Oxidative Metabolism of Healing Avian Bone Fractures: Effects of Estrogen and Hypergravity

Abstract

Two week old female Rhode Island Red chicks were subjected to closed fracture of the right radius in order to study the effect of estrogen and a 2 g hypergravity environment on post fracture metabolism of callus. The healing area showed a well formed callus after 1 week with a high degree of calcification in 2 weeks. Callus wet weight was lower in normogravity animals receiving estrogen for 1 week. Callus wet to dry weight ratios were significantly lower 2 weeks post fracture due to the increased mineralization. Mean wet weight of callus after 2 weeks of healing was 28% lower than one week control. Administration of estrogen lowered the observed wet weights. Exposure to a 2 g environment for 1 or 2 weeks tended to decrease the mean weight of callus as compared to normogravity control values, and 0.4 mg estrone produced a further decrease in wet weight. The oxidative metabolism of minced callus was significantly increased after 2 weeks of healing due to the large number of actively metabolizing cells. The estrogen treated normogravity and hypergravity exposed chicks showed significantly greater callus oxygen uptake as compared to normogravity saline injected controls at 2 weeks.