Scintigraphic studies to evaluate stability of ceramics (hydroxyapatite) in bone replacement.

In this study, the suitability of a radionuclide bone imaging technique was examined in cases of hydroxyapatite implants for segmental replacements of long bones. The radionuclide bone imaging technique, using [99mTc]MDP was applied to estimate osseous changes at the sites of the hydroxyapatite implants up to 2 yr after their implantation in an animal experimental model. The results were correlated with histological and radiographical findings at the same time. The radionuclide bone imaging with technetium proved to be a useful method to estimate the intensity of osseous changes after bone replacement by a hydroxyapatite implant. It proved to be more sensitive than radiography. The differences in elasticity of the implanted material and adjacent bone may cause an increase of radionuclide uptake at the site of the implant 2 yr after implantation. These osseous changes cannot be detected by standard histological and radiographical methods but could be detected by radionuclide bone imaging. It is submitted that the radionuclide bone imaging is a noninvasive, sensitive, and useful method for the estimation of osseous changes in sites of long term bone implants.