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INTRAOPERATIVE EVALUATION AND LEVEL OF CONTAMINATION DURING TOTAL KNEE ARTHROPLASTY
Abdulaziz Z Alomar1, Saud M Alfayez1,2, Ahmad Binnasser1
1Orthopaedic Department, College of Medicine, King Saud University Medical City, King Saud University, Riyadh, Saudi Arabia.
Introduction:
Despite numerous articles on intraoperative contamination in total knee arthroplasty (TKA) procedures, the available data on tissue contamination are scarce and mainly based on evaluating bacteriological swabs.
Methods:
Two hundred and forty specimens, divided between bone and soft tissue, were obtained from 40 consecutive unilateral primaries TKAs. The specimens were evaluated for aerobic and anaerobic bacterial growth. Colony-forming units/gram (CFU/g) were calculated on the contaminated specimens to determine the level of contamination.
Results:
The contamination rate in intraoperative specimens was 15% during TKA. The contamination level had a mean of 10.6 and a median of 5, ranging from 1-70 CFU/g. The most common contaminating organisms in all samples were Staphylococcus aureus (38.9%) and Staphylococcus epidermidis (30.6%). No clinical infections were detected in TKAs in the follow-up period.
Conclusion:
The contamination rate during TKA is relatively high, despite the practice of standard preventive measures. Contamination levels, measured by CFU/g, are considered low when compared to the infection threshold of 105 reported in the literature. However, contamination should not be underestimated due to the presence of foreign bodies (implants), which are known to significantly lower this threshold. .
Insights
Intraoperative tissue contamination during total knee arthroplasty (TKA) affects 15% of procedures, primarily by Staphylococcus species. While contamination levels are low, the presence of implants warrants careful consideration to prevent infection.
Area of Science:
- Orthopedic Surgery
- Microbiology
- Infection Control
Background:
- Intraoperative contamination in total knee arthroplasty (TKA) is a concern, yet data on tissue contamination are limited.
- Existing studies often rely on bacteriological swabs, with scarce information on actual tissue bacterial loads.
Purpose of the Study:
- To quantify the rate and level of intraoperative tissue contamination during primary TKA.
- To identify common bacterial species involved in TKA contamination.
- To assess the clinical significance of contamination in relation to infection thresholds.
Main Methods:
- Collected 240 bone and soft tissue specimens from 40 primary unilateral TKAs.
- Evaluated specimens for aerobic and anaerobic bacterial growth.
- Quantified contamination levels using colony-forming units per gram (CFU/g).
Main Results:
- A 15% contamination rate was observed in intraoperative TKA specimens.
- Mean contamination level was 10.6 CFU/g (median 5, range 1-70 CFU/g).
- Staphylococcus aureus (38.9%) and Staphylococcus epidermidis (30.6%) were the most frequent contaminants. No clinical infections were noted during follow-up.
Conclusions:
- Intraoperative contamination during TKA occurs at a notable rate despite preventive measures.
- Contamination levels are below the general infection threshold but require caution due to implants potentially lowering the threshold.
- Further vigilance is necessary to mitigate risks associated with even low-level contamination in TKA.
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