A comparison of five treatment protocols for contaminated bone grafts in reference to sterility and cell viability

Occasionally, a bone graft or comminuted fracture fragment is dropped on the operating-room floor and becomes contaminated. The purpose of this study was to determine an optimal method for sterilizing this bone with the minimum sacrifice of cell viability.

A set of discarded bone samples was taken from a series of twenty total knee arthroplasty operations. The bone samples were uniformly contaminated with use of a bacterial broth prepared from culture samples taken from the operating-room floor. The bone samples in each set underwent five different decontamination procedures. Specifically, one sample in each set was autoclaved and four other samples underwent mechanical agitation in normal saline solution, 2% chlorhexidine gluconate, or 10% povidone-iodine (which was either left wet or was dried). Positive and negative controls were used for comparison. Ten sets were then cultured to determine sterility, and ten underwent live/dead trypan blue staining to determine cell viability.

Autoclaving, chlorhexidine gluconate, and dry povidone-iodine sterilized all samples; wet povidone-iodine decontaminated four (40%) of ten samples; and saline solution sterilized none. While all decontamination methods reduced the cell count to some extent, autoclaving and chlorhexidine gluconate left no viable cells. When the cell counts were expressed as a percentage of the control value, dry povidone-iodine sterilization maintained significantly fewer live cells than controls (21%; p < 0.01), whereas saline solution and wet povidone-iodine were not significantly different from controls (77% and 66%; p = 0.40 and p = 0.22, respectively).

Of the easily accessible protocols studied, mechanical agitation and serial washes of bone graft in povidone-iodine that is allowed to dry offers the best balance between complete sterilization of contaminated bone and maintenance of tissue viability.