Temporal-spatial parameters of gait in transfemoral amputees: Comparison of bionic and mechanically passive knee joints

Gait Alteration in Individual with Limb Loss: The Role of Inertial Sensors

Amputation has a big impact on the functioning of patients, with negative effects on locomotion and dexterity. In this context, inertial measurement units represent a useful tool in clinical practice for motion analysis, and in the development of personalized aids to improve a patient's function. To date, there is still a gap of knowledge in the scientific literature on the application of inertial sensors in amputee patients. Thus, the aim of this narrative review was to collect the current knowledge on this topic and stimulate the publication of further research. Pubmed, Embase, Scopus, and Cochrane Library publications were screened until November 2022 to identify eligible studies. Out of 444 results, we selected 26 articles focused on movement analysis, risk of falls, energy expenditure, and the development of sensor-integrated prostheses. The results showed that the use of inertial sensors has the potential to improve the quality of life of patients with prostheses, increasing patient safety through the detection of gait alteration; enhancing the socio-occupational reintegration through the development of highly technologic and personalized prosthesis; and by monitoring the patients during daily life to plan a tailored rehabilitation program.

Normalized kinematic walking symmetry data for individuals who use lower-limb prostheses: considerations for clinical practice and future research

Introduction

Individuals who use unilateral transtibial or transfemoral prostheses have negative secondary health effects associated with decreased kinematic (e.g., spatiotemporal and joint angle) walking symmetry between prosthetic and intact limbs. Research studies have quantified kinematic walking symmetry, but studies can be difficult to compare owing to the inclusion of small sample sizes and differences in participant demographics, biomechanical parameters, and mathematical analysis of symmetry. This review aims to normalize kinematic walking symmetry research data across studies by level of limb loss and prosthetic factors to inform considerations in clinical practice and future research.

Methods

A search was performed on March 18, 2020, in PubMed, Scopus, and Google Scholar to encompass kinematic walking symmetry literature from the year 2000. First, the most common participant demographics, kinematic parameters, and mathematical analysis of symmetry were identified across studies. Then, the most common mathematical analysis of symmetry was used to recalculate symmetry data across studies for the five most common kinematic parameters.

Results

Forty-four studies were included in this review. The most common participant demographics were younger adults with traumatic etiology who used componentry intended for higher activity levels. The most common kinematic parameters were step length, stance time, and sagittal plane ankle, knee, and hip range of motion. The most common mathematical analysis was a particular symmetry index equation.

Conclusions

Normalization of data showed that symmetry tended to decrease as level of limb loss became more proximal and to increase with prosthetic componentry intended for higher activity levels. However, most studies included 10 or fewer individuals who were active younger adults with traumatic etiologies.

Clinical Relevance

Data summarized in this review could be used as reference values for rehabilitation and payer justification. Specifically, these data can help guide expectations for magnitudes of walking symmetry throughout rehabilitation or to justify advanced prosthetic componentry for active younger adults under 65 years of age with traumatic etiologies to payers.

Kinetic Gait Parameters in Unilateral Lower Limb Amputations and Normal Gait in Able-Bodied: Reference Values for Clinical Application

Unilateral lower limb amputations usually present with asymmetric interlimb gait patterns, in the long term leading to secondary physical conditions and carrying the risk of low physical activity and impairment of general health. To assess prosthetic fittings and rehabilitation measures, reference values for asymmetries as well as the most significant gait parameters are required. Kinetic gait data of 865 patients with unilateral lower limb amputations (hip and knee disarticulations, transfemoral, transtibial and foot amputations) and 216 able-bodied participants were quantitatively assessed by instrumented gait analyses. Characteristic spatiotemporal (stance time, walking speed, step length and width) and ground reaction force parameters (weight-acceptance and push-off peak) were contrasted to normal gait. All spatiotemporal and ground reaction force parameters differed significantly from normal gait with the largest differences in transfemoral amputations. These also differed between amputation levels and showed age-dependencies. The stance time and push-off peak difference were identified as the most discriminative parameters with the highest diagnostic specificity and sensitivity. The present results mark the first step to establishing universal reference values for gait parameters by means of which the quality and suitability of a prosthetic fitting and the rehabilitation progress can be assessed, and are generalizable for all adults with unilateral lower limb amputations in terms of level walking.

