Physical performance and self-report outcomes associated with use of passive, adaptive, and active prosthetic knees in persons with unilateral, transfemoral amputation: Randomized crossover trial

Controlling Powered Prosthesis Kinematics Over Continuous Inter-Leg Transitions Between Walking and Stair Ascent/Descent

Although powered prosthetic legs have enabled more biomimetic joint kinematics during steady-state activities like walking and stair climbing, transitions between these activities are usually handled by discretely switching controllers without considering biomimicry or the distinct role of the leading leg. This study introduces two data-driven, phase-based kinematic control approaches for seamless inter-leg transitions (i.e., initiated by either the prosthetic or intact leg) between walking and stair ascent/descent, assuming high-level knowledge of the upcoming activity. One approach employs a novel continuously-varying kinematic model that interpolates between steady-state activities as an approximate convex combination, and the other approach employs a simple switching-based model with optimized switching timing and tunable smoothing of kinematic discontinuities. Data-driven analysis indicates the continuously-varying controller remains beneficial over the switching controller for a range of classification delays. Experimental validation with a powered knee-ankle prosthesis used by two high-functioning transfemoral amputees demonstrates the continuous controller can provide more biomimetic and uninterrupted kinematic trajectories for both joints during transitions, irrespective of the initiating leg. This research underscores the potential for enabling more natural locomotion for high-functioning prosthetic leg users.

Prosthetic Componentry in Lower Limb Prosthetic Restoration

This article describes fundamental lower limb prosthesis concepts and componentry, including skeletal structure (endoskeletal vs exoskeletal), transtibial and transfemoral sockets, prosthetic suspension and interfaces, prosthetic knees, and prosthetic foot and ankle systems.

Automatic Stub Avoidance for a Powered Prosthetic Leg Over Stairs and Obstacles

Passive prosthetic legs require undesirable compensations from amputee users to avoid stubbing obstacles and stairsteps. Powered prostheses can reduce those compensations by restoring normative joint biomechanics, but the absence of user proprioception and volitional control combined with the absence of environmental awareness by the prosthesis increases the risk of collisions. This article presents a novel stub avoidance controller that automatically adjusts prosthetic knee/ankle kinematics based on suprasensory measurements of environmental distance from a small, lightweight, low-power, low-cost ultrasonic sensor mounted above the prosthetic ankle. In a case study with two transfemoral amputee participants, this control method reduced the stub rate during stair ascent by 89.95% and demonstrated an 87.50% avoidance rate for crossing different obstacles on level ground. No thigh kinematic compensation was required to achieve these results. These findings demonstrate a practical perception solution for powered prostheses to avoid collisions with stairs and obstacles while restoring normative biomechanics during daily activities.

Quantitative methods used to evaluate balance, postural control, and the fear of falling in lower limb prosthesis users: A systematic review

Problems with balance, postural control, and fear of falling are highly prevalent in lower limb prosthesis users, with much research conducted to understand these issues. The variety of tools used to assess these concepts presents a challenge when interpreting research outcomes. This systematic review aimed to provide a synthesis of quantifiable methods used in the evaluation of balance, postural control, and fear of falling in lower limb prosthesis users with an amputation level at or proximal to the ankle joint. A systematic search was conducted in CINAHL, Medline, AMED, Cochrane, AgeLine, Scopus, Web of Science, Proquest, PsycINFO, PsycArticles, and PubPsych databases followed by additional manual searching via reference lists in the reviewed articles databases. Included articles used quantitative measure of balance or postural control as one of the dependent variables, lower limb prosthesis users as a sample group, and were published in a peer-reviewed journal in English. Relevant assessment questions were created by the investigators to rate the assessment methods used in the individual studies. Descriptive and summary statistics are used to synthesize the results. The search yielded (n = 187) articles assessing balance or postural control (n = 5487 persons in total) and (n = 66) articles assessing fear of falling or balance confidence (n = 7325 persons in total). The most used test to measure balance was the Berg Balance Scale and the most used test to measure fear of falling was the Activities-specific Balance Confidence scale. A large number of studies did not present if the chosen methods were valid and reliable for the lower limb prosthesis users. Among study limitations, small sample size was common.

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.

Improving Amputee Endurance over Activities of Daily Living with a Robotic Knee-Ankle Prosthesis: A Case Study

Robotic knee-ankle prostheses have often fallen short relative to passive microprocessor prostheses in time-based clinical outcome tests. User ambulation endurance is an alternative clinical outcome metric that may better highlight the benefits of robotic prostheses. However, previous studies were unable to show endurance benefits due to inaccurate high-level classification, discretized mid-level control, and insufficiently difficult ambulation tasks. In this case study, we present a phase-based mid-level prosthesis controller which yields biomimetic joint kinematics and kinetics that adjust to suit a continuum of tasks. We enrolled an individual with an above-knee amputation and challenged him to perform repeated, rapid laps of a circuit comprising activities of daily living with both his passive prosthesis and a robotic prosthesis. The participant demonstrated improved endurance with the robotic prosthesis and our mid-level controller compared to his passive prosthesis, completing over twice as many total laps before fatigue and muscle discomfort required him to stop. We also show that time-based outcome metrics fail to capture this endurance improvement, suggesting that alternative metrics related to endurance and fatigue may better highlight the clinical benefits of robotic prostheses.

Use of Metamaterials to Reduce Acoustic Noise Emissions from Lower Limb Prostheses: An Experimental Validation

Recent human-centred design studies suggest that acoustic noise could affect the physical use and psychological acceptance of a biomedical device. These aspects are especially relevant in the prosthetic field, in which device loudness is often related to rejection. The aim of the study is to inquire on the possibility to reduce the acoustic noise emitted by a robotic leg prosthesis by improving its casing. First, acoustic noise emissions are characterized experimentally using an anechoic chamber, both for the whole prosthesis, and for its actuator (i.e., noise source) in isolation. The characterizations show that the whole prosthesis including its casing amplify the actuator noise, and that noise emissions are concentrated within a certain frequency range. Based on these findings, the prosthesis casing has been redesigned to include a panel of Helmholtz resonator-based acoustic metamaterials as proof of concept, which attenuate respective noise emissions. Experimental validations show that the use of such metamaterials in the prosthesis casing can significantly reduce noise emissions without compromising on prosthesis size and weight.

