Adult spinal deformities are a difficult and much debated focus of spinal surgical treatment. Etiology What is the universal staging of adult spinal deformities? As far as we know, the aging process includes segmental (changes between individual vertebrae), regional (cervical, thoracic, lumbar, or sacral), and global (encompassing the entire spine) changes in spinal forces. However, when these regions fail to balance each other’s curvatures, or when there is ligamentous muscle instability, it can develop into a poor force line and significant sagittal imbalance in the entire spine. Aging alone will only result in significant sagittal deformities. In the case of coronal deformities, aging can also cause loss of force lines or intervertebral subluxation (usually rotation and lateral displacement of the vertebrae and some degree of vertebral slippage) in some segments. This can result in scoliosis deformity (degenerative scoliosis). Another important subtype regarding adult coronal facet deformity is where the patient already had some degree of deformity before skeletal maturity, but was not aware of it (most commonly adult idiopathic scoliosis). With aging, the childhood deformity worsens and presents with significant pain or reduced activities of daily living.