Characterizing the Gait of People With Different Types of Amputation and Prosthetic Components Through Multimodal Measurements: A Methodological Perspective

Prosthetic gait implies the use of compensatory motor strategies, including alterations in gait biomechanics and adaptations in the neural control mechanisms adopted by the central nervous system. Despite the constant technological advancements in prostheses design that led to a reduction in compensatory movements and an increased acceptance by the users, a deep comprehension of the numerous factors that influence prosthetic gait is still needed. The quantitative prosthetic gait analysis is an essential step in the development of new and ergonomic devices and to optimize the rehabilitation therapies. Nevertheless, the assessment of prosthetic gait is still carried out by a heterogeneous variety of methodologies, and this limits the comparison of results from different studies, complicating the definition of shared and well-accepted guidelines among clinicians, therapists, physicians, and engineers. This perspective article starts from the results of a project funded by the Italian Worker's Compensation Authority (INAIL) that led to the generation of an extended dataset of measurements involving kinematic, kinetic, and electrophysiological recordings in subjects with different types of amputation and prosthetic components. By encompassing different studies published along the project activities, we discuss the specific information that can be extracted by different kinds of measurements, and we here provide a methodological perspective related to multimodal prosthetic gait assessment, highlighting how, for designing improved prostheses and more effective therapies for patients, it is of critical importance to analyze movement neural control and its mechanical actuation as a whole, without limiting the focus to one specific aspect.

Gait Performance of Friction-Based Prosthetic Knee Joint Swing-Phase Controllers in Under-Resourced Settings

Gait quality can influence walking ability and mobility outcomes making it an important part of prosthetic rehabilitation. Prosthetic knee joint designs can influence gait quality, and limited data exists to guide component selection in under-resourced settings. This study compared spatiotemporal and kinematic gait parameters for two common types of friction-based swing-phase controlled prosthetic knee joints. Two-dimensional optical gait analysis was conducted as part of a cross-over study design involving 17 individuals with unilateral transfemoral amputations. Two prosthetic knee joints were compared. One utilized constant-friction (CF) and the other a variable cadence controller (VCC) for swing-phase control. Gait was analyzed at normal and fast walking speeds. Primary gait parameters included swing-phase time, step length, and knee flexion. Swing-phase time and peak knee flexion angles, as well as their related symmetry indices, were lower for the VCC compared to the CF (p < 0.01), by 11.1 to 94.1%. The VCC resulted in faster walking speeds by approximately 15% compared to the CF (p = 0.002). Friction-based swing-phase knee control mechanisms can facilitate an appropriate and cost-effective prosthetic knee joint solution in under-resourced settings. The findings suggest that friction-based mechanism can be designed to improve gait quality, and in turn overall walking performance.

Performance of the CYBERLEGs motorized lower limb prosthetic device during simulated daily activities

Background

The CYBERLEGs-gamma (CLs-ɣ) prosthesis has been developed to investigate the possibilities of powerful active prosthetics in restoring human gait capabilities after lower limb amputation.

Objective

The objective of this study was to determine the performance of the CLs-ɣ prosthesis during simulated daily activities.

Methods

Eight participants with a transfemoral amputation (age: 55 ± 15 years, K-level 3, registered under: NCT03376919) performed a familiarization session, an experimental session with their current prosthesis, three training sessions with the CLs-ɣ prosthesis and another experimental session with the CLs-ɣ prosthesis. Participants completed a stair-climbing-test, a timed-up-and-go-test, a sit-to stand-test, a 2-min dual-task and a 6-min treadmill walk test.

Results

Comparisons between the two experimental sessions showed that stride length significantly increased during walking with the CLs-ɣ prosthesis (p = .012) due to a greater step length of the amputated leg (p = .035). Although a training period with the prototype was included, preferred walking speed was significantly slower (p = .018), the metabolic cost of transport was significantly higher (p = .028) and reaction times significantly worsened (p = .012) when walking with the CLs-ɣ compared to the current prosthesis.

Conclusions

It can be stated that a higher physical and cognitive effort were required when wearing the CLs-ɣ prosthesis. Positive outcomes were observed regarding stride length and stair ambulation. Future prosthetics development should minimize the weight of the device and integrate customized control systems. A recommendation for future research is to include several shorter training periods or a prolonged adaptation period.

