Reduced cortical brain activity with the use of microprocessor-controlled prosthetic knees during walking

Using mobile eye tracking to measure cognitive load through gaze behavior during walking in lower limb prosthesis users: A preliminary assessment

BACKGROUND

Lower limb amputation does not affect only physical and psychological functioning but the use of a prosthetic device can also lead to increased cognitive demands. Measuring cognitive load objectively is challenging, and therefore, most studies use questionnaires that are easy to apply but can suffer from subjective bias. Motivated by this, the present study investigated whether a mobile eye tracker can be used to objectively measure cognitive load by monitoring gaze behavior during a set of motor tasks.

METHODS

Five prosthetic users and eight able-bodied controls participated in this study. Eye tracking data and kinematics were recorded during a set of motor tasks (level ground walking, walking on uneven terrain, obstacle avoidance, stairs up and ramp down, as well as ramp up and stairs down) while the participants were asked to focus their gaze on a visual target for as long as possible. Target fixation times and increase in pupil diameters were determined and correlated to subjective ratings of cognitive load.

FINDINGS

Overall, target fixation time and pupil diameter showed strong negative and positive correlations, respectively, to the subjective rating of cognitive load in the able-bodied controls (-0.75 and 0.80, respectively). However, the individual correlation strength, and in some cases, even the sign, was different across participants. A similar trend could be observed in prosthetic users.

INTERPRETATION

The results of this study showed that a mobile eye tracker may be used to estimate cognitive load in prosthesis users during locomotor tasks. This paves the way to establish a new approach to assessing cognitive load, which is objective and yet practical and simple to administer. Nevertheless, future studies should corroborate these results by comparing them to other objective measures as well as focus on translating the proposed approach outside of a laboratory.

The influence of prosthetic suspension on gait and cortical modulations is persons with a transfemoral amputation: socket-suspended versus bone-anchored prosthesis

BACKGROUND

Persons with a transfemoral amputation (TFA) often experience difficulties in daily-life ambulation, including an asymmetrical and less stable gait pattern and a greater cognitive demand of walking. However, it remains unclear whether this is effected by the prosthetic suspension, as eliminating the non-rigid prosthetic connection may influence stability and cortical activity during walking. Spatiotemporal and stability-related gait parameters, as well as cortical activity during walking, were evaluated between highly active individuals (MFC-level K3-4) with a TFA and able-bodied (AB) persons, and between persons with a bone-anchored prosthesis (BAP) and those with a socket-suspended prosthesis (SSP).

METHODS

18 AB persons and 20 persons with a unilateral TFA (10 BAP-users, 10 SSP-users) walked on a treadmill at their preferred speed. Spatiotemporal and margin of stability parameters were extracted from three-dimensional movement recordings. In addition, 126-channel electroencephalogram (EEG) was recorded. Brain-related activity from several cortical areas was isolated using independent component analysis. Source-level data were divided into gait cycles and subjected to time-frequency analysis to determine gait-cycle dependent modulations of cortical activity.

RESULTS

Persons with TFA walked with smaller and wider steps and with greater variability in mediolateral foot placement than AB subjects; no significant differences were found between BAP- and SSP-users. The EEG analysis yielded four cortical clusters in frontal, central (both hemispheres), and parietal areas. No statistically significant between-group differences were found in the mean power over the entire gait cycle. The event-related spectral perturbation maps revealed differences in power modulations (theta, alpha, and beta bands) between TFA and AB groups, and between BAP- and SSP-users, with largest differences observed around heel strike of either leg.

CONCLUSIONS

The anticipated differences in gait parameters in persons with TFA were confirmed, however no significant effect of the fixed suspension of a BAP was found. The preliminary EEG findings may indicate more active monitoring and control of stability in persons with TFA, which appeared to be timed differently in SSP than in BAP-users. Future studies may focus on walking tasks that challenge stability to further investigate differences related to prosthetic suspension.

Use of Physical Activity Measures in Rehabilitation Interventions Following Lower Extremity Amputation

Purpose of Review

This systematic review aims to evaluate physical performance outcome tools that are used most frequently to assess rehabilitation interventions. The scope of this paper focused on outcomes used with established lower limb amputees when assessing interventions such as exercise programs or changes in prescription published in the last 5 years.

Recent Findings

The most recorded outcome measures used across all the papers were timed walk tests and the Activity Balance Confidence Scale. Many outcomes did not produce statistically significant results with established amputee cohorts. Understanding the minimal important clinical difference is key.