Clinical evaluation of fall risk in older adults who use lower-limb prostheses: A scoping review

BACKGROUND

No reviews or evidence-based clinical protocols exist to evaluate fall risk in older adults who use lower-limb prostheses, despite falls being prevalent and costly in this population. This scoping review sought to determine assessments, defined as clinical outcome measures and gait parameters, associated with fall risk in this population to determine if a systematic review is warranted and help inform an evidence-based clinical protocol.

METHODS

Google Scholar, PubMed, and Scopus were searched on April 19th, 2022 to include peer-reviewed original research. Included articles reported relationships between falls and clinical outcome measures or gait parameters in older adults who use transtibial or transfemoral prostheses. Clinical outcome measures included self-reported questionnaires and functional mobility tests. Gait parameters included spatiotemporal, kinematic, and kinetic data during walking and stair negotiation.

RESULTS

Nineteen articles were included. Clinical outcome measure scores, gait parameter data, and cutoff scores by fall status (nonfallers, single fallers, recurrent fallers) were summarized. Six articles determined clinical outcome measures that had statistically significant associations with falls, and two articles determined gait parameters that had statistically significant associations with falls.

CONCLUSIONS

The majority of articles found no clinical outcome measure or gait parameter alone was effective at identifying fall risks in this population. Future research should evaluate a combination of assessments and collect prospective fall data to move towards establishing an evidence-based protocol to evaluate fall risk in older adults using lower-limb prostheses.

Amputation and prosthetics of the lower extremity: The 2020 Dutch evidence-based multidisciplinary guideline

BACKGROUND

Lower-limb amputations are rare but debilitating events in the lives of affected persons. Treatment of persons with amputation inherently involves many different health care professions at different stages leading to and after an amputation. There are prevailing clinical questions within the work field related to different facets of care including peri/postoperative aspects, prosthetic components, rehabilitation treatment, and health care processes.

OBJECTIVES

To provide an up-to-date multidisciplinary evidence-based guideline for health care professionals involved in the treatment of persons with lower-limb amputation in the Netherlands.

METHODS

Identification of key questions in a focus group, systematic review of the evidence (up to March 2019, using Embase and MEDLINE databases), and weighing considerations, culminating in clinical recommendations.

RESULTS

Twelve key questions were formulated. Recommendations of two key questions were upheld in line with the previous 2012 guideline. Ten systematic literature searches were performed, leading to the inclusion of 59 studies.

CONCLUSION

A summary of evidence-based conclusions, considerations, and recommendations of the 2020 guideline is presented.

The effect of microprocessor controlled exo-prosthetic knees on limited community ambulators: systematic review and meta-analysis

PURPOSE

The clinical benefits of microprocessor-controlled prosthetic knees (MPKs) in community ambulators have been well-established. A systematic review in limited community ambulators published in 2014 found benefits in safety, performance-based, and patient-reported outcomes. This work updates the previous analysis to the current state of the published evidence.

METHODS

Systematic review and meta-analysis of the effect of MPKs in limited community ambulators.

RESULTS

Thirteen research projects presented in 15 publications were identified. Overall validity was "high" in nine studies, "moderate" in three, and "low" in one. The literature described a total of 2366 patients, with 704 classified as limited community ambulators. The use of MPKs in limited community ambulators led to a reduction in falls (SMD g: -0.59; 95% confidence interval (CI) [-0.85, -0.32; I²=0%]), fear of falling (SMD g: 1.2; 95%CI [0.55, 1.85; I²=80%]), risk of falling as indicated by the TUG (SMD g: -0.45, 95%CI [-0.87, -0.02; I²=0%]), an improvement in mobility grade (0.51; 95%CI [0.47,0.55]), self-selected walking speed (SMD g: 0.47; 95%CI [0.14,0.81; I²=0%]), and patient-reported ambulation (MD 9.32; 95%CI [3.61, 15.02; I²=7%]), and utility (MD 7.76; 95%CI [2.05-13.47; I²=0%]). Other outcomes exhibited trends in favor of MPK use or remained insensitive. No outcome was identified favoring non-MPKs.

CONCLUSIONS

These results suggest that MPKs may be considered a valuable therapeutic option in limited community ambulators with a transfemoral amputation.Implications for rehabilitationAbove knee amputees may be treated with a large variety of artificial exo-prosthetic knee components.Microprocessor-controlled prosthetic knees have proven to be advantageous and cost effective for community ambulators.The current analysis shows similar effects in safety, mobility, and patient perception also for limited community ambulators.Microprocessor-controlled prosthetic knees are a viable therapeutic option for limited community ambulators.

A lightweight robotic leg prosthesis replicating the biomechanics of the knee, ankle, and toe joint

Robotic leg prostheses promise to improve the mobility and quality of life of millions of individuals with lower-limb amputations by imitating the biomechanics of the missing biological leg. Unfortunately, existing powered prostheses are much heavier and bigger and have shorter battery life than conventional passive prostheses, severely limiting their clinical viability and utility in the daily life of amputees. Here, we present a robotic leg prosthesis that replicates the key biomechanical functions of the biological knee, ankle, and toe in the sagittal plane while matching the weight, size, and battery life of conventional microprocessor-controlled prostheses. The powered knee joint uses a unique torque-sensitive mechanism combining the benefits of elastic actuators with that of variable transmissions. A single actuator powers the ankle and toe joints through a compliant, underactuated mechanism. Because the biological toe dissipates energy while the biological ankle injects energy into the gait cycle, this underactuated system regenerates substantial mechanical energy and replicates the key biomechanical functions of the ankle/foot complex during walking. A compact prosthesis frame encloses all mechanical and electrical components for increased robustness and efficiency. Preclinical tests with three individuals with above-knee amputation show that the proposed robotic leg prosthesis allows for common ambulation activities with close to normative kinematics and kinetics. Using an optional passive mode, users can walk on level ground indefinitely without charging the battery, which has not been shown with any other powered or microprocessor-controlled prostheses. A prosthesis with these characteristics has the potential to improve real-world mobility in individuals with above-knee amputation.

