Studies on Bone Fracture Healing

Abstract

A method for studying healing in standard fractures of the rat fibula is described, in which calcification activity is determined by measuring the uptake of Sr* by the callus, and functional recovery by the increase in breaking strength of the fractured bone. In normal rats, the most active calcification in the callus occurs over the period from 8 to 16 days. The broken bone attains a strength comparable to that of the normal bone on the opposite side within 12 to 16 days. In vitamin A deficient rats, the callus is smaller than in normal animals, and the calcification is less active. In those treated with large doses of the vitamin the increase in strength of the fractured bone was comparable to that in normal rats. On the other hand the untreated animals showed a significant delay in fracture healing. This may have been due to the debilitated condition of the latter. In rachitic animals, there is no significant calcification of the callus, unless vitamin D is added to the diet. In animals receiving toxic doses of vitamin D, the callus is small, calcification activity is reduced, and recovery in strength is delayed.