Biomechanics of the paediatric foot and lower limb : associations with adiposity

Abstract

Childhood obesity is a growing problem in the UK and primary schoolchildren are particularly at risk. With this growing concern the associated co-morbidities of obesity are increasingly evident. There has been limited research undertaken to quantify the impact of excessive body fat mass (adiposity) on the function of the child’s lower limb and feet. The primary aim of this research was to explore the relationships between adiposity with lower limb and foot biomechanics in boys age 7 to 11 years old. Fifty five children were recruited to participate in protocols for body composition and three-dimensional gait analysis established in the initial phases of the study. Kinematic and kinetic variables from four lower limb joints (pelvis, hip, knee and ankle) and four foot joints (hindfoot-shank, midfoot-hindfoot, forefoot-midfoot and hallux-first metatarsal) were analysed over the gait cycle. Statistical analysis by principal component analysis was undertaken and allowed the determination of components, constructed of lower limb and foot variables, to be analysed in multiple regression. Multiple regression was also undertaken to assess the relationships between the lower limb and foot variables and body composition whilst accounting for confounding factors including age, anthropometric and spatiotemporal variables. The key findings demonstrated that higher adiposity was associated with greater hip flexion, knee adduction moments and a pronated foot type. These findings indicate that boys with higher fat mass are at risk of future musculoskeletal co-morbidities including concerns of developing flat feet. This work presents a novel protocol for advanced understanding of lower limb and foot biomechanics and comprehensive data of paediatric lower limb and foot function during gait in normal weight and obese children. The research details, for the first time, that obesity affects the dynamic function of the paediatric foot. This work underpins the need for further longitudinal research looking at the prevention and management of musculoskeletal complications associated with childhood obesity.