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

Price, Carina; Montagnani, Eleonora; Nester, Christopher; Morrison, Stewart C

Abstract

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. Gait development represents a unique phase where infants begin to move independently, explore their physical and social environments, and do so in complex ways 1. As they do so, higher loads are applied more frequently to the foot 2 and for longer total durations. Ambulation occurs through complex and changing patterns of movement under the management of a developing motor control system. Yet the application of forces during these tasks is critical to the shape and structure of the foot 3,4 and forms the basis for our understanding of typical developmental pathways for attainment of ambulatory skills. Characterising the pressures on the feet at various stages of gross-motor development reflects the infant's interaction with the support surface and has been the primary means by which gait and foot development has been studied. Loading on the infant foot has been characterised using contact area, peak plantar pressures and force time integrals for anatomical regions of interest e.g. the forefoot 5 and at various phases of gait development 6-9. However , importantly, this has only ever involved infants walking under direction and in a straight line. This approach facilitates data collection and analysis, and is typical for investigation of adult walking 10. This is at the cost of external validity of data because infants employ shorter bouts of steps in multiple directions 11,12 , with one quarter of steps involving turning once walking confidently 2. The importance of this disparity has been discussed at length 10 and means we are yet to fully understand what load infant feet experience during walking development. Recent work demonstrated that, as infants become more confident, they take more steps and that proportionately more of these steps are during turning and less in a straight line 2. This work described, but did not compare, plantar pressures under the infant foot during different types of step 2. We therefore do not know how straight-line, inward and outward turning steps differ during infant walking in terms of plantar pressure or centre of pressure. It is therefore important that we improve the external validity of our understanding of the demands placed on foot structures as walking develops by improving our research protocols. This will also impact future OPEN

Citation

Price, C., Montagnani, E., Nester, C., & Morrison, S. C. (2023). Foot plantar pressure and centre of pressure trajectory differ between straight and turning steps in infants. Scientific reports, 13(1), Article 7941. https://doi.org/10.1038/s41598-023-34568-z

• Journal Article Type: Article
• Acceptance Date: May 3, 2023
• Online Publication Date: May 16, 2023
• Publication Date: May 16, 2023
• Deposit Date: Sep 5, 2024
• Publicly Available Date: Sep 18, 2024
• Journal: Scientific Reports
• Print ISSN: 2045-2322
• Electronic ISSN: 2045-2322
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 13
• Issue: 1
• Article Number: 7941
• DOI: https://doi.org/10.1038/s41598-023-34568-z
• Keywords: Multidisciplinary
• Publisher URL: https://www.nature.com/articles/s41598-023-34568-z
• Additional Information: Received: 21 December 2022; Accepted: 3 May 2023; First Online: 16 May 2023; : The authors declare no competing interests.