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

Childhood obesity and its impact on the characteristics of gait stance phases: a cross-sectional study

This study aimed to investigate the variations in foot type, laxity, dynamic characteristics of gait, and the characteristics of the stance phase of gait, in relation to body mass index (BMI) and groups of children of different ages. Additionally, it aimed to explore the correlations between BMI and these variables across children groups of different ages. A cross-sectional study was conducted involving 196 infants aged between 5 and 10 years old. The variables assessed included BMI, foot type, laxity, dynamic variables, and characteristics of the stance phase of gait. Significant variations were observed in foot type, laxity, certain dynamic variables, and characteristics of the stance phase of gait between normoweight (NW) and overweight/obese (OW/OB) groups among children aged between 5 and 10 years old (p ranged between 0.019 and 0.050). Moreover, BMI was also positively associated with the initial forefoot contact, heel off, total duration of the step, and forefoot contact phase of children 7 to 10 years of age (p ranged between < 0.010 and 0.040).   Conclusion: Children who are OW/OB had alterations at different stages of gait. Being OW/OB is related to alterations of the phases of gait mainly from 7 to 10 years of age, and spending more time in each of the phases of walking. This could indicate that children who are OW/OB, in addition to walking slower, overload the musculoskeletal system, subjecting their joints and muscles to greater stress. What is Known: • Children who are overweight (OW) and obese (OB) can experience changes in their musculoskeletal systems, posture, and gait due to increased body mass index. • OW and OB children experience additional stress on their musculoskeletal systems, impacting posture, biomechanics, mobility, physical activity, and daily tasks. Excessive plantar loading is linked to foot pain in adults. What is New: • Body mass index was positively associated with initial forefoot contact, heel off, total duration of the step, and forefoot contact phase in children aged 7 to 10 years old. OW/OB children aged 5-6 exhibited less ankle dorsiflexion and smaller relaxed calcaneal stance position (RCSP) as compared to normal-weight children. • Obese children aged 5-6 showed less pronation excursion, suggesting altered frontal plane movement due to RCSP differences. Children aged 7-8 who are OW/OB spent more time in certain gait phases, particularly in the forefoot contact phase. Being OW/OB is linked to altered gait parameters such as initial forefoot, heel off, total step duration, and forefoot contact phase. Being OW/OB was associated with a longer forefoot contact phase, particularly in the right foot.

Analysis of mechanical characteristics of walking and running foot functional units based on non-negative matrix factorization

Objective: To explore the characteristics of Non-Negative Matrix Factorization (NNMF) in analyzing the mechanical characteristics of foot functional units during walking and running. Methods: Eighteen subjects (9 males and 9 females) were recruited, and the ground reaction force curves of each foot region during walking and running were collected using a plantar pressure measurement system. NNMF was used to extract the mechanical features of different foot regions and to determine the number of foot functional units. The differences between the base matrices of walking and running were compared by traditional t-tests, and the differences in coefficient matrices were compared by one-dimensional statistical parameter mapping. Results: 1) When the number of foot functional units for walking and running were both 2, the Variability Accounted For (VAF) by the matrix exceeded 0.90 (VAF walk = 0.96 ± 0.02, VAF run = 0.95 ± 0.04); 2) In foot functional unit 1, both walking and running exhibited buffering function, with the heel region being the main force-bearing area and the forefoot also participating in partial buffering; 3) In foot functional unit 2, both walking and running exhibited push-off function, with the middle part of the forefoot having a higher contribution weight; 4) In foot functional unit 1, compared to walking, the overall force characteristics of the running foot were greater during the support phase of the 0%-20% stage, with the third and fourth metatarsal areas having higher contribution weights and the lateral heel area having lower weights; 5) In foot functional unit 2, compared to walking, the overall force was higher during the beginning and 11%-69% stages of running, and lower during the 4%-5% and 73%-92% stages. During running, the thumb area, the first metatarsal area and the midfoot area had higher contribution weights than during walking; in the third and fourth metatarsal areas, the contribution weights were lower during running than during walking. Conclusion: Based on the mechanical characteristics of the foot, walking and running can both be decomposed into two foot functional units: buffering and push-off. The forefoot occupies a certain weight in both buffering and push-off functions, indicating that there may be a complex foot function transformation mechanism in the transverse arch of foot. Compared to walking, running completes push-off earlier, and the force region is more inclined towards the inner side of the foot, with the hallux area having a greater weight during push-off. This study suggests that NNMF is feasible for analyzing foot mechanical characteristics.

Foot plantar pressure and centre of pressure trajectory differ between straight and turning steps in infants

Plantar pressure has been used to understand loading on infant feet as gait develops. Previous literature focused on straight walking, despite turning accounting for 25% of infant self-directed steps. We aimed to compare centre of pressure and plantar pressure in walking steps in different directions in infants. Twenty-five infants who were walking confidently participated in the study (aged 449 ± 71 days, 96 ± 25 days after first steps). Plantar pressure and video were recorded whilst five steps per infant were combined for three step types: straight, turning inwards and outwards. Centre of pressure trajectory components were compared for path length and velocity. Pedobarographic Statistical Parametric Mapping explored differences in peak plantar pressure for the three step types. Significant differences were identified primarily in the forefoot with higher peak pressures in straight steps. Centre of pressure path was longer in the medial-lateral direction during turning (outward 4.6 ± 2.3, inward 6.8 ± 6.1, straight 3.5 ± 1.2 cm, p < .001). Anterior-posterior velocity was higher in straight steps and medial-lateral velocity highest turning inwards. Centre of pressure and plantar pressures differ between straight and turning steps with greatest differences between straight and turning. Findings may be attributed to walking speed or a function of turning experience and should influence future protocols.

