Chemical sterilization of bacterially contaminated bone without destruction of osteogenic potential

A method to sterilize bone that has been contaminated or to assure sterility of allografts would be quite useful in the practice of orthopedics. The literature documents the osteogenic potential of demineralized bone matrix, prepared by treatment with hydrochloric acid and ethanol. We became interested in whether these potent antibacterial agents could render contaminated bone sterile and thus usable. Thus, we tested immersion in 70% ethanol or 0.6 N hydrochloric acid as sterilization methods for contaminated bone specimens. Bone fragments were (heavily) surface contaminated for 30-60 s by immersion in a suspension of either Escherichia coli, Staphylococcus aureus, or Bacillus subtilis and then placed in either the ethanol or hydrochloric acid solutions for 15 min, 30 min, 1 h, 2 h, 4 h, or 8 h. Subsequently, they were incubated in broth culture for 14 days. Using 70% ethanol, 80-90% of contaminated bone specimens were sterile in 4 h and all were sterile in 8 h. Using 0.6 N hydrochloric acid, only 10% of bone specimens contaminated with Staphylococcus aureus, 60% with Escherichia coli, and 90% with Bacillus subtilis were sterile in 8 h. Consequently, 70% ethanol could possibly by used as an antiseptic or sterilizing agent for contaminated bone, although we feel that such bone should also be demineralized. Ethanol should not be used for routine treatment of mineralized cortical bone as it has been shown to diminish the already poor osteogenic potential of cortical bone.