Prosthetic Joint Infections
CME credit can be obtained if questions are completed through the following link: https://www.eeds.com/em/3949
Following series has four questions related to diagnosis and management of prosthetic joint infections.
25%
1 / 4
Which of the following is NOT a diagnostic criterion for the definition of PJI according to the IDSA guidelines (2013)?
Explanation : Elevated WBC within synovial fluid is not part of the diagnostic criteria set forth by the IDSA in 2013.
Patients need to have 1 of the following to meet the definition of PJI:
-Sinus tract communicating with prosthesis
-Presence of purulence
-Acute inflammation on histopathologic evaluation of periprosthetic tissue
-Single positive culture with virulent organism
50%
2 / 4
A 47 yo otherwise healthy avid runner presents to your office with a painful red R knee 2 weeks after undergoing a R TKA. He had seen his orthopedic surgeon 2d prior and underwent an xray which noted intact hardware, routine bloodwork noting a ESR of 105 and a CRP of 15. Aspiration of synovial fluid returned with 8,095 WBC with 87% PMNs. Right as you are about to evaluate the patient, you receive a call from the orthopedic surgeon that the synovial culture is now + for S aureus. After discussing the case with the orthopedic surgeon, what should you recommend to the patient be the next course of action?
Explanation : Patients diagnosed with a PJI who have a well-fixed prosthesis without a sinus tract who are within approximately 30 days of prosthesis implantation or <3 weeks from onset of infectious symptoms should be considered for debridement and retention of prosthesis, followed by chronic oral suppression for 6 months. Eradication of infection occurs in up to 70-90% of these cases.
Knee PJI related to S aureus is typically recommended to be treated with dedicated IV antibiotic therapy with the use of rifampin for 2-6 weeks, followed by appropriate chronic oral suppression for 6 months.
Additional Resources
75%
3 / 4
A 63 yo Indian F with a PMH of diabetes, hypertension and OA s/p L THA in 2019 was sent to you for evaluation after repeated appointments with her orthopedic surgeon for ongoing pain in her L hip for the last 6 months. She has had repeated evaluations for this, including a negative plain film, blood work with a ESR of 52, a CRP of 5 and an IL-6 level of 12. She also has had synovial aspirations done with no cell counts performed but with negative routine bacterial cultures done x 2; negative crystal analysis, alpha defensin (ELISA) of 59.6 mg/L (ULN 5.2 mg/L) and a CRP of 17. What do you recommend as the next course of action?
Explanation : This patient has some criteria that could be considered suggestive of a PJI. Although her ESR remains relatively low, her serum CRP is mildly elevated as is her IL-6 level. In the synovial fluid, both the alpha defensin and CPR are both elevated. These are both considered minor criteria from the ICM. At this point, it is important to rule out the possibility of atypical infection related to mycobacterial or fungal disease. Intraoperative inspection with histopath and microbiological analysis is also indicated. Given that the patient has had no suggestion of sepsis, antibiotic therapy should be withheld for up to 2 weeks to maximize intraoperative analysis
Additional Resources
100%
4 / 4
Intraoperatively, the patient in question #3 had a frozen section sent for histopathology, which noted >10 PMNs/hpf. The surgeon opts to perform a single stage procedure while in the OR. Pre-operative and 1 intraoperative cultures ultimately returned + for M tuberculosis. What do you recommend to the surgeon and to the patient?
Explanation : PJI related to MTb can often be treated with prolonged anti-TB therapy alone with good outcomes with no significant added benefit to 2 stage procedures.
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