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This is the first investigation to perform an unsupervised cluster analysis of activities performed by individuals with lower limb amputation (ILLAs) and individuals without gait impairment, in free-living conditions. Eight individuals with no gait impairments and four ILLAs wore a thigh-based accelerometer and walked on an improvised route across a variety of terrains in the vicinity of their homes. Their physical activity data were clustered to extract 'unique' groupings in a low-dimension feature space in an unsupervised learning approach, and an algorithm was created to automatically distinguish such activities. After testing three dimensionality reduction methods-namely, principal component analysis (PCA), t-distributed stochastic neighbor embedding (tSNE), and uniform manifold approximation and projection (UMAP)-we selected tSNE due to its performance and stable outputs. Cluster formation of activities via DBSCAN only occurred after the data were reduced to two dimensions via tSNE and contained only samples for a single individual. Additionally, through analysis of the t-SNE plots, appreciable clusters in walking-based activities were only apparent with ground walking and stair ambulation. Through a combination of density-based clustering and analysis of cluster distance and density, a novel algorithm inspired by the t-SNE plots, resulting in three proposed and validated hypotheses, was able to identify cluster formations that arose from ground walking and stair ambulation. Low dimensional clustering of activities has thus been found feasible when analyzing individual sets of data and can currently recognize stair and ground walking ambulation.
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Algoritmos , Caminata , Humanos , Extremidad Inferior/cirugía , Análisis por Conglomerados , Amputación QuirúrgicaRESUMEN
This pilot study aimed to investigate the implementation of supervised classifiers and a neural network for the recognition of activities carried out by Individuals with Lower Limb Amputation (ILLAs), as well as individuals without gait impairment, in free living conditions. Eight individuals with no gait impairments and four ILLAs wore a thigh-based accelerometer and walked on an improvised route in the vicinity of their homes across a variety of terrains. Various machine learning classifiers were trained and tested for recognition of walking activities. Additional investigations were made regarding the detail of the activity label versus classifier accuracy and whether the classifiers were capable of being trained exclusively on non-impaired individuals' data and could recognize physical activities carried out by ILLAs. At a basic level of label detail, Support Vector Machines (SVM) and Long-Short Term Memory (LSTM) networks were able to acquire 77-78% mean classification accuracy, which fell with increased label detail. Classifiers trained on individuals without gait impairment could not recognize activities carried out by ILLAs. This investigation presents the groundwork for a HAR system capable of recognizing a variety of walking activities, both for individuals with no gait impairments and ILLAs.
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Amputación Quirúrgica , Caminata , Actividades Humanas , Humanos , Extremidad Inferior/cirugía , Proyectos PilotoRESUMEN
In many populations like wheelchair and prosthetic users, the soft tissue is subject to excessive or repetitive loading, making it prone to Deep Tissue Injury (DTI). To study the skeletal muscle response to physical stress, numerous in vitro and in vivo models exist. Yet, accuracy, variability, and ethical considerations pose significant trade-offs. Here, we present an ex vivo approach to address these limitations and offer additional quantitative information on cellular damage. In this study, skeletal muscle tissue from Sprague Dawley rats was isolated and transversely loaded. Histological analysis and fluorescence staining demonstrated that the setup was suitable to keep the tissue alive throughout the experimental procedure. Mechanically induced cell damage was readily distinguishable through morphological changes and uptake of a membrane impermeable dye. Our comparably simple experimental setup can be adapted to different loading conditions and tissues to assess the cell response to mechanical loading in future studies.
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Músculo Esquelético , Ratas , Animales , Ratas Sprague-Dawley , Estrés Mecánico , Músculo Esquelético/metabolismo , Modelos AnimalesRESUMEN
Transtibial prosthetic users do often struggle to achieve an optimal prosthetic fit, leading to residual limb pain and stump-socket instability. Prosthetists face challenges in objectively assessing the impact of prosthetic adjustments on residual limb loading. Understanding the mechanical behaviour of the pseudo-joint formed by the residual bone and prosthesis may facilitate prosthetic adjustments and achieving optimal fit. This study aimed to assess the feasibility of using B-mode ultrasound to monitor in vivo residual bone movement within a transtibial prosthetic socket during different stepping tasks. Five transtibial prosthesis users participated, and ultrasound images were captured using a Samsung HM70A system during five dynamic conditions. Bone movement relative to the socket was quantified by tracking the bone contour using Adobe After-Effect. During the study a methodological adjustment was made to improve data quality, and the first two participants were excluded from analysis. The remaining three participants exhibited consistent range of motion, with a signal to noise ratio ranging from 1.12 to 2.59. Medial-lateral and anterior-posterior absolute range of motion varied between 0.03 to 0.88 cm and 0.14 to 0.87 cm, respectively. This study demonstrated that it is feasible to use B-mode ultrasound to monitor in vivo residual bone movement inside an intact prosthetic socket during stepping tasks.
