behavior of biological legs. However, the effect of these devices on the biomechanics of athletes with transtibial amputations remains uncertain.

MODELING METHOD DESCRIPTION

To address this issue, this study proposes a time-dependent finite element model that uses angles and dynamic loads during ground contact to evaluate RSP performance parameters such as stiffness and energy efficiency. The study also examines the impact of running speed and RSP geometry on performance.

NUMERICAL SIMULATION AND MODEL VERIFICATION

The in-silico characterization approach used in this study takes into account both the intrinsic characteristics of the RSP and the athlete's biomechanics to identify the influence of fundamental geometric variables of the RSP on performance. The model is verified by comparing its results with experimental data.

RESULTS AND DISCUSSION

The study found that as running speed increases, RSP stiffness, vertical ground reaction force (vGRF), and contact time decrease. The force-displacement profiles of RSP are nonlinear, but a linear function can be used to accurately represent their behavior at high sprinting speeds. Using higher RSP reduces energy efficiency and vGRF due to their lower stiffness. J-curve RSP result in higher stiffness, vGRF, and strain energy, while C-curve RSP are associated with longer contact times and higher energy efficiency.

Toward the Development of User-Centered Neurointegrated Lower Limb Prostheses

The last few years witnessed radical improvements in lower-limb prostheses. Researchers have presented innovative solutions to overcome the limits of the first generation of prostheses, refining specific aspects which could be implemented in future prostheses designs. Each aspect of lower-limb prostheses has been upgraded, but despite these advances, a number of deficiencies remain and the most capable limb prostheses fall far short of the capabilities of the healthy limb. This article describes the current state of prosthesis technology; identifies a number of deficiencies across the spectrum of lower limb prosthetic components with respect to users' needs; and discusses research opportunities in design and control that would substantially improve functionality concerning each deficiency. In doing so, the authors present a roadmap of patients related issues that should be addressed in order to fulfill the vision of a next-generation, neurally-integrated, highly-functional lower limb prosthesis.

Controlling Powered Prosthesis Kinematics over Continuous Transitions Between Walk and Stair Ascent

One of the primary benefits of emerging powered prosthetic legs is their ability to facilitate step-over-step stair ascent by providing positive mechanical work. Existing control methods typically have distinct steady-state activity modes for walking and stair ascent, where activity transitions involve discretely switching between controllers and often must be initiated with a particular leg. However, these discrete transitions do not necessarily replicate able-bodied joint biomechanics, which have been shown to continuously adjust over a transition stride. This paper presents a phase-based kinematic controller for a powered knee-ankle prosthesis that enables continuous, biomimetic transitions between walking and stair ascent. The controller tracks joint angles from a data-driven kinematic model that continuously interpolates between the steady-state kinematic models, and it allows both the prosthetic and intact leg to lead the transitions. Results from experiments with two transfemoral amputee participants indicate that knee and ankle kinematics smoothly transition between walking and stair ascent, with comparable or lower root mean square errors compared to variations from able-bodied data.

Sprinting performance of individuals with unilateral transfemoral amputation: compensation strategies for lower limb coordination

Understanding the sprinting patterns of individuals with unilateral transfemoral amputation (uTFA) is important for designing improved running-specific prostheses and for prosthetic gait rehabilitation. Continuous relative phase (CRP) analysis acquires clues from movement kinematics and obtains insights into the sprinting coordination of individuals with uTFA. Seven individuals with uTFA sprinted on a 40 m runway. The spatio-temporal parameters, joint and segment angles of the lower limbs were obtained, and CRP analysis was performed on thigh-shank and shank-foot couplings. Subsequently, the asymmetry ratios of the parameters were calculated. Statistical analyses were performed between the lower limbs. Significant differences in the stance time, stance phase percentage, ankle joint angles and CRP of the shank-foot coupling (p < 0.05) were observed between the lower limbs. The primary contributor to these differences could be the structural differences between the lower limbs. Despite the presence of different coordination features in the stance and swing phases between the lower limbs, no significant difference in the coordination patterns of the thigh-shank coupling was observed. This may be a compensation strategy for achieving coordination patterns with improved symmetry between the lower limbs. The results of this study provide novel insights into the sprinting movement patterns of individuals with uTFA.

Therapeutic benefits of lower limb prostheses: a systematic review

BACKGROUND

Enhancing the quality of life of people with a lower limb amputation is critical in prosthetic development and rehabilitation. Yet, no overview is available concerning the impact of passive, quasi-passive and active ankle-foot prostheses on quality of life.

OBJECTIVE

To systematically review the therapeutic benefits of performing daily activities with passive, quasi-passive and active ankle-foot prostheses in people with a lower limb amputation.

METHODS

We searched the Pubmed, Web of Science, Scopus and Pedro databases, and backward citations until November 3, 2021. Only English-written randomised controlled trials, cross-sectional, cross-over and cohort studies were included when the population comprised individuals with a unilateral transfemoral or transtibial amputation, wearing passive, quasi-passive or active ankle-foot prostheses. The intervention and outcome measures had to include any aspect of quality of life assessed while performing daily activities. We synthesised the participants' characteristics, type of prosthesis, intervention, outcome and main results, and conducted risk of bias assessment using the Cochrane risk of bias tool. This study is registered on PROSPERO, number CRD42021290189.

RESULTS

We identified 4281 records and included 34 studies in total. Results indicate that quasi-passive and active prostheses are favoured over passive prostheses based on biomechanical, physiological, performance and subjective measures in the short-term. All studies had a moderate or high risk of bias.

CONCLUSION

Compared to passive ankle-foot prostheses, quasi-passive and active prostheses significantly enhance the quality of life. Future research should investigate the long-term therapeutic benefits of prosthetics devices.

