The study by Bruce and coauthors is elegant and well designed. Importantly, it represents a clinically relevant investigation into both the antimicrobial efficacy as well as the impact on chondrocyte viability of several decontamination techniques for dropped osteochondral fragments.
In Phase I of the study, operating suite floors were swabbed and dropped fresh osteochondral fragments (n = 162) were cultured without disinfection to determine the microbiologic profile and the rate of contamination of dropped fragments. In Phase II, inoculated bone fragments (n = 340) were cleansed with 10% povidone-iodine, 4% chlorhexidine, 70% isopropyl alcohol/2% chlorhexidine gluconate, or 0.9% normal saline solution as decontamination solutions with either a five or a ten-minute "soak" followed by mechanical decontamination via either bulb syringe irrigation "rinse" or a physical "scrub" with a bristled sponge. Finally, in Phase III, articular chondrocyte viability of fragments (n = 101) was assessed following each of the various combinations of chemical and mechanical decontamination.
The two most common organisms identified on culture of both the swabs and the dropped fragments were coagulase-negative Staphylococcus and Bacillus. Both 10% povidone-iodine and 4% chlorhexidine proved superior with regard to decontamination efficacy, demonstrating negative cultures in all specimens regardless of the mechanical adjuvant technique utilized or chemical exposure ("soak") time. Mechanical scrubbing appeared to be superior to bulb syringe saline solution lavage for this purpose. However, both 4% chlorhexidine chemical decontamination as well as mechanical scrubbing of the fragments with a bristled scrub brush proved markedly deleterious to chondrocyte viability compared with other cleansing modalities. On the basis of these findings, the authors recommend a 10% povidone-iodine soak followed by bulb syringe saline solution lavage as the optimal technique to ensure both fragment decontamination and residual chondrocyte viability.
The strengths of the study lay in the multistep, logical progression between study phases: obtaining baseline operating suite floor bacteriology and contamination rates (although the latter, at 70%, were likely lower than anticipated), the use of multiple inoculation bacteria, the examination of both chemical and mechanical decontamination techniques, and, finally, the inclusion of chondrocyte viability in the study and ultimate decontamination recommendations. The use of direct bacterial inoculation, rather than dropped-fragment contamination, for the decontamination phase of the study is both a strength and a weakness. This was no doubt performed in an effort to ensure uniformity of contamination between study cohorts, removing the chances that baseline variability in culture rates could confound the subsequent results regarding decontamination efficacy. However, direct liquid inoculation also may result in deeper penetration into the relatively porous osteochondral fragments than the ostensibly dry, surface contamination that would occur when a fragment is dropped on the floor. Although direct liquid inoculation may have influenced the results with respect to mechanical scrubbing as compared with saline solution lavage, surgeons must assume and act on the "worst case scenario," in this case, deep penetration of pathogens within the graft. In addition, any untoward impact on the results was fortuitously mitigated by the decontamination efficacy of 10% povidone-iodine and the favorable chondrocyte viability following the use of this technique.
The decided rarity of these events precludes any meaningful human study of various decontamination protocols. However, our own clinical experience and the medical literature1,2 suggest that most of us have "been there." Regarding the duration of contamination, other authors have demonstrated that the so-called "five-second rule" does not apply3. Nevertheless, the present study raises additional questions. While the results of bacterial culture of operating room floors have been remarkably consistent in the literature4, does the method of operating room floor disinfection and cleansing matter, and, if so, does it matter enough, given the rarity of similar events, to change practice? Clearly, full disclosure to the patient and family following such events is advocated, but how should one best address the ethical and medicolegal implications of a joint, limb, or life-threatening infection following overt, physician-observed contamination? Even how large an osteochondral piece constitutes a critical, nondisposable fragment and justifies assuming the theoretical risks of reimplantation likely varies between the involved joint, fracture pattern, patient, and surgeon.
In summary, the authors are to be commended for having provided a novel, thought-provoking and useful addition to the literature. Fortunately, fragment decontamination following events such as those simulated and tested in this study is rarely required. However, for cases in which a critical-sized fragment falls to the floor, this manuscript provides us with very specific, evidence-based recommendations based on a well-designed study, thus providing timely and much-needed guidance on how best to proceed.