Compensatory mechanisms contributing to keep the sagittal balance of the spine.
BACKGROUND
Aging spine is characterized by facet joints arthritis, degenerative disc disease, bone remodeling and atrophy of extensor muscles resulting in a progressive kyphosis of the lumbar spine.


OBJECTIVE
The aim of this paper is to describe the different compensatory mechanisms for patients with severe degenerative lumbar spine.


METHODS
According to the severity of the imbalance, three stages are observed: balanced, balanced with compensatory mechanisms and imbalanced. For the two last stages, the compensatory mechanisms permit to limit the consequences of loss of lumbar lordosis on global sagittal alignment and therefore contribute to keep the sagittal balance of the spine.


RESULTS
The basic concept is to extend adjacent segments of the kyphotic spine allowing for compensation of the sagittal unbalance but potentially inducing adverse effects.


CONCLUSIONS
Finally, we propose a three-step algorithm to analyze the global balance status and take into consideration the presence of the compensatory mechanisms in the spinal, pelvic and lower limb areas.
Department of Neurosurgery C and Spine Surgery, Neurological Hospital, 59 boulevard Pinel, 69394, Lyon, France, c.barrey@wanadoo.fr.
Cédric
C
Barrey
Pierre
P
Roussouly
Jean-Charles
JC
Le Huec
Gennaro
G
D'Acunzi
Gilles
G
Perrin
D000465:Algorithms; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology / Q000503:physiopathology*; D008953:Models, Anatomic; D008954:Models, Biological; D010388:Pelvis / Q000000981:diagnostic imaging / Q000502:physiology; D004856:Postural Balance / Q000502:physiology; D011187:Posture / Q000502:physiology; D011859:Radiography