Preliminary study on static weight distribution under the human foot as a measure of lower extremity disability

Responsive fungal insoles for pressure detection

Mycelium bound composites are promising materials for a diverse range of applications including wearables and building elements. Their functionality surpasses some of the capabilities of traditionally passive materials, such as synthetic fibres, reconstituted cellulose fibres and natural fibres. Thereby, creating novel propositions including augmented functionality (sensory) and aesthetic (personal fashion). Biomaterials can offer multiple modal sensing capability such as mechanical loading (compressive and tensile) and moisture content. To assess the sensing potential of fungal insoles we undertook laboratory experiments on electrical response of bespoke insoles made from capillary matting colonised with oyster fungi Pleurotus ostreatus to compressive stress which mimics human loading when standing and walking. We have shown changes in electrical activity with compressive loading. The results advance the development of intelligent sensing insoles which are a building block towards more generic reactive fungal wearables. Using FitzHugh-Nagumo model we numerically illustrated how excitation wave-fronts behave in a mycelium network colonising an insole and shown that it may be possible to discern pressure points from the mycelium electrical activity.

Epidemiologic factors affecting plantar arch development in children with flat feet

BACKGROUND

Foot problems are reported by approximately 70% to 80% of adults and 30% of children. One of the most important characteristics affecting its incidence is medial longitudinal arch. Assessing arch height provides valuable information for prescribing appropriate footwear that reduces the consequences of flatfoot. The main goals of this study were to explore epidemiologic factors that affect arch height and to predict arch height in children with flatfoot based on five variables using widely accessible, low-cost tools.

METHODS

This study examined plantar arch height in 80 children with flatfoot aged 7 to 15 years. The evaluation criteria included low arch height, correct knee and heel position, and correct body symmetry. To measure arch height, the children sat in a chair and placed their feet on level ground. A caliper was used to measure the height between the bottom of the navicular tuberosity and the floor. Using least mean square error scheme, a multivariable model was fitted to the plantar arch height for all of the participants using independent variables, including age, Cole index, sex, place of residence, and physical activity.

RESULTS

Arch height increased as age increased in boys and girls in rural and urban areas. A significant increase in arch height occurred in 12- to 15-year-old boys and 10- to 15-year-old girls. In boys, arch height was 30% lower than in girls (P = .05). In children in cities, arch height was lower by 26% than in children in rural areas (P = .05). Arch height increased by 41.8% in inactive boys and by 115.2% in inactive girls in rural areas. It was reduced by 59.4% in boys and by 47.4% in girls as the Cole index increased from 82.2 to 152.0. The suggested model predicted arch height using the child's age, Cole index, sex, place of residence, and physical activity (r > 0.97, error < 0.04 mm [2%], P < .05).

CONCLUSIONS

Flat feet in children may be affected by age, sex, Cole index, place of residence, and physical activity. The proposed model allows plantar arch heights in children with flat feet to be predicted without the need for sophisticated technology via controlling the child's weight and physical activity for prescribing appropriate footwear.

A haptic feedback system for lower-limb prostheses

A haptic feedback system has been developed to provide sensory information to patients with lower-limb prostheses or peripheral neuropathy. Piezoresistive force sensors were mounted against four critical contact points of the foot to collect and relay force information to a system controller, which in turn drives four corresponding pneumatically controlled balloon actuators. The silicone-based balloon actuators were mounted on a cuff worn on the middle thigh, with skin contacts on the posterior, anterior, medial, and lateral surfaces of the thigh. Actuator characterization and human perceptual testing were performed to determine the effectiveness of the system in providing tactile stimuli. The actuators were determined to have a monotonic input pressure-vertical deflection response. Six normal subjects wearing the actuator cuff were able to differentiate inflation patterns, directional stimuli and discriminate between three force levels with 99.0%, 94.8%, and 94.4% accuracy, respectively. With force sensors attached to a shoe insole worn by an operator, subjects were able to correctly indicate the movements of the operator with 95.8% accuracy. These results suggest that the pneumatic haptic feedback system design is a viable method to provide sensory feedback for the lower limbs.

Foot pressure measurement: a review of clinical findings

In this review, a description of what is known about plantar pressure distribution in standing and in gait is followed by sections on clinical findings. Two major clinical areas are treated extensively, namely the diabetic foot and the foot in rheumatoid arthritis. Other applications, including the assessment of surgical procedures for orthopaedic corrections are also included. A large variety of different techniques for foot pressure measurement have been used; interpretation of the results has to be made on the basis of a firm understanding of the technique employed. Often, quantitative results from different pieces of apparatus are difficult to compare, indicating a need for accurate calibration and a standardized presentation. An up-to-date summary of pressure measurement systems reported over the past five years is included.

An integrated biomechanical-bioenergetic technique for evaluation of human locomotion

The existing locomotion evaluation techniques are based either on bioenergetic measurements or on biomechanical principles and procedures. While the former basis has been preferred by a few, published literature in this field has contained more information on the latter. No significant work combining both the approaches in a single measurement system is known so far. This paper reports an investigation where an attempt was made to combine both the techniques in relation to a mixed handicapped population composed of 10 test subjects as well as a matching control group. It has been found from the present investigation that the combined application of the above two types of measurements might lead to more useful information about the performance level of the subjects in locomotion. Further, the statistical analysis of the experimental data revealed the existance of a linear correlationship among the parameters used for such performance evaluation. Finally, the study findings have been discussed to indicate how the biomechanical measurements alone can throw sufficient light on the subject's locomotor status.