A novel portable sensor to monitor bodily positions and activities in transtibial prosthesis users

BACKGROUND

Step activity monitors provide insight into the amount of physical activity prosthesis users conduct but not how they use their prosthesis. The purpose of this research was to help fill this void by developing and testing a technology to monitor bodily position and type of activity.

METHODS

Thin inductive distance sensors were adhered to the insides of sockets of a small group of transtibial prosthesis users, two at proximal locations and two at distal locations. An in-lab structured protocol and a semi-structured out-of-lab protocol were video recorded, and then participants wore the sensing system for up to 7 days. A data processing algorithm was developed to identify sit, seated shift, stand, standing weight-shift, walk, partial doff, and non-use. Sensed distance data from the structured and semi-structured protocols were compared against the video data to characterize accuracy. Bodily positions and activities during take-home testing were tabulated to characterize participants' use of the prosthesis.

FINDINGS

Sit and walk detection accuracies were above 95% for all four participants tested. Stand detection accuracy was above 90% for three participants and 62.5% for one participant. The reduced accuracy may have been due to limited stand data from that participant. Step count was not proportional to active use time (sum of stand, walk, and standing weight-shift times).

INTERPRETATION

Step count may provide an incomplete picture of prosthesis use. Larger studies should be pursued to investigate how bodily position and type of activity may facilitate clinical decision-making and improve the lives of people with lower limb amputation.

The impact of added mass placement on metabolic and temporal-spatial characteristics of transfemoral prosthetic gait

BACKGROUND

Despite prosthetic technology advancements, individuals with transfemoral amputation have compromised temporal-spatial gait parameters and high metabolic requirements for ambulation. It is unclear how adding mass at different locations on a transfemoral prosthesis might affect these outcomes. Research question Does walking with mass added at different locations on a transfemoral prosthesis affect temporal-spatial gait parameters and metabolic requirements compared to walking with no additional mass?

METHODS

Fourteen participants with unilateral transfemoral amputations took part. A 1.8 kg mass was added to their prostheses in three locations: Knee, just proximal to the prosthetic knee; Shank, mid-shank on the prosthesis; or Ankle, just proximal to the prosthetic foot. Temporal-spatial gait parameters were collected as participants walked over a GAITRite® walkway and metabolic data were collected during treadmill walking for each of these conditions and with no mass added, the None condition. Separate linear mixed effects models were created and post-hoc tests to compare with the control condition of None were performed with a significance level of 0.05.

RESULTS

Overground self-selected walking speed for Ankle was significantly slower than for None (p < 0.05) (None: 1.16 ± 0.24; Knee: 1.15 ± 0.19; Shank: 1.14 ± 0.24; Ankle 0.99 ± 0.20 m/s). Compared to None, Ankle showed significantly increased oxygen consumption during treadmill walking (p < 0.05) (None: 13.82 ± 2.98; Knee: 13.83 ± 2.82; Shank: 14.30 ± 2.89; Ankle 14.56 ± 2.99 ml O₂/kg/min). Other metabolic outcomes (power, cost of transport, oxygen cost) showed similar trends. Knee and Shank did not have significant negative effects on any metabolic or temporal-spatial parameters, as compared to None (p > 0.05). Significance Results suggest that additional mass located mid-shank or further proximal on a transfemoral prosthesis may not have negative temporal-spatial or metabolic consequences. Clinicians, researchers, and designers may be able to utilize heavier components, as long as the center of mass is not further distal than mid-shank, without adversely affecting gait parameters or metabolic requirements.

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.

Functional Mobility Training With a Powered Knee and Ankle Prosthesis

Limb loss at the transfemoral or knee disarticulation level results in a significant decrease in mobility. Powered lower limb prostheses have the potential to provide increased functional mobility and return individuals to activities of daily living that are limited due to their amputation. Providing power at the knee and/or ankle, new and innovative training is required for the amputee and the clinician to understand the capabilities of these advanced devices. This protocol for functional mobility training with a powered knee and ankle prosthesis was developed while training 30 participants with a unilateral transfemoral or knee disarticulation amputation at a nationally ranked physical medicine and rehabilitation research hospital. Participants received instruction for level-ground walking, stair climbing, incline walking, and sit-to-stand transitions. A therapist provided specific training for each mode including verbal, visual, and tactile cueing along with patient education on the functionality of the device. The primary outcome measure was the ability of each participant to demonstrate independence with walking and sit-to-stand transitions along with modified independence for stair climbing and incline walking due to the use of a handrail. Every individual was successful in comfortable ambulation of level-ground walking and 27 out of 30 were successful in all other functional modes after participating in 1–3 sessions of 1–2 h in length (3 terminated their participation before attempting all activities). As these prosthetic devices continue to advance, therapy techniques must advance as well, and this paper serves as education on new training techniques that can provide amputees with the best possible tools to take advantage of these powered devices to achieve their desired clinical outcomes.

Reported Outcome Measures in Studies of Real-World Ambulation in People with a Lower Limb Amputation: A Scoping Review

BACKGROUND

The rapidly increasing use of wearable technology to monitor free-living ambulatory behavior demands to address to what extent the chosen outcome measures are representative for real-world situations. This scoping review aims to provide an overview of the purpose of use of wearable activity monitors in people with a Lower Limb Amputation (LLA) in the real world, to identify the reported outcome measures, and to evaluate to what extent the reported outcome measures capture essential information from real-world ambulation of people with LLA.

