Influence of metallic implants adjacent to the measurement site on DEXA measurements: a phantom study.

The use of dual-energy x-ray absorptiometry (DEXA) to measure changes in bone mineral density (BMD) at a healing fracture may be limited by the presence of a steel implant, such as an intramedullary nail or internal fixation plate. To determine the effect of steel implants adjacent to the measurement site on BMD measurements, tests were conducted on three geometries of steel and aluminium phantom. Analysis of variance performed on the BMD data from scans of the aluminium phantoms with and without steel present indicated that the steel had no effect on the results obtained at the 5% significance level. These results imply that the presence of a steel implant adjacent to an area of interest, for example a healing fracture, would not affect the reliability of DEXA scans, and that this method of monitoring healing could therefore be used with fractures stabilized by internal fixation.