RESUMEN
PURPOSE: Little is known with respect to changes in the segmental thoracic and thoracolumbar kyphosis, which are major parameters influencing sagittal balance of the spine. The authors investigated the detailed segmental changes of those parameters by ageing. MATERIALS AND METHODS: A total of 326 normal asymptomatic males were divided into 2 groups; group 1 (mean age, 21.2+/-1.7; n=175) and group 2 (mean age, 64.1+/-6.4; n=151). After taking a standing sagittal radiograph, the sagittal spinal and pelvic parameters were measured. Thoracic and thoracolumbar kyphosis were classified according to segments A, C7 UEP (upper end vertebra)-T5 UEP; B, T5 UEP-T10 UEP; C, T10 UEP-T12 LEP (lower end vertebra); and D, (T12 LEP-L2 LEP), and analyzed between 2 groups, respectively. RESULTS: Thoracic kyphosis (21.1degrees+/-7.7degrees vs. 30.0degrees+/-8.8degrees, p<0.001), segment B (15.8degrees+/-6.1degrees vs. 18.1degrees+/-7.9degrees, p=0.003), and segment C (5.3degrees+/-5.1degrees vs. 11.8degrees+/-6.5degrees, p<0.001) were increased in group 2. In group 2 segment A showed decreased kyphosis (12.1degrees+/-6.4degrees vs. 9.8degrees+/-6.4degrees, p=0.001). In segment D no significant difference was observed between groups. CONCLUSION: Increased thoracic kyphosis was observed in the middle and lower thoracic regions. The authors provided important references of sagittal parameters to determine the expected ranges of kyphosis for a normal asymptomatic male of a given age.