Trunk asymmetry in juveniles

Trunk asymmetry (TA) is a common phenomenon in children, but its incidence in juveniles is not known. The present cross sectional study reports TA in normal juveniles and provides data which describe the evolution of TA from early childhood to adolescence.

The scoliometer readings in both standing and sitting forward bending position (FBP) of 3301 children, (1645 boys, and 1656 girls) aged from 3 to 9 years old were studied. TA was quantified by measuring angle of trunk rotation (ATR) and children were categorized as symmetric (ATR = 0 degrees ), mild asymmetric (ATR 1 degrees - 6 degrees ) and severely asymmetric (ATR >/= 7 degrees ). The difference of TA between standing and sitting FBP as well as differences between boys and girls in frequency of TA were also calculated. The scoliometer readings were analyzed by age to reveal at which age the juvenile pattern of TA changes into the adolescent one.

74.2% of boys and 77% of girls were symmetric (ATR = 0 degrees ) in the thoracic region in standing FBP, while 82.7% of boys and 84.1% of girls were symmetric in the thoracic region in sitting FBP. Juvenile girls are more symmetric than boys but severe TA was found almost the same between the two genders. A significant reduction in the frequency of mild TA from standing into sitting FBP, in all the examined regions in both boys and girls was found, but in severe TA this reduction is very small. Analysing scoliometer readings by age it appears that significant TA changes take place between 8-9 years of age for boys and between 6-7 and 8-9 years for girls. TA in boys is changing into the adolescent pattern at a later age than in girls.

Juveniles were found more symmetric than adolescents, who were studied previously in a different study. Furthermore, juvenile girls were found more symmetric than boys. Juvenile TA pattern seems to be in accordance with the higher incidence of juvenile idiopathic scoliosis in boys. Furthermore, severe TA, which could be correlated with a scoliotic curve, was found to be more common to the left side. The present report provides information about the variability of back morphology in normal juveniles. The amount of TA in children is the indicator for referral and further orthopaedic assessment if a spinal curve is detected, but can also be used as a baseline for further research on idiopathic scoliosis aetiology.