Biomechanical analysis of the spino-pelvic organization and adaptation in pathology.

Introduction: Standing in an erect position is a human property. The pelvis anatomy and position, defined by the pelvis incidence, interact with the spinal organization in shape and position to regulate the sagittal balance between both the spine and pelvis. Sagittal balance of the human body may be defined by a setting of different parameters such as (a) pelvic parameters: pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS); (b) C7 positioning: spino-pelvic angle (SSA) and C7 plumb line; (c) shape of the spine: lumbar lordosis.

Sagittal parameters of the spine: biomechanical approach.

According to the anatomical segmentation, spine curves are the sacral kyphosis (sacrum), lumbar lordosis (L1 to L5), thoracic kyphosis (T1 to T12) and cervical lordosis (C1 to C7). From the morphological point of view the vertebrae of a curve are not identical: from cranial to caudal and vice versa there is a progressive anatomical modification. Both curves of the thoraco-lumbar spine may be divided at the Inflexion Point where lordosis turns into kyphosis.