RADICALS GENERATED BY BONE CUTTING AND FRACTURE

When bone fractures, a remarkably high yield of radicals is generated. By working at 77K, these are stable enough for detection and study. M ajor species have been identified by ESR (EPR) spectroscopy as alkyl p eroxyl radicals and RCH(2)(.) radicals. Also, a species thought to be O-.- radicals, formed in the mineral phase, was detected in relatively low yield. It is suggested that as a break is generated, the mineral crystallites separate at grain boundaries with no major chemical damag e, but that the tightly bound collagen strands running through the min eral phase are forced to break homolytically. Some probably react toge ther, others react with oxygen, while the remainder are trapped in the ir primary form. The characteristic hyperfine triplet is assigned in p art to RCH(2)(.) radicals from glycine units, which constitute about o ne-third of the total amino acid components in collagen, and in part t o RNHCO radicals. The possible significance of the formation of active radicals during bone fracture is discussed.