Variability of mineral density in coralline hydroxyapatite spheres: study by quantitative computed tomography

Quantitative computed tomography (qCT) can be employed to determine the mineral density (MD) of bone or similar mineralized alloplastic materials with high precision. Porous spheres made from coralline hydroxyapatite are currently used for reconstruction after enucleation procedures. The long-term fate of these implants is unknown. Using qCT, MD was determined in hydroxyapatite spheres prior to implantation. Intersphere MD varied up to 200% with a near Gaussian distribution. Intrasphere MD did not vary significantly when comparing central to peripheral sites. The density of coralline hydroxyapatite spheres was approximately 400% greater than the density of newly formed endochondral bone. This study demonstrates that qCT data were an invaluable tool for MD determination, detecting a marked variability in hydroxyapatite MDs. Because the long-term fate of these implants is unknown and fibrovascular ingrowth is an important event in the integration of these implants, monitoring of MDs of coralline hydroxyapatite implants is of interest.