Are Dropped Bone Grafts Safe to be Re-used? - An Experimental Study Comparing Efficacy of Chlorhexidine, Povidone-Iodine and Alcohol

Introduction: A dilemma arises when a bone graft or fracture fragment is accidentally dropped on the operation theatre floor and becomes contaminated. This study aimed to determine the efficacy of simple and readily available antiseptic solutions in disinfecting contaminated bones.

Material and Methods: This experimental study involved 225 bone specimens prepared from discarded bone fragments during a series of 45 knee and hip arthroplasty surgeries. The bone fragments were cut into five identical cubes and were randomly assigned to either control (positive or negative), or experimental groups (0.5% chlorhexidine, 10% povidone-iodine or 70% alcohol). The control negative was to determine pre-contamination culture. All bone specimens, except the control negative group were uniformly contaminated by dropping on the operation theatre floor. Subsequently, the dropped bone specimens except for the control positive group, were disinfected by immersing in a respective antiseptic solution for 10 minutes, before transported to the microbiology laboratory for incubation.

Results: The incidence of a positive culture from a dropped bone fragment was 86.5%. From the 37 specimens sent for each group, the incidence of positive culture was 5.4% (2 specimens) after being disinfected using chlorhexidine, 67.6% (25 specimens) using povidone-iodine and 81.1% (30 specimens) using alcohol. Simple logistic regression analysis demonstrated that chlorhexidine was significantly effective in disinfecting contaminated bones (p-value <0.001, odd ratio 0.009). Povidone-iodine and alcohol were not statistically significant (p-value 0.059 and 0.53, respectively). Organisms identified were Bacillus species and coagulase negative Staphylococcus. No gram-negative bacteria were isolated.

Conclusion: A total of 0.5% chlorhexidine is effective and superior in disinfecting contaminated bones.