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

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