COULD LOWER EXTREMITY INJURIES INCREASE BMI IN CHILDREN?

Abstract

PURPOSE: The purpose of this investigation is to examine the relationship between forced sedentariness attributed to the management of a lower extremity injury and change in BMI in pediatric patients. INTRODUCTION: Over the past 30 years, childhood obesity has significantly increased. Lack of physical activity and rising levels of sedentary living are associated with rising childhood obesity. As the effects of childhood obesity are long lasting, it is important to characterize childhood conditions that lead to increases in BMI. Traumatic lower extremity injuries in children commonly result in casting and forced immobilization. Children and adolescents who cease physical activity at a younger age are at a higher risk for weight gain and inactive lifestyles as adults. Presently, the data examining short term and longitudinal effects of injury on weight changes are lacking. Therefore, the purpose of this investigation is to examine the relationship between forced sedentariness attributed to the management of a lower extremity injury and change in BMI in pediatric patients. METHODS: Eighty eight subjects aged 5 to 18 with lower extremity fractures managed with non-weight bearing for a minimum of 6 weeks were identified. This group was compared to a cohort of controls, who presented to the pediatric orthopaedic clinic for upper extremity injuries. For each subject, BMI was calculated from height and weight data obtained at each clinic visit for which the data were available for a minimum of 6 months. Percent change in BMI was then calculated and compared between the lower extremity injury group and controls utilizing ANOVA. Logistic regression was then performed to determine if age, gender, and undergoing surgery were correleated with a BMI change of greater than 10%. RESULTS: The results of initial ANOVA analysis demonstrated no difference in BMI trends between children with lower extremity injuries and controls. On average, both groups showed a modest increase in BMI over time (lower extremity injuries = 3.40%, controls = 3.23%). Logistic analysis of the lower extremity revealed male gender to be associated with a 10% increase in BMI during the study period, though this was not significant (p = 0.153) CONCLUSIONS: Our investigation yielded a negative result. As there is limited literature on BMI trends in children, our power calculation may have underestimated the subjects needed to demonstrate a statistically significant difference between groups. SIGNIFICANCE: The increases observed in both groups may indicate that the experience of being injured is associated with increases in BMI regardless of the location of injury. Further investigation would involve assessing BMI trends prospectively to identify opportunities to obviate possible weight gain with injury.