Impact of foot progression angle on the distribution of plantar pressure in normal children.

Background: Plantar pressure distribution during walking is affected by several gait factors, most especially the foot progression angle which has been studied in children with neuromuscular diseases. However, this relationship in normal children has only been reported in limited studies. The purpose of this study is to clarify the correlation between foot progression angle and plantar pressure distribution in normal children, as well as the impacts of age and sex on this correlation.

Methods: This study retrospectively reviewed dynamic pedobarographic data that were included in the gait laboratory database of our institution. In total, 77 normally developed children aged 5-16 years who were treated between 2004 and 2009 were included. Each child's footprint was divided into 5 segments: lateral forefoot, medial forefoot, lateral midfoot, medial midfoot, and heel. The percentages of impulse exerted at the medial foot, forefoot, midfoot, and heel were calculated.

Findings: The average foot progression angle was 5.03° toe-out. Most of the total impulse was exerted on the forefoot (52.0%). Toe-out gait was positively correlated with high medial (r = 0.274; P < 0.001) and forefoot impulses (r = 0.158; P = 0.012) but negatively correlated with midfoot impulse (r = -0.273; P<0.001). The moderating effects of age and sex on these correlations were insignificant.

Interpretation: Foot progression angle demonstrates significant impact on the distribution of foot pressure, regardless of age or sex. Foot progression angle should be taken into consideration when conducting pedobarographic examinations and balancing plantar pressure as part of the treatment of various foot pathologies.