An assessment of the information lost when applying data reduction techniques to dynamic plantar pressure measurements

Masking approaches to analyse plantar pressure data of new and confident walking infants

BACKGROUND

Due to its easy and straightforward use, regional analysis with the "standard" mask is the most common approach for quantifying plantar pressures in infancy. Such a mask, however, identifies foot regions based on typical foot proportions and pressure gradients. Alternatively, the use of a customised mask retaining infants' feet proportions has not been explored.

RESEARCH QUESTION

Does a customised mask scaled on infants' feet improve processing of pressure data collected during walking development compared with a standard mask?

METHODS

Thirteen infants walked across an EMED xl platform. Steps were grouped applying eight foot-regions standard and customised masks. To evaluate masks' performance, peak pressure (PP) and contact area (CA) were extracted from each region, and mask. Intra-individual coefficients of variation were then calculated for each variable, and compared between masks using a Mann-Whitney U test (p < 0.05). Unsuccessful masks application was reported, expressed as percentage of data loss.

RESULTS

For CA variation, significant differences were found in all the regions but the lateral toes in new (Z = -0.184, p = 0.8540) and confident walking (Z = -1.562, p = 0.118). For PP variation, a significant difference was found in confident walking within the lateral midfoot (Z = -2.598, p = 0.009). With the standard mask, 22-27 % of data was lost in new and confident walking respectively, compared to 1.6-0 % with the customised. As a result, the customised mask characterised the more variable steps, demonstrating higher variation compared to the standard mask.

SIGNIFICANCE

Identifying foot regions using a mask based on infants' feet proportions yielded an improved performance compared to the standard mask. With the customised mask, we retained almost all the steps and characterised the variability of the data, thereby providing an appropriate approach for infants' pressure data processing. Application of the customised mask could therefore be beneficial in future studies analysing highly variable data sets.

Dynamic Characteristics of Foot Development: A Narrative Synthesis of Plantar Pressure Data During Infancy and Childhood

PURPOSE

Quantifying plantar pressure throughout childhood enables clinicians to enhance knowledge of typical changes in foot function. This narrative review aims to describe existing research reporting plantar pressure analysis in infants and children developing typically, to advance understanding of foot development.

METHODS

A narrative approach was used; 263 articles were identified and 13 met inclusion criteria.

RESULTS

Plantar pressures during walking rapidly change in infancy and childhood. With development, pressures increasingly resemble those in adults with the development of initial heel contact, shift in pressure distribution from medial to lateral foot side, decreasing midfoot pressure magnitude. The literature has a variety of study designs, data collection protocols, and analysis.

CONCLUSION

This review describes plantar pressure changes occurring as walking develops, emphasizing the typical trajectory of foot function development in infancy and childhood. The present finding describes the complex biomechanical development of foot function in typically developing infancy and childhood.

PAPPI: Personalized analysis of plantar pressure images using statistical modelling and parametric mapping

Quantitative analyses of plantar pressure images typically occur at the group level and under the assumption that individuals within each group display homogeneous pressure patterns. When this assumption does not hold, a personalized analysis technique is required. Yet, existing personalized plantar pressure analysis techniques work at the image level, leading to results that can be unintuitive and difficult to interpret. To address these limitations, we introduce PAPPI: the Personalized Analysis of Plantar Pressure Images. PAPPI is built around the statistical modelling of the relationship between plantar pressures in healthy controls and their demographic characteristics. This statistical model then serves as the healthy baseline to which an individual’s real plantar pressures are compared using statistical parametric mapping. As a proof-of-concept, we evaluated PAPPI on a cohort of 50 hallux valgus patients. PAPPI showed that plantar pressures from hallux valgus patients did not have a single, homogeneous pattern, but instead, 5 abnormal pressure patterns were observed in sections of this population. When comparing these patterns to foot pain scores (i.e. Foot Function Index, Manchester-Oxford Foot Questionnaire) and radiographic hallux angle measurements, we observed that patients with increased pressure under metatarsal 1 reported less foot pain than other patients in the cohort, while patients with abnormal pressures in the heel showed more severe hallux valgus angles and more foot pain. Also, incidences of pes planus were higher in our hallux valgus cohort compared to the modelled healthy controls. PAPPI helped to clarify recent discrepancies in group-level plantar pressure studies and showed its unique ability to produce quantitative, interpretable, and personalized analyses for plantar pressure images.

A Novel Helmet Fitness Evaluation Device Based on the Flexible Pressure Sensor Matrix

Helmet comfort has always been important for the evaluation of infantry equipment accessories and has for decades not been well addressed. To evaluate the stability and comfort of the helmet, this paper proposes a novel type of helmet comfort measuring device. Conventional pressure measuring devices can measure the pressure of flat surfaces well, but they cannot accurately measure the pressure of curved structures with large curvatures. In this paper, a strain-resistive flexible sensor with a slice structure was used to form a matrix network containing more than a 100 sensors that fit the curved surface of the head well. Raw data were collected by the lower computer, and the original resistance value of the pressure was converted from analog to digital by the A/D conversion circuit that converts an analog signal into a digital signal. Then, the data were output to the data analysis and image display module of the upper computer. The complex curved surface of the head poses a challenge for the appropriate layout design of a head pressure measuring device. This study is expected to allow this intuitive and efficient technology to fit other wearable products, such as goggles, glasses, earphones and neck braces.