Dilute Betadine Lavage Reduces Implant-Related Bacterial Burden in a Rabbit Knee Prosthetic Infection Model
Treatment of acute postoperative arthroplasty infection with polyethylene exchange and retention of components has a limited success rate, potentially because of residual bacterial burden. We hypothesized that dilute Betadine (povidone-iodine) lavage would decrease bacterial burden in a rabbit knee infection model.
We inserted a stainless steel screw with a polyethylene washer into the lateral femoral condyle in 16 bilateral rabbit knees, and the sites were infected with Staphylococcus aureus. After 1 week, all knees were treated with a polyethylene washer exchange and either a saline lavage or a 3.5% Betadine lavage.
We assessed bacterial growth after 7 days. Betadine-treated knees showed a statistically significant decrease in the bacterial count on the stainless steel screw and polyethylene washer but no difference in soft-tissue growth. Betadine lavage as a treatment adjunct may improve component retention for acute arthroplasty infection.
Our arthroplasty model mimics an intra-articular environment and accounts for an implant–polyethylene interface.15 Limitations of our study include the use of MSSA as opposed to MRSA. However, povidone-iodine has the same effects on both MSSA and MRSA.12 We also treated our postoperative infection with 1 dose of antibiotics and not a course, although it should be noted that the single dose of ceftriaxone allowed us to isolate the independent effect of the Betadine lavage. A baseline level of infection severity could have been measured with cultures obtained at the time of irrigation and débridement. Also, a decrease in CFU does not directly correlate to a clinically significant outcome, such as a defined surgical site infection requiring intervention. Nevertheless, it is noteworthy that the decrease in bacterial counts on the stainless steel screws and polyethylene washers were maintained 1 week after the Betadine lavage.
Conclusion
Dilute Betadine lavage is a simple and inexpensive adjunct for the treatment of acute postoperative arthroplasty infection and may increase the rate of component retention. Additionally, the bactericidal and antibiofilm activities of Betadine may improve the effectiveness of systemic antibiotics. Further clinical investigation is warranted.
