The assessment of fracture healing using dual x-ray absorptiometry: a feasibility study using phantoms

Tissue substitute materials of water and Perspex for soft tissue and aluminium and hydroxyapatite for bone have been combined into phantoms to simulate tibial fractures and have been used to assess the viability of using dual x-ray absorptiometry to quantitatively measure changes in bone density during fracture healing. It was found that it was possible to detect small gaps created in the aluminium phantoms to simulate a tibial fracture down to a gap size of 0.95 mm with the gap oriented both parallel and perpendicular to the x-ray beam. The mass and area density of small samples of calcium hydroxyapatite were found to be closely correlated with the values of bone mineral content (r2 = 0.97) and density (r2 = 0.99) given by the scanner, and low values of bone mineral content and density, which might be expected around a healing fracture, could be precisely measured. Reproducibility of the results was found to be good with a coefficient of variation of less than 1.5%.