Interface Pressure System to Compare the Functional Performance of Prosthetic Sockets during the Gait in People with Trans-Tibial Amputation.

The interface pressure between the residual limb and prosthetic socket has a significant effect on the amputee's mobility and level of comfort with their prosthesis. This paper presents a socket interface pressure (SIFP) system to compare the interface pressure differences during gait between two different types of prosthetic sockets for a transtibial amputee. The system evaluates the interface pressure in six critical regions of interest (CROI) of the lower limb amputee and identifies the peak pressures during certain moments of the gait cycle. The six sensors were attached to the residual limb in the CROIs before the participant with transtibial amputation donned a prosthetic socket. The interface pressure was monitored and recorded while the participant walked on a treadmill for 10 min at 1.4 m/s. The results show peak pressure differences of almost 0.22 kgf/cm2 between the sockets. It was observed that the peak pressure occurred at 50% of the stance phase of the gait cycle. This SIFP system may be used by prosthetists, physical therapists, amputation care centers, and researchers, as well as government and private regulators requiring comparison and evaluation of prosthetic components, components under development, and testing.

Pelvic floor pressure distribution profile in urinary incontinence: a classification study with feature selection.

BACKGROUND: Pelvic floor pressure distribution profiles, obtained by a novel instrumented non-deformable probe, were used as the input to a feature extraction, selection, and classification approach to test their potential for an automatic diagnostic system for objective female urinary incontinence assessment. We tested the performance of different feature selection approaches and different classifiers, as well as sought to establish the group of features that provides the greatest discrimination capability between continent and incontinent women. METHODS: The available data for evaluation consisted of intravaginal spatiotemporal pressure profiles acquired from 24 continent and 24 incontinent women while performing four pelvic floor maneuvers: the maximum contraction maneuver, Valsalva maneuver, endurance maneuver, and wave maneuver. Feature extraction was guided by previous studies on the characterization of pressure profiles in the vaginal canal, where the extracted features were tested concerning their repeatability. Feature selection was achieved through a combination of a ranking method and a complete non-exhaustive subset search algorithm: branch and bound and recursive feature elimination. Three classifiers were tested: k-nearest neighbors (k-NN), support vector machine, and logistic regression. RESULTS: Of the classifiers employed, there was not one that outperformed the others; however, k-NN presented statistical inferiority in one of the maneuvers. The best result was obtained through the application of recursive feature elimination on the features extracted from all the maneuvers, resulting in 77.1% test accuracy, 74.1% precision, and 83.3 recall, using SVM. Moreover, the best feature subset, obtained by observing the selection frequency of every single feature during the application of branch and bound, was directly employed on the classification, thus reaching 95.8% accuracy. Although not at the level required by an automatic system, the results show the potential use of pelvic floor pressure distribution profiles data and provide insights into the pelvic floor functioning aspects that contribute to urinary incontinence.

Novel instrumented probe for measuring 3D pressure distribution along the vaginal canal.

We developed an intravaginal instrumented probe (covered with a 10×10 matrix of capacitive sensors) for assessing the three-dimensional (3D) spatiotemporal pressure profile of the vaginal canal. The pressure profile was compared to the pelvic floor (PF) digital assessment, and the reliability of the instrument and repeatability of the protocol was tested. We also tested its ability to characterize and differentiate two tasks: PF maximum contraction and Valsalva maneuver (maximum intra-abdominal effort with downward movement of the PF). Peak pressures were calculated for the total matrix, for three major sub-regions, and for 5 planes and 10 rings throughout the vaginal canal. Intraclass correlation coefficients indicated excellent inter- and intra-rater reliability and intra-trial repeatability for the total and medial areas, with moderate reliability for the cranial and caudal areas. There was a moderate correlation between peak pressure and PF digital palpation [Spearman's coefficient r=0.55 (p<0.001)]. Spatiotemporal profiles were completely different between tasks (2-way ANOVAs for repeated measures) with notably higher pressures (above 30kPa) for the maximum contraction task compared to Valsalva (below 15kPa). At maximum contraction, higher pressures occurred in the mid-antero-posterior zone, with earlier peak pressure onsets and more variable along the vaginal depth (from rings 3 to 10-caudal). During Valsalva, the highest pressures were observed in rings 4-6, with peak pressure onsets more synchronized between rings. With this protocol and novel instrument, we obtained a high-resolution and highly reliable innovative 3D pressure distribution map of the PF capable of distinguishing vaginal sub-regions, planes, rings and tasks.

