Lipid extracted freeze-dried bank bone sterilized with low temperature plasma.

Ethylene oxide gas (EOG) is widely used for sterilization of freeze-dried bone. Recently EOG is regulated for clinical use because of cytotoxicity and environmental pollution concerns. Low Temperature Plasma Sterilization (LTPS) has no toxicity and mutagenicity working with a hydrogen peroxide gas plasma at 45 degrees centigrade. We have now used this method experimentally and clinically to sterilize freeze-dried bone. Cortical bone with a thickness of 5 mm and cancellous bone with a 10 mm cubic size were prepared, washed, defatted, dehydrated by freeze drying and finally sterilized by LTPS. As a Microbiological test, defatted freeze-dried bone was contaminated with B. subtilis, and after then the contaminated bone was treated with LTPS and the bacteria was proven inactive. Mechanical testing on rabbit cortical bone was investigated by compression testing using a mechanical testing machine. No differences between EOG treated and LTPS treated bone were found. From December 1996, 52 patients who had small and middle bone defects were treated with defatted, freeze-dried and LTPS sterilized bone. Clinical result was good. No deep infections, no transmission of virus infections or severe graft absorption were noted. The LTPS bank bone is safe and useful to reconstruction to small bone defects.