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Miembros Artificiales , Tibia , Ultrasonografía , Humanos , Masculino , Tibia/diagnóstico por imagen , Tibia/cirugía , Tibia/fisiología , Ultrasonografía/métodos , Persona de Mediana Edad , Femenino , Adulto , Rango del Movimiento Articular , Anciano , Muñones de Amputación/fisiopatología , Muñones de Amputación/diagnóstico por imagen , Movimiento/fisiología , Diseño de Prótesis , AmputadosRESUMEN
Residual limb shape capturing (Casting) consistency has a great influence on the quality of socket fit. Magnetic Resonance Imaging was used to establish a reliable reference grid for intercast and intracast shape and volume consistency of two common casting methods, Hands-off and Hands-on. Residual limbs were cast for twelve people with a unilateral below knee amputation and scanned twice for each casting concept. Subsequently, all four volume images of each amputee were semiautomatically segmented and registered to a common coordinate system using the tibia and then the shape and volume differences were calculated. The results show that both casting methods have intra cast volume consistency and there is no significant volume difference between the two methods. Inter- and intracast mean volume differences were not clinically significant based on the volume of one sock criteria. Neither the Hands-off nor the Hands-on method resulted in a consistent residual limb shape as the coefficient of variation of shape differences was high. The resultant shape of the residual limb in the Hands-off casting was variable but the differences were not clinically significant. For the Hands-on casting, shape differences were equal to the maximum acceptable limit for a poor socket fit.
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Amputados , Miembros Artificiales , Pierna , Imagen por Resonancia Magnética , Ajuste de Prótesis , Miembros Artificiales/normas , Humanos , Ajuste de Prótesis/normasRESUMEN
Lower limb prosthetic socket shape and volume consistency can be quantified using MRI technology. Additionally, MRI images of the residual limb could be used as an input data for CAD-CAM technology and finite element studies. However, the accuracy of MRI when socket casting materials are used has to be defined. A number of six, 46 mm thick, cross-sections of an animal leg were used. Three specimens were wrapped with Plaster of Paris (POP) and the other three with commercially available silicone interface liner. Data was obtained by utilising MRI technology and then the segmented images compared to corresponding calliper measurement, photographic imaging, and water suspension techniques. The MRI measurement results were strongly correlated with actual diameter, surface area, and volume measurements. The results show that the selected scanning parameters and the semiautomatic segmentation method are adequate enough, considering the limit of clinical meaningful shape and volume fluctuation, for residual limb volume and the cross-sectional surface area measurements.
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Muñones de Amputación , Miembros Artificiales , Imagen por Resonancia Magnética/métodos , Ajuste de Prótesis , AnimalesRESUMEN
Reliability of three-dimensional gait analysis is important for repetitive assessments in clinical or research studies. In this paper, we hypothesized that a Strathclyde Functional Cluster Model (SFCM) in which all the joint centers and flexion axes were determined by functional methods, could improve the reliability of joint kinematics within and between operators' sessions compared to an anatomical model, Plug-in Gait (PiG). A preliminary study of intra- and inter-assessor reliability of the SFCM was been analyzed and compared to the PiG. One able-bodied participant performed eight sessions measured by four operators who have different experience level on the two models. Intra- and inter-operator reliability of the SFCM and PiG were assessed using the intraclass correlation coefficient (ICC) and standard deviation (SD). Results showed that the SFCM generated smaller SD and greater ICC values for all joint variables compared to the PiG in the inter-operator condition, suggesting that functional methods could improve the inter-operator reliability. Moreover, the intra-operator ICC results indicated that the SFCM performance was less influenced by operator experience compared to the PiG. In conclusion, as the model requires less palpation of ALs, it would benefit the users who have less experience in practical use.
