Saturday, December 8, 2012

Relevant to the shoulder?: Diagnosis and Management of Prosthetic Joint Infection: Clinical Practice Guidelines by the Infectious Diseases Society of America

Diagnosis and Management of Prosthetic Joint Infection: Clinical Practice Guidelines by the Infectious Diseases Society of America.

When folks publish "evidence based guidelines", it is important to establish to what circumstances the guidelines can be applied (viz thromboembolic prophylaxis). In this report, the authors signal the importance and cost of periprosthetic infections as well as the challenges of diagnosis and treatment. With candor they admit that many of their guidelines are based on Level V evidence: opinion. As folks concerned primarily about the shoulder, our task is to determine to what degree these guidelines relate to the care of our patients.

In our experience, any painful or stiff shoulder arthroplasty or any loose arthroplasty components may be associated with a periprosthetic infection, often in the absence of the findings mentioned in this article: drainage, fevers, chills, elevated sedimentation rate, and elevated C-reactive protein. While the authors recommend arthrocentesis, joint aspiration is associated with a high rate of false-negative results in the shoulder. While the authors report that intraoperative histolopathological examination of periprosthetic tissue samples is 'highly reliable', in the shoulder false negative results are common. Because dedicated efforts to culture for slow growing organisms (Propionibacterium and Coagulase negative Staph) are the key to diagnosing most shoulder infections, we concur with the recommendation to obtain "at least 3 and optimally 5 or 6 periprosthetic intraoperative samples or the explanted prosthetic parts" and, like the authors, we prefer to withhold antibiotics prior to surgery in most cases. 

The next part of the article deals with the definition of a periprosthetic infection. We can agree that sinus tracts communicating with the prosthesis, purulence, and acute inflammation are highly suggestive. As for culture results, the chance of a positive culture depends not only on the presence or absence of bacteria in the surgical field, but also on the number of specimens submitted, the media on which the specimens are cultured and the length of time the cultures are observed. These authors state that "One of multiple tissue cultures or a single aspiration culture that yields an organism that is a common contaminant (eg, coagulase-negative staphylococci, Propionibacterium) should not necessarily be considered evidence of definite PJI and should be evaluated in the context of other available evidence." At this point in the shoulder world it is apparent that Propionibacterium is a common cause of infection and its presence cannot be attributed to external contamination. It appears likely that Propionibacterium infections may indeed arise from contamination of the wound from the organisms residing in the patient's skin introduced at the time of surgery leading to the formation of biofilms.

With respect to the treatment of periprosthetic infections we note that most of the guidelines do not have evidence support and are based on the authors' opinions. The decision among (a) washout+prosthesis retention, (b) one stage exchange, (c) two stage exchange, (d) prosthesis resection, (e) amputation, and (f) long term antibiotic supression must be highly individualized. Here's an interesting article on decision analysis in hip revision. In this article it was of interest to read of the diverging opinions of the authors on antibiotic therapy.

Their recommendations of Penicillin or Clindamycin for the treatment of Propionibacterium is in contrast to our infectious disease consultant's common recommendation of Cephtriaxone with or without Rifampin. We do concur that with all antibiotic therapy, patients and their physicians must be on the lookout for diarrhea from C Diff and that Amoxacillin or Doxycycline may be useful for chronic suppression of Propionibacterium.

We heartily concur that collaboration between orthopaedic surgeons, infectious disease experts and experts in laboratory medicine is critical to refining protocols and to individualizing treatment for specific patients.

We found the concluding sections of this article "Research Gaps" of particular interest with respect to the epidemiology, diagnosis, management, and prevention of these major complications of joint replacement.


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