Walking asymmetry and its relation to patient-reported and performance-based outcome measures in individuals with unilateral lower limb loss

Gait asymmetry persists for most people after lower limb amputation and is associated with slower walking speeds. However, the relationship between gait asymmetry and patient-reported function remains unclear because they are not commonly assessed together. The purpose of this study was to determine relationships between gait asymmetries in people with lower limb loss and (1) patient-reported outcomes and (2) performance-based prosthetic functional measures. This cross-sectional analysis included nine people with unilateral limb loss aged 48.2 ± 13.1 years of mixed amputation etiology. Patient-reported outcomes included the Prosthetic Evaluation Questionnaire mobility subscale and Activities-specific Balance Confidence scale. Performance outcomes included the Berg Balance Scale and the 30-second sit-to-stand test. Walking performance measures included the 2-Minute Walk Test, during which APDM Opal sensors recorded spatiotemporal gait parameters, and daily step-counts from StepWatch4 activity monitors. The study found that the most asymmetric gait symmetry ratios (prosthetic-limb divided by intact-limb) could be attributed to prosthetic foot dorsiflexion-plantarflexion and rotation motion limitations: prosthetic-limb trailing double support (0.789 ± 0.052), toe-off (0.760 ± 0.068) and toe-out angle (0.653 ± 0.256). Single limb stance, and stance and swing phase durations were most strongly associated with balance and walking performance measures. Notably, no symmetry ratio was significantly associated with patient-reported prosthetic function (unadjusted Pearson correlation coefficients r < 0.50, P > 0.05). More gait symmetry was associated with better balance and walking performance but had no significant relationship with patient-reported function. Although achieving gait symmetry after lower limb loss is a common walking goal, symmetry was unrelated to the perception of functional mobility for people with lower limb loss.

Sex and gender differences in quality of life and related domains for individuals with adult acquired lower-limb amputation: a scoping review

PURPOSE

To understand what is known about sex and gender differences in quality of life (QoL) and related domains for individuals with an adult acquired lower limb amputation (LLA).

METHODS

A computer-assisted literature search of four online databases was completed. Articles were included if they incorporated sex or gender as part of their data analysis with a focus on QoL-related domains. Data were analyzed using descriptive numerical analysis and thematic analysis.

RESULTS

One hundred and eleven articles were included in this review. Women were under-represented across studies, with most of the participants being men. No articles described the inclusion of trans or non-binary persons. Differences by sex or gender were reported by 66 articles. Articles reporting on gender seldom provided descriptions of how gender was defined. Overall, women/females seemed to have worse outcomes in terms of prosthesis-related outcomes, mental health, and return to occupations.

CONCLUSION

Articles included in this review were not clear with how gender was defined. In order for more targeted interventions that account for sex and gender differences, studies need to be more forthcoming about how they use and define gender. Future research should seek to include gender non-conforming participants to identify additional needs.Implications for rehabilitationSex and gender are important constructs that influence outcomes following lower limb amputation.Rehabilitation professionals should consider sex and gender-specific outcomes when tailoring programs to ensure ethical clinical care.

Mechanisms and component design of prosthetic knees: A review from a biomechanical function perspective

Prosthetic knees are state-of-the-art medical devices that use mechanical mechanisms and components to simulate the normal biological knee function for individuals with transfemoral amputation. A large variety of complicated mechanical mechanisms and components have been employed; however, they lack clear relevance to the walking biomechanics of users in the design process. This article aims to bridge this knowledge gap by providing a review of prosthetic knees from a biomechanical perspective and includes stance stability, early-stance flexion and swing resistance, which directly relate the mechanical mechanisms to the perceived walking performance, i.e., fall avoidance, shock absorption, and gait symmetry. The prescription criteria and selection of prosthetic knees depend on the interaction between the user and prosthesis, which includes five functional levels from K0 to K4. Misunderstood functions and the improper adjustment of knee prostheses may lead to reduced stability, restricted stance flexion, and unnatural gait for users. Our review identifies current commercial and recent studied prosthetic knees to provide a new paradigm for prosthetic knee analysis and facilitates the standardization and optimization of prosthetic knee design. This may also enable the design of functional mechanisms and components tailored to regaining lost functions of a specific person, hence providing individualized product design.

Voices of Women Veterans with Lower Limb Prostheses: a Qualitative Study

BACKGROUND

Women Veterans with amputation are a group with unique needs whose numbers have grown over the last 5 years, accounting for nearly 3% of all Veterans with amputation in 2019. Although identified as a national priority by the Veterans Health Administration, the needs of this population have remained largely underrepresented in amputation research.

OBJECTIVE

To describe the experiences of women Veterans with lower extremity amputation (LEA) related to prosthetic care provision and devices.

DESIGN

National qualitative study using semi-structured individual interviews.

PARTICIPANTS

Thirty women Veterans with LEA who had been prescribed a prosthesis at least 12 months prior.

APPROACH

Inductive content analysis.

KEY RESULTS

Four key themes emerged: (1) a sense of "feeling invisible" and lacking a connection with other women Veterans with amputation; (2) the desire for prosthetic devices that meet their biological and social needs; (3) the need for individualized assessment and a prosthetic limb prescription process that is tailored to women Veterans; the current process was often perceived as biased and either dismissive of women's concerns or failing to adequately solicit them; and (4) the desire for prosthetists who listen to and understand women's needs.

CONCLUSIONS

Women Veterans with LEA articulated themes reminiscent of those previously reported by male Veterans with LEA, such as the importance of prostheses and the central role of the provider-patient relationship. However, they also articulated unique needs that could translate into specific strategies to improve prosthetic care, such as integrating formal opportunities for social support and peer interaction for women Veterans with LEA, advocating for administrative changes and research efforts to expand available prosthetic component options, and ensuring that clinical interactions are gender-sensitive and free of bias.

Evaluation of an articulated passive ankle-foot prosthesis

Background

Current ankle prostheses for people with unilateral transtibial amputation (TTA) or transfemoral amputation (TFA) are unable to mimic able-bodied performance during daily activities. A new mechanical ankle–foot prosthesis was developed to further optimise the gait of people with a lower-limb amputation. This study aimed to evaluate the Talaris Demonstrator (TD) during daily activities by means of performance-related, physiological and subjective outcome measures.

Materials and methods

Forty-two participants completed a protocol assessing performance and functional mobility with their current prosthesis and the TD. The protocol comprised the L-test, 2 min of stair climbing, 2 min of inclined treadmill walking, 6 min of treadmill walking at 3 different speeds in consecutive blocks of 2 min, and a 3-m Backward Walk test (3mBWT). Heart rate was measured during each task, and oxygen uptake was collected during all tasks except for the L-test and 3mBWT. Time of execution was recorded on the L-test and 3mBWT, and the rate of perceived exertion (score = 6–20), fatigue and comfort (score = 0–100) were assessed after each task. Paired sample t-tests and Wilcoxon Signed-rank tests were performed to compare outcomes between prosthetic devices. Benjamini–Hochberg corrections were applied to control for multiple comparisons with a level of significance set at α = 0.05.

Results

Subjects with a TTA (N = 28) were faster with their current prosthesis compared to the TD on the L-test and 3mBWT (p = 0.005). In participants with a TFA (N = 14), we observed a tendency towards a higher heart rate during the L-test and towards increased comfort during inclined walking, with the TD compared to the participants’ current prosthetic device (0.05 < p < 0.10). Further, no significant results were observed.

