Is it safe to use surgical instruments with debris from a previous surgery after sterilization?

Aims: The presence of biological debris on surgical instruments after reprocessing poses potential risks of infection in orthopaedic surgery. While autoclave sterilization is the standard method, its effectiveness in eliminating microbial contamination from residual bone, cement, and fatty tissue remains insufficiently studied. The primary objective was to study in vitro the sterility of retained cement, bone, and fat tissue debris on surgical instruments after autoclave sterilization. The secondary objective was to compare, based on colony-forming units (CFU), which material exhibits greater biofilm formation. Methods: An in vitro study was conducted to evaluate the sterility of retained biological debris on surgical instruments after autoclave sterilization. The autoclave sterilization procedure was performed at 1 atmosphere pressure (121°C) for 20 minutes. A total of 350 repetitions were performed, including five instruments used as sample specimens (drill bit, cannulated flexible reamer, femoral broach, cannulated screwdriver, and wire passer), with 70 repetitions per specimen. CFU/mL were counted and biofilm morphology was assessed through scanning electron microscopy (SEM). Results: After autoclave sterilization, no positive cultures were detected in any of the 350 repetitions (0%, 95% CI 0 to 5; n = 0), demonstrating complete absence of viable microorganisms. Due to the lack of microbial recovery, no statistical comparisons between instrument types were performed. We did not find any structural deformity in the mixed biofilms on bone, cement, and stainless steel as observed by SEM. Conclusion: Autoclave sterilization was effective in eliminating microorganisms from surgical instruments with retained biological debris. Although no apparent structural deformities of microorganisms were observed by SEM in the mixed biofilms, no bacterial growth was detected after sterilization, supporting the microbiological effectiveness of autoclave sterilization even in the presence of retained biological debris. These findings provide microbiological evidence supporting current sterilization practices, and highlight the need for further studies evaluating alternative sterilization methods such as ethylene oxide or plasma.