Resorption of, and bone formation from, new β‐tricalcium phosphate‐monocalcium phosphate cements: An in vivo study

Hard cylinders (4.7 × 10 mm) of two kinds of β-tricalcium phosphate-monocalcium phosphate monohydrate-calcium sulfate hemihydrate (β-TCP-MCPM-CSH) cements with and without β-TCP granules (500–1000 μm) were implanted into holes drilled in rabbit femoral condyles for up to 16 weeks. Empty cavities were used as control. Cement resorption and new bone formation in the cylinders were evaluated with contact microradiography and quantified through an automatic image analysis system. At 4 weeks, both kinds of cement cylinders were surrounded by new bone. At 8 weeks, except for β-TCP granules, both cement cylinders were almost completely resorbed and replaced by bone tissue. At 16 weeks the bone in the cavities of both cements recovered a trabecular pattern, but only the bone trabeculae in the initial cavity of the cement with β-TCP granules became thick and mature. However, the cavities of the empty control were still empty and large. These results show that the β-TCP-MCPM-CSH cements stimulate bone formation and are rapidly replaced by bone tissue. When added with nonresorbable β-TCP granules, this cement maintains bone formation for a longer time. © 1996 John Wiley & Sons, Inc.