Bone penetration of intravenous flucloxacillin and gentamicin as antibiotic prophylaxis during total hip and knee arthroplasty.

AIMS

To investigate the bone penetration of intravenous antibiotic prophylaxis with flucloxacillin and gentamicin during hip and knee arthroplasty, and their efficacy against () and .

PATIENTS AND METHODS

Bone samples from the femoral head, neck and acetabulum were collected from 18 patients undergoing total hip arthroplasty (THA) and from the femur and tibia in 21 patients during total knee arthroplasty (TKA). The concentration of both antibiotics in the samples was analysed using high performance liquid chromatography. Penetration was expressed as a percentage of venous blood concentration. The efficacy against common infecting organisms was measured against both the minimum inhibitory concentration 50, and the more stringent epidemiological cutoff value for resistance (ECOFF).

RESULTS

The bone penetration of gentamicin was higher than flucloxacillin. Relative to ECOFF, flucloxacillin concentrations were effective against and in all THAs and 20 (95%) TKAs. Gentamicin concentrations were effective against in all bone samples. Gentamicin was effective against in 11 (61.1%) femoral neck samples in THA. Effective concentrations of gentamicin against were only achieved in four (19%) femoral and six (29%) tibial samples in TKA.

CONCLUSION

Flucloxacillin and gentamicin were found to penetrate bone during THA and TKA. Gentamicin was effective against in both THA and TKA, while levels were subtherapeutic against in most TKAs. Bone penetration of both antibiotics was less in TKA than THA, and may relate to the use of a tourniquet. Using this antibiotic combination, effective cover against the two common infective organisms was achieved in all THAs and all but one TKA. Cite this article: 2017;99-B:358-64.