Paper of the Week: Vancomycin-Gentamicin Prefabricated Spacers in 2-Stage Revision Arthroplasty for Chronic Hip and Knee Periprosthetic Joint Infection: Insights Into Reimplantation Microbiology and Outcomes.

Corró S, Vicente M, Rodríguez-Pardo D, Pigrau C, Lung M, Corona PS

The Journal of arthroplasty. 2020 Jan 1;35(1):247-54.
doi: 10.1016/j.arth.2019.07.043. Epub 2019 Aug 19. PMID: 31530462

Summary by Walaa Abdelfadeel, BA

A common method of treatment of chronic PJI is using an antibiotic-loaded cement spacer in a 2-stage revision [1,2]. There is concern about the impact that spacers have on the presence of positive cultures during implantation, which have been suggested to be risk factors for treatment failure [3,4]. The type and dosage of antibiotic used in the bone cement has been thought to play a role in the risk of spacer colonization, as its elution properties are not as enhanced as they are in the preformed spacer [5-8]. This suggests that increasing the dose of antibiotic in the cement may compensate for the poor elution rates and provide a more protective effect.

In this study, Corró et al. studied the incidence of positive cultures during 2-stage reimplantation using vancomycin-gentamicin cement spacers and the association of these cultures with percentage of treatment failure and patient risk factors. They also investigated the impact that cement dosed with antibiotics had on the percent of positive cultures in the 2^nd stage. There was a total of 108 hips and knees that had undergone 2-stage revision due to chronic PJI, with 92 (85.2%) of these cases having used extra-antibiotic loaded cement at the first stage. Microbiological cultures were evaluated after each stage. The authors found that 22.2% (24/108) of cases had ≥1 second-stage positive cultures, while 9.3% (10/108) had ≥2 positive cultures. There was a success rate of 77.8%, with failure of treatment higher among cases with positive cultures, regardless of the number of positive samples. Diabetes was identified as a risk factor for second-stage positive cultures (P = 0.03), while the use of the extra-antibiotics in the cement used for spacer fixation showed a protective effect (92.9% vs 58.3% negative cultures, P<0.01). The authors acknowledged certain limitations of the study, including the limitations of a retrospective design, as well as the variables introduced by having the already small number of patients treated by 3 different surgeons. Additionally, the lack of an internationally accepted definition of a true-positive culture in the 2^nd stage precludes comparisons between studies. The study concluded that patients with a positive culture after 2-stage revision using vancomycin-gentamicin spacers face a higher risk of treatment failure, and that high doses of antibiotics in the cement should be considered to fix spacers in revision procedures.

References:

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