Conclusion

The Talaris Demonstrator is a novel state-of-the-art passive ankle–foot prosthesis for both people with a TTA and TFA. Subjective measures indicate the added value of this device, while overall task performance and intensity of effort do not differ between the Talaris Demonstrator and the current prosthesis. Further investigations unravelling both acute and more prolonged adaptations will be conducted to evaluate the TD more thoroughly.

A Multimodal Sensory Apparatus for Robotic Prosthetic Feet Combining Optoelectronic Pressure Transducers and IMU

Timely and reliable identification of control phases is functional to the control of a powered robotic lower-limb prosthesis. This study presents a commercial energy-store-and-release foot prosthesis instrumented with a multimodal sensory system comprising optoelectronic pressure sensors (PS) and IMU. The performance was verified with eight healthy participants, comparing signals processed by two different algorithms, based on PS and IMU, respectively, for real-time detection of heel strike (HS) and toe-off (TO) events and an estimate of relevant biomechanical variables such as vertical ground reaction force (vGRF) and center of pressure along the sagittal axis (CoPy). The performance of both algorithms was benchmarked against a force platform and a marker-based stereophotogrammetric motion capture system. HS and TO were estimated with a time error lower than 0.100 s for both the algorithms, sufficient for the control of a lower-limb robotic prosthesis. Finally, the CoPy computed from the PS showed a Pearson correlation coefficient of 0.97 (0.02) with the same variable computed through the force platform.

New technologies applied to canine limb prostheses: A review

Although only a few studies have investigated about the development of animal prosthesis, currently, there is an increasing interest in canine limb prosthesis design and its clinical application since they offer an alternative to killing the animal in extreme situations where amputating the limb is the only option. Restoring normal function of amputated canine limbs with the use of a prosthesis is challenging. However, recent advances in surgical procedures and prosthesis design technology appear promising in developing devices that closely recreate normal canine limb function. Surgical advances such as evolution of osseointegration (bone-anchored) prostheses present great promise. Likewise, modern computer-aided design and manufacturing technology, as well as novel motion analysis systems are now providing improved prosthesis designs. Advances in patient-customized prostheses have the potential to reduce the risk of implant failure. The objective of this investigation is to present a general review of the existing literature on modern surgical approaches, design and manufacturing methods, as well as biomechanical analyses so that veterinarians can make more and better-informed decisions on the development and selection of proper canine limb prosthesis. Isolated research efforts have made possible an improvement in stability, comfort, and performance of canine limb prosthesis. However, continued multidisciplinary research collaboration and teamwork among veterinarians, engineers, designers, and industry, with supporting scientific evidence, is required to better understand the development of canine limb prosthesis designs that closely replicate the normal limb function.

Content comparison of four commonly used amputee mobility assessment scales in the literature by linking to the International Classification of Functioning, Disability, and Health

BACKGROUND

Despite the fact that there are a number of studies revealing the linkage of scales with the World Health Organization's international classification of functioning, disability, and health (ICF), there is a need for comprehensive studies examining the relationship between amputee mobility scales and ICF.

OBJECTIVE

To analyze the content of four amputee mobility scales at the item level using the ICF.

METHODS

The Locomotor Capacity Index, Rivermead Mobility Index, Amputee Mobility Predictor, and Prosthetic Limb Users Survey of Mobility were analyzed by two health professionals for content comparison according to the ICF categories. Kappa statistic was used to calculate the degree of agreement between the two investigators.

RESULTS

A total of 62 items in the scales were analyzed and linked with ICF codes. The scale questions were linked with 27 different ICF codes as follows: 1 (3.7%) "body function", 23 (85.1%) "activity and participation", 2 (7.5%) "environmental factors," and 1 (3.7%) "not definable. The estimated kappa values ranged from 0.83 to 0.90 for ICF codes.

CONCLUSION

As a result of the study, the ICF is a highly effective resource that can be used in the analysis of amputee mobility scales. Because the scale items are more concentrated on the mobility chapter, it was seen that the scales generally served their purposes. In the light of the findings obtained, it is thought that the diversity of the scales in the concept distribution will guide clinicians and researchers in choosing scales according to their target groups.

Design of a bioinspired cable driven actuator with clutched elastic elements for the ankle

Bioinspiration can be used to improve the efficiency of these assistive biomechatronic devices. In this paper, a cable driven actuator for the human ankle was designed using a bioinspired approach. The torque reduction was achieved by means of force amplifying elements such as cables with pulley, and, to reduce the power requirements for the motor, the actuator mimics a muscle using a clutched parallel elastic element. The simulations to validate the model were performed using real gait data and the results prove the viability of the device to be used in anthropomorphic legs and exoskeletons. Although the losses due to friction were not considered, the simulations showed a reduction of 60% in the force peak and 40% in the power peak.

Effects of prosthetic feet on metabolic energy expenditure in people with transtibial amputation: a systematic review and meta-analysis

OBJECTIVE

To assess the effects of different prosthetic feet on energy costs associated with walking and running in people with transtibial amputation.

LITERATURE SURVEY

The Pubmed, CINAHL, and Web-of-Science bibliographic databases were searched for original research published through June 30, 2018. References from identified articles were also reviewed.

METHODOLOGY

Two reviewers screened titles, abstracts, and articles for pertinent studies. Details were extracted with a standardized template. Risk of bias was assessed using domain-based methods. Prosthetic feet were grouped into categories, and compared according to energy costs associated with walking or running over various terrain conditions. Meta-analyses were conducted when data quantity and homogeneity permitted. Evidence statements were formed when results were consistent or undisputed.

SYNTHESIS

15 studies were included. Participants (n = 144) were predominantly male (88.2%), had unilateral amputation (95.8%) from non-dysvascular causes (87.5%), and were classified as unlimited community ambulators or active adults (56.9%). Participants were often young, but varied in age (mean age 24.8-66.6 years). Available evidence indicates that feet with powered dorsiflexion reduce energy costs relative to dynamic response feet in unlimited community ambulators or active adults when walking on level or declined surfaces. Dynamic response feet do not significantly reduce energy costs compared to energy storing, flexible keel, or solid ankle feet when walking on level terrain. Running feet do not reduce energy costs relative to dynamic response in active adults when running. Select feet may reduce energy costs under specific conditions, but additional research is needed to confirm preliminary results.

