[Evaluation of the importance of a ready-made, gentamicin-impregnated spacer in relation to bacteriological findings in patients with periprosthetic joint infections].

BACKGROUND

Periprosthetic infection is a serious complication in total hip and knee arthroplasty. The complex therapeutic approach within two-stage reimplantation includes the use of antibiotic-impregnated spacers (temporary joint replacements). The aim of this paper was to evaluate bacteriological findings in selected patients with periprosthetic infection in whom a ready-made gentamicin-impregnated spacer was used to treat the infection.

MATERIALS AND

METHODS

Between 2008 and 2012, a ready-made, gentamicin-impregnated cement spacer was used in 24 patients to treat periprosthetic hip or knee infection within two-stage reimplantation. All components of the prosthesis and periprosthetic tissue samples were sent for microbiological examination at the first revision surgery, while at the second revision surgery, the spacer and surrounding tissue samples were sent in. In six patients with an inserted knee spacer, the level of gentamicin in the joint fluid was measured. Subsequently, the patients were regularly monitored.

RESULTS

Twenty-two (92%) of 24 patients were bacteriologically positive by culture. The most commonly detected causative agents were coagulase-negative staphylococci. Other isolates were Staphylococcus aureus, Corynebacterium, anaerobic bacteria, and Salmonella serotype Enteritidis. Nineteen (76%) of 25 primary pathogens were gentamicin sensitive. Spacers from two patients were culture positive for coagulase-negative staphylococci that tested resistant to gentamicin. During the follow-up of at least two years, none of the patients developed another periprosthetic infection.

CONCLUSION

The success rate of two-stage-reimplantation total hip and knee arthroplasty using ready-made, gentamicin-impregnated spacers was 100 % in our cohort of patients; no other periprosthetic infection was reported during the follow-up of at least two years. From the bacteriological results, it appears that the ready-made, gentamicin-impregnated spacer only covers 76 % of the range of the causative agents. The solution would be to use a spacer impregnated with a combination of vancomycin and gentamicin that would be effective against all cultured species.