Remodeling of the avian fracture callus by estrone treatment and exposure to a 2 g environment.

Rhode Island Red female chicks were subjected to complete closed fracture of the right radius at two weeks post hatching. The animals were allowed to heal for 2 weeks at either earth gravity (1 g) or a 2 g environment with saline injected controls and estrone injected experimentals. Total fractured bone weight was decreased by exposure to the 2 g environment regardless of whether the animal received saline or estrone treatment. The mean weight of fracture callus was significantly decreased when the hypergravity exposed animals received low hormonal levels of 0.2 mg estrone. The average mid-cross sectional diameter of fracture callus was significantly decreased when the centrifuged chicks received saline or 0.2 mg estrone and it was increased with the administration of high hormonal levels of 0.4 mg to the 2 g animal. The mean thickness of the subperiosteal trabeculae of the bridging callus was decreased by exposure to hypergravity either with or without estrone treatment.