In Reply: So the Bone Flap Hit the Floor, Now What? An In Vitro Comparison of Cadaveric Bone Flap Decontamination Procedures

To the Editor: We thank Dr Afshari for his letter1 commending our recently published manuscript “So the Bone Flap Hit the Floor, Now What? An In Vitro Comparison of Cadaveric Bone Flap Decontamination Procedures.”2 We read his commentary with great interest. Dr Afshari raised excellent points regarding real-life microbiological and surgical considerations. We agree with the highlighted limitations. Bone flaps removed for infectious reasons or which had a breach in storage protocol were excluded from this study. Routine flap culture is not a common practice in our hospital, and flaps are typically reimplanted as long as no breach in sterility is observed. We therefore considered all flaps as sterile. The study was performed to mirror our clinical practice: control flaps represent flaps that would have been reimplanted, regardless of their “real” initial contamination status. It should be noted that all flaps were subjected to all decontamination protocols, so even if a flap was indeed nonsterile, it would technically have affected all decontamination procedures equally. We agree that foreign materials such as plates and screws add a layer of complexity and risk of infection through biofilm formation. More studies would be needed to assess our proposed disinfection method on such materials long term. The risk of infections is always a balance between bacterial load, proliferation, and host factors such as the immune response (which itself can be iatrogenically modulated). Although our protocols attempt to limit bacterial count, it does not address host factors which, given the variable and mostly low contamination observed, might in reality be the most critical element. Cranioplasty wound infection can have an incidence up to 26.43%3 even when performed electively in a completely sterile environment. Although undetected contaminations in our protocol might theoretically lead to a delayed, chronic infection, it is also possible that a proper immune response would have completely cleared the bone flaps even in the absence of a decontamination protocol. The goal, therefore, was to minimize patient harm by balancing safety and simplicity. We believe the risk of a persistent infection following a 99.98% effective decontamination protocol will be less than the risk of infection associated with wound closure, synthetic implant creation, and a—third—wound reopening in an additional setting to implant a synthetic flap. At this point, the wound will become the most likely point of failure. It is always a question of balance, as risk cannot be completely eliminated. Given that a real clinical trial is obviously not feasible, we believe our study is as close as we can get to the truth in this matter unless significant investment was made into a large animal model study.