CONCLUSIONS

The overall body of evidence is based on small samples, comprised mostly of participants who may not well represent the population of prosthesis users, and test conditions that may not well reflect how prostheses are used in daily life. However, evidence suggests energy costs are affected by prosthetic foot type, but only under select conditions. This article is protected by copyright. All rights reserved.

A review of history of CAD/CAM system application in the productionof transtibial prosthetic socket in developing countries (from 1980to 2019)

The development of the CAD/CAM (Computer-aided design and computer-aided manufacturing) system has globally changed the fabrication and delivery of prosthetics and orthotics. Furthermore, since the introduction of CAD/CAM in the 1980s, many successful CAD/CAM system are available in the market today. However, less than 20% of amputees have access to digital fabrication technology and large portion of the amputees are from the developing countries. This review designed to examine selected studies from 1980 to 2019 on CAD/CAM systems in the production of transtibial prosthetic sockets. A review was conducted based on articles gathered from Web of Science, Pubmed and Science Direct. From the findings, 92 articles found related to CAD/CAM-derived transtibial prosthetic socket (TPS). After a further screening of the articles, 20 studies were chosen and only one study was done in a developing country. The results showed an increase interest in CAD/CAM application in Transtibial prosthetic socket (TPS) production for both developed and developing countries, yet the technology has not fully utilised in the developing countries. Factors such as resources, accessibility, knowledge-gap and lack of experienced prosthetists remain the major causes of the lack of CAD/CAM system studies. Large-scale trials are required to employ digital fabrication in the developing regions, consequently advancing the production of high-quality CAD-CAM-derived TPS where most prosthetic and orthotics are needed.

Internet of Things and Robotics in Transforming Current-Day Healthcare Services

Technology has become an integral part of everyday lives. Recent years have witnessed advancement in technology with a wide range of applications in healthcare. However, the use of the Internet of Things (IoT) and robotics are yet to see substantial growth in terms of its acceptability in healthcare applications. The current study has discussed the role of the aforesaid technology in transforming healthcare services. The study also presented various functionalities of the ideal IoT-aided robotic systems and their importance in healthcare applications. Furthermore, the study focused on the application of the IoT and robotics in providing healthcare services such as rehabilitation, assistive surgery, elderly care, and prosthetics. Recent developments, current status, limitations, and challenges in the aforesaid area have been presented in detail. The study also discusses the role and applications of the aforementioned technology in managing the current pandemic of COVID-19. A comprehensive knowledge has been provided on the prospect of the functionality, application, challenges, and future scope of the IoT-aided robotic system in healthcare services. This will help the future researcher to make an inclusive idea on the use of the said technology in improving the healthcare services in the future.

Trends in the Surgical Management of Lower Extremity Gustilo Type IIIB/IIIC Injuries

BACKGROUND

Over the past 20 years, innovations in microsurgical technique have coincided with advances in orthoplastic approaches. However, no single algorithm exists to guide management of limb salvage versus amputation. As such, one would expect these procedures to be performed at equal rates given studies showing similar outcomes. Anecdotally, the observation at the authors' institution is that amputations are being performed more frequently. The purpose of this study was to determine trends in lower extremity trauma management.

METHODS

A retrospective cohort study was conducted at a Level I trauma center on patients with Gustilo type IIIB/IIIC lower extremity trauma from 2005 to 2014. Overall, 148 patients were included. Patients were subdivided into amputation (n = 69) and reconstruction (n = 79) cohorts. The Spearman rank correlation coefficient was used to compare trends in amputation and reconstruction groups. Plastic surgery consultation data were analyzed using the Mann-Whitney U and chi-square tests and the Pearson correlation coefficient.

RESULTS

Amputation was performed more frequently over the study period (r = 0.292; p < 0.001). Plastic surgeons were consulted in 67.5 percent of cases. A plastic surgery consultation was obtained in only 30 percent of amputation cases (p < 0.001).

CONCLUSIONS

Although the data show a trend toward amputation and a shift in management of lower extremity trauma, the observed trend may be attributable in part to deviation from an orthoplastic approach to lower extremity trauma. However, lower extremity reconstruction remains a viable option in select patients, and advances in microsurgery can provide excellent outcomes in the face of severe lower extremity trauma.

Synthesis and characterization of a silver nanoparticle-containing polymer composite with antimicrobial abilities for application in prosthetic and orthotic devices

Background

The presence of skin problems in patients using external lower limb prosthesis is recurrent. This has generated the need to develop interfaces for prosthesis with the ability to control microbial growth. Silver nanoparticles (AgNPs) have been implemented in the development of biomaterials because of their high antimicrobial activity. This article discusses the development of an AgNP-containing polymer composite with antimicrobial activity for developing prosthetic liners.

Methods

AgNPs were synthesized using a photochemical method and certain physicochemical properties were characterized. Furthermore, the antimicrobial activity of AgNPs against Staphylococcus aureus ATCC 25923 and methicillin-resistant Staphylococcus aureus (MRSA), was assessed on the basis of their minimum inhibitory concentrations (MICs). AgNPs were incorporated into a silicon elastomer to assess certain physicomechanical properties, antimicrobial activity and cytotoxic effect of the material.

Results

The maximum antimicrobial activity of the material against Staphylococcus aureus ATCC 25923 and MRSA was 41.58% ±2.97% at AgNP concentration of 32.98 μg/mL and 14.85% ±5.94% at AgNP concentration of 16.49 μg/mL, respectively. Additionally, the material exhibited tensile yield strength, rupture tensile strength, and tensile modulus of elasticity of 0.70 - 1.10 MPa, 0.71–1.06 MPa, and 0.20 - 0.30 MPa, respectively. The mechanical characteristics of the material were within the acceptable range for use in external lower limb prosthetic and orthotic interfaces.

Conclusions

It was possible to incorporate the AgNPs in a silicone elastomer, finding that the composite developed presented antimicrobial activity against Staphylococcus aureus ATCC 25923 and MRSA when compared to non-AgNP material samples.

Effects of extended powered knee prosthesis stance time via visual feedback on gait symmetry of individuals with unilateral amputation: a preliminary study

BACKGROUND

Establishing gait symmetry is a major aim of amputee rehabilitation and may be more attainable with powered prostheses. Though, based on previous work, we postulate that users transfer a previously-learned motor pattern across devices, limiting the functionality of more advanced prostheses. The objective of this study was to preliminarily investigate the effect of increased stance time via visual feedback on amputees' gait symmetry using powered and passive knee prostheses.