Assessment of Three Alternating Pressure Sequences Applied to a Dynamic Cushion to Relieve Pressure on Seating Areas / Evaluación de tres secuencias de inflado alternantes aplicadas a un cojín dinámico para la liberación de presión en el área de sentado

Pressure ulcers are injuries to the skin and/or underlying tissues caused by prolonged high pressures on supporting body areas, they affect mainly people with poor mobility that have stayed in seating position for a long time. Reducing the amount and duration of pressure has been widely accepted for minimizing the risk of formation of pressure ulcers. Recently, dynamic cushions have been developed to relieve pressure on supporting areas; nevertheless, there is no sufficient information about the adequate characteristics of alternating sequences for pressure ulcers prevention. Therefore, the aim of this work is to explore three sequences of alternating movements designed for an air cell cushion by comparing pressure redistribution on supporting areas when applied on healthy volunteers. The purpose of these sequences is to redistribute the pressure over a larger contact area. To evaluate the effect of the alternating sequences, eight healthy volunteers were asked to sit on the air cell cushion, and to try the three alternating sequences for 12 minutes, 2 minutes on static mode and 10 minutes on alternating mode. A parameter for quantitative assessment of alternating sequences was proposed in this work by determining the coefficient of variation of interface pressure. Furthermore, the percentage of relative change of coefficient of variation was computed for evaluating performance of the alternating sequences comparing to the static mode. It was found that the three proposed strategies maintained values of interface pressure lower than previous work. Additionally, the relative change allowed to differentiate the effects of alternation of each sequence showing the second strategy as the most effective. The results are encouraging for further studies in subjects who require a wheelchair for mobility.

Las úlceras por presión son lesiones en la piel y tejidos subyacentes, causadas por presiones excesivas y prolongadas en las superficies de apoyo del cuerpo. Estas lesiones afectan principalmente a personas con poca movilidad física, como aquellas que permanecen sentados por largos periodos. Para disminuir el riesgo del padecimiento de estas lesiones, se ha recomendado como punto de partida reducir la magnitud y el tiempo de acción de las presiones en las zonas de apoyo. Se han desarrollado cojines dinámicos para sillas de ruedas, los cuales generan movimientos alternantes en las diferentes zonas de apoyo, producido por la inyección de aire, con el fin de disminuir las presiones en esas zonas. Sin embargo, no se han encontrado referencias de las características adecuadas de las secuencias de movimientos alternantes para prevenir la aparición de esas lesiones. El propósito de este trabajo es evaluar tres secuencias de movimientos alternantes diseñadas para un cojín de aire. La evaluación se realizó comparando la distribución de presiones en zonas de apoyo antes y durante la aplicación de estas secuencias alternantes en personas sanas. Las secuencias propuestas se aplican para el inflado y desinflado de celdas que forman el cojín y fueron diseñadas con el objetivo de distribuir las presiones en un área mayor de apoyo. La prueba se realizó en 8 sujetos sanos, con un tiempo de estudio de 12 minutos para cada secuencia diseñada; 2 minutos en modo estático y 10 minutos en modo alternante. Se propuso determinar el coeficiente de variación para evaluar de forma cuantitativa el efecto de las secuencias alternantes sobre la presión de interfaz. Además se calculó el porcentaje de variación relativa del coeficiente de variabilidad entre los modos basal (estático) y alternante como una herramienta para evaluar el desempeño de las secuencias propuestas en relación a la presión de interfaz. Se encontró que las tres estrategias mantuvieron presiones de interfaz por debajo de los valores reportados en trabajos previos. El porcentaje de variación relativa permitió diferenciar el efecto de la alternancia de cada una de las secuencias propuestas, mostrando la segunda estrategia como la más efectiva. Los resultados obtenidos son alentadores para continuar el estudio en sujetos que requieren una silla de ruedas para su movilidad.

Comparação da distribuição de pressão plantar em sujeitos com pés normais e com pés planos durante a marcha / Comparison of plantar pressure distribution in subjects with normal and flat feet during gait

