Lumbar vertebral body compressive strength evaluated by dual-energy X-ray absorptiometry, quantitative computed tomography, and ashing

Bone densitometry with DXA (dual energy X-ray absorptiometry) and QCT (quan titative computed tomography) techniques are used for in vivo assessment of bone strength and thereby prediction of fracture risk, However, only few i n vitro studies have investigated and compared these techniques' ability to determine vertebral compressive strength, The aim of the present study was to (1) assess the predictive value of DXA, QCT, and pQCT (peripheral QCT) for vertebral bone compressive strength assessed by mechanical testing; (2) describe both linear and power relationship between density and strength; and (3) evaluate whether gender-related differences in the above relations were present. The material comprised human lumbar vertebrae L3 from 51 wome n and 50 men (age range: 18 to 96 years). The study showed that both DXA an d CT techniques (QCT and pQCT) have a high predictive value for vertebral s trength. The DXA BMD had a high correlation with maximum compressive load ( r(2) = 0.86), The QCT and pQCT had high correlations with maximum compressi ve stress (r(2) = 0.75 and r(2) = 0.86, respectively). The correlation betw een ash density of the biomechanically tested specimen and maximum compress ive stress was r(2) = 0.88, There were no differences between linear and po wer fit in the degree of determination between density and strength. There was no gender-related difference in the relationship between volumetric den sity and maximum compressive stress. In conclusion, it was demonstrated tha t DXA, QCT, and pQCT are ex situ equally capable of predicting vertebral co mpressive strength with a degree of determination (r(2)) between 75% and 86 %. No differences were found between linear and power analysis of the relat ionship between density and strength, and no difference was found in the de nsity strength relationship between women and men, (C) 1999 by Elsevier Sci ence Inc. All rights reserved.