Accuracy of dual photon absorptiometry in excised femurs

We investigated the accuracy of assessment of bone mineral content (BMC) by dual photon absorptiometry (DPA). Measurements were compared between BMC and ashed weight using two related scanners. The BMC in different locations of the femur was determined. Twelve cadaver femurs were cleaned of all soft tissue, divided into four parts (head, neck, trochanteric region, and shaft), and measured for BMC in an ethanol/water solution. The bones were then ashed and weighed. Volumetric density was also determined. The correlation coefficient between ash weight and BMC was 0.99 with an s.e.e. of 0.51 g and relative error of 4.8%. Similar correlations were seen within each region. The correlation between the machines was 0.99. Differences in volumetric density were found, with the density of the shaft greater than other regions, and the neck greater than the head or trochanteric regions.