The stabilizing axial spinal pillar in the lumbar spine

Abstract

Study design: A theoretical model of spinal stability is proposed. Objective: To present a biomechanical study in vitro using flexibility and loading tests of the normal lumbar spine and of two lumbar models of spinal stability in order to determine which of the lumbar middle-column model and the personal suggested model of lumbar central axial pillar is more resistant and stable. Setting: Hospital 'Sf. Treime', Iasi, Romania. Methods: Twenty-three fresh human cadaveric lumbar spines were tested with flexibility and loading tests of the intact lumbar functional units and of two types of spinal model specimens: 10 lumbar middle-column models and 13 lumbar central pillar model specimens. Parameters of vertebral motion and vertebral compression were compared to determine the differences between the types of spinal models. Results: The flexibility tests show a significant increase in motion of the lumbar middle-column model specimens compared to the lumbar central pillar model specimens. The lumbar central pillar model specimens are three times more stable compared to the middle-column models. The compression tests show that the lumbar central axial pillar model specimens were more resistant, on average by 10% (30% maximum) compared to the other model. Conclusions: The lumbar model formed by the axial overlapping of the posterior half moon of vertebral body continued by the pedicles and the articular processes is more stable and more resistant compared to the middle-column model of the three-columns theory of Denis. In the lumbar spine this central axis spinal pillar is the structure of spinal stability and resistance, and I propose this central axial spinal pillar as the stabilizing structure for all the spine.