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Marcha , Osteopatía , Animales , Humanos , Manipulación Ortopédica , Rango del Movimiento Articular , Reproducibilidad de los ResultadosRESUMEN
A major source of error in reliability of gait analysis arises from the palpation of anatomical landmarks (ALs). The purpose of this study was to investigate whether less reliance on manually identifying ALs could improve inter-assessor reliability of joint kinematics compared to two anatomical models. It was hypothesised that the Strathclyde functional cluster model (SFCM), in which the hip, knee and ankle joint centres and knee and ankle flexion axes were determined by functional methods, would obtain greater inter-assessor reliability. Ten able-bodied participants and seven assessors were recruited. Each participant completed three trials conducted by different assessors on non-consecutive days. Agreement and inter-assessor reliability between the models were compared and analysed, whilst factor effects of assessor experience and body mass index (BMI) were investigated. The SFCM obtained excellent agreement with anatomical models for all sagittal angles and hip ab/adduction angle, and it showed slightly higher inter-assessor reliability with smaller variations in the knee and ankle. The assessor experience was not a significant factor, but the BMI had a significant effect on the inter-assessor reliability. The results demonstrate that the SFCM may be more beneficial for less experienced assessors.
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Marcha/fisiología , Modelos Anatómicos , Adulto , Análisis de Varianza , Puntos Anatómicos de Referencia , Fenómenos Biomecánicos , Índice de Masa Corporal , Femenino , Humanos , Articulaciones/fisiología , Masculino , Rango del Movimiento Articular/fisiología , Reproducibilidad de los Resultados , Adulto JovenRESUMEN
BACKGROUND: The soft tissue of the residual limb in transtibial prosthetic users encounters unique biomechanical challenges. Although not intended to tolerate high loads and deformation, it becomes a weight-bearing structure within the residuum-prosthesis-complex. Consequently, deep soft tissue layers may be damaged, resulting in Deep Tissue Injury (DTI). Whilst considerable effort has gone into DTI research on immobilised individuals, only little is known about the aetiology and population-specific risk factors in amputees. This scoping review maps out and critically appraises existing research on DTI in lower-limb prosthetic users according to (1) the population-specific aetiology, (2) risk factors, and (3) methodologies to investigate both. RESULTS: A systematic search within the databases Pubmed, Ovid Excerpta Medica, and Scopus identified 16 English-language studies. The results indicate that prosthetic users may be at risk for DTI during various loading scenarios. This is influenced by individual surgical, morphological, and physiological determinants, as well as the choice of prosthetic componentry. However, methodological limitations, high inter-patient variability, and small sample sizes complicate the interpretation of outcome measures. Additionally, fundamental research on cell and tissue reactions to dynamic loading and on prosthesis-induced alterations of the vascular and lymphatic supply is missing. CONCLUSION: We therefore recommend increased interdisciplinary research endeavours with a focus on prosthesis-related experimental design to widen our understanding of DTI. The results have the potential to initiate much-needed clinical advances in surgical and prosthetic practice and inform future pressure ulcer classifications and guidelines.
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Functional methods identify joint centres as the centre of rotation (CoR) of two adjacent movements during an ad-hoc movement. The methods have been used for functionally determining hip joint centre in gait analysis and have revealed advantages compared to predictive regression techniques. However, the current implementation of functional methods hinders its application in clinical use when subjects have difficulties performing multi-plane movements over the required range. In this study, we systematically investigated whether functional methods can be used to localise the CoR during a quasi-planar movement. The effects of the following factors were analysed: the algorithms, the range and speed of the movement, marker cluster location, marker cluster size and distance to the joint centre. A mechanical linkage was used in our study to isolate the factors of interest and give insight to variation in implementation of functional methods. Our results showed the algorithms and cluster locations significantly affected the estimate results. For all algorithms, a significantly positive relationship between CoR errors and the distance of proximal cluster coordinate location to the joint centre along the medial-lateral direction was observed while the distal marker clusters were best located as close as possible to the joint centre. By optimising the analytical and experimental factors, the transformation algorithms achieved a root mean square error (RMSE) of 5.3 mm while the sphere fitting methods yielded the best estimation with an RMSE of 2.6 mm. The transformation algorithms performed better in presence of random noise and simulated soft tissue artefacts.
