Body mass index and elbow range of motion in a healthy pediatric population: A possible mechanism of overweight in children

Background: Childhood overweight has become a serious health problem among children and adolescents in the United States. No previous study, to our knowledge, has analyzed the effect of body mass index (BMI) on range of motion and carrying angle of the elbow joint in a healthy pediatric population. The primary objective of this study was to determine the effect of BMI on orthopedic parameters of the elbow joint, including range of motion, flexion, extension, and carrying angle. Study Participants and Methods: Healthy children age 2 to 18 years (mean 12.0 +/- 3.9 years) were recruited at an urban pediatric orthopedic clinic as pediatric orthopedic patients or as the siblings or friends of patients. Measures of range of motion (flexion and extension) and carrying angle of 226 elbows and of BMI from 113 study participants were analyzed. Results: BMI was negatively correlated with right and left elbow range of motion (r=-0.54, P<0.01; r=-0.43, P<0.01) and right and left elbow flexion (r=-0.59, P<0.01; r=-0.50, P<0.01). BMI had a positive correlation with right elbow extension (r=0.20, P=0.04). BMI did not correlate with left elbow extension or right or left carrying angle. After adjustment for age, sex, and ethnic group, BMI was associated with right (P<0.01) and left (P < 0.01) elbow range of motion. Conclusions: These data demonstrate that increased BMI in children is negatively correlated with range of motion of the elbow joint. Further studies are needed to evaluate the consequences of impaired range of motion associated with overweight on activity levels and energy expenditure in growing children and adolescents.