High and low pressure pulsatile lavage of contaminated tibial fractures: an in vitro study of bacterial adherence and bone damage.

OBJECTIVE: This study was designed to examine the effect of pulsatile irrigation on microscopic bone architecture and its time-dependent efficacy in removing adherent slime-producing bacteria from cortical bone.

DESIGN: Using an in vitro model, ten-millimeter transverse cut sections from five human tibiae were contaminated with Staphylococcus aureus and subjected to either high pressure pulsatile lavage (HPPL; seventy pounds per square inch, normal saline) or low pressure pulsatile lavage (LPPL; fourteen pounds per square inch, normal saline) or served as controls. Alteration of bony architecture was quantified by using a previously described ordinal scale and histomorphometric analysis of each transverse cut section of tibia. To assess the time-dependent effectiveness of pulsatile lavage in removing adherent bacteria from bone, ten-millimeter transverse cut sections from ten canine tibiae were contaminated with S. aureus and subjected to high or low pressure pulsatile lavage immediately or after one, three, or six hours. Scanning electron microscopy and bacterial cultures were used to assess the removal of adherent bacteria.

RESULTS: HPPL resulted in significantly greater macroscopic damage than was seen with LPPL or in controls (ANOVA, p < 0.001). Histomorphometry revealed that HPPL was associated with significantly larger and more numerous fissures or defects in the cortical bone when compared with low pressure irrigation (p < 0.001). However, high and low pressure lavage were associated with similar degrees of periosteal separation from the cortical bone surface (p = 0.87). Both high and low pressure lavage were effective in removing adherent bacteria from bone at three hours irrigation delay, but only high pressure lavage removed adherent bacteria from bone at six hours delay.

CONCLUSION: In this in vitro study, compared with HPPL, LPPL led to less structural damage and was equally effective in removing bacteria within three hours debridement delay; however, the efficacy of LPPL at six hours debridement delay is questionable. This finding may have clinical significance in the development of infection following open tibial fractures.