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Análisis de la Marcha/métodos , Marcha/fisiología , Articulaciones/fisiología , Modelos Biológicos , Algoritmos , Fenómenos Biomecánicos , Simulación por Computador , Análisis de la Marcha/estadística & datos numéricos , Humanos , Articulaciones/anatomía & histología , Modelos Lineales , Movimiento/fisiología , Rango del Movimiento Articular/fisiología , RotaciónRESUMEN
[This corrects the article DOI: 10.1371/journal.pone.0167466.].
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Increased temperature and perspiration within a prosthetic socket is a common complaint of many amputees. The heat dissipation in prosthetic sockets is greatly influenced by the thermal conductive properties of the socket and interface liner materials. These materials influence the body's temperature regulation mechanism and might be the reason for thermal discomfort in prosthetic sockets. Monitoring interface temperature at skin level is notoriously complicated. The problem might be considered notorious because embedding wires and sensors in an elastomer eventually results in elastomer failures because of the high strain induced when donning a liner (amputees roll the liners onto their limbs). Another reason is because placing sensors and wires directly against the skin could cause irritation and chaffing over just a short period of time. We describe a route wherein if the thermal properties of the socket and liner materials are known, the in-socket residual limb temperature could be accurately predicted by monitoring the temperature between socket and liner rather than skin and liner using the Gaussian process technique.
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Amputados/rehabilitación , Miembros Artificiales , Modelos Estadísticos , Temperatura Cutánea/fisiología , Anciano , Humanos , Aprendizaje Automático , Masculino , Distribución Normal , TemperaturaRESUMEN
Monitoring of the interface temperature at skin level in lower-limb prosthesis is notoriously complicated. This is due to the flexible nature of the interface liners used impeding the required consistent positioning of the temperature sensors during donning and doffing. Predicting the in-socket residual limb temperature by monitoring the temperature between socket and liner rather than skin and liner could be an important step in alleviating complaints on increased temperature and perspiration in prosthetic sockets. In this work, we propose to implement an adaptive neuro fuzzy inference strategy (ANFIS) to predict the in-socket residual limb temperature. ANFIS belongs to the family of fused neuro fuzzy system in which the fuzzy system is incorporated in a framework which is adaptive in nature. The proposed method is compared to our earlier work using Gaussian processes for machine learning. By comparing the predicted and actual data, results indicate that both the modeling techniques have comparable performance metrics and can be efficiently used for non-invasive temperature monitoring.
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Miembros Artificiales , Lógica Difusa , Extremidad Inferior , Redes Neurales de la Computación , Temperatura Cutánea , Amputados , Distribución NormalRESUMEN
Elevated skin temperature at the body/device interface of lower-limb prostheses is one of the major factors that affect tissue health. The heat dissipation in prosthetic sockets is greatly influenced by the thermal conductive properties of the hard socket and liner material employed. However, monitoring of the interface temperature at skin level in lower-limb prosthesis is notoriously complicated. This is due to the flexible nature of the interface liners used which requires consistent positioning of sensors during donning and doffing. Predicting the residual limb temperature by monitoring the temperature between socket and liner rather than skin and liner could be an important step in alleviating complaints on increased temperature and perspiration in prosthetic sockets. To predict the residual limb temperature, a machine learning algorithm - Gaussian processes is employed, which utilizes the thermal time constant values of commonly used socket and liner materials. This Letter highlights the relevance of thermal time constant of prosthetic materials in Gaussian processes technique which would be useful in addressing the challenge of non-invasively monitoring the residual limb skin temperature. With the introduction of thermal time constant, the model can be optimised and generalised for a given prosthetic setup, thereby making the predictions more reliable.