A systematic review on design technology and application of polycentric prosthetic knee in amputee rehabilitation

The objective of this paper is to conduct a systematic review on design technology and clinical application of polycentric prosthetic knee joint in the rehabilitation of trans-femoral amputees. Relevant studies were identified using electronic database such as PubMed, EMBASE, SCOPUS and the Cochrane Controlled Trials Register (Rehabilitation and Related Therapies) up to February 2020. Screening of abstracts and application of inclusion and exclusion criteria were made. Design, modeling, material use, kinematic study, simulation technique and clinical application of polycentric knee models used in many developed and developing countries have been reviewed. Out of 516 potentially relevant studies, 43 articles were included. Specific variables on technical and clinical aspects were extracted and added to summary tables. The results reveal that polycentric knees have a variety of geometries but the methods for comparing their performances are rare. The data of structural analysis using different simulation techniques are validated with experimental results for determining model accuracy. Gait analysis using the polycentric knee components provides a valid tool to correlate with experimental results. There are well-designed studies on the technological development of polycentric knees, however, high-quality clinical researches are scarce. Conventional clinical knowledge had considerable gaps concerning the effects of polycentric knee and their mechanical characteristics on human functioning with a lower-limb prosthesis. Still, further research is needed to develop and implement standardized measures on prosthetic knee joints for their effective use, function, durability, and cost-effectiveness.

CLINICAL GAIT ANALYSIS OF SUBJECTS WITH TRANS-FEMORAL AMPUTATION USING POLYCENTRIC FOUR-BAR LINKAGE PROSTHETIC KNEE JOINT

Background: Adequate research is not reported so far to underline the influence of commonly used polycentric knee joints on gait performance of subjects with trans-femoral amputation. Objective: The intent of this investigation is to analyze prosthetic gait of unilateral traumatic trans-femoral amputees with polycentric four-bar linkage knee and compare it with normal subjects for evaluating any asymmetry in gait performance. Methods: Objective three-dimensional gait analysis of 15 subjects [mean (age): 36.4 (10.7) years] were performed in gait lab through force plate and optoelectronic devices to measure temporal-spatial parameters, kinematic and kinetic performances. Gait patterns of amputees were compared with those of 15 individuals with normal gait to analyze distinct functionalities of existing polycentric knee. Results: Asymmetry in gait was observed between amputees and normal subjects for all variables concerned ([Formula: see text]). Amputee gait was with significantly lesser velocity, cadence with shorter step and stride length. There was significantly less hip, knee and pelvic motions, however, pelvic obliquity and rotation did not show significant difference from the normal subjects. The vertical component of the ground reaction force differed significantly between prosthetic and intact limb [49.7 (8.5)% and 90.4 (7.4)% body weight] and also from normal subjects [107.5 (2.4)% body weight] during stance ([Formula: see text]). Interpretation and Conclusion: This difference may be attributed to nonproportionate loading of limbs and mechanical adaptations for counteracting deficiencies of prosthetic side. This study will help to explain gait asymmetry in trans-femoral amputees and to identify underlying mechanisms to enhance the quality of the existing design of prosthetic knee through optimizing design parameters and utilizing appropriate materials.

The effects of domestic mechanical knee joints on pelvic motion in transfemoral amputees

PURPOSE

Pelvic asymmetry in the sagittal and horizontal planes among prosthesis users is related to the strength of the abdominal and back muscles. Considering that lumbosacral pathologies and pain in long-term transfemoral prosthesis users can cause asymmetric pelvic motion, it is necessary to investigate pelvic asymmetry caused by prosthetic components. The aim was to compare the gait symmetry of the pelvis of active transfemoral amputees using different types of prosthetic knee joints (Non-microprocessor-controlled prostheses (NMCPs) and microprocessor-controlled prostheses (MCP) knees).

METHODS

The two patient groups comprised eight transfemoral amputees: four patients had NMCP joints (Turkish products), and four patients had MCP knees. The reference group consisted of ten normal volunteers. In this work, the 3-D motion of the pelvis, hip, knee and ankle was assessed using the VICON system.

RESULTS

The results revealed that during stance, the kinematics of pelvic movement in the amputee group differed from those of the control group in terms of the total excursion anterior pelvic tilt (APT) and maximum and minimum degrees of APT (p < .05). We evaluated the graphics of the NMCP and MCP knee joints and found that the prosthesis-side APT was closer to that of the control group during the stance phase among the NMCP users, while the APT of the MCP users was closer to that of the control group during the swing phase.

CONCLUSION

The investigated MCP benefitted the patients considerably. The NMCP did not provide as much walking as the MCP but produced less APT.Implications for RehabilitationThe MCP may not provide symmetrical pelvic motion during all phases of the gait cycle. In transfemoral amputees using MCP, focusing on pelvis in walking training will contribute to pre-prosthetic and post-prosthetics rehabilitation.The NMCP knee joint may be closer in terms of APT.

