Evaluating the density of fracture callus from radiographs and by quantitative CT

Fracture healing and callus formation have traditionally been evaluated by using X-ray radiography. Here we compared X-ray radiography and peripheral quantitative computed tomography (pQCT) in evaluating the density of healing callus of tibial fractures in 141 female rats. The densitometric results were compared with the tensile and compressive failure load of the callus. The mean optical density (MOD) of the callus analyzed from the radiographs had only a weak correlation with the pQCT-defined bone mineral density (BMD) of callus (r=0.21, p<0.05). A slightly higher correlation was found between MOD and bone mineral content (BMC) (r =0.28, p<0.001). MOD did not correlate with the tensile or compressive failure load of callus. pQCT-defined BMC and BMD were associated with the compressive failure load (r=0.42-0.57, p<0.001), while both radiographs and pQCT were poor in explaining the failure load in tension