1. A method is described for making uniform lesions in the bone to permit a study of its healing.
2. A method of using radio-active tracers to stutdy the healing of bone in vivo is described.
3. The uptake by healing bone of radiophosphorus and radiostrontium is determined at different. stages in the healing process.
4. The uptake by healing bone of phosphorus and strontium is compared.
5. The effect of the age of the animals upon the uptake of phosphorus in the healing of bone is studied.
6. In young animals, the latent period for an increased uptake of phosphorus is shorter than in older animals (2 as compared with 4 days).
7. The maximum uptake of phosphorus and strontium occurs on the eighth to the tenth day in young rats, as compared with the maximum of 15 days reached in old rats. This parallels the gross healing of the old and young bones.
8. By comparing the ratio of uptake of strontium and phosphorus, it is seen that this ratio tends to increase later in the healing process; it may be possible to utilize this tendency to differentiate between the proliferating and the calcifying stages of bone healing.