Summary

The use of outcome measures is essential. Training and education are likely to increase the use of outcome measures. Quality of life measures are important in conjunction with physical outcomes. Simple timed walk tests are commonly used. These are in general easy to administer requiring a small space, limited equipment, and a short time frame.

A review of user needs to drive the development of lower limb prostheses

Background

The development of bionic legs has seen substantial improvements in the past years but people with lower-limb amputation still suffer from impairments in mobility (e.g., altered balance and gait control) due to significant limitations of the contemporary prostheses. Approaching the problem from a human-centered perspective by focusing on user-specific needs can allow identifying critical improvements that can increase the quality of life. While there are several reviews of user needs regarding upper limb prostheses, a comprehensive summary of such needs for those affected by lower limb loss does not exist.

Methods

We have conducted a systematic review of the literature to extract important needs of the users of lower-limb prostheses. The review included 56 articles in which a need (desire, wish) was reported explicitly by the recruited people with lower limb amputation (N = 8149).

Results

An exhaustive list of user needs was collected and subdivided into functional, psychological, cognitive, ergonomics, and other domain. Where appropriate, we have also briefly discussed the developments in prosthetic devices that are related to or could have an impact on those needs. In summary, the users would like to lead an independent life and reintegrate into society by coming back to work and participating in social and leisure activities. Efficient, versatile, and stable gait, but also support to other activities (e.g., sit to stand), contribute to safety and confidence, while appearance and comfort are important for the body image. However, the relation between specific needs, objective measures of performance, and overall satisfaction and quality of life is still an open question.

Conclusions

Identifying user needs is a critical step for the development of new generation lower limb prostheses that aim to improve the quality of life of their users. However, this is not a simple task, as the needs interact with each other and depend on multiple factors (e.g., mobility level, age, gender), while evolving in time with the use of the device. Hence, novel assessment methods are required that can evaluate the impact of the system from a holistic perspective, capturing objective outcomes but also overall user experience and satisfaction in the relevant environment (daily life).

Impact of microprocessor prosthetic knee on mobility and quality of life in patients with lower limb amputation: a systematic review of the literature

INTRODUCTION

Advanced technologies have made available the development of microprocessor prosthetic knee (MPK) to improve autonomy of patients with lower limb amputation. In the present systematic review, we aimed to evaluate the impact of the use of all types of MPK on patients' functional status and quality of life.

EVIDENCE ACQUISITION

We conducted this review according to the PRISMA Guidelines on Medline (via Ovid), Scopus and SportDiscuss. All identified articles were screened for their eligibility by two reviewers using Covidence software. The Cochrane Risk of Bias (RoB) or the NIH Quality Assessment Tool were used to assess the quality of the studies.

EVIDENCE SYNTHESIS

Eighteen articles were included in the present review (7 randomized controlled trials - RCT), 6 cross-sectional and 5 follow-up studies). Number of participants included varied from 20 to 602, protocols' length varied from a single session to 12 weeks of use of MPK. Taken together, MPK users compared to NMPK users tend to present better functional status and mobility. Quality of life was also positively impacted in MPK users. On the other hand, the superiority of more advanced MPKs such as the Genium^® is less clear, especially given the improvements over time of other MPKs such as the C-leg^® and the Rheo knee^®.

CONCLUSIONS

Based on our results, while it is clear that MPKs outperform NMPKs both for functional status and quality of life, additional benefits of one MPK over another is less clear. Future studies are needed to clarify these aspects.

Measuring mental workload in assistive wearable devices: a review

As wearable assistive devices, such as prostheses and exoskeletons, become increasingly sophisticated and effective, the mental workload associated with their use remains high and becomes a major challenge to their ecological use and long-term adoption. Numerous methods of measuring mental workload co-exist, making analysis of this research topic difficult. The aim of this review is to examine how mental workload resulting from the use of wearable assistive devices has been measured, in order to gain insight into the specific possibilities and limitations of this field. Literature searches were conducted in the main scientific databases and 60 articles measuring the mental workload induced by the use of a wearable assistive device were included in this study. Three main families of methods were identified, the most common being 'dual task' and 'subjective assessment' methods, followed by those based on 'physiological measures', which included a wide variety of methods. The variability of the measurements was particularly high, making comparison difficult. There is as yet no evidence that any particular method of measuring mental workload is more appropriate to the field of wearable assistive devices. Each method has intrinsic limitations such as subjectivity, imprecision, robustness or complexity of implementation or interpretation. A promising metric seems to be the measurement of brain activity, as it is the only method that is directly related to mental workload. Finally, regardless of the measurement method chosen, special attention should be paid to the measurement of mental workload in the context of wearable assistive devices. In particular, certain practical considerations, such as ecological situations and environments or the level of expertise of the participants tested, may be essential to ensure the validity of the mental workload assessed.

