The efficacy of low-pressure lavage with different irrigating solutions toremove adherent bacteria from bone

Background: Recent studies have suggested that high-pressure irrigation may have adverse effects on bone. However, the use of low-pressure irrigation may not remove all adherent bacteria from bone. The type of irrigating solu tion may be an important factor in the removal of adherent bacteria with pu lsatile lavage. In this study, we compared the effects of various irrigatin g solutions on the number and function of osteoblasts and osteoclasts and w e examined the effectiveness of these solutions in removing adherent bacter ia from bone. Methods: To examine the effect of irrigating solutions on the number and ac tivity of osteoblasts, we isolated calvarial cells from newborn C57Bl/6 mic e and exposed the cells to equivalent concentrations of ethanol, povidone-i odine, liquid soap, antimicrobial wash (50 U/L of bacitracin), or chlorhexi dine gluconate, for two, ten, or twenty minutes. The cells were then cultur ed in the presence of bone-nodule-enhancing medium (beta -glycerophosphate and ascorbic acid) for twenty-one days. The medium was changed every three or four days. Mineralized nodules were stained with alizarin red S, and ost eoblasts were stained with a histochemical stain for alkaline phosphatase. Osteoclasts were identified with tartrate-resistant acid-phosphatase staini ng. In a second experiment, canine cortical tibiae were contaminated with S taphylococcus aureus for six hours and subjected to different irrigating so lutions with or without low-pressure lavage. Bacterial colony-forming units were quantitated under each set of conditions. Results: Each solution resulted in a time-dependent decrease in the number of calvarial osteoblasts and osteoclasts compared with that in the controls . The 1% soap solution resulted in greater preservation of both alkaline-ph osphatase activity and bone-nodule formation than did the other solutions. Moreover, the soap solution preserved the number of osteoclasts to the grea test extent. The povidone-iodine and chlorhexidine-gluconate solutions resu lted in the largest decline in bone-nodule formation, alkaline-phosphatase activity, and number of osteoclasts. Low-pressure pulsatile lavage with the soap solution removed the most bacteria from the contaminated tibia when c ompared with either the soap solution alone or low-pressure irrigation with saline solution. Conclusions: Our findings suggest that certain solutions may be more effect ive in removing bacteria from bone than mechanical irrigation with saline s olution alone. Among the various solutions examined, the soap solution pres erved the number and activity of osteoblasts the most. Low-pressure lavage with the soap solution resulted in the greatest removal of adherent bacteri a from bone. Clinical Relevance: Meticulous debridement is regarded as the most importan t initial step in the management of open tibial fractures. The optimal tech nique for bone debridement should maximize the removal of adherent bacteria while preserving the structure and function of bone. It has been shown tha t low-pressure irrigation results in significantly less macroscopic and mic roscopic damage to bone and is as effective as high-pressure lavage in remo ving bacteria within three hours after contamination. However, irrigation i s often delayed beyond three hours. In the current study, we report that de bridement with low-pressure irrigation and detergent solutions can be effec tive for up to six hours after contamination.