Development and evaluation of thoracic kyphosis and lumbar lordosis during growth

Purpose The aim of this study was to establish ranges of angular variation in lordotic and kyphotic curves in normal male and female children and adolescents. Methods We developed a pantograph to measure dorsal curves. It consisted of a tripod-supported vertical strut to which an articulated bar was fixed and which had an arm that was able to follow the dorsal surface while moving up and down. This arm was positioned over the C7 spinous process and followed spinous processes to L5 at constant speed. A laser beam was used to ensure the proper positioning of the pantograph and the subject. The motion was recorded using software so that the dorsal outline was represented on a computer screen, and lordotic and kyphotic curves were automatically measured. Before performing the population study, the pantograph was validated in 20 normal subjects by comparing the pantograph measurements with lateral spine radiographs. There were no statistically significant differences in the measurements. There were 718 subjects with no race selection, of whom 350 were males and 368 females ranging in age from 5 to 20 years and presenting normal weight and height. Individuals with generalized ligament laxity, trunk asymmetry, muscle retraction, or any orthopedic anomaly were excluded from the study. Data were analyzed according to age and gender. Student’s t tests and regression analysis were performed. Results Kyphotic curves increased linearly from 25° at 7 years of age to 38° at 19 years of age (kyphotic angle = 25° + 0.58 × age). Lordotic curves increased linearly from 22° at 5 years of age to 32° at 20 years of age (lordotic angle = 24° + 0.51 × age). There were no differences between males and females. Conclusions The pantograph that was developed for this study was successfully used to establish the normal ranges and progression of thoracic kyphosis and lumbar lordosis in the studied population. Both curves increased linearly with age, with no differences between males and females.