METHODS

Five individuals with transfemoral amputation or knee disarticulation walked at their self-selected speed on a treadmill. Visual feedback was used to promote an increase in the amputated-limb stance time. Individuals were fit with a commercially-available powered prosthesis by a certified prosthetist and practiced walking during a prior visit. The same protocol was completed with a passive knee and powered knee prosthesis on separate days. We used repeated-measures, two-way ANOVA (alpha = 0.05) to test for significant effects of the feedback and device factors. Our main outcome measures were stance time asymmetry, peak anterior-posterior ground reaction forces, and peak anterior propulsion asymmetry.

RESULTS

Increasing the amputated-limb stance time via visual feedback significantly improved the stance time symmetry (p = 0.012) and peak propulsion symmetry (p = 0.036) of individuals walking with both prostheses. With the powered knee prosthesis, the highest feedback target elicited 36% improvement in stance time symmetry, 22% increase in prosthesis-side peak propulsion, and 47% improvement in peak propulsion symmetry compared to a no feedback condition. The changes with feedback were not different with the passive prosthesis, and the main effects of device/ prosthesis type were not statistically different. However, subject by device interactions were significant, indicating individuals did not respond consistently with each device (e.g. prosthesis-side propulsion remained comparable to or was greater with the powered versus passive prosthesis for different subjects). Overall, prosthesis-side peak propulsion averaged across conditions was 31% greater with the powered prosthesis and peak propulsion asymmetry improved by 48% with the powered prosthesis.

CONCLUSIONS

Increasing prosthesis-side stance time via visual feedback favorably improved individuals' temporal and propulsive symmetry. The powered prosthesis commonly enabled greater propulsion, but individuals adapted to each device with varying behavior, requiring further investigation.

Materials for lower limb prosthetic and orthotic interfaces and sockets: Evolution and associated skin problems

Introduction: Sockets and interfaces are important elements for lower limb orthoses and prostheses, as they allow for proper contact and fit between the devices and the affected limb or stump.Objective: To review the different polymers used in the development of lower limb sockets and external prosthetic and orthotic interfaces, their functional requirements and the possible skin problems caused by their use.Materials and methods: A literature review was conducted using the databases EBSCO, Embase, LILACS, SciELO, ScienceDirect and Scopus.Results: 47 articles and papers that met the inclusion criteria were retrieved. Thermoplastics, thermosets, foams, gels and elastomers are among the polymers used for manufacturing prosthetic and orthotic interfaces and sockets. However, studies estimate that between 32% and 90.9% of the population that use these devices have experienced skin problems on the affected stump or limb, such as excessive sweating, wounds and irritation.Conclusion: There is a clear need for further research to develop prosthetic and orthotic interfaces and sockets for lower limbs that can prevent or control damage to the skin of users.

Innovative Techniques for Maximizing Limb Salvage and Function

Concurrent injuries to multiple extremities present unique challenges to the reconstructive surgeon. The primary goal in such scenarios is to optimize functional outcomes. The goal of this article is to present an overview of various techniques necessary to provide sufficient soft tissue and preserve amputation limb lengths and function. The concept of innovative techniques for maximizing limb savage and function is presented using an index patient with multiple extremity third- and fourth-degree burn injuries resulting in nonsalvageable lower extremities and severe left-hand wounds. A review of other potential innovative techniques is discussed. The burn injury resulted in a need for bilateral guillotine below-knee amputations. Above-knee amputation was avoided in the left leg using a parascapular free fasciocutaneous flap, while through-knee amputation was preferred to above-knee amputation in the right leg. The preservation of areas with questionable viability resulted in salvaging the left hand of the patient using digital palmar flaps to resurface the dorsum with creation of a first web-space. Maintenance of maximal viable length of limbs and any residual function in the limbs can be of significant functional benefit to multiple limb amputation patients. Maximizing the limb length in such patients is critical, and typical "rules" that have traditionally been utilized to minimize numbers of operations and optimize prosthetic fit may not apply.

A systematic literature review of physiotherapy and rehabilitation approaches to lower-limb amputation

BACKGROUND

Successful use of prostheses after lower-limb amputation (LLA) depends on undergoing physiotherapy and rehabilitation both physically and psychologically. The aim of this systematic literature review is to systematically review the scientific evidence regarding prosthetic rehabilitation and physiotherapy after LLA.

METHODS

A systematic literature search was conducted using PubMed, Web of Science, Cochrane, CINAHL, EMBASE, SCOPUS, and EMB Reviews databases on December 31, 2015. Studies with the search keywords were identified and independently assessed by reviewers. The search yielded 403 potentially relevant articles after the removal of duplicates. Of these, only nine articles met the inclusion criteria. All studies were original articles, one of which was a randomized controlled study. Different measurement methods were used and positive results in terms of functional status, weight-lifting capacity with prosthesis, walking and balance ability, and acute care process were gained with a physiotherapy program. Conventional methods still possess high importance; however, it is safe to say that virtual reality and software-based programs for rehabilitation are increasingly being developed and getting more and more support.

DISCUSSION

LLA rehabilitation is a topic that requires the focus of current and future studies; evidence-based studies are required on the approaches to rehabilitation for specific LLA groups.

The effect of damping in prosthetic ankle and knee joints on the biomechanical outcomes: A literature review

BACKGROUND

Given the growing number of variable-damping prosthetic knee and ankle components and broad number of potential biomechanical outcomes, a systematic review is needed to assess advantages of damped knee and ankle units over non-damped prostheses.

OBJECTIVES

This study provides an overview of the biomechanical outcomes associated with the use of prosthetic knees and ankles with damping mechanisms in individuals with lower limb amputation.

STUDY DESIGN

Literature review.

METHODS

A systematic search was performed through PubMed, Science Direct, Web of Science, Cochrane, and Scopus databases from June 1994 to March 2016. The level of evidence of each article was assessed using a 13-element checklist for evaluating non-randomized controlled trials for quality assessment. Afterward, the studies were classified as A-level, B-level, or C-level based on total score and positive scores from certain key categories.

RESULTS

In total, 22 papers remained for the quality assessment based on the inclusion criteria. In total, 15 studies scored sufficiently high quality scores to be classified. One article scored as A-level, eight as B-level, and six as C-level. In total, 10 studied knees and 5 examined ankles. Sample sizes ranged from 5 to 28 subjects.

CONCLUSION

Available studies were evaluated in detail and biomechanical outcomes were extracted from the studies that met criteria. Results of this review indicate that study methodology and outcome measures were heterogeneous across reviewed papers. This could be an explanation for inconsistent findings of the reviewed studies. Only self-selected gait speed showed a consistent difference when dampers were applied to the leg. Thus, further research is required in this area. Clinical relevance This study provides an overview of evidence related to prosthetic knee and foot/ankle components with damping attachments. Research related to biomechanical outcomes is of great importance for researchers and practitioners in this area. The studies drew mixed conclusions, but walking speed was consistently different for damped versus non-damped components.