The effect of robot-assisted gait training on cortical activation in stroke patients: A functional near-infrared spectroscopy study

OBJECTIVE

To investigate the effects of the robot-assisted gait training on cortical activation and functional outcomes in stroke patients.

METHODS

The patients were randomly assigned: training with Morning Walk® (Morning Walk group; n = 30); conventional physiotherapy (control group; n = 30). Rehabilitation was performed five times a week for 3 weeks. The primary outcome was the cortical activation in the Morning Walk group. The secondary outcomes included gait speed, 10-Meter Walk Test (10MWT), FAC, Motricity Index-Lower (MI-Lower), Modified Barthel Index (MBI), Rivermead Mobility Index (RMI), and Berg Balance Scale (BBS).

RESULTS

Thirty-six subjects were analyzed, 18 in the Morning Walk group and 18 in the control group. The cortical activation was lower in affected hemisphere than unaffected hemisphere at the beginning of robot rehabilitation. After training, the affected hemisphere achieved a higher increase in cortical activation than the unaffected hemisphere. Consequently, the cortical activation in affected hemisphere was significantly higher than that in unaffected hemisphere (P = 0.036). FAC, MBI, BBS, and RMI scores significantly improved in both groups. The Morning Walk group had significantly greater improvements than the control group in 10MWT (P = 0.017), gait speed (P = 0.043), BBS (P = 0.010), and MI-Lower (P = 0.047) scores.

CONCLUSION

Robot-assisted gait training not only improved functional outcomes but also increased cortical activation in stroke patients.

Interest in technology among medical students early in their clinical experience

BACKGROUND

The world is in the midst of the "digital" revolution characterized by the ascendency of computerization, information systems and artificial intelligence with an emphasis on innovation and creativity. This revolution has affected current medical practice and promises to significantly impact it in the future. This requires physician's understanding and participation in adopting such technology. This study aimed to explore the role technology plays in the future career plans of medical students.

METHODS

A questionnaire examining selection criteria for medical specialty choice, criteria for choosing a post-residency job and demographic data was completed by a convenience sample of 5th-year Israeli medical students.

RESULTS

Two-hundred forty-two students (51 % men) completed the questionnaire, an 84 % response rate. Only a third (35 %) rated the specialty selection criterion "provides mechanical/ technological challenges" as important, while only 7% considered as important that a specialty requires skills in computer science. Few students were interested in post-residency positions requiring much technological knowledge (25 %) and requiring much skill with computerized information systems (13 %). Male students were significantly more interested than females in such positions and these students more often reported that they were considering careers in surgery and its subspecialties. This surgical bent was confirmed by the 42 % of students interested in post-residency positions that include time in the operating room having more interest in positions requiring much technological knowledge than the students not interested in operating room time.

CONCLUSIONS

This preliminary study demonstrated that as a group the students' expressed relatively little interest in medical specialties and post-residency positions involving technological challenges and knowledge of information (computer) science. Yet, the sub-group interested in the surgical specialties had such interests. These findings were perplexing since the students belong to Generations Y and Z who are steeped in the use of smartphones and social media. Therefore, we failed to support our hypothesis that Generation Y and Z students would be attracted to specialties and positions that provide them with technological challenges. Furthermore, medical educators need to explore this apparent lack of interest in technology in order to insure that the future physician workforce is ready to face future "digital" challenges.

Finger orthoses for management of joint hypermobility disorders: Relative effects on hand function and cognitive load

BACKGROUND

Joint hypermobility refers to joints that move beyond their normal limits. Individuals with hypermobility of the fingers experience difficulties in activities of daily living. Finger orthoses are available for managing hypermobility of the fingers, but their effectiveness has received little attention in scholarly literature.

OBJECTIVES

To determine if use of custom fit finger orthoses leads to improvements in time needed to perform standardised hand function tests, and attentional demand required to perform these tests, in individuals with joint hypermobility syndrome, Hypermobile Ehlers-Danlos syndrome or Classical Ehlers-Danlos syndrome.

