This paper proposes an anatomical parameter, the pelvic incidence, as the key factor for managing the spinal balance. There is a close relationship for both normal individuals and those with spinal deformities between the anatomical parameter of pelvic incidence and the sacral slope, which determine lumbar lordosis. The Cobb angle and the apical vertebral rotation serve as a tool for understanding the three-dimensional aspect of the spine and its relationships with the pelvis. A predictive equation of lordosis is postulated. The pelvic incidence seems to be the determining factor of the sagittal balance of the spine. It determines spinal curves and varies according to other parameters.
Pélvis; Lordosis; Scoliosis; Sagital balance; Posture
