CT Hounsfield Units as a Predictor for the Worsening of Traumatic Vertebral Compression Fractures

Abstract

With vertebral compression fractures (VCF), height loss has been associated with kyphotic deformity and intractable pain, 2 indications for potential surgical intervention. Consequently, assessment of factors associated with continual height loss can provide insights regarding management. Computed tomography (CT) Hounsfield units (HU), a measure of radiodensity, have been implicated for the assessment of bone quality. No studies have assessed the relationship between CT HU and traumatic VCF. Consequently, the objective of this study was to evaluate this relationship. Patients who sustained a traumatic VCF from a motor vehicle accident from 2006 to 2015 were reviewed retrospectively. Inclusion criteria were single VCF from L1 to L4, appropriate imaging, and appropriate follow-up. Clinical data were extracted (age, gender, history of osteoporosis, body mass index [BMI], and length of follow-up). Initial CT imaging was evaluated for averaged HU at the levels above and below the index level of the VCF. Interval percentage change (Δ%) in anterior compression was evaluated between radiographs obtained during initial presentation and at follow-up. Age, BMI, and CT HU significantly correlated with Δ% (P < 0.01), whereas initial height loss, history of osteoporosis, and length of follow-up did not. A multiple linear regression for Δ% that combined age, BMI, and CT HU values elicited a regression model with R(2) 0.648, and adjusted R(2) 0.606; each variable in the model showed P<0.05. A receiver operating characteristic analysis to predict Δ% < 10% from Δ% ≥10% showed an area under the curve 0.983 (P < 0.01), where CT HU at 171.58 showed a combination of sensitivity at 0.923 and specificity at 0.91. Age, BMI, and CT HU values are independent predictors of worsening VCF. These factors can help determine appropriate clinical follow-up and need for surgical intervention.