METHODS

The literature search included a search in three databases (MEDLINE, CINAHL, and EMBASE) for articles published between January 1999 and January 2022, and a hand-search.

RESULTS AND CONCLUSIONS

98 articles met the inclusion criteria. According to the included studies' main objective, the articles were classified into observational (n = 46), interventional (n = 34), algorithm/method development (n = 12), and validity/feasibility studies (n = 6). Reported outcome measures were grouped into eight categories: step count (reported in 73% of the articles), intensity of activity/fitness (31%), type of activity/body posture (27%), commercial scores (15%), prosthetic use and fit (11%), gait quality (7%), GPS (5%), and accuracy (4%). We argue that researchers should be more careful with choosing reliable outcome measures, in particular, regarding the frequently used category step count. However, the contemporary technology is limited in providing a comprehensive picture of real-world ambulation. The novel knowledge from this review should encourage researchers and developers to engage in debating and defining the framework of ecological validity in rehabilitation sciences, and how this framework can be utilized in the development of wearable technologies and future studies of real-world ambulation in people with LLA.

Control Framework for Sloped Walking With a Powered Transfemoral Prosthesis

User customization of a lower-limb powered Prosthesis controller remains a challenge to this date. Controllers adopting impedance control strategies mandate tedious tuning for every joint, terrain condition, and user. Moreover, no relationship is known to exist between the joint control parameters and the slope condition. We present a control framework composed of impedance control and trajectory tracking, with the transitioning between the two strategies facilitated by Bezier curves. The impedance (stiffness and damping) functions vary as polynomials during the stance phase for both the knee and ankle. These functions were derived through least squares optimization with healthy human sloped walking data. The functions derived for each slope condition were simplified using principal component analysis. The weights of the resulting basis functions were found to obey monotonic trends within upslope and downslope walking, proving the existence of a relationship between the joint parameter functions and the slope angle. Using these trends, one can now design a controller for any given slope angle. Amputee and able-bodied walking trials with a powered transfemoral prosthesis revealed the controller to generate a healthy human gait. The observed kinematic and kinetic trends with the slope angle were similar to those found in healthy walking.

Microprocessor feet improve prosthetic mobility and physical function relative to non-microprocessor feet

Introduction: The clinical benefits associated with the microprocessor regulation of prosthetic ankle position and resistance have largely been reported through manufacturer conducted research in controlled laboratory environments. Measures with greater ecological validity are needed. This study aimed to understand if there are differences in physical function and mobility outcomes as patients transitioned from a non-Microprocessor to Microprocessor Feet. Method: A retrospective analysis of patient outcomes was performed. Patient-reported benefits associated with the adoption of such prosthetic foot-ankle mechanisms were collected from 23 individuals through the longitudinal use of a custom short form of the Patient-Reported Outcomes Measurement Information System-Physical Function and individual items from the Prosthesis Evaluation Questionnaire. Results: The impact of Microprocessor Feet upon physical function and mobility were observed in a significant increase in physical function (mean increase in t-score of 5.4 ± 1.25; p = .0004) and significant improvements in several mobility items. Conclusions: Collectively, these measures support the beneficial impact of Microprocessor Feet on improving socket comfort, reducing back pain, improving sit to stand transfers and enhancing hill ascent and descent as well as stair negotiation.

Taking Both Sides: Seeking Symbiosis Between Intelligent Prostheses and Human Motor Control during Locomotion

Robotic lower-limb prostheses aim to replicate the power-generating capability of biological joints during locomotion to empower individuals with lower-limb loss. However, recent clinical trials have not demonstrated clear advantages of these devices over traditional passive devices. We believe this is partly because the current designs of robotic prothesis controllers and clinical methods for fitting and training individuals to use them do not ensure good coordination between the prosthesis and user. Accordingly, we advocate for new holistic approaches in which human motor control and intelligent prosthesis control function as one system (defined as human-prosthesis symbiosis). We hope engineers and clinicians will work closely to achieve this symbiosis, thereby improving the functionality and acceptance of robotic prostheses and users' quality of life.

A qualitative pilot study exploring reasons for prosthetic preference in a veteran amputee population

Background/Aims

For people with transfemoral amputations, newer technology, microprocessor-controlled prosthetic limbs, offer a level of performance that exceeds that of older, non-microprocessor controlled limbs. They are often requested by members of Her Majesty's Armed Forces who have been discharged from service (veterans) during applications for replacement limbs. However, as microprocessor-controlled prosthetic limbs cost far exceeds that of non-microprocessor controlled limbs, justification for their provision is essential to ensure that they are seen as value for money for the NHS in the UK. To date, literature focuses on measures of objective performance when demonstrating the value of one limb over another, but it ignores individual lifestyles within this process. This project aims to explore the reasons underpinning individual requests for specific types of prosthetic lower limb in a population of veterans with amputations.

Methods

This pilot study explored secondary data, consisting of patient statements, from the evaluation process associated with applications for new microprocessor-controlled prosthetic limbs. The data referred to a sample population of non-serving veterans with amputations who attended a veteran prosthetic centre for the ongoing maintenance and replacement of their prosthetic limbs (n=15).

Results

Findings from the study suggest an interconnection between function, psychology and emotional context. Individual statements demonstrate that, while functional performance influences choice, it is the application of function to life and lifestyle that underpins the meaning of improvements in performance for the individual.

Conclusions

Further research investigating the meaning of limb performance to the life of an individual is essential to facilitate effective prescription of limbs that meet individual need, and ensuring accurate distribution of what are currently limited funds.

Technology for monitoring everyday prosthesis use: a systematic review

BACKGROUND

Understanding how prostheses are used in everyday life is central to the design, provision and evaluation of prosthetic devices and associated services. This paper reviews the scientific literature on methodologies and technologies that have been used to assess the daily use of both upper- and lower-limb prostheses. It discusses the types of studies that have been undertaken, the technologies used to monitor physical activity, the benefits of monitoring daily living and the barriers to long-term monitoring, with particular focus on low-resource settings.

