The Effect of Locally Applied Heat on Bone Growth. II

¹ Fairleigal Dickinson University, Teaneck, New Jersey

In order to study in some detail the effect of locally applied heat on bone growth, rabbit mandibles and crania ( in which a small excavation was made) were heated by induction. Vitallium units were surgically applied to the bone, and heat was produced by placing the animal with the unit in a high-frequency electric field. Heating lasted for 5 hours daily for from 10 to 24 days. At sacrifice, the heated bones and their controls were observed grossly and subsequently sectioned for histological study.

Ridges of bone grew around the heated units on the mandibles. The heated mandible halves were also heavier than the unheated halves. Histological observations show that these ridges contain osteoid tissue, bony trabeculae, and mature lamellated bone. Some trabecular formation was observed adjacent to the unheated units, but it was far less extensive.

A white connective-tissue growth was observed around all units attached to the parietal bone, both heated and unheated.

Histological studies revealed little difference between the heated and unheated bones, especially in regard to the amount of bone formation in the cavities previously made. In the heated cavitations there is a somewhat greater degree of formation of trabeculae from osteoblasts which have differentiated from fibroblasts.

The growths observed at the edge of the unit contain cancellous bone which is usually greater in the heated crania.

It is concluded that locally applied heat has caused extensive growth of bone in the rabbit mandible but more study is required before definite statements can be made about the crania.