Fundamental study on the healing of bone injuries with bone scintigraphy and xeroradiography

The healing process of bone injuries in the rat mandiblae was examined with bone scintigraphy, soft X-ray radiography, xeroradiography and microradiography. Fifty rats of about 200 g were offered to this study and fractures were experimentally produced in the left mandiblae. Five of them were examined with bone scintigraphy using a pinhole collimeter improved by Kaneko and his co-workers, and the others were examined with soft X-ray radiography, xeroradiography and microradiography. These radiological observations were carried out immediately, 4 days, 7 days, 14 days, 28 days, 35 days, 42 days and 49 days after fracturing. Histological examinations, in addition, were made to evaluate the relationships between the findings. The bone scintigrams obtained on the 4th day showed a slight uptake of 99mTc, although no noteworthy findings were demonstrated on the soft X-ray radiograms and xeroradiograms. The uptake of 99mTc was gradually increased. The most remarkable accumulation was seen on the 21st day after fracturing. The bone scintigrams obtained on the 49th day showed as same images as were obtained from the normal rats. Soft X-ray radiograms and xeroradiograms demonstrated no changes in radiolucency until the 4th day after fracturing, although the bone scintigrams revealed an uptake of 99mTc. The radiopacity was gradually increased until the 49th day. Microradiograms obtained on the 4th day revealed some early changes, which appeared on the periosteal regions. New callus formation was observed from the 7th day after fracturing. The calcification of new callus was gradually increased until the 49th days. Histological findings obtained on the each stages supported these findings. (author)