METHODS

A systematic literature search was conducted in PubMed, Web of Science, Scopus, CINAHL and EMBASE of studies that monitored the activity of prosthesis users during daily-living.

RESULTS

Sixty lower-limb studies and 9 upper-limb studies were identified for inclusion in the review. The first studies in the lower-limb field date from the 1990s and the number has increased steadily since the early 2000s. In contrast, the studies in the upper-limb field have only begun to emerge over the past few years. The early lower-limb studies focused on the development or validation of actimeters, algorithms and/or scores for activity classification. However, most of the recent lower-limb studies used activity monitoring to compare prosthetic components. The lower-limb studies mainly used step-counts as their only measure of activity, focusing on the amount of activity, not the type and quality of movements. In comparison, the small number of upper-limb studies were fairly evenly spread between development of algorithms, comparison of everyday activity to clinical scores, and comparison of different prosthesis user populations. Most upper-limb papers reported the degree of symmetry in activity levels between the arm with the prosthesis and the intact arm.

CONCLUSIONS

Activity monitoring technology used in conjunction with clinical scores and user feedback, offers significant insights into how prostheses are used and whether they meet the user's requirements. However, the cost, limited battery-life and lack of availability in many countries mean that using sensors to understand the daily use of prostheses and the types of activity being performed has not yet become a feasible standard clinical practice. This review provides recommendations for the research and clinical communities to advance this area for the benefit of prosthesis users.

OASIS 1: Retrospective analysis of four different microprocessor knee types

INTRODUCTION

Microprocessor knee analyses to date have been primarily limited to microprocessor knees as a category rather than comparisons across different models. The purpose of the current analysis was to compare outcomes from four common knee models.

METHODS

A retrospective analysis of clinical outcomes was performed. Outcomes for functional mobility, quality of life, satisfaction with amputee status, and injurious falls were compared. Specific knee types represented were C-Leg (Ottobock), Orion (Blatchford), Plié (Freedom Innovations), and Rheo (Össur).

RESULTS

Outcomes from 602 individuals were included. No significant differences were noted for functional mobility (H = 2.91, p = 0.406) or satisfaction (H = 4.43, p = 0.219). For quality of life, differences existed for C-Leg versus Plié (p = 0.010). For injurious falls, C-Leg (χ2 (1,137) = 10.99, p < 0.001) and Orion (χ2 (1,119) = 4.34, p = 0.037) resulted in significantly reduced injurious falls compared to non-microprocessor knee users. C-Leg (H = 19.63, p < 0.001) and Plié (H = 14.04, p = 0.003) users saw declines with advanced aging.

CONCLUSIONS

Our data indicate relative parity among the 4 microprocessor knees with regard to functional mobility and satisfaction. In contrast to mobility, neither satisfaction nor quality of life values reflected declines with aging. Finally, when compared to non-microprocessor knees, significant differences were observed across the microprocessor knee types in relation to the reduction of injurious falls.Keywords: MPK, mobility, quality of life, falls, amputee, outcomes.

Motorized Biomechatronic Upper and Lower Limb Prostheses-Clinically Relevant Outcomes

People with major limb amputations are severely impaired when it comes to activity, body structure and function, as well as participation. Demographic statistics predict a dramatic increase of this population and additional challenges with their increasing age and higher levels of amputation. Prosthetic use has been shown to have a positive impact on mobility and depression, thereby affecting the quality of life. Biomechatronic prostheses are at the forefront of prosthetic development. Actively powered designs are now regularly used for upper limb prosthetic fittings, whereas for lower limbs the clinical use of actively powered prostheses has been limited to a very low number of applications. Actively powered prostheses enhance restoration of the lost physical functions of an amputee but are yet to allow intuitive user control. This paper provides a review of the status of biomechatronic developments in upper and lower limb prostheses in the context of the various challenges of amputation and the clinically relevant outcomes. Whereas most of the evidence regarding lower limb prostheses addresses biomechanical issues, the evidence for upper limb prostheses relates to activities of daily living (ADL) and instrumental ADL through diverse outcome measures and tools.

Orthosis Comfort Score: Establishing initial evidence of reliability and validity in ankle foot orthosis users

BACKGROUND

Comfort of an orthosis is an important characteristic that is likely to dictate use of and satisfaction with a device. However, instruments to assess only orthosis user comfort do not exist. The Prosthetic Socket Fit Comfort Score, developed previously for prosthesis users, may be adapted to serve this purpose.

OBJECTIVES

This study's purpose was to assess the validity and reliability of the Orthosis Comfort Score, a self-report instrument adapted from the Prosthetic Socket Fit Comfort Score.

STUDY DESIGN

This is a prospective, observational study designed to establish initial evidence of validity and reliability for an outcome measure that assesses comfort.

METHODS

Ankle foot orthosis users completed the Orthosis Comfort Score and two validated patient satisfaction questionnaires. An orthotist documented an assessment of fit. Post-visit Orthosis Comfort Scores were documented after the appointment and 2-4 weeks later. Orthosis Comfort Scores were compared to the patient satisfaction questionnaires, assessment of fit and orthosis use (hours per week).

RESULTS

There were 46 study participants. Orthosis Comfort Scores had a moderate positive correlation with their orthotist's assessment of fit, very strong positive correlations with patient satisfaction questionnaires and fair positive correlation with orthosis use (all correlations p < 0.05).

CONCLUSION

This study demonstrates initial evidence for the validity and reliability of the Orthosis Comfort Score in ankle foot orthosis users.

CLINICAL RELEVANCE

The Orthosis Comfort Score is a simple patient-reported outcome measure that can be readily incorporated into clinical practice or research study to obtain a rapid assessment of comfort. It can be used to facilitate communication about device fit, evaluate comfort over time and/or assess changes in comfort with a new device.

