Correlations between uptake of technetium, calcium, phosphate, and mineralization in rat tibial bone repair

Technetium-99m-(^99mTc) phosphates are extensively used for detection of bone formation and resorption. The present is a study of ^99mTc incorporation during bone remodeling. Uptake of ^99mTc-labeled phosphate was studied in an animal model of primary osteogenesis following tibial marrow injury and incorporation was correlated to that of calcium-47 (⁴⁷Ca), phosphorus-32 (³²P), and with matrix vesicle calcification. Isotope uptake on Day 6 in the whole bone was increased compared to controls. On this day, an increase in vesicular diameter and distance from the calcified front was previously observed. Technetium-99m-labeled phosphates were detected only in the organic phase. Phosphorus-32 and ⁴⁷Ca were detected in both organic and inorganic phases. It is suggested that ^99mTc serves as a specific marker to the anabolic phase of remodeling. Increased incorporation of ^99mTc during bone healing indicates enhanced organic matrix formation and not calcification.