Optimizing the Disinfection of Devitalized Bone for Retained Use in Open Fractures: An in vitro Study

OBJECTIVES: To compare several methods of disinfection of a grossly contaminated cortical fragment with regards to residual bacterial load and mechanical properties. METHODS: Microbiological Testing: 60 (0.5 x 0.5 x 0.5 cm) cortical pieces of cadaveric femora were immersed in live S. aureus (1 x 108 CFU/mL) for 60 minutes. Samples were randomized to no treatment, saline irrigation, povidone-iodine, chlorohexidine, pasteurization, or autoclave treatment andunderwent bacterial enumeration using serial dilution and plating as well as broth turbidity testing. MECHANICAL TESTING: Separately, 60 diaphyseal cortical beams were created (2mm x 2mm x 3cm) and underwent the aforementioned treatments, and subsequently were mechanically tested using four-point bending. RESULTS: Microbiological Testing: Mean bacterial load was not significantly different with saline irrigation (4 x 107 CFU/mL) versus no treatment (5 x 107 CFU/mL), (p = 1). Povidone-Iodine (90 CFU/mL), pasteurization (250 CFU/mL), autoclave (0.6 CFU/mL), and chlorohexidine (0 CFU/mL) treatments significantly decreased bacterial load compared with the no treatment and saline groups (p = 0.002). Samples treated with autoclave (0.6 CFU/mL) and chlorohexidine (zero, 0 CFU/mL) achieved near-complete or complete disinfection. MECHANICAL TESTING: Autoclave treatment decreased maximum force to failure compared with no treatment (84 N vs. 100 N, respectively, p = 0.012). No significant difference was noted in this parameter for the remaining groups (p = 1). No difference was noted among groups for bending stiffness (p = 0.318), work to failure (p = 0.720), or flexural rigidity (p = 0.235). CONCLUSION: Chlorohexidine treatment achieved complete disinfection of a grossly contaminated cortical segment without affecting mechanical properties. Povidone-Iodine, chlorohexidine, pasteurization, and autoclave disinfection achieved profound reductions in bacterial load. Autoclave treatment modestly decreased the mechanical properties of cortical bone.