Prosthetists' perceptions and use of outcome measures in clinical practice: Long-term effects of focused continuing education

BACKGROUND

Continuing education is intended to facilitate clinicians' skills and knowledge in areas of practice, such as administration and interpretation of outcome measures.

OBJECTIVE

To evaluate the long-term effect of continuing education on prosthetists' confidence in administering outcome measures and their perceptions of outcomes measurement in clinical practice.

DESIGN

Pretest-posttest survey methods.

METHODS

A total of 66 prosthetists were surveyed before, immediately after, and 2 years after outcomes measurement education and training. Prosthetists were grouped as routine or non-routine outcome measures users, based on experience reported prior to training.

RESULTS

On average, prosthetists were just as confident administering measures 1-2 years after continuing education as they were immediately after continuing education. In all, 20% of prosthetists, initially classified as non-routine users, were subsequently classified as routine users at follow-up. Routine and non-routine users' opinions differed on whether outcome measures contributed to efficient patient evaluations (79.3% and 32.4%, respectively). Both routine and non-routine users reported challenges integrating outcome measures into normal clinical routines (20.7% and 45.9%, respectively).

CONCLUSION

Continuing education had a long-term impact on prosthetists' confidence in administering outcome measures and may influence their clinical practices. However, remaining barriers to using standardized measures need to be addressed to keep practitioners current with evolving practice expectations. Clinical relevance Continuing education (CE) had a significant long-term impact on prosthetists' confidence in administering outcome measures and influenced their clinical practices. In all, approximately 20% of prosthetists, who previously were non-routine outcome measure users, became routine users after CE. There remains a need to develop strategies to integrate outcome measurement into routine clinical practice.

Characterisation of the responsive properties of two running-specific prosthetic models

BACKGROUND

The need for information regarding running-specific prosthetic properties has previously been voiced. Such information is necessary to assist in athletes' prostheses selection.

OBJECTIVES

This study aimed to describe the characteristics of two commercially available running-specific prostheses.

STUDY DESIGN

The running-specific prostheses were tested (in an experimental setup) without the external interference of athlete performance variations.

METHODS

Four stiffness categories of each running-specific prosthetic model (Xtend^™ and Xtreme^™) were tested at seven alignment setups and three drop masses (28, 38 and 48 kg). Results for peak ground reaction force (GRF_peak), contact time ( t_c), flight time ( t_f), reactive strength index (RSI) and maximal compression (Δ L) were determined during controlled dropping of running-specific prostheses onto a force platform with different masses attached to the experimental setup.

RESULTS

No statistically significant differences were found between the different setups of the running-specific prostheses. Statistically significant differences were found between the two models for all outcome variables (GRF_peak, Xtend > Xtreme; t_c, Xtreme > Xtend; t_f, Xtreme > Xtend; RSI, Xtend > Xtreme; Δ L, Xtreme > Xtend; p < 0.05).

CONCLUSION

These findings suggest that the Xtreme stores more elastic energy than the Xtend, leading to a greater performance response. The specific responsive features of blades could guide sprint athletes in their choice of running-specific prostheses. Clinical relevance Insights into the running-specific prosthesis (RSP) properties and an understanding of its responsive characteristics have implications for athletes' prosthetic choice. Physiologically and metabolically, a short sprint event (i.e. 100 m) places different demands on the athlete than a long sprint event (i.e. 400 m), and the RSP should match these performance demands.

Elastomeric liners for people with transtibial amputation: Survey of prosthetists' clinical practices

BACKGROUND

A diverse range of elastomeric liner products are available to people with transtibial amputation. However, little information is available about how prosthetists select the product best suited to each patient.

OBJECTIVES

To determine how prosthetists obtain information about liners, which features are most relevant to the selection process, and which products are used most for patients with transtibial amputation.

STUDY DESIGN

Cross-sectional survey.

METHODS

A custom online survey was developed to solicit information about prosthetists' liner selection practices. Prosthetists with experience managing transtibial patients were recruited via advertisements posted in magazines, at conferences, and on a listserv. Responses were analyzed to characterize prosthetists' liner selection practices.

RESULTS

Data from 106 experienced prosthetists (mean age: 44.4 years, mean experience: 15.7 years) were included. Most prosthetists (94%) obtained liner information from manufacturer representatives, websites, or literature. On average, respondents factored nine different liner characteristics into their selection processes. Prosthetists reported experience with 16 unique liner products with their transtibial patients, but routinely used fewer than 3.

CONCLUSION

Although many different prosthetic liners are available, prosthetists regularly use only a few select liner products. Tools or strategies to objectively compare prosthetic liners across manufacturers are likely needed to facilitate more diverse prescription practices. Clinical relevance Knowledge of prosthetists' prosthetic liner selection practices may guide development of evidence-based resources or tools to facilitate matching patients with appropriate liners. Results of this study may also inform researchers and manufacturers about desirable liner characteristics and direct development of novel liner products to address prosthetists' clinical needs.

[Artificial organs]

Research has been fighting against organ failure and shortage of donations by supplying artificial organs for many years. With the raise of new technologies, tissue engineering and regenerative medicine, many organs can benefit of an artificial equivalent: thanks to retinal implants some blind people can visualize stimuli, an artificial heart can be proposed in case of cardiac failure while awaiting for a heart transplant, artificial larynx enables laryngectomy patients to an almost normal life, while the diabetic can get a glycemic self-regulation controlled by smartphones with an artificial device. Dialysis devices become portable, as well as the oxygenation systems for terminal respiratory failure. Bright prospects are being explored or might emerge in a near future. However, the retrospective assessment of putative side effects is not yet sufficient. Finally, the cost of these new devices is significant even if the advent of three dimensional printers may reduce it.

Construct Validity of the Prosthetic Limb Users Survey of Mobility (PLUS-M) in Adults With Lower Limb Amputation

OBJECTIVE

To assess construct validity of the Prosthetic Limb Users Survey of Mobility (PLUS-M), a self-report mobility measure for people with lower limb amputation (LLA).

DESIGN

Cross-sectional study.

SETTING

Private prosthetic clinics (n=37).

