Lower Preoperative Hounsfield Units Predict Distal Junctional Kyphosis After Posterior Cervical Decompression and Fusion

INTRODUCTION: Low bone mineral density (BMD) may predispose patients to structural and adjacent segment complications after spine surgery. While dual energy X-ray absorptiometry (DEXA) remains the gold standard for BMD quantification, it is rarely performed on a routine basis prior to cervical fusion. Alternatively, vertebral body Hounsfield Units (HU) may provide useful and convenient estimates on BMD. However, minimal evidence exists to evaluate the value of HU in predicting postoperative complications after cervical fusion. METHODS: A retrospective, single-institution analysis was conducted, focusing on patients who underwent PCDF without a history of cervical spine surgery. Preoperative vertebral body HU were measured at each level of the cervical spine, and demographic, clinical, and postoperative complication data were recorded. RESULTS: 166 patients were eligible for inclusion (mean age 66 ± 12 years), with an average follow-up time of 13.5 months. In a multivariate logistic regression analysis, controlling for age, gender, and construct length, lower HU at the superior instrumented level were associated with increased rates of distal junctional kyphosis (p = 0.042, AUC = 0.86). Additionally, lower HU at the superior adjacent level were associated with increased rates of revision surgery (p = 0.016, AUC > 0.99). CONCLUSIONS: Preoperative cervical HU offer valuable insight in anticipating structural complications after PCDF, and HU may be useful for identifying patients who require preoperative BMD optimization.