Intuitive Clinician Control Interface for a Powered Knee-Ankle Prosthesis: A Case Study

This paper presents a potential solution to the challenge of configuring powered knee-ankle prostheses in a clinical setting. Typically, powered prostheses use impedance-based control schemes that contain several independent controllers which correspond to consecutive periods along the gait cycle. This control strategy has numerous control parameters and switching rules that are generally tuned by researchers or technicians and not by a certified prosthetist. We propose an intuitive clinician control interface (CCI) in which clinicians tune a powered knee-ankle prosthesis based on a virtual constraint control scheme, which tracks desired periodic joint trajectories based on a continuous measurement of the phase (or progression) of gait. The interface derives virtual constraints from clinician-designed joint kinematic trajectories. An experiment was conducted in which a certified prosthetist used the control interface to configure a powered knee-ankle prosthesis for a transfemoral amputee subject during level-ground walking trials. While it usually takes engineers hours of tuning individual parameters by trial and error, the CCI allowed the clinician to tune the powered prosthesis controller in under 10 min. This allowed the clinician to improve several amputee gait outcome metrics, such as gait symmetry. These results suggest that the CCI can improve the clinical viability of emerging powered knee-ankle prostheses.

Dual-task walking over a compliant foam surface: A comparison of people with transfemoral amputation and controls

People with lower limb amputation are unable to reliably sense ground characteristics due to compromised sensory inputs from the missing limb. As a result, they may rely on compensatory strategies, such as use of cognitive resources, when walking over complex surfaces. This study examined interactions between cognition and walking over a compliant surface in 14 people with transfemoral amputation (TFA) and 14 controls using a dual-task paradigm. Walking was assessed with quantitative motion analysis in both single-task (walking alone) and dual-task (walking while performing a cognitive task) conditions over a compliant foam surface. Outcomes were walking speed, step width, step time asymmetry, step time variability, and the speed and accuracy of cognitive task performance. For each outcome, effects of task (single-task, dual-task) and group (TFA, control) were examined with repeated-measures analysis of variance. No significant group-by-task interactions were observed for cognitive task performance. A significant group-by-task interaction for step time asymmetry indicated that participants with TFA increased temporal asymmetry in dual-task relative to single-task conditions, while control participants maintained symmetrical gait. The addition of a concurrent cognitive task did not differentially affect other aspects of gait between groups. Significant main effects of group for all walking outcomes indicated that participants with TFA walked slower, with wider, more asymmetric, and more variable steps than controls. Results suggest that gait quality degrades in challenging dual-task conditions for people with TFA, but not controls, consistent with the idea that people with TFA may use increased cognitive resources to control walking in complex environments.

Assessing a low-cost accelerometer-based technique to estimate spatial gait parameters of lower-limb prosthesis users

BACKGROUND AND AIM

Inexpensive methods for characterizing lower-limb prosthetic gait allow clinicians to monitor gait quality. This study assessed an established method for estimating step length using a low-cost accelerometer to estimate distance walked in lower-limb prosthesis users and explore the use of subject-specific correction factors.

TECHNIQUE

A three-axis accelerometer was attached to participants using straps. Validity and test-retest reliability of step length was assessed in able-bodied individuals using a motion capture system. Validity of distance walked was assessed with lower-limb prosthesis users. A regression equation was developed for prosthesis users to estimate a correction factor that minimized error.

DISCUSSION

The system demonstrated excellent reliability and minimal mean error for both participant groups, but subject-specific correction factors did not provide substantial benefit. Estimate variability was high, suggesting the need for further refinement. Estimating distance walked and step length from low-cost accelerometers may be a valid, clinically accessible method for characterizing prosthetic gait.

CLINICAL RELEVANCE

The use of a low-cost accelerometer may provide valid means for estimating step length and distance walked of lower-limb prosthesis users in a clinical environment for monitoring patient outcomes.

Does the impedance of above-knee powered prostheses need to be adjusted for load-carrying conditions?

Powered knee prostheses provide substantial advantages for amputees compared to traditional passive devices during basic walking tasks (i.e. level-ground, stairs, ramps), but the impedance control parameters are fixed. For environments that differ from the well-controlled setting of the clinic, amputees must compensate their gait patterns because fixed control parameters ideal for walking on level ground in the clinic do not meet real-life task demands. Load carriage is one instance where fixed control parameters may lead to undesired gait patterns and potentially result in injury. To evaluate the importance of impedance control parameters for different walking tasks, we tested one above-knee amputee walking using an experimental powered prosthesis under four walking conditions. The amputee walked with and without added mass with both load-specific and non-specific impedance control parameters. The load-specific parameters significantly reduced the amputee's intact-leg compensations, asymmetry, and perceived exertion compared to the non-specific control parameters. Powered lower limb prostheses that modulate impedance control parameters for load-carrying tasks may improve the gait performance, safety, and comfort of amputees.