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Assessment of stress patterns on a spinal motion segment in healthy versus osteoporotic bony models with or without disc degeneration: A finite element analysis

BACKGROUND CONTEXT: With an increasing prevalence of low back pain, physicians
strive to optimize the treatment of patients with degenerated motion segments. There
exists a consensus in literature that osteoporotic patients exhibit nonphysiologic loading patterns,
while degenerated intervertebral discs (IVDs) are also believed to alter spine
biomechanics.
PURPOSE: To evaluate alterations occurring in lumbosacral spine biomechanics of an osteoporotic
model, with or without IVD degeneration, when compared with a healthy spine
segment.
STUDY DESIGN: The investigation was based on finite element (FE) analysis of a patientspecific
lumbosacral spine model.
METHODS: A biorealistic model of a lumbosacral spine segment is introduced to determine the
morbidity of disc degeneration and osteoporosis. The model was verified and validated for the purpose
of the study and subjected to a dynamic FE analysis, considering anisotropic bone properties
and solid ligamentous tissue.
RESULTS: The yielded results merit high clinical interest. Osteoporosis resulted in a nonuniform
increase of facet joint loading, which was even more pronounced in the scenario simulating a degenerated
disc. The results also revealed an enslavement of intradiscal pressure to the disc state (in
the degenerated and superior adjacent level).
CONCLUSIONS: The investigation presented refined insight into the dynamic biomechanical
response of a degenerated spine segment. The increase in the calculated occurring stresses
was considered as critical in the motion segment adjacent and superior to the degenerated
one. This suggests that prevalent trauma in a motion segment may be a symptomatic condition
of a poorly treated formal pathology in the inferior spine level. 2015 Elsevier Inc. All rights
reserved.