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OBJECTIVE: A recurring complication in trans-tibial prosthetic limb users is "poor socket fit" with painful residuum-socket interfaces, a consequence of excess pressure. This is due to both poor socket fit and poor socket alignment; however, the interaction of these factors has not been quantified. Through evaluation of kinetic data this study aimed to articulate an interaction uniting socket design, alignment and interface pressures. The results will help to refine future studies and will hopefully help determine whether sockets can be designed, fitted and aligned to maximize mobility whilst minimizing injurious forces. METHODS: Interface pressures were recorded throughout ambulation in one user with "optimal (reference) alignment" followed by 5 malalignments in a patellar tendon-bearing and a hydrocast socket. RESULTS: Marked differences in pressure distribution were discovered when equating the patellar tendon-bearing against the hydrocast socket and when comparing interface pressures from reference with offset alignment. Patellar tendon-bearing sockets were found to be more sensitive to alignment perturbations than hydrocast sockets. A complex interaction was found, with the most prominent finding demonstrating the requisite for attainment of optimal alignment: a translational alignment error of 10 mm can increase maximum peak pressures by 227% (mean 17.5%). CONCLUSION: Refinements for future trials are described and the necessity for future research into socket design, alignment and interface pressures has been estabilished.
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Diseño de Prótesis , Tibia/patología , Anciano , Miembros Artificiales , Femenino , Humanos , Proyectos PilotoRESUMEN
INTRODUCTION: Prosthetic alignment, positioning of a prosthetic foot relative to a socket, is an iterative process in which an amputee's gait is optimized through repetitive optical gait observation and induction of alignment adjustments when deviations are detected in spatiotemporal and kinematic gait parameters. An important limitation of the current prosthetic alignment approach is the subjectivity and the lack of standardized quantifiable baseline values. The purpose of this systematic review is to investigate if an optimal alignment criterion can be derived from published articles. Moreover, we investigated the effect of alignment changes on spatiotemporal, kinematic and kinetic gait parameters. RESULTS: A total of 11 studies were included, two controlled before-and-after studies and nine-interrupted time series studies. DISCUSSION: The results demonstrate that alignment changes have a predictable influence on the included kinetic parameters. However, the effect of alignment changes on spatio-temporal and kinematic gait parameters are generally unpredictable. These findings suggest that it is imperative to include kinetics in the process of dynamic prosthetic alignment. Partially this can be established by communication with the prosthetic user in terms of perceived socket comfort, but the use of measurement tools should also be considered. While current literature is not conclusive about an optimal alignment, future alignment research should focus on alignment optimisation based on kinetic outcomes.
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Marcha/fisiología , Ajuste de Prótesis/métodos , Rango del Movimiento Articular , Amputados , Miembros Artificiales , Fenómenos Biomecánicos , Humanos , Análisis de Series de Tiempo Interrumpido , Diseño de Prótesis , Ajuste de Prótesis/normas , TibiaRESUMEN
BACKGROUND: Walking cadence has shown promise for estimating walking intensity in healthy adults. Auditory cues have been shown to improve gait symmetry in populations with movement disorders. We investigated the walking cadence-energy expenditure relationship in unilateral transtibial amputees (TTAs), and the potential of music cues for regulating walking cadence and improving gait symmetry. METHODS: Seventeen unilateral TTAs performed 2 5-min treadmill walking trials, followed by 2 5-min overground walking trials (self-regulated "brisk" intensity, and while attempting to match a moderate-tempo digital music cue). RESULTS: Walking cadence significantly (P < .001) and accurately (R(2) = .55, SEE = 0.50 METs) predicted energy expenditure, and a cadence of 86 steps·min(-1) was equivalent to a 3-MET intensity. Although most participants were able to match cadence to prescribed music tempo, gait symmetry was not improved during the music-guided condition, compared with the self-regulated condition. CONCLUSIONS: This is the first study to investigate the utility of walking cadence for monitoring and regulating walking intensity in adults with lower limb prosthesis. Cadence has similar or superior accuracy as an indicator of walking intensity in this population, compared with the general population, and adults with a unilateral TTA are capable of walking at moderate intensity and above for meaningful bouts of time.
