Hounsfield unit values are a better predictor than DXA T-score for adjacent vertebral fracture following balloon kyphoplasty.

Abstract

Background: Hounsfield unit values (HU) are known to correlate with dual-energy X-ray absorptiometry (DXA), and they are gaining attention as a new method for assessing Bone mineral density (BMD) that is not affected by the limitations of DXA, such as degeneration, scoliosis, and vascular calcification. The purpose of this study was to compare the efficacy of HU and DXA T-scores in predicting adjacent vertebral fractures (AVF) following balloon kyphoplasty (BKP) using the same computed tomography and DXA at one institution.

Methods: The study included 84 cases (20 males, 64 females, mean age 79.3 ± 6.9) who underwent BKP for osteoporotic vertebral fractures. Cases were divided into two groups based on the presence or absence of AVF within 2 months postoperatively. BMD assessment included DXA T-scores (lumbar spine, hip, the lowest), HU of the fractured adjacent vertebra (adjacent-HU) and HU of the L1 vertebra (L1-HU). Logistic regression analysis was performed to identify risk factors for AVF, and the accuracy of AVF prediction was evaluated using the area under the receiver operating characteristics curve (AUC).

Results: AVF occurred in 23 of the 84 cases (27.4 %) within 2 months postoperatively. In the logistic regression analysis, T-score was not identified as an independent risk factor, but L1-HU was identified as an independent risk factor for AVF (odds ratio: 0.982, P = 0.044∗). The AUC for predicting AVF was 0.515, 0.568, and 0.510 for T-score (lumbar spine, hip, the lowest), and 0.551 for adjacent-HU. The highest AUC was observed for L1-HU at 0.629 (95 % confidence interval 0.495-0.764).

Conclusions: In the risk assessment of AVF, L1-HU was a better evaluation method than DXA T-score.