Infection Watch

At last: A useful guideline for diagnosis of periprosthetic joint infection

Javad Parvizi, MD, FRCS
Javad Parvizi

Diagnosis of periprosthetic joint infection (PJI) remains a true challenge to the orthopedic community. There are multiple problems. First, there is no gold standard for diagnosis, in other words none of the available tests have absolute accuracy. The second problem relates to the fact that there is no accepted “standard” definition for PJI. Thus, in an effort to reach or refute the diagnosis of PJI, various investigations are usually performed, which in addition to cost, may delay the diagnosis or at worse misdiagnose.

Selection of patients for hip aspiration

AAOS workgroup

A workgroup convened by the American Academy of Orthopedic Surgeons (AAOS), on which I served as vice-chair, was given the task to devise an algorithmic and evidence based approach to diagnosis of PJI. The workgroup consisted of surgeons, infectious disease specialists, and a pathologist who interacted with the Guideline Committee at the AAOS to extensively evaluate the available literature and produce what has proved to be an extremely useful guidelines. The guidelines were evaluated and endorsed by numerous societies, including the Knee Society, the Hip Society, The Musculoskeletal Infection Society (MSIS), The Infectious Diseases Society of North America (IDSA), and others.

These guidelines have positively impacted my daily practice and have enhanced care of the unfortunate patients with PJI. I highly recommend that you consider implementing these guidelines in your practice also.

Summary of recommendations

The following is a summary of the recommendations in the AAOS’ clinical practice guideline, “The Diagnosis of Periprosthetic Joint Infections of the Hip and Knee.” I do, however, recommend that you view the full guidelines which contains the rationale for each of these recommendations at www.aaos.org/guidelines.

  1. In the absence of reliable evidence about risk stratification of patients with a potential periprosthetic joint infection, it is the opinion of the workgroup that testing strategies be planned according to whether there is a higher or lower probability that a patient has a hip or knee periprosthetic infection. Strength of recommendation: Consensus.
  2. We recommend erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) testing for patients assessed for PJI. Strength of recommendation: Strong.
  3. We recommend joint aspiration of patients being assessed for periprosthetic knee infections who have abnormal ESR and/or CRP results. We recommend that the aspirated fluid be sent for microbiologic culture, synovial fluid white blood cell count and differential. Strength of recommendation: Strong.
  4. We recommend a selective approach to aspiration of the hip based on the patient’s probability of PJI and the results of the ESR and CRP. We recommend that the aspirated fluid be sent for microbiologic culture, synovial fluid white blood cell count and differential (See table). Strength of recommendation: Strong.
  5. We suggest a repeat hip aspiration when there is a discrepancy between the probability of PJI and the initial aspiration culture result. Strength of recommendation: Moderate.
  6. In the absence of reliable evidence, it is the opinion of the work group that patients judged to be at lower probability for periprosthetic hip infection and without planned reoperation who have abnormal ESRs or abnormal CRP levels be re-evaluated within 3 months. We are unable to recommend specific diagnostic tests at the time of this follow-up. Strength of recommendation: Consensus.
  7. In the absence of reliable evidence, it is the opinion of the workgroup that a repeat knee aspiration be performed when there is a discrepancy between the probability of periprosthetic joint infection and the initial aspiration culture result. Strength of recommendation: Consensus.
  8. We suggest patients be off of antibiotics for a minimum of 2 weeks prior to obtaining intra-articular culture. Strength of recommendation: Moderate.
  9. Nuclear imaging (labeled leukocyte imaging combined with bone or bone marrow imaging, FDG-PET imaging, Gallium imaging, or labeled leukocyte imaging) is an option in patients in whom diagnosis of PJI has not been established and are not scheduled for reoperation. Strength of recommendation: Weak.
  10. We are unable to recommend for or against CT or MRI as a diagnostic test for PJI. Strength of recommendation: Inconclusive.
  11. We recommend against the use of intraoperative Gram stain to rule out PJI. Strength of recommendation: Strong.
  12. We recommend the use of frozen sections of peri-implant tissues in patients who are undergoing reoperation for whom the diagnosis of PJI has not been established or excluded. Strength of recommendation: Strong.
  13. We recommend that multiple cultures be obtained at the time of reoperation in patients being assessed for PJI. Strength of recommendation: Strong.
  14. We recommend against initiating antibiotic treatment in patients with suspected PJI until after cultures from the joint have been obtained. Strength of recommendation: Strong.
  15. We suggest that prophylactic preoperative antibiotics not be withheld in patients at lower probability for PJI and those with an established diagnosis of PJI who are undergoing reoperation. Strength of recommendation: Moderate.

References:

  • Bauer TW, et al. Diagnosis of Periprosthetic Infection. J Bone Joint Surg. 2006;88(4):869-882.
  • Della Valle C, et al. Diagnosis of periprosethtic joint infection of the hip and knee. J Am Acad Orthop Surg. 2010; 18(12): 760-770.
  • Parvizi J, Della Valle CJ. AAOS clinical practice guideline: Diagnosis and treatment of periprosthetic infections of the hip and knee. J Am Acad Orthop Surg. 2010;18(12): 771-772.

Javad Parvizi, MD, FRCS, editor of Infection Watch, can be reached at the Rothman Institute, 925 Chestnut St., 5th Floor, Philadelphia, PA 19107; 267-339-3617; e-mail: parvj@aol.com.

Disclosure: Parvizi serves on the speakers bureau for Johnson & Johnson, is a paid consultant for Stryker and Smith & Nephew and receives research or institutional support from Stryker (as reported in the guideline).