PARTICIPANTS

Current lower limb prosthesis users (N=199; mean age ± SD, 55.4±14.3y; 71.4% men) were assessed before receiving a replacement prosthesis, prosthetic socket, and/or prosthetic knee.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Convergent construct validity was examined using correlations between participants' PLUS-M T-scores and measures of physical function, mobility, and balance, including the Amputee Mobility Predictor (AMP), timed Up and Go (TUG), Patient-Reported Outcomes Measurement Information System-Physical Function (PROMIS-PF), Prosthesis Evaluation Questionnaire-Mobility Subscale (PEQ-MS), and Activities-specific Balance Confidence (ABC) Scale. Known-groups construct validity was evaluated by comparing differences in PLUS-M T-scores among participants grouped by Medicare Functional Classification Level (MFCL).

RESULTS

PLUS-M T-scores demonstrated a moderate positive relationship with AMP scores (ρ=.54, P<.001) and a moderate negative relationship with TUG times (ρ=-.56, P<.001). The PLUS-M also showed a strong positive relationship with PEQ-MS scores (ρ=.78, P<.001), ABC Scale scores (ρ=.81, P<.001), and PROMIS-PF T-scores (ρ=.81, P<.001). Significant differences (P<.05) in PLUS-M T-scores were found among groups of people classified by different MFCLs.

CONCLUSIONS

Study results support the validity of the PLUS-M as a self-report measure of prosthetic mobility. Correlations between PLUS-M and measures of physical function, mobility, and balance indicate convergent construct validity. Similarly, significant differences in PLUS-M T-scores across MFCL groups provide evidence of known-groups construct validity. In summary, evidence indicates that PLUS-M has good construct validity among people with LLA.

Physical activity barriers and enablers in older Veterans with lower-limb amputation

Little is known about the types of physical activities that older individuals with lower-limb loss perform, correlates of regular physical activity (PA), and barriers and facilitators to PA. We conducted an exploratory study in 158 older Veterans from the Pacific Northwest with a partial foot (35%), below-knee (39%) and above-knee (26%) amputation. Ninety-eight percent of survey respondents were male, on average 65 yr of age and 15 yr postamputation; 36% of amputations were trauma-related. The most commonly reported physical activities were muscle strengthening (42%), yard work and/or gardening (30%), and bicycling (11%). Forty-three percent were classified as physically active based on weekly moderate- and vigorous-intensity PA. History of vigorous preamputation PA was positively associated with being active, while low wealth and watching ≥5 h/d of television/videos were inversely associated. While pain- and resource-related barriers to PA were most frequently reported, only knowledge-related and interest/motivation-related barriers were inversely associated with being active. Family support and financial assistance to join a gym were the most commonly reported factors that would facilitate PA. To increase PA in the older amputee population, interventions should address motivational issues, knowledge gaps, and television watching; reduce financial barriers to exercising; and consider involving family members.

Assessing functional mobility after lower limb reconstruction: a psychometric evaluation of a sensor-based mobility score

OBJECTIVE

To develop and validate a robust, objective mobility assessment tool, Hamlyn Mobility Score (HMS), using a wearable motion sensor.

BACKGROUND

Advances in reconstructive techniques allow more limbs to be salvaged. However, evidence demonstrating superior long-term outcomes compared with amputation is unavailable. Lack of access to quality regular functional mobility status may be preventing patients and health care staff from optimizing rehabilitation programs and evaluating the reconstructive services.

METHODS

In this prospective cohort study, 20 patients undergoing lower limb reconstruction and 10 age-matched controls were recruited. All subjects completed the HMS activity protocol twice under different instructors at 3 months postoperatively, and again at 6 months, while wearing an ear-worn accelerometer. Demographic and clinical data were also collected including a short-form health survey (SF-36). HMS parameters included standard test metrics and additional kinematic features extracted from accelerometer data. A psychometric evaluation was conducted to ascertain reliability and validity.

RESULTS

The HMS demonstrated excellent reliability (intraclass correlation coefficient >0.90, P < 0.001) and internal consistency (Cronbach α = 0.897). Concurrent validity was demonstrated by correlation between HMS and SF-36 scores (Spearman ρ = 0.666, P = 0.005). Significant HMS differences between healthy subjects and patients, stratified according to fracture severity, were shown (Kruskal-Wallis nonparametric 1-way analysis of variance, χ = 21.5, P < 0.001). The HMS was 50% more responsive to change than SF-36 (effect size: 1.49 vs 0.99).

CONCLUSIONS

The HMS shows satisfactory reliability and validity and may provide a platform to support adaptable, personalized rehabilitation and enhanced service evaluation to facilitate optimal patient outcomes.

EMG control of a bionic knee prosthesis: exploiting muscle co-contractions for improved locomotor function

This paper presents the development and experimental evaluation of a volitional control architecture for a powered-knee transfemoral prosthesis that affords the amputee user with direct control of knee impedance using measured electromyogram (EMG) potentials of antagonist muscles in the residual limb. The control methodology incorporates a calibration procedure performed with each donning of the prosthesis that characterizes the co-contraction levels as the user performs volitional phantom-knee flexor and extensor contractions. The performance envelope for EMG control of impedance is then automatically shaped based on the flexor and extensor calibration datasets. The result is a control architecture that is optimized to the user's current co-contraction activity, providing performance robustness to variation in sensor placement or physiological changes in the residual-limb musculature. Experimental results with a single unilateral transfemoral amputee user demonstrate consistent and repeatable control performance for level walking at self-selected speed over a multi-week, multi-session period of evaluation.

Global position sensing and step activity as outcome measures of community mobility and social interaction for an individual with a transfemoral amputation due to dysvascular disease

BACKGROUND AND PURPOSE

Community mobility of individuals following lower limb amputation is highly variable and has a great impact on their quality of life. Currently, clinical assessments of ambulatory ability and motivation influence prosthetic prescription. However, these outcome measures do not effectively quantify community mobility (ie, mobility outside of the clinic) of individuals with an amputation. Advances in global positioning systems (GPSs) and other wearable step-monitoring devices allow for objective, quantifiable measurement of community mobility. This case report will examine the combined use of a GPS unit and a step activity monitor to quantify community mobility and social interaction of an individual with transfemoral amputation due to dysvascular disease.

CASE DESCRIPTION

A 76-year-old woman with a unilateral transfemoral amputation due to vascular disease carried a commercial GPS unit and step activity monitor to quantify her community mobility and social interaction every day over a period of 1 month. The step activity monitor was affixed to her prosthesis. The patient used a wheelchair as well as her prosthesis for everyday mobility.

OUTCOME

Information from the GPS unit and step activity monitor provided quantitative details on the patient's steps taken in and out of the home, wheelchair use, prosthesis use, driving trips, and time spent on social and community trips.

