The effects of adult degenerative lumbar scoliosis on the facet joint contact forces: a finite element study

Adult degenerative lumbar scoliosis usually occurs in people aged over 45 years. Although its etiology is still unknown, it is well-accepted that the spinal disorder starts with the degeneration of the intervertebral disc. In this study, the influence of the disc degeneration on the facet joint contact force was investigated in four loading cases, i.e., straight-standing, flex/extension, lateral-bending and axial-rotation cases. First, a 3D finite element model of normal lumbar spine was validated, and further it was modified to simulate the degenerative scoliosis of lumbar spine by decreasing the disc height on one side and simultaneously altering its material properties. For all loading cases, the facet joint forces in the degenerated segment are much greater than the others. The present study can be helpful to understand the hyperostosis of the facet joints and pain in the lower back, and further to clinical application