Effect of Phosphoric Acid Esters on Fracture Healing.

Abstract

The erythrocytes contain an abundance of phosphoric esters hydrolyzable by phosphatase, but the plasma contains only 0.2-0.5 mg phosphorus per 100 cc in the form of phosphatase hydrolyzable esters. The phosphatase activity of a fracture callus increases rapidly beginning 3-4 days after the injury.,, Although the site of an old fibrous non-united fracture may exhibit low phosphatase activity and infected fractures contain somewhat reduced amounts of this enzyme there is no evidence that defective calcification of bone or delay in fracture healing is primarily a result of a quantitative deficiency of this enzyme. It appears possible that one of the factors limiting the speed of the calcification process is the low content of plasma with respect to the substrate of bone phosphatase and this consideration suggested that some cases of delayed or nonunion of fractures might be so explained. It seemed desirable, therefore, to investigate the effect of the intravenous injection of sodium betaglycerophosphate on the healing of fresh fractures. The right radius of rabbits, weighing between 4.25 and 4.75 lb, was fractured while the animals were anesthetized. The fractures were produced by grasping the middle of the shaft of the bone between two adjacent and parallel Kocher forceps and exerting steady rotation of the forceps in opposite direction until the bone was heard to break. A few animals, in which breaks of both the radius and ulna were produced, or which displayed marked bruising of the skin, were discarded. Roentgenological examination showed that the fractures usually were transverse and that the fragments were in good alignment with little comminution of the bone. The undamaged ulna served as an effective splint and the animals were able to use the limb upon recovery from the anesthesia.