Overweight and Obesity: Its Impact on Foot Type, Flexibility, Foot Strength, Plantar Pressure and Stability in Children from 5 to 10 Years of Age: Descriptive Observational Study

BACKGROUND

Overweight (OW) and childhood obesity (OB) may cause foot problems and affect one's ability to perform physical activities. The study aimed to analyze the differences in descriptive characteristics, foot type, laxity, foot strength, and baropodometric variables by body mass status and age groups in children and, secondly, to analyze the associations of the BMI with different physical variables by age groups in children.

METHODS

A descriptive observational study involving 196 children aged 5-10 years was conducted. The variables used were: type of foot, flexibility, foot strength and baropodometric analysis of plantar pressures, and stability by pressure platform.

RESULTS

Most of the foot strength variables showed significant differences between the normal weight (NW), OW and OB groups in children aged between 5 and 8. The OW and OB groups showed the highest level of foot strength. In addition, the linear regression analyses showed, in children aged 5 to 8 years, a positive association between BMI and foot strength (the higher the BMI, the greater the strength) and negative association between BMI and stability (lower BMI, greater instability).

CONCLUSIONS

Children from 5 to 8 years of age with OW and OB show greater levels of foot strength, and OW and OB children from 7 to 8 years are more stable in terms of static stabilometrics. Furthermore, between 5 and 8 years, having OW and OB implies having more strength and static stability.

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.

The Development of a Built-In Shoe Plantar Pressure Measurement System for Children

There is a rapid increase in plantar pressure from the infant to toddler stage, yet little is known about the reasons for this change. More information about plantar pressure distribution can help clinicians identify early-stage foot-related diseases that may occur during transitions from childhood to adulthood. This information also helps designers create shoes that adapt to different needs. This research describes the development of a low-cost, built-in shoe plantar pressure measurement system that determines foot pressure distribution in toddlers. The study aimed to improve and provide data on pressure distribution during foot growth. This was accomplished by implementing a plantar pressure capacitive measurement system within shoes. The capacitive sensors were laminated using a copper tape sheet on plastic backing with adhesive, elastomer layers, and a combination of conductive and non-conductive fabrics. Constructed sensors were characterized using compression tests with repeated loads. Results demonstrated that the sensors exhibited rate-independent hysteresis in the estimation of pressure. This enabled a calibration model to be developed. The system can mimic more expensive plantar pressure measurement systems at lower fidelity. This emerging technology could be utilized to aid clinicians, researchers, and footwear designers interested in how pressure distribution changes from infants to toddlers.

Longitudinal study of foot pressures during real-world walking as infants develop from new to confident walkers

Onset of walking in infants leads to regular cyclic loading of the plantar foot surface for the first time. This is a critical period for evolving motor skills and foot structure and function. Plantar pressure literature typically studies gait only once walking is established and under conditions that artificially constrain the walking direction and bouts compared to how infants move in the real-world. We therefore do not know how the foot is loaded when self-directed walking is first achieved and whether it changes as walking is practiced. Research question How do pressures on the plantar foot in real-world walking change from new to confident walking? Methods Fifty-seven infants participated in a two-site longitudinal study. Bespoke child-friendly spaces incorporated large pressure platforms and video. Data was collected at two milestones: new (403 days) and confident (481 days) walking. Steps were defined as walking straight or turning medially/laterally. Pressure variables were calculated for eight-foot regions and compared between milestones. Results Confident walking resulted in more steps (median: 18 v 35) and almost twice as many turning steps. During straight-line steps, confident walking increased peak pressures in the medial heel (median: 99.3 v 106.7kPa, p < .05) and lateral forefoot (median: 53.9 v 65.3kPa, p < .001) and reduced medial toe pressure (median: 98.1 v 80.0kPa, p < .05). Relative medial midfoot contact area reduced (median: 12.4 v 11.2%, p < .05) as absolute foot contact increased. A faster transition across stance and a reduced relative contact time in the forefoot were recorded in confident walking. Significance Pressures change rapidly as walking is initiated with significant differences in foot loading evident within an average 77 days. Importantly, these changes differ in straight and turning walking. Continued reliance on assessment of straight-line walking during early stages of ambulation likely fails to characterise 26% of steps experienced by infant feet.

Pedobarographic Statistical Parametric Mapping of plantar pressure data in new and confident walking infants: A preliminary analysis

In infancy, plantar pressure data during walking has been investigated through regional approaches, whilst the use pedobarographic Statistical Parametric Mapping (pSPM) has not been reported. Analysis of pressure data using pSPM is higher in resolution and can enhance understanding of foot function development, providing novel insights into plantar pressure changes. This work aims to detail the implementation of the pSPM data processing framework on infants' pressure data, comparing plantar pressure patterns between new and confident walking steps. Twelve infants walked across an EMED- xl platform. Steps were extracted and imported into MATLAB for analysis. Maximum pressure pictures were transformed to point clouds and registered within and between participants with iterative closest point and coherent point drift algorithms, respectively. Root mean square error (RMSE) was calculated within both registrations as a quality measure. Pressure patterns were compared between new and confident walking using nonparametric-paired sample SPM1D t-test. RMSEs were under 1 mm for both registration algorithms. In the transition to confident walking, significantly increasing pressure was detected in the left central forefoot. Implementing pSPM to infants' pressure data was non-trivial, as several phases of data processing were required to ensure a robust approach. Our analysis highlighted the presence of significant changes in pressure in central left forefoot after 2.2 months of walking, which have not been reported before. This can be explained as previous regional approaches in infancy considered the forefoot as whole, preventing detection of changes in discrete anatomical regions.