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.

The minimal clinically-important difference of the Prosthesis Evaluation Questionnaire - Mobility Scale in subjects undergoing lower limb prosthetic rehabilitation training

BACKGROUND

There is increasing interest in psychometrically sound outcome measures of mobility for people with lower limb amputation (LLA), in order to accurately monitor the impact of the prosthetic training during and after rehabilitation.

AIM

To determine the minimum detectable change (MDC) and minimal clinically important difference (MCID) for the Prosthesis Evaluation Questionnaire-Mobility Scale (PEQ-MS) in people with LLA.

DESIGN

Prospective single-group observational study.

SETTING

Two free-standing Rehabilitation Hospitals.

POPULATION

Eighty-seven adult inpatients with LLA undergoing prosthetic rehabilitation.

METHODS

Patients completed the self-report PEQ-MS twice, immediately before and after prosthetic rehabilitation training. We administered a 7-point Global Rating of Change scale at the end of training as external anchor, to quantify the effect (improvement/deterioration) of the intervention.

RESULTS

Test-retest reliability of the PEQ-MS (N.=24) was high (ICC2,1=0.90). The MDC at the 95% confidence level was 5.5 points. This value, together with those of the mean-change approach and receiver-operating characteristic-curve analysis (AUC>0.89), suggested the selection of a MCID for PEQ-MS of eight points of change, i.e. 16.7% of the maximum possible score (95% CI: 6.5-9.5).

CONCLUSIONS

The PEQ-MS showed a high ability to detect change over time (responsiveness).The above MCID value - derived from a triangulation of distribution (MDC) and anchor-based methods - represents a minimal level of change (perceived as important by the patient) in mobility of people with LLA undergoing prosthetic rehabilitation training.

CLINICAL REHABILITATION IMPACT

The PEQ-MS is a widely used and analyzed outcome measure. The present study calculated - in a sample of people with LLA undergoing prosthetic training - both the MDC and MCID of the PEQ-MS, showing the high responsiveness of this tool. These values increase confidence in interpreting change in PEQ-MS values, and can help in clinical decision making.

A Comparison of Control Strategies in Commercial and Research Knee Prostheses

GOAL

To provide an overview of control strategies in commercial and research microprocessor-controlled prosthetic knees (MPKs).

METHODS

Five commercially available MPKs described in patents, and five research MPKs reported in scientific literature were compared. Their working principles, intent recognition, and walking controller were analyzed. Speed and slope adaptability of the walking controller was considered as well.

RESULTS

Whereas commercial MPKs are mostly passive, i.e., do not inject energy in the system, and employ heuristic rule-based intent classifiers, research MPKs are all powered and often utilize machine learning algorithms for intention detection. Both commercial and research MPKs rely on finite state machine impedance controllers for walking. Yet while commercial MPKs require a prosthetist to adjust impedance settings, scientific research is focused on reducing the tunable parameter space and developing unified controllers, independent of subject anthropometrics, walking speed, and ground slope.

CONCLUSION

The main challenges in the field of powered, active MPKs (A-MPKs) to boost commercial viability are first to demonstrate the benefit of A-MPKs compared to passive MPKs or mechanical non-microprocessor knees using biomechanical, performance-based and patient-reported metrics. Second, to evaluate control strategies and intent recognition in an uncontrolled environment, preferably outside the laboratory setting. And third, even though research MPKs favor sophisticated algorithms, to maintain the possibility of practical and comprehensible tuning of control parameters, considering optimal control cannot be known a priori.

SIGNIFICANCE

This review identifies main challenges in the development of A-MPKs, which have thus far hindered their broad availability on the market.

Prosthetic rehabilitation for older dysvascular people following a unilateral transfemoral amputation

BACKGROUND

Dysvascularity accounts for 75% of all lower limb amputations in the UK. Around 37% of these procedures are done at the transfemoral level (mid-thigh), with most patients over the age of 60 and having existing comorbidities. A significant number of these amputees are prescribed a lower limb prosthesis for walking. However, many amputees do not achieve a high level of function following prosthetic rehabilitation. This is the third update of the review first published in 2005.

OBJECTIVES

To identify and summarise the evidence evaluating prosthetic rehabilitation interventions for prosthetic ambulation following unilateral transfemoral or transgenicular amputation in older dysvascular people, whether community dwelling or institutionalised.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register and CENTRAL, MEDLINE, Embase, and CINAHL databases; the World Health Organization International Clinical Trials Registry Platform; and the ClinicalTrials.gov trials registry to 14 June 2018. We performed additional searches by handsearching citations of studies identified by the electronic search. We applied no restrictions on language or publication status.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials testing prosthetic rehabilitation interventions following a unilateral transfemoral or transgenicular amputation in older (aged 60 years or older) dysvascular people.

DATA COLLECTION AND ANALYSIS

Two review authors independently scanned the search results for potentially eligible studies and, on obtaining full reports of these, selected studies for inclusion and exclusion. Two review authors independently assessed the methodological quality of studies and extracted data. We used GRADE to assess the overall quality of evidence supporting the outcomes assessed in this review.

MAIN RESULTS

We identified no new studies for inclusion in this update. In total we included one trial, excluded 18 trials, classed one trial as ongoing, and classed another as awaiting classification. The total number of participants in the included trial was 10, and the methodological quality of this trial was moderate because of high risk of bias in relation to two domains (random sequence generation and allocation concealment) but low risk of bias for the four remaining domains (blinding, incomplete outcome data, selective reporting, and any other bias). The included trial was a short-term cross-over randomised trial undertaken in Canada, which tested the effects of adding three seemingly identical prosthetic weights (150 g vs 770 g vs 1625 g) to the prostheses of a total of 10 participants with unilateral dysvascular transfemoral amputation. Eight participants were over 60 years of age. Trial authors found that four participants preferred the addition of the lightest weight (150 g), five preferred the middle weight (770 g), and one preferred the heaviest weight (1625 g). Researchers interpreted this as equating to user satisfaction (success) and reported no adverse effects.