Javad Parvizi, MD, FRCS
Javad Parvizi

Diagnosis of periprosthetic joint infection (PJI) remains a true challenge to the orthopedic community. There are multiple problems. First, there is no gold standard for diagnosis, in other words none of the available tests have absolute accuracy. The second problem relates to the fact that there is no accepted “standard” definition for PJI. Thus, in an effort to reach or refute the diagnosis of PJI, various investigations are usually performed, which in addition to cost, may delay the diagnosis or at worse misdiagnose.

Selection of patients for hip aspiration

AAOS workgroup

A workgroup convened by the American Academy of Orthopedic Surgeons (AAOS), on which I served as vice-chair, was given the task to devise an algorithmic and evidence based approach to diagnosis of PJI. The workgroup consisted of surgeons, infectious disease specialists, and a pathologist who interacted with the Guideline Committee at the AAOS to extensively evaluate the available literature and produce what has proved to be an extremely useful guidelines. The guidelines were evaluated and endorsed by numerous societies, including the Knee Society, the Hip Society, The Musculoskeletal Infection Society (MSIS), The Infectious Diseases Society of North America (IDSA), and others.

These guidelines have positively impacted my daily practice and have enhanced care of the unfortunate patients with PJI. I highly recommend that you consider implementing these guidelines in your practice also.

Summary of recommendations

The following is a summary of the recommendations in the AAOS’ clinical practice guideline, “The Diagnosis of Periprosthetic Joint Infections of the Hip and Knee.” I do, however, recommend that you view the full guidelines which contains the rationale for each of these recommendations at www.aaos.org/guidelines.

  1. In the absence of reliable evidence about risk stratification of patients with a potential periprosthetic joint infection, it is the opinion of the workgroup that testing strategies be planned according to whether there is a higher or lower probability that a patient has a hip or knee periprosthetic infection. Strength of recommendation: Consensus.
  2. We recommend erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) testing for patients assessed for PJI. Strength of recommendation: Strong.
  3. We recommend joint aspiration of patients being assessed for periprosthetic knee infections who have abnormal ESR and/or CRP results. We recommend that the aspirated fluid be sent for microbiologic culture, synovial fluid white blood cell count and differential. Strength of recommendation: Strong.
  4. We recommend a selective approach to aspiration of the hip based on the patient’s probability of PJI and the results of the ESR and CRP. We recommend that the aspirated fluid be sent for microbiologic culture, synovial fluid white blood cell count and differential (See table). Strength of recommendation: Strong.
  5. We suggest a repeat hip aspiration when there is a discrepancy between the probability of PJI and the initial aspiration culture result. Strength of recommendation: Moderate.
  6. In the absence of reliable evidence, it is the opinion of the work group that patients judged to be at lower probability for periprosthetic hip infection and without planned reoperation who have abnormal ESRs or abnormal CRP levels be re-evaluated within 3 months. We are unable to recommend specific diagnostic tests at the time of this follow-up. Strength of recommendation: Consensus.
  7. In the absence of reliable evidence, it is the opinion of the workgroup that a repeat knee aspiration be performed when there is a discrepancy between the probability of periprosthetic joint infection and the initial aspiration culture result. Strength of recommendation: Consensus.
  8. We suggest patients be off of antibiotics for a minimum of 2 weeks prior to obtaining intra-articular culture. Strength of recommendation: Moderate.
  9. Nuclear imaging (labeled leukocyte imaging combined with bone or bone marrow imaging, FDG-PET imaging, Gallium imaging, or labeled leukocyte imaging) is an option in patients in whom diagnosis of PJI has not been established and are not scheduled for reoperation. Strength of recommendation: Weak.
  10. We are unable to recommend for or against CT or MRI as a diagnostic test for PJI. Strength of recommendation: Inconclusive.
  11. We recommend against the use of intraoperative Gram stain to rule out PJI. Strength of recommendation: Strong.
  12. We recommend the use of frozen sections of peri-implant tissues in patients who are undergoing reoperation for whom the diagnosis of PJI has not been established or excluded. Strength of recommendation: Strong.
  13. We recommend that multiple cultures be obtained at the time of reoperation in patients being assessed for PJI. Strength of recommendation: Strong.
  14. We recommend against initiating antibiotic treatment in patients with suspected PJI until after cultures from the joint have been obtained. Strength of recommendation: Strong.
  15. We suggest that prophylactic preoperative antibiotics not be withheld in patients at lower probability for PJI and those with an established diagnosis of PJI who are undergoing reoperation. Strength of recommendation: Moderate.

References:

  • Bauer TW, et al. Diagnosis of Periprosthetic Infection. J Bone Joint Surg. 2006;88(4):869-882.
  • Della Valle C, et al. Diagnosis of periprosethtic joint infection of the hip and knee. J Am Acad Orthop Surg. 2010; 18(12): 760-770.
  • Parvizi J, Della Valle CJ. AAOS clinical practice guideline: Diagnosis and treatment of periprosthetic infections of the hip and knee. J Am Acad Orthop Surg. 2010;18(12): 771-772.

Javad Parvizi, MD, FRCS, editor of Infection Watch, can be reached at the Rothman Institute, 925 Chestnut St., 5th Floor, Philadelphia, PA 19107; 267-339-3617; e-mail: parvj@aol.com.

Disclosure: Parvizi serves on the speakers bureau for Johnson & Johnson, is a paid consultant for Stryker and Smith & Nephew and receives research or institutional support from Stryker (as reported in the guideline).