DISCUSSION

This case report describes a potential clinical measurement procedure for quantifying community mobility and social interaction of an individual with lower limb amputation. Future efforts are needed to validate this measurement tool on large sample sizes and in individuals with different mobility levels. Additionally, automatization of data analysis and technological approaches to reduce compromised GPS signals may eventually lead to a practical, clinically useful tool.

Muscle activation patterns during walking from transtibial amputees recorded within the residual limb-prosthetic interface

BACKGROUND

Powered lower limb prostheses could be more functional if they had access to feedforward control signals from the user's nervous system. Myoelectric signals are one potential control source. The purpose of this study was to determine if muscle activation signals could be recorded from residual lower limb muscles within the prosthetic socket-limb interface during walking.

METHODS

We recorded surface electromyography from three lower leg muscles (tibilias anterior, gastrocnemius medial head, gastrocnemius lateral head) and four upper leg muscles (vastus lateralis, rectus femoris, biceps femoris, and gluteus medius) of 12 unilateral transtibial amputee subjects and 12 non-amputee subjects during treadmill walking at 0.7, 1.0, 1.3, and 1.6 m/s. Muscle signals were recorded from the amputated leg of amputee subjects and the right leg of control subjects. For amputee subjects, lower leg muscle signals were recorded from within the limb-socket interface and from muscles above the knee. We quantified differences in the muscle activation profile between amputee and control groups during treadmill walking using cross-correlation analyses. We also assessed the step-to-step inter-subject variability of these profiles by calculating variance-to-signal ratios.

RESULTS

We found that amputee subjects demonstrated reliable muscle recruitment signals from residual lower leg muscles recorded within the prosthetic socket during walking, which were locked to particular phases of the gait cycle. However, muscle activation profile variability was higher for amputee subjects than for control subjects.

CONCLUSION

Robotic lower limb prostheses could use myoelectric signals recorded from surface electrodes within the socket-limb interface to derive feedforward commands from the amputee's nervous system.

Microscopic magnetic stimulation of neural tissue

Electrical stimulation is currently used to treat a wide range of cardiovascular, sensory and neurological diseases. Despite its success, there are significant limitations to its application, including incompatibility with magnetic resonance imaging, limited control of electric fields and decreased performance associated with tissue inflammation. Magnetic stimulation overcomes these limitations but existing devices (that is, transcranial magnetic stimulation) are large, reducing their translation to chronic applications. In addition, existing devices are not effective for deeper, sub-cortical targets. Here we demonstrate that sub-millimeter coils can activate neuronal tissue. Interestingly, the results of both modelling and physiological experiments suggest that different spatial orientations of the coils relative to the neuronal tissue can be used to generate specific neural responses. These results raise the possibility that micro-magnetic stimulation coils, small enough to be implanted within the brain parenchyma, may prove to be an effective alternative to existing stimulation devices.

Electrical stimulation is used to treat a range of neurological diseases, but there are limitations that reduce its benefits. Bonmassar and colleagues show that magnetic stimulation delivered by small coils, close to the targeted neural tissue, can also be used to activate neurons and with fewer limitations.

A biomechanical model for encoding joint dynamics: applications to transfemoral prosthesis control

This paper presents and tests a framework for encoding joint dynamics into energy states using kinematic and kinetic knee joint sensor data and demonstrates how to use this information to predict the future energy state (torque and velocity requirements) of the joint without a priori knowledge of the activity sequence. The intended application is for enhancing micro-controlled prosthetics by making use of the embedded sensory potential of artificial limbs and classical mechanical principles of a prosthetic joint to report instantaneous energy state and most probable next energy state. When applied to the knee during preferred and fast speed walking in 8 human subjects (66 preferred-speed trials and 50 fast-speed trials), it was found that joint energy states could be consistently sequenced (75% consensus) according to mechanical energy transference conditions and subsequences appeared to reflect the stability and energy dissipation requirements of the knee during gait. When simple constraints were applied to the energy transfer input conditions (their signs), simulations indicated that it was possible to predict the future energy state with an accuracy of >80% when 2% cycle in advance (∼20 ms) of the switch and >60% for 4% (∼40 ms) in advance. This study justifies future research to explore whether this encoding algorithm can be used to identify submodes of other human activity that are relevant to TFP control, such as chair and stair activities and their transitions from walking, as well as unexpected perturbations.

Comparison of prosthetic feet prescribed to active individuals using ISO standards

BACKGROUND

Little research has been done on the robustness of prosthetic feet prescribed to military personnel, and manufacturers are not required to test their products prior to sale. This is problematic because the prosthetic feet used by active individuals are subjected to loading conditions not seen in normal gait.

OBJECTIVES

To evaluate whether commercially available heavy-duty prosthetic feet intended for use by military personnel meet ISO 10328 standards.

STUDY DESIGN

Bench testing of heavy-duty prosthetic feet using ISO 10328 standards.

METHODS

Prosthetic feet from three different manufacturers were tested according to ISO 10328 standards, using a testing frame fitted with axial load and displacement transducers. Pass/fail information was recorded as well as the stiffness and creep of each foot before and after cyclic testing.

RESULTS

All feet passed the ISO 10328 standards at the highest loading level, and some significant differences were found within a given model of prosthesis when comparing stiffness and creep before and after cyclic testing.

CONCLUSIONS

This study demonstrated that manufacturers of heavy-duty prosthetic feet adhere to the voluntary ISO 10328 standards. However, these standards may be insufficient because the tests simulate only idealized gait. Further development of the standards may be necessary to reproduce the circumstances that occur during extreme usage to ensure that prosthetic feet do not fail.

Building the bionic eye: an emerging reality and opportunity

Once the topic of folklore and science fiction, the notion of restoring vision to the blind is now approaching a tractable reality. Technological advances have inspired numerous multidisciplinary groups worldwide to develop visual neuroprosthetic devices that could potentially provide useful vision and improve the quality of life of profoundly blind individuals. While a variety of approaches and designs are being pursued, they all share a common principle of creating visual percepts through the stimulation of visual neural elements using appropriate patterns of electrical stimulation. Human clinical trials are now well underway and initial results have been met with a balance of excitement and cautious optimism. As remaining technical and surgical challenges continue to be solved and clinical trials move forward, we now enter a phase of development that requires careful consideration of a new set of issues. Establishing appropriate patient selection criteria, methods of evaluating long-term performance and effectiveness, and strategies to rehabilitate implanted patients will all need to be considered in order to achieve optimal outcomes and establish these devices as viable therapeutic options.