When to Use Commercially Available Antibiotic Cement: An Ongoing Debate

Commentary The use of antibiotic-loaded bone cement (ABC) to prevent periprosthetic joint infection, the most devastating complication following arthroplasty, remains a topic of contention. Furthermore, there is considerable geographic variation in the utilization of ABC, as the majority of the literature supporting the use of ABC has been from the registries of Finland1 and the United Kingdom2. However, there are numerous meta-analyses and large-scale studies that have demonstrated no difference in clinical outcomes between the use of ABC and regular cement. Given the contrasting literature, there was substantial difficulty creating a consensus recommendation during the International Consensus Meeting on Musculoskeletal Infection in 2018, and after hours of debate, the consensus group ultimately hedged the recommendation and stated that “antibiotic may be used” and that “the benefits of antibiotic-impregnated cement versus its cost and other potential adverse effects, may be most justified in patients at high risk of infection.3” Routine use of ABC is not without consequences. In addition to the possibility of increasing antimicrobial resistance, 1 of the 3 greatest human threats according to the World Health Organization4, multiple studies have shown no reduction in the rate of periprosthetic joint infection and indicated that ABC is not cost-effective for routine use, which has major implications given the transition to value-based health care. Thus, although it is sensible to reserve ABC for high-risk patients in theory, there is no evidence to suggest that ABC prevents periprosthetic joint infection in patients with increased risk. This concept is similar to the risk-stratification-based approach to venous thromboembolism; we use aggressive anticoagulants in patients who are at an increased risk because we are willing to accept the side effects of the stronger anticoagulants in exchange for a theoretical reduction in the rate of venous thromboembolism; however, there is little evidence to support even that practice, despite its wide adoption. Thus, what makes the study by Namba et al. interesting is that it is the first study that supports the current International Consensus Meeting recommendation for a risk-stratification-based approach to the use or nonuse of ABC. The aim of the study by Namba et al. was to investigate the role of commercially available ABC and to elucidate its viability among specific high-risk subgroups (i.e., obese patients, diabetic patients, and patients with a high American Society of Anesthesiologists score). Perhaps the biggest strength of the study was the enormous sample size (87,018 primary total knee arthroplasties), which was obtained from an integrated regional health-care system registry in the U.S. The authors found that the use of regular cement was not inferior to commercially available ABC; however, a lower risk of infection was observed with ABC in diabetic patients, and the authors suggested that antibiotic cement may be indicated in this specific population. There were several limitations to the study that need to be considered when interpreting the results. Firstly, the registry nature of the database lacks substantial granularity. This lack of granularity is important because some, including the International Consensus Meeting, argue that infection studies should not be evaluated with a registry5. This lack of granularity can be seen in the fact that culture and organism information was not recorded, which is important because the development of organism resistance is a huge concern. Furthermore, the type of commercially available ABC utilized was heterogenous, but all included aminoglycosides, which may alter the organisms encountered because there is excellent gram-negative but weak gram-positive coverage. Secondly, the analysis of high-risk patients only included 3 groups even though numerous risk factors (>20) for periprosthetic joint infection have been reported in the literature. Furthermore, the complex and additive nature of risk factors for periprosthetic joint infection (e.g., as in a risk calculator) could not be evaluated. In conclusion, although the literature is mixed regarding the routine use of ABC, the study by Namba et al. suggests that there may be a role in diabetics. However, numerous questions remain unanswered. What other high-risk groups (e.g., smokers or malnourished patients) may benefit from the use of ABC? When is the use of ABC cost-effective? Can you add your own antibiotics rather than using commercially premixed ABC? Ultimately, the decision to use ABC depends on the risk-to-benefit ratio; however, the risks of ABC, such as antimicrobial resistance and alterations in the infecting organism unfortunately remain unknown. Although there may be a role for risk stratification when using ABC, further research—preferably not just from registries—is needed to establish the indications for the use of ABC.