Effects of Traction on Interpretation of Lumbar Bone Mineral Density in Patients with Duchenne Muscular Dystrophy: A New Measurement Method and Diagnostic Criteria Based on Comparison of Dual-Energy X-Ray Absorptiometry and Quantitative Computed Tomography

Introduction: This study aimed to compare the performance of dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) in evaluating bone mineral density (BMD) of patients with Duchenne muscular dystrophy and scoliosis. Methodology: Twenty-nine participants (mean age 19.72 +/- 6.13 years) underwent whole spine radiography, DXA before and after traction, and QCT alone without traction. Scoliosis and vertebral rotation angles obtained before and after traction were compared, and BMD values from DXA were compared to those obtained via QCT. The scoliosis angle, presented as Cobb's angle of L1-L4, was measured. Results: Cobb's angle significantly decreased from 30.38 degrees +/- 24.83 degrees before traction to 22.78 degrees +/- 20.41 degrees after traction (p < 0.0001) and the Z-score decreased from -1.88 +/- 1.59 to -2.86 +/- 2.16 (p < 0.0001). Changes in rotation angle, BMD, and bone mineral content were not significant. Post-traction BMD values and Z-scores showed a higher correlation with QCT measurements than pretraction. Moreover, pre and post-traction Z-scores (<= -1.1 and -1.36, respectively) were more accurate in identifying patients with osteoporosis according to QCT scans compared with the preexisting Z-score of -2 or less. Conclusion: Lumbar BMD measured via DXA and scoliosis allowed a more accurate diagnosis of osteoporosis when traction was applied.