Sagittal spinal alignment in asymptomatic patients over 30 years old in the Korean population.

Background: We aim to provide sagittal and pelvic parameters according to different age groups in an asymptomatic population all over 30 years old and to investigate the possible causes of changes in these parameters.
Methods: Whole-spine, standing lateral radiographs were taken in 128 asymptomatic Korean people over 30 years old. The spinal parameters (the total thoracic kyphosis (TTK), maximal lumbar lordosis (MLL), total lumbar lordosis (TLL), lower lumbar lordosis (LLL), thoracolumbar junctional angle (TLJA), and lumbar inclination (LI)), pelvic parameters (pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT)), and spinal balance parameters (spinal balance, sacropelvic balance, and spinopelvic balance) were measured. The body mass index, body protein mass, waist line, skeletal muscle mass, and body fat mass were also measured for potential causes.
Results: TTK and TLJA were significantly increased in the group over 70 years of age compared to the other age groups (p = 0.0002, <0.001). TLL was significantly decreased in the group over 70 years of age (p = 0.002), whereas the PI values were similar to PI even in over 70-year age group. LLL did not differ in the group over 70 years of age (p = 0.29), gradually increasing with an increase in age. SS was significantly decreased and PT was significantly increased in the group over 70 years of age as compared to the other age groups (p = 0.049, 0.049, respectively). PI was similar in all age groups (p = 0.75). Spinal balance was significantly decreased in the group over 70 years of age (p = <0.0001). PT was significantly associated with body protein mass and skeletal muscle mass (p = 0.01, 0.001, respectively). Body protein mass and skeletal muscle mass were significantly lower in the group over 70 years of age (p = 0.02, 0.02) and were possible causes.
Conclusions: Several sagittal and pelvic parameters are different in asymptomatic adults over 70 years of age. Decreased body protein mass and skeletal muscle mass are possible causes of these changes.