STUDY DESIGN

Repeated-measures study.

METHODS

Fourteen participants performed three different hand function tests (target box and block test, writing and picking up coins), with and without their finger orthoses. Time to complete each test was recorded as a measure of functional performance. Brain activity was recorded in the pre-frontal cortices as a measure of attentional demand.

RESULTS

Functional performance significantly improved for all but one test (picking up coins with non-dominant hand) when participants wore finger orthoses (p < 0.05). Activity in the pre-frontal cortex was lower when using the orthosis to perform the coin test (dominant hand; p < 0.05). No differences were observed in other tests (p > 0.05).

CONCLUSIONS

Results suggested that finger orthoses improved hand function and provided limited evidence to suggest that they may also affect attentional demand. While the limited sample does not provide conclusive evidence supporting the use of finger orthosis in this clinical population, results warrant further investigation in large scale longitudinal studies or randomised controlled trials.

Cortical brain activity in transfemoral or knee-disarticulation prosthesis users performing single- and dual-task walking activities

Introduction

Walking with a prosthesis while performing secondary tasks increases demand on cognitive resources, compromising balance and gait. This study investigated effects of a secondary task on patterns of brain activity and temporospatial gait parameters in individuals using a prosthesis with or without a microprocessor-controlled prosthetic knee(MPK) and controls.

Methods

A cross-sectional study with repeated measures was performed. Twenty-nine individuals with amputations and 16 controls were recruited. Functional near-infrared spectroscopy was used to evaluate changes in oxygenated and de-oxygenated haemoglobin in the prefrontal cortex and temporospatial variables during single-and dual-task walking.

Results

Differences in brain activity were observed within the MPK-group and controls without changes in temporospatial parameters. The Trail-Walking test was associated with highest levels of brain activity in both groups. No differences were observed between single- and dual-task walking in the non-MPK-group (p > 0.05). The Non-MPK and the MPK-group recorded higher levels of brain activity than controls during single-task walking and poorer results on temporospatial variables compared to controls.

Conclusions

For the MPK-group and controls, introduction of a secondary task led to an increase in brain activity. This was not seen in the Non-MPK-group. Significant differences in brain activity were observed in the absence of changes in temporospatial parameters.

Advanced techniques in amputation surgery and prosthetic technology in the lower extremity

Bone-anchored implants give patients with unmanageable stump problems hope for drastic improvements in function and quality of life and are therefore increasingly considered a viable solution for lower-limb amputees and their orthopaedic surgeons, despite high infection rates.Regarding diversity and increasing numbers of implants worldwide, efforts are to be supported to arrange an international bone-anchored implant register to transparently overview pros and cons.Due to few, but high-quality, articles about the beneficial effects of targeted muscle innervation (TMR) and regenerative peripheral nerve interface (RPNI), these surgical techniques ought to be directly transferred into clinical protocols, observations and routines.Bionics of the lower extremity is an emerging cutting-edge technology. The main goal lies in the reduction of recognition and classification errors in changes of ambulant modes. Agonist-antagonist myoneuronal interfaces may be a most promising start in controlling of actively powered ankle joints.As advanced amputation surgical techniques are becoming part of clinical routine, the development of financing strategies besides medical strategies ought to be boosted, leading to cutting-edge technology at an affordable price.Microprocessor-controlled components are broadly available, and amputees do see benefits. Devices from different manufacturers differ in gait kinematics with huge inter-individual varieties between amputees that cannot be explained by age. Active microprocessor-controlled knees/ankles (A-MPK/As) might succeed in uneven ground-walking. Patients ought to be supported to receive appropriate prosthetic components to reach their everyday goals in a desirable way.Increased funding of research in the field of prosthetic technology could enhance more high-quality research in order to generate a high level of evidence and to identify individuals who can profit most from microprocessor-controlled prosthetic components. Cite this article: EFORT Open Rev 2020;5:724-741. DOI: 10.1302/2058-5241.5.190070.

Factors Associated With Prolonged Length of Stay and Failed Lower Limb Prosthetic Fitting During Inpatient Rehabilitation

Objective

To identify variables associated with rehabilitation length of stay (LOS) and prosthetic fitting success for people with lower limb amputation (LLA).

Design

Retrospective analysis of clinically collected cohort.

Setting

Canadian inpatient rehabilitation hospital.

