Mechanical assessment of the effects of metastatic lytic defect on the structural response of human thoracolumbar spine

Ron N. Alkalay, Timothy P. Harrigan

Research output: Contribution to journalArticlepeer-review

Abstract

To investigate the effects of a clinical lytic defect on the structural response of human thoracolumbar functional spinal unit. A novel CT-compatible mechanical test system was used to image the deformation of a T12-L1 motion segment and measure the change in strain response under compressive loads ranging from 50 to 750 N. A lytic lesion (LM) with cortex involvement (33% by volume) was introduced to the upper vertebral body and the CT experiments were repeated. Finite element models, established from the CT volumes, were used to investigate the defect's effects on the structural response and the state of principal and shear stresses within the affected and adjacent vertebrae. The lytic lesion resulted in severe loss of the vertebral structural competence, resulting in significant, non-linear, and asymmetric increase in the experimentally measured strains and computed stresses within both vertebrae (p < 0.01). At the cortex, the tensile strains were significantly increased, while compressive strains significantly decreased, (p < 0.05). Both the vertebral bone and cortex regions adjacent to the defect showed significant increase in computed compressive, tensile, and shear stresses (p < 0.01). Changes in stress and strain distribution within the affected and adjacent vertebral bone and the experimentally observed bulging and buckling of the vertebral cortices suggested that initiation of catastrophic vertebral failure may occur under load magnitudes encountered in daily living. Although the effect of LM on the global deformation of the spine was well-predicted, our results show that FE predictions of local strain changes must be carefully assessed for clinical relevance.

Original languageEnglish (US)
Pages (from-to)1808-1819
Number of pages12
JournalJournal of Orthopaedic Research
Volume34
Issue number10
DOIs
StatePublished - Oct 1 2016

Keywords

  • experimental study
  • finite element model
  • human spine
  • mechanical response
  • osteolytic defect

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

Fingerprint

Dive into the research topics of 'Mechanical assessment of the effects of metastatic lytic defect on the structural response of human thoracolumbar spine'. Together they form a unique fingerprint.

Cite this