Above-knee Prosthesis Research Articles

Piloting a Novel Computational Framework for Identifying Prosthesis-Specific Contributions to Gait Deviations.

This paper introduces a novel computational framework for evaluating above-knee prostheses, addressing a major challenge in gait deviation studies: distinguishing between prosthesis-specific and patient-specific contributions to gait deviations. This innovative approach utilizes three separate computational models to quantify the changes in gait dynamics necessary to achieve a set of ideal gait kinematics across different prosthesis designs. The pilot study presented here employs a simple two-dimensional swing-phase model to conceptually demonstrate how the outcomes of this three-model framework can assess the extent to which prosthesis design impacts a user's ability to replicate the dynamics of able-bodied gait. Furthermore, this framework offers potential for optimizing passive prosthetic devices for individual patients, thereby reducing the need for real-life experiments, clinic visits, and overcoming rehabilitation challenges.

Transfemoral limb loss modestly increases the metabolic cost of optimal control simulations of walking.

In transtibial limb loss, computer simulations suggest that the maintenance of muscle strength between pre- and post-limb loss can maintain the pre-limb loss metabolic cost. These results are consistent with comparable costs found experimentally in select cases of high functioning military service members with transtibial limb loss. It is unlikely that similar results would be found with transfemoral limb loss, although the theoretical limits are not known. Here we performed optimal control simulations of walking with and without an above-knee prosthesis to determine if transfemoral limb loss per se increases the metabolic cost of walking. OpenSim Moco was used to generate optimal control simulations of walking in 15 virtual "subjects" that minimized the weighted sum of (i) deviations from average able-bodied gait mechanics and (ii) the gross metabolic cost of walking, pre-limb loss in models with two intact biological limbs, and post-limb loss with one of the limbs replaced by a prosthetic knee and foot. No other changes were made to the model. Metabolic cost was compared between pre- and post-limb loss simulations in paired t-tests. Metabolic cost post-limb loss increased by 0.7-9.3% (p < 0.01) depending on whether cost was scaled by total body mass or biological body mass and on whether the prosthetic knee was passive or non-passive. Given that the post-limb loss model had numerous features that predisposed it to low metabolic cost, these results suggest transfemoral limb loss per se increases the metabolic cost of walking. However, the large differences above able-bodied peers of ∼20-45% in most gait analysis experiments may be avoidable, even when minimizing deviations from able-bodied gait mechanics. Portions of this text were previously published as part of a preprint (https://www.biorxiv.org/content/10.1101/2023.06.26.546515v2.full.pdf).

FEM-based fatigue analysis on a four-bar polycentric knee of above-knee prostheses

FEM-based fatigue analysis on a four-bar polycentric knee of above-knee prostheses

A new passive transfemoral prosthesis mechanism based on 3R36 knee and ESAR foot providing walking and squatting

Researchers have proposed various linkage mechanisms to connect knee and ankle joints for above-knee prostheses, but most of them only offer natural walking. However, studies have shown that people assume a squatting posture during daily activities. This paper introduces a novel mechanism that connects the knee joint with the foot-ankle joint to enable both squatting and walking. The prosthetic knee used is the well-known 3R36, while the energy storing and return (ESAR) prosthetic foot is used for the ankle-foot joint. To coordinate knee and ankle joint movements, a six-bar linkage mechanism structure is proposed. Simulation results demonstrate that the proposed modular transfemoral prosthesis accurately mimics the motion patterns of a natural human leg during walking and squatting. For instance, the prosthesis allows a total knee flexion of more than 140° during squatting. The new prosthesis design also incorporates energy-storing mechanisms to reduce energy expenditure during walking for amputees.

Psychological adjustments among lower limb amputees in North Indian population: A cross-sectional study.

