Higher cefazolin concentrations in synovial fluid with intraosseous regional prophylaxis in knee arthroplasty: a randomized controlled trial.

Background: Prophylactic antibiotics reduce the risk of periprosthetic joint infection. However, conventional systemic administration may not provide adequate tissue concentrations against more resistant organisms such as coagulase-negative staphylococci. Intraosseous regional administration is known to achieve significantly higher antibiotic tissue concentrations than systemic administration, but it is unclear how synovial fluid concentrations are affected. We aimed to compare synovial fluid cefazolin concentrations achieved by regional intraosseous versus systemic intravenous administration, and also to compare synovial fluid cefazolin concentrations with those in subcutaneous fat. Methods: A total of 60 patients undergoing primary knee arthroplasty were randomized into 2 groups: group IO received 2 g interosseous cefazolin in 100 mL saline through a tibial cannula after tourniquet inflation and before skin incision; group IV received 2 g cefazolin in 100 mL saline via the median basilic or median cephalic vein 30 min before tourniquet inflation. Subcutaneous fat and synovial fluid samples were collected immediately after skin incision, and cefazolin concentrations were measured by high-performance liquid chromatography. Results: The cefazolin concentration in synovial fluid was 391.3 ± 70.1 μg/ml in group IO and 17.6 ± 3.5 μg/ml in group IV. The cefazolin concentration in subcutaneous fat was 247.9 ± 64.9 μg/g in group IO and 11.4 ± 1.9 μg/g in group IV. Conclusion: Intraosseous regional administration results in several times higher tissue concentrations than systemic administration, especially in the synovial fluid. [ABSTRACT FROM AUTHOR]