The Canal Bone Ratio: A Novel Indicator for Opportunistic Osteoporosis Screening in Adult Spinal Deformity Patients Through Radiographs.

Study design: Retrospective diagnostic study.

Objectives: To evaluate the utility of quantitative assessment of bone density using proximal femoral morphological parameters based on full-spine x-rays.

Summary of background data: CT and MRI are commonly utilized methods for opportunistic assessment of bone density. However, there is currently a lack of means to quantitatively assess bone density in adult spinal deformity (ASD) patients through radiographs.

Methods: Data collection involved medical records of ASD patients treated at our hospital. Patients were categorized into osteoporotic and nonosteoporotic groups based on dual-energy x-ray absorptiometry T-scores. Demographic information, radiographic parameters (canal bone ratio, canal bone ratio (CBR); cortical bone thickness, cortical bone thickness (CBT)), Hounsfield units, and vertebral body quality (VBQ) scores were compared. Pearson correlation analysis was conducted to assess the correlation between CBR, CBT, and T-scores. Multiple linear regression analysis identified independent predictors of bone density T-scores. Receiver operating characteristic curves and area under the curve calculations were performed to investigate the predictive performance for osteoporosis.

Results: A total of 102 patients were included, with the osteoporotic group showing larger CBR and smaller CBT compared with the nonosteoporotic group. Proximal femoral morphological parameters exhibited the strongest correlation with total hip T-scores. Advanced age (β=-0.028, 95% CI=-0.054 to -0.002, P =0.032), low BMI (β=0.07, 95% CI=0.014-0.126, P =0.015), and high CBR (β=-7.772, 95% CI=-10.519 to -5.025, P <0.001) were identified as independent predictors of low bone density. Receiver operating characteristic analysis demonstrated that CBR had a similar osteoporosis screening capability as Hounsfield units, followed by CBT and VBQ scores.

Conclusions: The utilization of CBR from full-spine x-rays is a simple and effective osteoporosis screening indicator for ASD patients, facilitating bone density assessments by spine surgeons for all attending patients.