['Cross-sectional study and systematic review of the literature.', 'Describe the natural history of spinopelvic alignment parameters and their behavior in patients with degenerative spinal deformity.', "Normal stance and gait requires congruence between the spine-sacrum and pelvis-lower extremities. This is determined by the pelvic incidence (PI), and 2 positional parameters, the pelvic tilt, and sacral slope (SS). The PI also affects lumbar lordosis (LL), a positional parameter. The final goal is to position the body's axis of gravity to minimize muscle activity and energy consumption.", 'Two study cohorts were recruited: 32 healthy teenagers (Risser IV-V) and 54 adult patients with symptomatic spinal deformity. Standing radiographs were used to measure spinopelvic alignment and positional parameters (SS, PI, sacral-femoral distance [SFD], C7-plumbline [C7P], LL, and thoracic kyphosis). Data from comparable groups of asymptomatic individuals were obtained from the literature.', 'PI increases linearly with age (r2 = 0.8646) and is paralleled by increasing SFD (r2 = 0.8531) but not by SS. Patients with symptomatic deformity have higher SFD (42 +/- 13.6 mm vs. 63.6 +/- 21.6 mm; P < 0.001) and lower SS (42 degrees +/- 9.6 degrees vs. 30.7 degrees +/- 13.6 degrees; P < 0.001) but unchanged PI. The C7P also presents a linear increase throughout life (r2 = 0.8931), and is significantly increased in patients with symptomatic deformity (40 +/- 37 mm vs. 70.3 +/- 59.5 mm; P < 0.001).'] Does natural history of spinopelvic alignment differ from symptomatic deformity of the spine?