Diagnostic Accuracy of Dynamic Supine-to-Sitting Radiography for Acute Osteoporotic Vertebral Fractures. A Preliminary Single-Center Diagnostic Accuracy Study
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Background
Acute osteoporotic vertebral fractures (OVFs) may be difficult to detect on conventional radiographs, particularly before substantial vertebral collapse occurs. Comparing supine and sitting lateral radiographs may reveal load-dependent vertebral mobility. This preliminary study evaluated the diagnostic accuracy of supine-to-sitting dynamic radiography for detecting MRI-confirmed acute OVFs.
Methods
This retrospective, single-center diagnostic accuracy study included consecutive patients who underwent paired supine and sitting lateral radiography and MRI of the same spinal region between April 2024 and July 2026. Dynamic radiographs were interpreted by a board-certified orthopedic and spine surgeon who was blinded to the MRI findings. MRI was independently interpreted by a second board-certified orthopedic surgeon and served as the reference standard. The primary outcome was patient-level sensitivity and specificity. Vertebra-level diagnostic accuracy was evaluated secondarily, with patient-cluster bootstrap confidence intervals used to account for within-patient correlation.
Results
Sixty-three patients (mean age, 80.6 ± 9.0 years; 51 women [81.0%]) and 490 evaluable vertebrae were analyzed. MRI identified acute OVFs in 34 patients and 36 vertebrae. At the patient level, dynamic radiography yielded 31 true-positive, no false-positive, three false-negative, and 29 true-negative results. Sensitivity was 91.2% (95% confidence interval [CI], 76.3%–98.1%), specificity was 100.0% (95% CI, 88.1%–100.0%), positive predictive value was 100.0%, negative predictive value was 90.6%, and overall accuracy was 95.2%. At the vertebral level, sensitivity was 91.7% (33/36; patient-cluster bootstrap 95% CI, 81.3%–100.0%) and specificity was 100.0% (454/454). The three missed fractures involved T9, L2, and L3. No false-positive vertebrae were observed.
Conclusions
Supine-to-sitting dynamic radiography demonstrated high patient-level sensitivity and no observed false-positive findings for MRI-confirmed acute OVFs. It may provide a practical complementary diagnostic option when MRI is not immediately available. However, a negative dynamic radiographic examination does not exclude an acute fracture, and the apparent perfect specificity requires validation in larger, prospective multi-reader studies.