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Amputación Quirúrgica , Miembros Artificiales , Metabolismo Energético/fisiología , Marcha/fisiología , Caminata/fisiología , Adulto , Anciano , Señales (Psicología) , Prueba de Esfuerzo/métodos , Femenino , Frecuencia Cardíaca , Humanos , Masculino , Persona de Mediana Edad , Música , Consumo de Oxígeno/fisiología , Conducta Sedentaria , Controles Informales de la SociedadRESUMEN
BACKGROUND: Disability is inextricably linked to poverty. A total of 80% of the disabled population lives in low-income countries. The demand for prosthetic and orthotic services in these countries is increasing, and a variety of methods to provide services are currently used. OBJECTIVES: To assess current models of provision to facilitate sustainable, evidence-based prosthetic and orthotic services. STUDY DESIGN: Literature review. METHODS: A literature search was performed through Medline (Ovid), PubMed, ISI Web of Knowledge, EMBASE and RECAL Legacy using combinations of subject heading and text word searching strategies. Full-text publications were critically appraised and ranked according to the Scottish Intercollegiate Guidelines Network guidelines. RESULTS: Three areas were deemed pertinent to the research question. Studies were grouped into one or more of these categories based on the issues addressed: instigators, types of service provision, demographics and region-specific issues. It was found that many complex factors influence prosthetic and orthotic services in low-income countries. Demographic and regional idiosyncrasies require prosthetic and orthotic services to be tailored to address the specific needs of individual countries. CONCLUSIONS: The lack of and quality of available research made efficacy of methods used to provide services in low-income countries difficult to determine.
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Países en Desarrollo , Servicios de Salud/tendencias , Aparatos Ortopédicos/tendencias , Pobreza/tendencias , Prótesis e Implantes/tendencias , Demografía , Personas con Discapacidad/rehabilitación , Práctica Clínica Basada en la Evidencia , HumanosRESUMEN
The quality of lower-limb prosthetic socket fit is influenced by shape and volume consistency during the residual limb shape-capturing process (i.e., casting). Casting can be quantified with magnetic resonance imaging (MRI) technology. However, chemical shift artifact and image distortion may influence the accuracy of MRI when common socket/casting materials are used. We used a purpose-designed rig to examine seven different materials commonly used in socket fabrication during exposure to MRI. The rig incorporated glass marker tubes filled with water doped with 1 g/L copper sulfate (CS) and 9 plastic sample vials (film containers) to hold the specific material specimens. The specimens were scanned 9 times in different configurations. The absolute mean difference of the glass marker tube length was 1.39 mm (2.98%) (minimum = 0.13 mm [0.30%], maximum = 5.47 mm [14.03%], standard deviation = 0.89 mm). The absolute shift for all materials was <1.7 mm. This was less than the measurement tolerance of +/-2.18 mm based on voxel (three-dimensional pixel) dimensions. The results show that MRI is an accurate and repeatable method for dimensional measurement when using matter containing water. Additionally, silicone and plaster of paris plus 1 g/L CS do not show a significant shape distortion nor do they interfere with the MRI image of the residual limb.
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Miembros Artificiales , Imagen por Resonancia Magnética , Diseño de Prótesis , Artefactos , Ajuste de PrótesisRESUMEN
BACKGROUND: There are currently no published prosthetic-related outcome measurement tools (OMT) available in the Arabic language. OBJECTIVE: The aim of this study was to translate the Prosthetic Evaluation Questionnaire (PEQ) into Arabic, ensuring cross-cultural equivalence with the original English language version. STUDY DESIGN: Psychometric property testing. METHODS: The PEQ was culturally and linguistically adapted from English to Arabic using a process of forward translation, backward translation, committee review and pre-testing. Pre-testing was carried out in a clinical trial where subjects each completed the questionnaire in Arabic and English, and underwent random probe questioning. The data were compared and analysed, using intraclass correlation (ICC) and Bland Altman plots. RESULTS: Seven patients gave consent and completed the study. For all nine PEQ scales, the ICC point estimate scores were above 0.8, indicating a good degree of correlation. However, for some scales, the 95% confidence interval was wide, indicating a large level of variation. The Bland Altman plots displayed a good distribution around the mean for most of the scales, although the results were affected by the small sample size. CONCLUSION: The results of the analysis showed that the Arabic version of the PEQ was linguistically equivalent to the original version, although further testing with a larger sample group is recommended. CLINICAL RELEVANCE: The availability of a prosthetic outcome measurement tool in Arabic will enable clinicians to collect evidence that can be used to monitor and improve patient care. As there is currently little information available about amputees in the Gulf region, this tool will be a useful resource to both clinicians and decision makers.