Trabecular and cortical bone mineral density in human vertebrae: comparison of frozen and thawed States with qCT

PURPOSE: Bone mineral density (BMD) is a key determinant of skeletal strength, relevant in many disciplines. Freezing is widely used to preserve cadaveric bone, but its effect on BMD remains controversal. This study assessed whether a vBMD is altered in frozen versus thawed state of human vertebral bodies measured by quantitative computed tomography (qCT). MATERIALS AND METHODS: Thirty-three human vertebrae (14 C7, 9 Th1, 10 Th2) were stored at - 20 °C. Trabecular and cortical vBMD were measured in the frozen state (- 15 to - 20 °C) using qCT with a calibration phantom. After thawing overnight at room temperature, identical scans were performed. Paired t-tests and Pearson correlation coefficients compared frozen and thawed values. RESULTS: One trabecular specimen was excluded as an outlier. Mean trabecular volometeic bone mineral density (vBMD) was 154.68 mg Ca-HA/ml (frozen) vs. 148.93 mg Ca-HA/ml (thawed), mean difference - 5.74 mg Ca-HA/ml (p = 0.164). Cortical vBMD was 219.56 mg Ca-HA/ml (frozen) vs. 219.90 mg Ca-HA/ml (thawed), mean difference 0.34 mg Ca-HA/ml (p = 0.948). Correlations between frozen and thawed values were strong (r = 0.89 trabecular; r = 0.94 cortical). CONCLUSION: A single freeze-thaw cycle at - 20 °C does not significantly alter cortical or trabecular vBMD in human vertebral bodies measured by qCT. These results support the measurement of BMD of frozen specimens, minimizing handling and avoiding unnecessary thawing in research and forensic settings.