AUTHORS' CONCLUSIONS

The limited evidence presented in this review is of very low quality and is insufficient to inform the choice of prosthetic rehabilitation, including the optimum weight of the prosthesis, after unilateral transfemoral amputation in older dysvascular people. A programme of research that includes randomised controlled trials to examine key interventions is urgently required in this area.

Economic benefits of microprocessor controlled prosthetic knees: a modeling study

BACKGROUND

Advanced prosthetic knees allow for more dynamic movements and improved quality of life, but payers have recently started questioning their value. To answer this question, the differential clinical outcomes and cost of microprocessor-controlled knees (MPK) compared to non-microprocessor controlled knees (NMPK) were assessed.

METHODS

We conducted a literature review of the clinical and economic impacts of prosthetic knees, convened technical expert panel meetings, and implemented a simulation model over a 10-year time period for unilateral transfemoral Medicare amputees with a Medicare Functional Classification Level of 3 and 4 using estimates from the published literature and expert input. The results are summarized as an incremental cost effectiveness ratio (ICER) from a societal perspective, i.e., the incremental cost of MPK compared to NMPK for each quality-adjusted life-year gained. All costs were adjusted to 2016 U.S. dollars and discounted using a 3% rate to the present time.

RESULTS

The results demonstrated that compared to NMPK over a 10-year time period: for every 100 persons, MPK results in 82 fewer major injurious falls, 62 fewer minor injurious falls, 16 fewer incidences of osteoarthritis, and 11 lives saved; on a per person per year basis, MPK reduces direct healthcare cost by $3676 and indirect cost by $909, but increases device acquisition and repair cost by $6287 and total cost by $1702; on a per person basis, MPK is associated with an incremental total cost of $10,604 and increases the number of life years by 0.11 and quality adjusted life years by 0.91. MPK has an ICER ratio of $11,606 per quality adjusted life year, and the economic benefits of MPK are robust in various sensitivity analyses.

CONCLUSIONS

Advanced prosthetics for transfemoral amputees, specifically MPKs, are associated with improved clinical benefits compared to non-MPKs. The economic benefits of MPKs are similar to or even greater than those of other medical technologies currently reimbursed by U.S. payers.

Transfemoral amputee intact limb loading and compensatory gait mechanics during down slope ambulation and the effect of prosthetic knee mechanisms

BACKGROUND

Intact limb knee osteoarthritis is a prevalent secondary disability in transfemoral amputees. Walking down a ramp may increase this risk due to excessive limb loading. We sought to determine whether intact limb loading differed between transfemoral amputees and controls during down slope ambulation, and the compensatory strategies transfemoral amputees used to modify intact limb loading. Secondarily, we sought to determine the effect of prosthetic knee type.

METHODS

Five unilateral transfemoral amputees and five non-amputee controls walked down a ramp and the following outcome measures were compared between amputees and controls and across prosthetic knee type (C-leg versus Power Knee): step length, walking speed, leading limb ground reaction forces, and trailing and leading limb ankle and knee energy absorption. Linear mixed effects regression was used to test for association between gait variables and limb.

FINDINGS

There were no significant differences in intact limb loading between amputees and controls or between prosthetic knee types. Transfemoral amputees walked slower (C-leg - control = -0.29 m/s; P = 0.008, Power Knee - control = -0.38 m/s; P < 0.001) with a shorter intact limb step length (C-leg - control = -0.12 m/s; P < 0.001, Power Knee - control = -0.16 m/s; P < 0.001). The prosthetic trailing limb ankle absorbed less energy throughout stance than the trailing limb in controls (C-leg-control = -0.22 J/kg; P < 0.001, Power Knee - control = -0.22 J/kg; P < 0.001).

INTERPRETATION

Intact limb loading in transfemoral amputees is equivalent to controls during down ramp ambulation, in spite of reduced prosthetic trailing limb energy absorption. The primary compensatory strategies include a reduced ambulation speed and intact limb step length, which reduces center of mass velocity at heel contact.

Enhancement of a prosthetic knee with a microprocessor-controlled gait phase switch reduces falls and improves balance confidence and gait speed in community ambulators with unilateral transfemoral amputation

BACKGROUND

Despite the evidence for improved safety and function of microprocessor stance and swing-controlled prosthetic knees, non-microprocessor-controlled prosthetic knees are still standard of care for persons with transfemoral amputations in most countries. Limited feature microprocessor-control enhancement of such knees could stand to significantly improve patient outcomes.

OBJECTIVES

To evaluate gait speed, balance, and fall reduction benefits of the new 3E80 default stance hydraulic knee compared to standard non-microprocessor-controlled prosthetic knees.

STUDY DESIGN

Comparative within-subject clinical study.

METHODS

A total of 13 young, high-functioning community ambulators with a transfemoral amputation underwent assessment of performance-based (e.g. 2-min walk test, timed ramp/stair tests) and self-reported (e.g. falls, Activities-Specific Balance Confidence scale, Prosthesis Evaluation Questionnaire question #1, Satisfaction with the Prosthesis) outcome measures for their non-microprocessor-controlled prosthetic knees and again after 8 weeks of accommodation to the 3E80 microprocessor-enhanced knee.

RESULTS

Self-reported falls significantly declined 77% ( p = .04), Activities-Specific Balance Confidence scores improved 12 points ( p = .005), 2-min walk test walking distance increased 20 m on level ( p = .01) and uneven ( p = .045) terrain, and patient satisfaction significantly improved ( p < .01) when using the 3E80 knee. Slope and stair ambulation performance did not differ between knee conditions.