Limb amputation is an extremely stressful event for an individual, following which the amputee develops inferior body image, anxiety, and changes in self-concept and identity. For holistic rehabilitation, understanding the psychosocial status of the amputee and its' predictors is of utmost importance. The aim of the article is to assess the psychological adjustments in patients with lower limb amputation and determine its clinical and sociodemographic correlates. A observational cross-sectional study was conducted from 2020 to 2022 among lower limb amputees of a tertiary care hospital in Lucknow which serves as the only rehabilitation and artificial limb center for the whole state of Uttar Pradesh. Baseline sociodemographic and clinical data were collected. The Hospital Anxiety and Depression Scale was used to determine underlying depression and anxiety, while the Trinity Amputation and Prosthesis Experience Scale was used for understanding the psychological adjustment. The mean age of the amputee was 39.47 ± 16.99 years. The mean general, social adjustment, and adjustment to limitation score was 16.3 ± 3.34, 15.19 ± 3.59, and 12.76 ± 3.15, respectively. Male amputees, aged >40 years, and pensioners had significantly higher scores for general adjustment (P < 0.05). Those aged >40 years were pensioners and had no underlying depression and anxiety and had better social adjustment (P < 0.05). Those with transfemoral amputation had a significantly lesser adjustment to limitation (P = 0.003). Young age amputees had poor general and social adjustments and more activity restriction but high prosthesis satisfaction as compared to the elderly. Those with transfemoral amputation had a poor adjustment to limitation while those wearing above-knee prosthesis had more activity restriction.

Energy Minimization of New Robotic-Type Above-Knee Prosthesis for Higher Battery Lifetime

In this paper, an optimization problem for the energy minimization of a new robotic-type three-axes above-knee prosthesis is carried out based on the actuator power consumption. The optimization problem aims to find the optimal link masses with which to minimize the electrical energy drawn from the battery of the new prosthesis, subject to the kinematic and dynamic constraints. Particle swarm optimization (PSO) is used as the optimization algorithm. A discrete-time PID controller is used to represent the saved energy by means of mass optimization. Optimization illustrated that energy consumption in the batteries can be reduced 51% and provides 1.89 h of additional battery lifetime, according to the literature, by optimizing prosthetic link masses while providing acceptable prosthesis stiffness.

Analysis of Four-bar Linkages Suitable for Above-knee Prosthesis

Analysis of Four-bar Linkages Suitable for Above-knee Prosthesis

Vibration transmission in bone-anchored prosthesis under vertical load. Cadaver study.

Sensory feedback between a device and its user helps to improve the effectiveness of control and training processes. These improvements involve corrective actions and the accumulation of experience to accelerate patient training in device control. Vibrations from rehabilitation devices are used as sensory feedback signals for improving rehabilitation outcomes. Variations in the bone-anchored prosthesis frequency responses and vibration transmissibility under compressive loading were studied. Five laboratory samples consisting of the above-knee prosthesis, custom-made implant, and cadaver bone were first axially compressed using universal testing machine; preloaded construction vibrations were generated with a shaker to imitate external forces acting on these samples. The oscillations at the sample surface control points were tested with a laser vibrometer. For different values of axial loading, the frequency responses of the samples and indexes of vibration attenuation were obtained to examine the correlations between vibration transmissibility in the samples and axial loads. Increase in axial loading caused an increase in the resonance frequency and a simultaneous decrease in vibratory displacement within the sample. At low frequencies (40-80 Hz), increasing the axial load degraded transmissibility; at medium and high frequencies, transmissibility changes were unstable on increasing the axial load. The osseoperception phenomenon is because of perceived prosthesis vibration analysis by the user. Vibration transmissibility of a prosthesis sample depends on the axial compression and frequency of excitation. Decreasing the vibration amplitude while increasing axial load is the primary reason for reduced perception of vibration.

Optimal Backstepping Controller Design for Prosthetic Knee Joint

The mobility of people who have had a lower limb amputated is slower, less stable, and needs more metabolic energy than the movement of physically fit, also, often have difficulty moving on uneven terrain and stairs. In most cases, these problems may be traced back to the usage of controllers for an above-knee prosthesis, which enhances movement and more quality of life for millions of individuals who have lost lower limbs. In this work addresses the dynamic modeling and parameter identification of the lower limb, and the control of a 2-DOF joint prosthetic, because the uncertainty, high nonlinearity, problems with imbalance, and external perturbations, which can occur during movement. Backstepping control algorithm based on the Lyapunov theory was used, this is to ensure system stability with enhanced dynamic performance. The Bat algorithms optimization technique was used to fine-tune these design parameters to improve the performance of the proposed controller. From the results, found that the quantitative comparison between the present study and the related articles previously published which used sliding mode observer control, showed reasonable agreement. To comparison between convolution Backstepping control and optimal Backstepping control with Bat algorithms, at the control action consumptions. It was found that the position error of the prosthetic knee is enhanced by 9% at joint1 and 7.4% at joint2, respectively. Therefore, the results are considered satisfactory for such biomedical systems.