O objetivo do estudo/pesquisa foi verificar possíveis relações entre a queda do arco longitudinal medial, mensurada em situação estática pela altura do osso navicular e um conjunto de variáveis relacionadas à distribuição de pressão plantar, mensuradas em situação dinâmica. Participaram do estudo 11 (onze) sujeitos do gênero masculino, comidade média de 21 anos ± 3 anos, massa corporal 74 kg ± 10 kg e estatura 175 cm ± 4 cm. Para aquisição dos dados de Distribuição de Pressão Plantar (Pico de Pressão, Pressão Média, Área de Contato e Carga Relativa), foi utilizado o Novel Emed-AT System com uma taxa de amostragem de 50 Hz e para análise da Altura do Navicular para classificação dos sujeitos em grupos, foi utilizado o protocolo Navicular Drop Test proposto por Brody (1982). Os dados foram comparados a partir dos resultados da aplicação da estatística não paramétrica através do teste U de Mann-Whitney com p ? 0,05. Os resultados demonstraramque os grupos foram significativamente diferentes entre si, na região do mediopé, em todas as variáveis analisadas, sendo que foram encontrados os maiores valores médios no grupo dos indivíduos com os Pés Planos. Também apresentaram diferenças significativas na variável Área de Contato, Carga Relativa, Pico de Pressão Plantar e Pressão PlantarMédia quando comparados os grupos. Os resultados demonstram a importância que se deve dar aos sujeitos com pés planos, pois alterações na Distribuição de Pressão Plantar estão associadas ao surgimento de desconforto e também de lesões.

The aim of this study was to determine the possible relationship between loss of the normal medial longitudinal arch measured by the height of the navicular bone in a static situation and variables related to plantar pressure distribution measured in a dynamic situation. Eleven men (21 ± 3 years, 74 ± 10 kg and 175 ± 4 cm) participated in the study. The Novel Emed-AT System was used for the acquisition of plantar pressure distribution data (peak pressure, mean pressure, contact area, and relative load) at a sampling rate of 50 Hz. The navicular drop testproposed by Brody (1982) was used to assess the height of the navicular bone for classification of the subjects. The results were compared by the Mann-Whitney U test, with the level of significanceset at p ? 0.05. Differences were observed between the two groups in the mid-foot regionfor all variables studied, with the observation of higher mean values in subjects with flat feet. There were also significant differences in contact area, relative load, peak pressure, and mean pressure between groups. The present study demonstrates the importance of paying attentionto subjects with flat feet because changes in plantar pressure distribution are associated with discomfort and injuries.

INTRA ARTICULAR CALCANEAL FRACTURES: A CLINICAL AND BIOMECHANICAL ANALYSIS.

OBJECTIVE: Verify the variables of plantar pressure distribution of patients submitted to surgical procedure for calcaneal fracture, and correlate them with two different surgical approaches. METHOD: The authors studied 15 patients between 20 and 53 years of age (average 40.06 yrs.) who had intra-joint calcaneal fractures, submitted to surgical treatment by means of two different approaches: the lateral and the sinus tarsi. The authors checked the plantar pressure distribution by correlating these variables with the two different surgical approaches. The plantar pressure distribution was assessed using the Pedar System (Novel, Gmbh, Munich, Germany), by checking the maximum peak of the hindfoot and forefoot pressure on the affected and the normal sides. RESULTS: the mean maximum pressure of the hindfoot plantigram in both approaches showed no statistical difference (t=0.11; p=0.91), as well as the mean maximum pressure of the forefoot plantigram (t=-0,48; p=0,64). CONCLUSION: The authors have concluded that there were no significant statistical differences between the average maximum peak of the hindfoot and forefoot pressure on the affected side as compared to the normal side, and these variables have showed no differences when compared to the surgical approach used.

Fraturas intra-articulares do calcâneo: análise clínica e biomecânica / Intraarticular calcaneal fracture: a clinical and biomechanical analysis

OBJETIVO: Verificar as variáveis de distribuição da pressão plantar de pacientes submetidos a tratamento cirúrgico de fratura de calcâneo e correlacioná-las com duas diferentes vias de acesso cirúrgico. Métodos: Os autores estudaram 15 pacientes com idade entre 20 e 53 anos (média de 40,06 anos) que apresentaram fraturas intra-articulares do calcâneo, submetidos ao tratamento cirúrgico por duas vias de acesso cirúrgico, a via lateral e a via do seio do tarso. Avaliaram a distribuição da pressão plantar, correlacionando essas variáveis com as duas vias de acesso. A avaliação da distribuição da pressão plantar foi rea-lizada através do sistema Pedar (Novel, GmbH, Munique, Alemanha), verificando o pico máximo de pressão do retropé e do antepé do lado fraturado e do lado normal. RESULTADOS: A média das pressões máximas dos plantigramas do retropé dos pés operados pela via de acesso lateral e pela via curta não apresentou diferença estatística entre as duas vias de acesso (t = 0,11; p = 0,91), bem como a média das pressões máximas dos plantigramas do antepé também não mostrou diferença estatística significativa (t = -0,48; p = 0,64). CONCLUSÃO: Os autores concluíram que não houve diferença estatística entre as médias dos picos máximos de pressão do retropé e do antepé do lado operado, comparados com o lado normal, bem como não houve diferença estatística dessas variáveis comparadas com a via de acesso cirúrgico utilizada.