CONCLUSION

The 3E80 knee reduced self-reported fall incidents and improved balance confidence. Walking performance on both level and uneven terrains also improved compared to non-microprocessor-controlled prosthetic knees. Subjects' satisfaction was significantly higher than with their previous non-microprocessor-controlled prosthetic knees. The 3E80 may be considered a prosthetic option for improving gait performance, balance confidence, and safety in highly active amputees. Clinical relevance This study compared performance-based and self-reported outcome measures when using non-microprocessor and a new microprocessor-enhanced, default stance rotary hydraulic knee. The results inform rehabilitation professionals about the functional benefits of a limited-feature, microprocessor-enhanced hydraulic prosthetic knee over standard non-microprocessor-controlled prosthetic knees.

Relationship between Asymmetry of Gait and Muscle Torque in Patients after Unilateral Transfemoral Amputation

Many studies have shown that unilateral transfemoral amputation involves asymmetric gait. Transfemoral amputation leads to muscle atrophy in a tight stump resulting in asymmetry in muscle torque between the amputated and intact limb. This research is aimed at verifying if a relationship between torque values of hip joint flexors and extensors and gait asymmetry in patients with TFA exists. Fourteen adult subjects with unilateral TFA took part in the experiment. Gait symmetry was evaluated based on the ground reaction force (GRF). Measurements of muscle torque of hip flexors and extensors were taken with a Biodex System. All measurements were taken under isokinetic (60°/s and 120°/s) and isometric conditions. The symmetry index of vertical GRF components was from 7.5 to 11.5%, and anterio-posterior GRF from 6.2 to 9.3%. The symmetry index for muscle torque was from 24.3 to 44% for flexors, from 39 to 50.5% for extensors, and from 28.6 to 50% in the flexor/extensor ratio. Gait asymmetry correlated with muscle torque in hip joint extensors. Therapy which enhances muscle torque may be an effective form of patient therapy. The patient needs to undergo evaluation of their muscle strength and have the therapy programme adjusted to their level of muscle torque deficit.

Crossover study of amputee stair ascent and descent biomechanics using Genium and C-Leg prostheses with comparison to non-amputee control

This study was a randomized crossover of stair ambulation of Transfemoral Amputees (TFAs) using the Genium and C-Leg prosthetic knees. TFAs typically have difficulty ascending and descending stairs, limiting community mobility. The objective of this study was to determine the relative efficacy of the Genium and C-Leg prostheses for stair ascent and descent, and their absolute efficacy relative to non-amputees. Twenty TFAs, and five non-amputees participated in the study. TFAs were randomized to begin the study with the Genium or C-Leg prosthesis. Informed consent was obtained from all participants prior to data collection and the study was listed on clinicaltrials.gov (#NCT01473662). After fitting, accommodation, and training, participants were asked to demonstrate their preferred gait pattern for stair ascent and descent and a step-over-step pattern if able. TFAs then switched prosthetic legs and repeated fitting, accommodation, training, and testing. An eight camera Vicon optical motion analysis system, and two AMTI force plates were used to track and analyze the participants' gait patterns, knee flexion angles, knee moment normalized by body weight, and swing time. For stair descent, no significant differences were found between prostheses. For stair ascent, Genium use resulted in: increased ability to use a step-over-step gait pattern (p=0.03), increased prosthetic side peak knee flexion (p<0.01), and increased swing duration (p<0.01). Changes in contralateral side outcomes and in knee moment were not significant. Overall the Genium knee decreased deficiency in gait patterns for stair ascent relative to the C-Leg, by enabling gait patterns that more closely resembled non-amputees.

Review of the actuators of active knee prostheses and their target design outputs for activities of daily living

Active prosthetic knees have the capability to provide net positive work, which is required in daily activities like stair and ramp negotiation or sit-to-stand transfers. Adding this capability might help to increase user mobility, safety, and independence. This article summarizes the biomechanical knee requirements for different activities of daily living and critically compares them with the actuator characteristics of state-of-the-art active prosthetic knee joints. As a result of a systematic literature research 22 active prosthetic knee joints were identified. Most systems use a stiff actuator in combination with a ball screw and are capable of supporting the majority of daily tasks for the average US citizen (82.5 kg) at self-selected movement speed. Physiological requirements exceed most system specifications if increased user mass, walking speed, or inclinations are assumed. To cope with the requirements, springs and dampers are used to assist the motor. The comparison of the prostheses characteristics with anthropometric data shows that most of the devices are in the physiological range for the system height and even when being tethered it is critical to achieve a physiological mass. Also while just one active knee is commercialized so far, physiological knee biomechanics show that there is a potential for active prosthetic knee solutions. Summarized biomechanical and anthropometric data can be used as a framework to develop prototypes. Further, the overview of state-of-the-art systems can provide possible solutions to deal with the task specific prosthetic knee requirements.

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.

Effects of socket size on metrics of socket fit in trans-tibial prosthesis users

The purpose of this research was to conduct a preliminary effort to identify quantitative metrics to distinguish a good socket from an oversized socket in people with trans-tibial amputation. Results could be used to inform clinical practices related to socket replacement. A cross-over study was conducted on community ambulators (K-level 3 or 4) with good residual limb sensation. Participants were each provided with two sockets, a duplicate of their as-prescribed socket and a modified socket that was enlarged or reduced by 1.8mm (∼6% of the socket volume) based on the fit quality of the as-prescribed socket. The two sockets were termed a larger socket and a smaller socket. Activity was monitored while participants wore each socket for 4 weeks. Participants' gait; self-reported satisfaction, quality of fit, and performance; socket comfort; and morning-to-afternoon limb fluid volume changes were assessed. Visual analysis of plots and estimated effect sizes (measured as mean difference divided by standard deviation) showed largest effects for step time asymmetry, step width asymmetry, anterior and anterior-distal morning-to-afternoon fluid volume change, socket comfort score, and self-reported utility. These variables may be viable metrics for early detection of deterioration in socket fit, and should be tested in a larger clinical study.