Design and Initial Evaluation of a Low-Cost Microprocessor-Controlled Above-Knee Prosthesis: A Case Report of 2 Patients

For prosthesis users, knee units can range from simple devices costing $2000 up to $45,000 for high-end, microprocessor-controlled systems. These higher-end electronic knees provide significant advantages in stability, gait, and metabolic rate compared to their passive or mechanical counterparts. However, the high cost of such systems makes them inaccessible to most amputees. In this study, it was hypothesized that a microprocessor knee could be manufactured for less than $1000, with comparable stability and user experience to a high-end industry standard device. A prototype (E-Knee) was designed with a specific emphasis on stance stability, and was tested during patient gait trials. The gait trials used a repeated measures design to compare three knee devices (a simple passive knee, the prototype E-Knee, and a high-end knee). Ground reaction forces and a functionality questionnaire were used to compare devices. A microprocessor locking test was used to evaluate the prototype’s ability to prevent falls. Building on the LIMBS M3, a passive four-bar polycentric device, the E-Knee added sensing, computing, and controlling capabilities for a material cost of $507. Initial data from a two-subject trial served as proof-of-concept to validate the prototype and found that it improved gait by providing more stability than the M3 and had more gait-pattern similarities to the Ottobock C-Leg than to the M3. Patients reported no perceived differences in stability between the E-Knee and the C-Leg. Patient trials supported that the E-Knee prototype behaved more naturally than the low-end M3 device and had similar ground reaction forces to the C-Leg.

보행 역학 데이터를 활용한 대퇴 의지 실시간 제어를 위한 딥러닝 모델 구조 연구

Training data of the deep learning model for the control of the above-knee prosthesis should have a sufficient amount of data to fit with the model. Also, this data can be used for gait classification to control the prosthesis. However, in real-time control, the number of the gait dynamics data counted by the sensor is only measured to the level that the deep learning model is difficult to learn., In this study, the most efficient deep learning model case was developed to resolve this problem in the case of a real-time control situation where data measurement time is insufficient. The data is collected through a hall sensor, load cell and Inertial Measurement Unit (IMU) mounted on the above-knee prosthesis. Subsequently, the collected data is divided into 5 phases (Loading Response (LR), Mid Stance (MS), Push Off (PO), Early Swing (ES), and Late Swing (LS)) of the gait cycle according to the point of inflection of hall sensors and load cells. Afterward, training data of the deep learning were generated by sliding window algorithm and the treated data was exercised on four deep learning models by changing the value of width and depth configurations. The results are assessed on accuracy, loss and F1-Score. In conclusion, the loss function statistically decreased in the case of the values of width and depth of the deep learning model were low. Accuracy and F1-Score were not shown significant difference statistically. Therefore, the results provided an efficient deep learning model for above-knee prosthesis to gait analysis and expected to lead to a more reasonable gait model for the control of the above-knee prosthesis via a more detailed gait classification study in the future.

Compare Between Gait Analysis of Patient with Ilizarov Leg and Prosthesis Leg

Gait analysis can be described as a field of biomechanical engineering dealing with the subject of human locomotion. This study aimed to identify the effect of Ilizarov on gait when the presence the above-knee prosthesis. The study was made on a 50-year-old male patient was underwent correction right tibia with Ilizarov fixation due to war accident in July 2012. Also, this accident led to trans-femoral amputation. Two-dimensional gait system of a synchronized 25 Hz camera with an AMTI force platform was use for measuring gait kinematics and kinetics data while walking at a self-selected speed. These data can be used as standard measures in pathology studies, as input to theoretical joint models, and as input to mechanical joint simulators treated with Ilizarov and prosthetics.

