Comparison between the effects of dexamethasone and indomethacin on bone wound healing

The area of wound holes made in the parietal bone of 4-week-old rats was measured at 1, 2 and 4 weeks after the operation using Alizarin red S staining without the use of histological sections. Dexamethasone and indomethacin were administered s.c. after the operation every day except Sunday. The inhibitory action of dexamethasone on bone wound healing was stronger than that of indomethacin, as was its inhibitory action on skin wound healing. Inhibition of the age-related decrease in radiolucency of femurs and some changes in serum calcium level were also observed by dexamethasone administration, but not by indomethacin. These results suggest that dexamethasone inhibits bone wound healing through its effects on calcium metabolism in addition to its general inhibitory action on wound healing which is shared with indomethacin. Dexamethasone also strongly inhibited the decrease in Alcian blue stainability which occurs with an increase in age, both in the normal portion and in the wound hole portion of the calvaria, whereas indomethacin showed a weak inhibitory effect only in the wound hole portion. This result suggests that one of the mechanisms by which dexamethasone inhibits bone wound healing may be based on the retardation of mineralization caused by the inhibition of removal of acid mucopolysaccharide.