No effect of growth hormone on recovery of load-protected bone. Cortical bone mass and strength studied in rabbits.

The effect of human growth hormone on the recovery of a previously atrophied diaphyseal bone, stress-shielded by plating, was studied in 56 adult rabbits using the contralateral tibia as a control. At removal of the plates, an initial 40 per cent reduction of torsional strength was seen. The strength was normalized in 3 weeks. A concomitant reduction of bone mineral density was normalized in 1.5 weeks. No difference in the rate of strength regeneration was found between growth hormone-treated rabbits and controls. In the treated rabbits an increase in cortical bone area due to subperiosteal new bone formation was seen in previously plated bones, as well as in sham-operated bones.