The importance of sagittal balance for the treatment of lumbar degenerative disk disease

Abstract

The last two decades brought to light an important issue concerning degenerative disc disease: the sagittal balance of the spine. The search for a good sagittal balance is a natural intrinsic course of the aging human spine. During aging, degenerative changes occur, generally inducing loss of lordosis and/or increasing focal kyphosis. If the balance is disturbed, compensatory mechanisms may act. The original sagittal morphology of the spine, defined initially by the pelvic incidence, plays an important role in the way the spine may adapt itself to eventual degenerative aging changes. The functional pelvic parameters sacral slope and pelvic tilt represent the positioning of the pelvis in space and change according to balance needs. Roussouly et al. defined a geometrical classification of lordosis, according to spinopelvic parameters pelvic incidence and sacral slope, with four spinopelvic morphotypes of lumbar lordosis. These authors hypothesized that each type of lordosis would have a mechanical tendency to undergo certain patterns of degenerative changes. The importance of this hypothesis is that, if confirmed, it would bring extremely pertinent information concerning the natural history and treatment strategies for different spinopelvic morphotypes.