OBJECTIVE: Verify the variables of plantar pressure distribution of patients submitted to surgical procedure for calcaneal fracture, and correlate them with two different surgical approaches. Method: The authors studied 15 patients between 20 and 53 years of age (average 40.06 yrs.) who had intra-joint calcaneal fractures, submitted to surgical treatment by means of two different approaches: the lateral and the sinus tarsi. The authors checked the plantar pressure distribution by correlating these variables with the two different surgical approaches. The plantar pressure distribution was assessed using the Pedar System (Novel, Gmbh, Munich, Germany), by checking the maximum peak of the hindfoot and forefoot pressure on the affected and the normal sides. RESULTS: the mean maximum pressure of the hindfoot plantigram in both approaches showed no statistical difference (t=0.11; p=0.91), as well as the mean maximum pressure of the forefoot plantigram (t=-0,48; p=0,64). CONCLUSION: The authors have concluded that there were no significant statistical differences between the average maximum peak of the hindfoot and forefoot pressure on the affected side as compared to the normal side, and these variables have showed no differences when compared to the surgical approach used.

Effects of trimming on dairy cattle hoof weight bearing surfaces and pressure distributions / Efeito do casqueamento na distribuição de pressões e suporte de pesona superfície dos cascos de vacas leiteiras

Claw lameness can be associated to biomechanical factors caused by unbalanced pressure distribution under the hooves when cows are confined in modern dairy operations with hard concrete flooring. In the present study, an original claw subdivision4 was slightly modified to differentiate between the anterior (typical sole lesion spot) and posterior portions of the medial sole, and to emphasize the maximum pressures applied only on the area of contact without including the total area within these regions during midstance. The results, obtained showed significance (p < 0.044) for the interaction among Group, Leg and region (G*L*R). It was observed that the rear portion of the claws (heels) on the hind limb of untrimmed cows, are more stressed than the heel region on trimmed cows (23 % versus 16.72% of total pressure applied on the claw for untrimmed and trimmed respectively). The typical sole lesion spot pressures were increased slightly on trimmed cows as compared to untrimmed (20.20% versus 15.9%). The front feet presented differences in pressure concentration on the lateral sole between both groups (29% versus 23.25% for untrimmed versus trimmed respectively). It was concluded that, although the differences were small (5%) changes in pressure concentration, untrimmed cows stress more the sole lateral as compared to trimmed on the front feet, and on the rear feet, they stress more the heel region whereas trimmed cows tend to have a slight better balance among regions. Conversely, when cows are trimmed, the typical sole lesion spot concentrates more pressure than the heel itself (20.20% versus 16.72% respectively) and may favor the occurrence of sole ulcers.(AU)

Laminite (manqueira) pode ser associado a fatores mecânicos, causados por falta de balanceamento na distribuição de pressão na sola dos cascos de vacas confinadas em instalações modernas, que utilizam pisos de concreto. No presente estudo, a subdivisão original dos cascos de vacas leiteiras foi modificada para diferenciar-se entre a porção anterior (local típico de lesão) e posterior da sola medial dos cascos, e para enfatizar as pressões máximas aplicadas somente na área de contato não levando em consideração a área total da sola. Os resultados mostraram significância estatística (p < 0.044) para a interação entre Grupo, Pata e Região (G*L*R). Foi observado que a porção posterior (calcanhar) das patas traseiras de vacas não-casqueadas foram estressadas mais intensamente que de vacas casqueadas (23 % versus 16.72% da pressão total aplicada nas patas em não-casqueadas e casqueadas respectivamente). As pressões na região do local típico de lesão aumentaram em animais casqueados comparado com não-casqueados (20.20% versus 15.9%). As patas da frente apresentaram diferenças na concentração de pressão da sola lateral (29% versus 23.25% em não-casqueadas versus casqueadas, respectivamente). Foi concluído que, apesar das diferenças serem pequenas (5%) mudanças nas concentrações de pressão, vacas não-casqueadas estressaram mais a porção da sola lateral, comparado a vacas casqueadas nas patas da frente, enquanto nas traseiras elas estressam mais a região do calcanhar, e as vacas casqueadas tendem a ter uma distribuição melhor de pressão entre as regiões. No entanto, quando as vacas são casqueads, a região típica de lesão tende a concentrar mais pressão do que o próprio calcanhar (20.20% versus 16.72% respectivamente) podendo favorecer a incidência de úlcera de sola.(AU)