Results of Aspiration, Erythrocyte Sedimentation Rate, and C-Reactive Protein in Patients With Known Prosthetic Joint Infection on Chronic Suppression.

Abstract

Introduction: Chronic antibiotic suppression (CAS) is regarded as a reasonable treatment option for persistent prosthetic joint infection in patients with multiple failed surgical eradication attempts or comorbidities that preclude surgical treatment. However, patient response to CAS has been highly variable. The purpose of this study is to determine if inflammatory marker values predict success with CAS and assess average inflammatory marker values to facilitate more accurate periprosthetic joint infection (PJI) diagnoses in patients suspected of having prosthetic joint infection who were already started on antibiotics.

Methods: A retrospective cohort study was conducted, identifying 46 patients on CAS. Inclusion based on culture-proven PJI and treatment with chronic suppressive antibiotics. Failure was defined as requirement of revision surgery or death related to PJI. Laboratory values (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], polymorphonuclear neutrophilic [PMN] leukocyte, synovial white blood cell [WBC]) within 2 years following suppression initiation were collected. Wilcoxon rank-sum tests were used to compare laboratory values between those with success and failure.

Results: This study analyzed 33 total knee and 16 total hip arthroplasties. The strongest predictor of failure with CAS within 2 years of treatment was elevated ESR (P < 0.05). Despite antibiotic treatment, 0 to 2 years following CAS initiation, 75% of patients had an elevated PMN% and 83.3% had elevated synovial WBC. CRP remained elevated in only 39.3% of patients, and ESR remained elevated in 66.7% of patients.

Conclusion: The primary laboratory predictor of those who failed with CAS was elevated ESR. