Prosthetic joint arthroplasty is an extremely popular and successful procedure that relieves pain, restores function to a diseased joint, and improves the quality of life for many. Approximately 1.2 million arthroplasties are performed annually in the United States.1 Compared with 1997, there was an 84% increase in knee arthroplasties and a 33% increase in hip replacements in 2009.1 It is expected that, if this trend continues, more than 3.8 million arthroplasties are projected by 2020 with an estimated 75,000 periprosthetic joint infections (PJIs) annually.2 Although the associated mortality is low, these infections result in substantial patient morbidity and medical costs. The management of PJI is challenging, with patients often requiring multiple procedures, including staged, revision surgeries and prolonged courses of antibiotics. The increasing number of projected PJIs is expected to impose an immense burden on an already strained health care system. According to Kurtz et al,2 from 2001 to 2009, the relative incidence of PJI ranged between 2.0% and 2.4% of total hip arthroplasties and total knee arthroplasties and increased over time. The annual cost of infected revisions to US hospitals increased from $320 million to $566 million during the study period and was projected to exceed $1.62 billion by 2020.2
In this issue of Infectious Diseases in Clinical Practice, Moerhing and Anderson3 present a typical case of a patient with a PJI and concisely outline the current knowledge on treatment of PJI. They appropriately observe that much of the recommended treatment is based on consensus and expert opinion. Many studies of PJI are case series from a single institution, with small numbers of patients and lack of adequate follow-up or appropriate controls. It is bothersome that there is so little high-quality information on optimal therapy of an increasingly common clinical entity that virtually every infectious diseases clinician deals with on a regular basis. There are a number of practical questions that require answers: Can I use oral antibiotics instead of intravenous antibiotics? Is a 2-stage revision really better than single-stage revision? How long do I need to treat if the prosthesis is debrided and retained? Does the nature of the infecting organism play a role? Is antibiotic-loaded “cement” really necessary? Is there a difference between articulated and nonarticulated spacers? Should antibiotics be continued after a staged revision? If so, what is the optimal route, and what is the duration? What is the role of rifampin? Can biofilm formation be prevented, and will this prevent infections? How can we identify patients at the greatest risk of acquiring early and late infections?
There are many reasons for the lack of good data. First of all, you know there is a problem when experts don’t agree on the definition of PJI.4 In addition, while increasing in incidence, PJI remains relatively uncommon. Many general orthopedists will see only a handful of PJIs in their careers. Although these infections are best managed by a combination of medical and surgical treatment, there is often conflict between the infectious diseases clinicians and their orthopedic colleagues on the best approach. This is not surprising given the lack of information. And lastly, there is a lack of public or private funding to adequately study this problem. Pharmaceutical companies are generally not interested in PJIs because the Food and Drug Administration does not have an indication for this entity. Even if drug companies could get an indication, it is unlikely many would pursue this avenue given the perception that this is a small market relative to respiratory and skin/skin structure infections.
I believe that it is time that we start to reexamine our funding priorities to address the increasing incidence of PJIs with its attendant increasing cost and patient pain and suffering. Although prospective, blinded trials may not be economically feasible; we certainly should be able to fund large prospective, multicenter, observational trials that aim to answer our most basic questions of how do I treat, how long do I treat, and how do I know if the infection is eradicated? In addition, pharmaceutical interest may increase if the Food and Drug Administration offered a treatment indication for PJIs and allowed for surrogate markers of response, such as cultures and histopathology at the time of reimplantation for 2-stage revisions. Hopefully, when the topic of PJI is reviewed in the future, some of these questions will have been answered.
2. Kurtz SM, Lau E, Watson H, et al.. Economic burden of periprosthetic joint infection in the United States. J Arthroplasty
3. Moerhing, Anderson. Infect Dis Clin Pract
4. Della Valle C, Parvizi J, Bauer TW, et al.. The diagnosis of periprosthetic joint infections of the hip and knee. J Bone Joint Surg Am
. 2011; 93: 1355–1357.