Participants

Consecutive individuals with LLA (N=103) admitted for prosthetic fitting (mean age, 65.3±10.6y).

Interventions

Not applicable.

Main Outcome Measures

Independent variables included the Lower Limb Amputee Measurement Scale (LLAMS), which is a 31-question tool to predict LOS with items in medical, cognitive, social, physical, activities of daily living, and other subsections; admission FIM; age; sex; level of amputation (below- or above-knee); and time from surgery to admission. LOS was measured as days from admission to discharge. Successful prosthetic fitting was defined as the ability to use a prosthesis on discharge.

Results

The mean LOS was 63.6 ± 33.3 days, and 21.4% of patients failed prosthetic fitting. Higher LLAMS, lower FIM, and above-knee amputation were significantly associated with longer LOS (P<.001, R²=0.36). Age, sex, and time from surgery were not significantly associated with LOS or prosthetic fitting. Higher LLAMS was significantly associated with unsuccessful prosthetic fitting (P=.032). Of the 31 items in the LLAMS, 5 were associated with prolonged LOS and 5 were associated with failed prosthetic fitting (P<.10).

Conclusions

The LLAMS, level of amputation, and admission FIM can be used to predict LOS in lower limb amputees admitted for prosthetic fitting. The LLAMS was weak in identifying patients who failed prosthetic fitting. Future research should consider shortening the LLAMS.

Increased prefrontal cortical activation during challenging walking conditions in persons with lower limb amputation - an fNIRS observational study

Background: Lower limb amputation (LLA) alters the sensorimotor control systems. Despite the self-reports of increased attention during mobility, the interaction between mobility and cognitive control mechanisms is not fully understood.Objective: Concurrently evaluate walking performance and prefrontal cortical (PFC) activity in persons with and without LLA during different walking conditions.Methods: Thirty-nine persons with LLA and thirty-three able-bodied controls participated. Walking performance was evaluated using the Figure-of 8-walk-test during three conditions: 1) UW (Usual walking with self-selected walking speed); 2) WCT (walking and carrying a tray with two cups filled with water); and 3) WUT (walking on uneven terrain). PFC activity was assessed using functional near-infrared spectroscopy (fNIRS). Linear mixed models were used to detect changes between groups and between walking conditions within each group.Results: Between-group comparisons showed increased PFC activity in persons with LLA during UW and WUT, and a significant decrease in walking performance during WCT and WUT compared to controls. Within-group comparisons showed increased PFC activity during WUT compared with UW and WCT and an overall difference in walking performance between the conditions (WU > WUT > WCT) in both groups. However, the effect of walking condition on PFC activity and walking performance was not modified by group (P > .1).Conclusion: The results suggest that persons with LLA have increased attentional demands during walking but choose the same cognitive-mobility strategy during challenging walking conditions as able-bodied persons. However, the attentional demands seem to depend on the complexity of the task.

Transitioning to a microprocessor-controlled prosthetic knee: Executive functioning during single and dual-task gait

BACKGROUND

Walking with a prosthesis requires substantial concentration on behalf of the user and places increased demands on executive functions. Little is known of the effects that prosthetic knee joint prescription may have on executive functioning.

OBJECTIVES

Evaluate executive functioning in trans-femoral prosthesis users during single and dual-task walking, before and after they transition to a Microprocessor-controlled prosthetic knee unit.

STUDY DESIGN

Multiple case-study design.

METHODS

Single and dual task gait was evaluated while recording cortical brain activity. Testing occasion 1 occurred prior to participants receiving their microprocessor-controlled prosthetic knee, while testing occasion 2 was conducted a minimum of 8 months after they had been fitted with an microprocessor-controlled prosthetic knee.

RESULTS

During single-task level walking and walking while performing a dual-task key finding test, executive functions, measured as the relative haemodynamic response in the frontal cortex, reduced for most, but not all participants after transitioning to an Microprocessor-controlled prosthetic knee. There did not appear to be any difference when participants performed a trail walk test.

CONCLUSIONS

Results suggest Microprocessor-controlled prosthetic knee prosthetic knees may have a positive effect on executive functioning for some individuals who have undergone a lower-limb amputation. A larger, longitudinal study with careful control of extraneous variables (e.g. age, training) is needed to confirm results and determine causality.

CLINICAL RELEVANCE

This article provides some evidence to suggest that prosthetic prescription may influence executive functioning and that microprocessor-controlled prosthetic knee mechanisms may reduce cognitive effort when walking.