An investigation into a locking mechanism designed for a gear-based knee joint prosthesis

AbstractBackground: The knee-locking mechanism in an above-knee prosthesis is crucially important to protect the prosthesis user from sudden falling down due to unexpected disturbance while standin...

Robotic prosthesis that maintains flexion posture.

The number of lower limb amputations in Japan has recently been increasing. Lower limb amputation is classified based on the amputated part,and its two main types are below-knee (28.4%) and above-knee (58.8%). Especially for patients with above-knee amputation, an above-knee prosthesis with artificial knee and ankle joints is commonly applied. This prostheses also vary according to an individual's activity level. Thus there are varieties of uses of above-knee prostheses. Therefore, various knee joints are being developed corresponding to various activity levels. Passive multi linkage-type knee joints aim to guarantee the stability of the stance phase during walking, and electronically controlled knee joints use a hydraulic cylinder to provide stability in both the swing and stance phases as well as during slope walking and so on. As described above, many knee joints focused on walking are commercially available. But in recent years knee joints focusing on other everyday activities, such as sitting or rising, are being developed. However, there has been no assistive prosthesis designed to enable the standing action involved in stopping in a state where the knee remains slightly flexed. In this study, we developed a robotic prosthesis to provide stability during standing as well as during normal walking. A ratchet mechanism was used for the knee joint, and it reproduced the flexion extension motion of the knee. We also tried to electronically control the movement of the claw of the ratchet mechanism based on the state transition model by finite state machine. Furthermore, the effectiveness of the developed robot prosthesis was shown in a walking experiment by a healthy person.

Clinical and demographic characteristics of patients with lower limb amputation

Aim: Lower limb loss affects an individual’s ability to stand, transfer, and ambulate. The aim of this study is to assess clinical and demographic characteristics of patients with lower limb amputation.Materials and Methods: Our study is a retrospective cohort study. 836 patients with lower limb amputation applied to our hospital between January 2012 and May 2013 were included in this study. Demographic and clinical characteristics of patients were reviewed and saved from patient’s folder. Descriptive variables were shown as mean±standard deviation(min–max). And categorical variables were shown as the number of cases (n%).SPSS software Version 15.0 was used in the evaluation of the data.Results: The mean age of total 836 lower limb amputees was 36.12±11.69 years (9-78). The percentage of unilateral amputation was 770(92.3%) and bilateral lower limb amputation was 59(7.1%). According to the level of amputation, 456(54.5%) of the patients had unilateral above-knee, 236(28.3%) had unilateral below-knee amputation. For etiology, we found that 373(44.6%) of them were traffic accidents, 103(12.5%) occupational accidents. The majority of patients 456(54.5%) were ambulated microprocessor-controlled above-knee prosthesis and then below-knee prosthesis with active vacuum system 224(26.7%).Conclusion: Although trauma is recognized to be the most common cause of amputation among applying amputees, we think that those amputees do not reflect the general profile in our country but that it is instructive with regard to the features of amputees. This data is important for the community rehabilitation of amputees and the development of new prosthetics.

Development of a Mechanistic Hypothesis Linking Compensatory Biomechanics and Stepping Asymmetry during Gait of Transfemoral Amputees.

Objective Gait asymmetry is a common adaptation observed in lower-extremity amputees, but the underlying mechanisms that explain this gait behavior remain unclear for amputees that use above-knee prostheses. Our objective was to develop a working hypothesis to explain chronic stepping asymmetry in otherwise healthy amputees that use above-knee prostheses. Methods Two amputees (both through-knee; one with microprocessor knee, one with hydraulic knee) and fourteen control subjects participated. 3D kinematics and kinetics were acquired at normal, fast, and slow walking speeds. Data were analyzed for the push-off and collision limbs during a double support phase. We examined gait parameters to identify the stepping asymmetry then examined the external work rate (centre of mass) and internal (joint) power profiles to formulate a working hypothesis to mechanistically explain the observed stepping asymmetry. Results Stepping asymmetry at all three gait speeds in amputees was characterized by increased stance phase duration of the intact limb versus relatively normal stance phase duration for the prosthesis limb. The prosthesis limb contributed very little to positive and negative work during the double support phase of gait. To compensate, the intact leg at heel strike first provided aid to the deficient prosthetic ankle/foot during its push-off by doing positive work with the intact knee, which caused a delayed stance phase pattern. The resulting delay in toe-off of the intact limb then facilitated the energy transfer from the more robust intact push-off limb to the weaker colliding prosthesis side. This strategy was observed for both amputees. Conclusions There is a sound scientific rationale for a mechanistic hypothesis that stepping asymmetry in amputee participants is a result of a motor adaptation that is both facilitating the lower-leg trajectory enforced by the prosthesis while compensating for the lack of work done by the prosthesis, the cost of which is increased energy expenditure of the intact knee and both hips.

