The normal reference values of carrying angle from birth to adolescence

Abstract

© 2018, Siriraj Medical Journal. Objective: The aim of this study was to establish normal carrying angle reference values from birth to adolescence, and to identify variations in carrying angle relative to age, gender, and elbow side. Methods: The prospective cross-sectional study was performed in normal healthy children aged newborn to sixteen years during May 1959 to April 1961. Children were recruited from newborn units, nurseries, and schools located in Bangkok, Thailand. There was a total of 17 groups - one for each year of age from 0 (at birth) to 16. The carrying angles of both arms were measured using a clear plastic full-circle orthopedic goniometer. The data of age, side, and gender of each child were recorded. Results: A total of 921 children with 1,842 measurements were included. There were 407 boys and 514 girls. The mean carrying angle was lowest at birth and highest in the 15- year and 16-year age groups. The increase in the carrying angle was observed to progress to valgus 6 degrees at 6 years of age, and to valgus 11 degrees and stabilization at 15 years of age. There was no statistically significant difference between the mean carrying angle of the left and right side for any of the 17 evaluated age groups. Girls demonstrated a significantly greater carrying angle than boys (p < 0.001). The intraclass correlation coefficient (ICC) of inter-observer variation between two observers was 0.848. Conclusion: This study established normal carrying angle reference values from birth to adolescence. Our results revealed that the elbow is slightly varus at birth, then increases in carrying angle until reaching stabilization of skeletal growth and development at 15 years of age. The carrying angle is slightly greater in girls than in boys. This normal reference value data will benefit orthopedists who take care of the pediatric patients with elbow-related disorders.