Female Human Spines with Simulated Osteolytic Defects: CT-based Structural Analysis of Vertebral Body Strength.

Purpose To evaluate a CT structural analysis protocol (SAP) for estimating the strength of human female cadaveric spines with lytic lesions. Materials and Methods Osteolytic foci was created in the middle vertebra of 44 thoracic and lumbar three-level segments from 11 female cadavers (age range, 50-70 years). The segments underwent CT by using standard clinical protocol and their failure strength was assessed at CT SAP. The spines were mechanically tested to failure in pure axial compression or in compression with torsion. The relationships of defect size, bone mineral density, and predicted failure load (at CT SAP) with measured vertebral strength were assessed with linear regression. Analysis of variance and Tukey test were used to evaluate the effect of region and mechanical test on spine strength. Results With axial compression, CT SAP predictions of vertebral strength correlated with the thoracic (r = 0.84; P < .001) and lumbar (r = 0.85; P < .001) segment-measured strength. Bone mineral density correlated with the lumbar (r = 0.64; P = .003) and thoracic (r, 0.51; P = .050) strength. At compression with torsion, CT SAP predictions of strength were moderately correlated with vertebral strength (r = 0.66; P = .018). At compression with torsion, bone mineral density was not correlated with spinal strength (thoracic and lumbar: r = 0.31 and r = 0.26, respectively; P = .539 and .610, respectively). The lytic focus size (range, 28%-41%) was not associated with vertebral strength. Conclusion CT SAP assessment of strength in vertebrae with lytic lesions correlated with the measured strength of female vertebral bodies.