Gait symmetry and regularity in transfemoral amputees assessed by trunk accelerations

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to evaluate a method based on a single accelerometer for the assessment of gait symmetry and regularity in subjects wearing lower limb prostheses.</p> <p>Methods</p> <p>Ten transfemoral amputees and ten healthy control subjects were studied. For the purpose of this study, subjects wore a triaxial accelerometer on their thorax, and foot insoles. Subjects were asked to walk straight ahead for 70 m at their natural speed, and at a lower and faster speed. Indices of step and stride regularity (Ad1 and Ad2, respectively) were obtained by the autocorrelation coefficients computed from the three acceleration components. Step and stride durations were calculated from the plantar pressure data and were used to compute two reference indices (SI1 and SI2) for step and stride regularity.</p> <p>Results</p> <p>Regression analysis showed that both Ad1 well correlates with SI1 (<it>R</it>²up to 0.74), and Ad2 well correlates with SI2 (<it>R</it>²up to 0.52). A ROC analysis showed that Ad1 and Ad2 has generally a good sensitivity and specificity in classifying amputee's walking trial, as having a normal or a pathologic step or stride regularity as defined by means of the reference indices SI1 and SI2. In particular, the antero-posterior component of Ad1 and the vertical component of Ad2 had a sensitivity of 90.6% and 87.2%, and a specificity of 92.3% and 81.8%, respectively.</p> <p>Conclusions</p> <p>The use of a simple accelerometer, whose components can be analyzed by the autocorrelation function method, is adequate for the assessment of gait symmetry and regularity in transfemoral amputees.</p

Recommended number of strides for automatic assessment of gait symmetry and regularity in above-knee amputees by means of accelerometry and autocorrelation analysis

<p>Abstract</p> <p>Background</p> <p>Symmetry and regularity of gait are essential outcomes of gait retraining programs, especially in lower-limb amputees. This study aims presenting an algorithm to automatically compute symmetry and regularity indices, and assessing the minimum number of strides for appropriate evaluation of gait symmetry and regularity through autocorrelation of acceleration signals.</p> <p>Methods</p> <p>Ten transfemoral amputees (AMP) and ten control subjects (CTRL) were studied. Subjects wore an accelerometer and were asked to walk for 70 m at their natural speed (twice). Reference values of step and stride regularity indices (Ad1 and Ad2) were obtained by autocorrelation analysis of the vertical and antero-posterior acceleration signals, excluding initial and final strides. The Ad1 and Ad2 coefficients were then computed at different stages by analyzing increasing portions of the signals (considering both the signals cleaned by initial and final strides, and the whole signals). At each stage, the difference between Ad1 and Ad2 values and the corresponding reference values were compared with the minimum detectable difference, MDD, of the index. If that difference was less than MDD, it was assumed that the portion of signal used in the analysis was of sufficient length to allow reliable estimation of the autocorrelation coefficient.</p> <p>Results</p> <p>All Ad1 and Ad2 indices were lower in AMP than in CTRL (P < 0.0001). Excluding initial and final strides from the analysis, the minimum number of strides needed for reliable computation of step symmetry and stride regularity was about 2.2 and 3.5, respectively. Analyzing the whole signals, the minimum number of strides increased to about 15 and 20, respectively.</p> <p>Conclusions</p> <p>Without the need to identify and eliminate the phases of gait initiation and termination, twenty strides can provide a reasonable amount of information to reliably estimate gait regularity in transfemoral amputees.</p