Research on the Nonlinear Computer Torque control of the MR Damper Based Above-knee Prosthesis

Aiming at the motion track controlling of the semi-active magnetorheological damper based above-knee prosthesis (MRAKP), according to the LaSalle’s invariant set theorem, a kind of nonlinear compute torque (NCT) control law for the track controlling of the AKMR, is proposed to promote the robustness and performance of the intelligent above-knee prosthesis. The proposed NCT controller includes the feedforward control and the feedback control. The former one is used to compensate the nonlinear terms in the dynamic model of the MRAKP, such as the Coriolis force, the centripetal force, and the gravity. The feedback control, utilizing a nonlinear PD controller, adaptively adjusts the control gain coefficients and reduces the system error. On these bases, numerical simulations on the MRAKPare carried out to analyze the performance of the proposed NCT controller in ADAMS and simulink. For comparing, the track controlling performance of the PD controller and the CT+PD controller are also presented in the paper. Simulation results indicate that the proposed NCT controller for the MRAKP is able to adaptively adjust the control gain coefficients with lower track error and higher robustness than the conventional PD controller and the CT+PD controller.

Mobility analysis of amputees (MAAT 3): Matching individuals based on comorbid health reveals improved function for above-knee prosthesis users with microprocessor knee technology

ABSTRACT The objective of this cross-sectional observational study was to determine whether the use of a microprocessor knee for individuals with an above-the-knee amputation results in improved functional mobility compared to their peers of matched comorbid-health with a non-microprocessor knee, and to inform how this compares to the mobility observed in below-knee prosthesis users. A sample of 450 individuals with lower limb amputation were divided into three groups (n = 150 each). The groups included: nonmicroprocessor knee users (NMPK, age: 57.6 ± 17.2 years), microprocessor knee users (MPK, age: 56.5 ± 13.8 years), and below-knee prosthesis users (BKA, age: 58.4 ± 12.2 years). Primary outcome measure was functional mobility measured through Prosthetic Limb Users’ Survey of Mobility (PLUS-M®). Results showed MPK mobility (48.49 ± 0.86) was greater than NMPK (43.49 ± 0.86, p < 0.001), but less than BKA (52.11 ± 0.86, p = 0.003). These results persisted when removing potential confounding effects of age, body mass index, cause of amputation, and comorbid health (MPK: 47.15 ± 0.97; NMPK: 43.47 ± 0.88; BKA: 52.61 ± 0.91). In conclusion, these results show the use of a MPK can improve functional mobility for individuals with an above-knee amputation.

Non-Energized Above Knee Prosthesis Enabling Stairs Ascending and Descending with Hydraulic Flow Controller

This paper deals with an above-knee prosthesis (AKP) that allows stair ascending/descending with no external energy source. It controls the passive resistance and interlocking strength of the knee and ankle joints with a flow control valve (FCV) equipped with a hydraulic system. The FCV is also mechanically controlled by an automatic flow controller (AFC). Our previous study certified that the experimental AKP allows step-over-step gait in stair ascending and a slight knee flexion at the initial stage of the stance phase in level ground walking, as observed from non-amputees’ walking. However, the experiments showed that the AKP does not allow smooth flexing of the knee in the stance phase during stairs descending because of the improper timing of the AFC opening. This paper shows the total walking performance of the AKP equipped with a refined AFC.

Poster 2: Matching Individuals Based on Comorbid Health Reveals Improved Function for Above-Knee Prosthesis Users with Modern Knee Technology

Poster 2: Matching Individuals Based on Comorbid Health Reveals Improved Function for Above-Knee Prosthesis Users with Modern Knee Technology