Gaitography on lower-limb amputees:Repeatability and between-methods agreement

Background: Gaitography is gait parametrization from center-of-pressure trajectories of walking on an instrumented treadmill. Gaitograms may be useful for prosthetic gait analyses, as they can be rapidly and unobtrusively collected over multiple gait cycles without constraining foot placement. However, its reliability must still be established for prosthetic gait. Objectives: To evaluate (a) within-method test–retest repeatability and (b) between-methods agreement for temporal gait events (foot contact, foot off) and gait characteristics (e.g. step times, single-support duration). Study design: Cohort study with repeated measurements. Methods: Ten male proficient prosthetic walkers with a unilateral trans-femoral or trans-tibial amputation were equipped with a pressure-insole system and were invited to walk on separate days on an instrumented treadmill. Results: We found better between-methods reproducibility than within-method repeatability in temporal gait characteristics. Step times, stride times, and foot-contact events matched well between the two methods. In contrast, insole-based foot-off events were detected one-to-two samples earlier. Likewise, a similar bias was observed for temporal gait characteristics that incorporated foot-off events. Conclusion: Notwithstanding small systematic biases, the good between-methods agreement indicates that temporal gait characteristics may be determined interchangeably with gaitograms and insoles in persons with a prosthesis. However, the relatively poorer test–retest repeatability hinders longitudinal assessments with either method. Clinical relevance: Clinical practice could potentially benefit from gaitography as an efficient, unobtrusive, easy to use, automatized, and patient-friendly means to objectively parametrize prosthetic gait, with immediate availability of test results allowing for prompt clinical decision-making. Temporal gait parameters demonstrate good between-methods agreement, but poorer within-method repeatability hinders detecting prosthetic gait changes

Instrumentation of sprint and long jump tracks of an indoor athletics field to study athletes’ performances

Introduction: The in-depth study of the performances of athletes is crucial to evaluate and improve their technique. However, collecting representative data is not trivial, as several factors could affect the measurements. Laboratory measurements can lack in realism (artificial environment, athlete’s lack of challenge), whereas data collected in-field using on-board devices can be influenced by the instrumentation itself (weight, encumbrance) [1-2]. The aim of this work is the design of an instrumented track, which will allow to collect kinematic and kinetic data of able bodied and paralimpic athletes in their natural environment, ensuring that the influence of the sensory apparatus is negligible. Methods: The instrumentation set-up of the indoor athletics track of Padova (Padova, 35136, Italy) is represented in the plan view of figure 1a. Seven 60x90 cm and two 40x60 cm force platforms (AMTI, BMS600900 and BMS400600) will be installed following the disposition depicted in figure 1b on the eighth lane of the sprint track, leading to a total of 6.9 metres of force sensing lane. The two smaller force platforms will be installed side-by-side to allow the possibility of mounting one single starting block on each force transducer to collect separate right and left ground reaction forces during the starting phase of sprinting. An additional 60x90 cm force platform will be installed on the long jump track at 1.6 metres from the sand pit in order to collect the last step of the athlete before the flight phase of the long jump (figure 1c). Kinematic data will be collected using 10 optoelectronic motion capture cameras (Vicon, Vantage5), which will be installed on a double portal structure made of aluminium trusses with an overall size of 13 x 7 x 3.5 metres (length x width x height). The structure size allows more than one athlete to run simultanesously, in order to recreate the “challenge effect” typical of official races. Compared to other motion capture mounting solutions, such as using tripods to support each individual camera [3], the use of this single support structure offers the advantage of allowing to rigidly translate the motion capture calibrated volume in different part of the athletics field using wheels. This feature reduces drastically the set-up time of the motion capture system, particularly when the data collection focus has to be moved between the sprint and the long jump area. Moreover, this structure allows to avoid the presence of any cable on the track, as wires will pass through the trusses and descend via the vertical columns. Results and discussion: The design of the sensorized athletics track is complete and the installation of the instrumentation will take place in the next few months. This track will allow to collect insightfull in-field data regarding able bodied and paralimpic athletes performances outside the laboratory environment. Examples of these data will be presented in June at the ISEA 2022 conference

STIFFNESS COMPARISON OF RUNNING PROSTHETIC FEET OF DIFFERENT CATEGORIES AFTER BENCH TESTING

The purpose of the work is the comparison of stiffness properties of Running Prosthetic Feet (RPF) for transtibial amputee athletes after the introduction of test methods to collect and analyse their Load-deflection curves. The study explores the effect of the orientation of the socket (ϑG) with respect to ground during a load cycle.The three Ossur feet Cheetah Xtreme Category 4th, 5th ,6th underwent extensive testing on a multi-component test bench. Results show that the unit interval between categories does not matches with the interval in terms of equivalent stiffness Keq introduced as synthetic stiffness parameter

GRF ANALYSIS OF TWO ELITE PARALYMPIC SPRINTERS IN STEADY AND RESISTED ACCELERATED TREADMILL RUNNING

Analysis of ground reaction forces (GRFs) allows evaluating performances of paralympic runners with transfemoral amputation. Instrumented treadmills are expensive and low-cost solutions to gather GRFs are worth to be studied. This study aimed to use a commercial treadmill placed on four force platforms to evaluate vertical impulse, braking and propulsive horizontal impulses during steady-speed (SSR) and resisted accelerated (RAR) running. The RAR vertical impulses of the unaffected limb (UL) of the two athletes doubled the values of the affected limb (AL) that has, however, on average 23% larger propulsive action than UL in SSR. The horizontal impulse of AL remains positive in the first 10 steps during RAR, as expected. Agreement between present results and literature confirms that the proposed setup gives sufficient confidence in the evaluation of the sprint technique

Aplicación del design thinking para el aprendizaje de diseño de interiores. Caso: Proyecto Productivo IIB - Instituto Continental Huancayo

El aprendizaje de diseño constituye un proceso de solución de problemas para obtener un resultado, el trabajo de investigación presentado tiene como objetivo el experimentar como la metodología del Design Thinking (DT) influye en ramas ligadas a la educación y en este caso particular en el proceso de aprendizaje de diseño de interiores. Los participantes fueron 24 estudiantes de un salón de Proyecto Productivo IIB, quienes cursaron el IV ciclo de la carrera de Diseño de Interiores en el Instituto Continental de la ciudad de Huancayo, periodo 2021-I. La metodología utilizada desarrolló un enfoque cuasi experimental, prospectivo, longitudinal y analítico con un diseño mixto concurrente porque se trabajaron las variables de forma paralela. La información de resultados está en función a las variables trabajadas, donde el DT evidenció a través de los instrumentos utilizados que esta metodología se maneja en clases de forma empírica (a priori) para obtener resultados de diseño, sin embargo, no se desarrolla de manera ordenada, demostrando que estableciendo un orden del proceso se llegan a mejores resultados. Se detectó una baja en la capacidad de producir ideas innovadoras, sin embargo, el progreso de esta falencia se evidencia en las últimas 02 fases, lo que impulsa a considerar estudios posteriores sobre la innovación en las carreras de diseño. En conclusión, la aplicación del DT en las aulas aportó en el aprendizaje del diseño a través de la aplicación de procedimientos ordenados y secuenciales para producir ideas innovadoras, y enfoca esfuerzos en cumplir con los requerimientos necesarios para desarrollar proyectos reales y observar a pequeña escala como la mejora continua es parte del resultado final

A Workflow for Studying the Stump-Socket Interface in Persons with Transtibial Amputation through 3D Thermographic Mapping

The design and fitting of prosthetic sockets can significantly affect the acceptance of an artificial limb by persons with lower limb amputations. Clinical fitting is typically an iterative process, which requires patients' feedback and professional assessment. When feedback is unreliable due to the patient's physical or psychological conditions, quantitative measures can support decision-making. Specifically, monitoring the skin temperature of the residual limb can provide valuable information regarding unwanted mechanical stresses and reduced vascularization, which can lead to inflammation, skin sores and ulcerations. Multiple 2D images to examine a real-life 3D limb can be cumbersome and might only offer a partial assessment of critical areas. To overcome these issues, we developed a workflow for integrating thermographic information on the 3D scan of a residual limb, with intrinsic reconstruction quality measures. Specifically, workflow allows us to calculate a 3D thermal map of the skin of the stump at rest and after walking, and summarize this information with a single 3D differential map. The workflow was tested on a person with transtibial amputation, with a reconstruction accuracy lower than 3 mm, which is adequate for socket adaptation. We expect the workflow to improve socket acceptance and patients' quality of life

TOWARDS THE DEVELOPMENT OF BENCH TESTING FOR LOWER-LIMB PROSTHETIC SOCKETS FOR SPORT APPLICATIONS

Prosthetic sockets are the bespoken part of lower-limb prostheses. Knowledge about the mechanical properties of sockets is essential to ensure patient safety and comply with current medical device regulations. This includes sockets designed for sport activities. Unfortunately, the literature is extremely limited and contradictory as described in a recent systematic review. The aim of this study was to initiate a research activity aiming to design a mechanical bench system for socket testing and perform a comparative analysis of the ultimate strength of alternative socket layups. Results highlight substantial differences in the maximum loading at failure, stressing the importance of increasing the knowledge about socket mechanical properties to support prosthetists provide reliable and safe products to patients and athletes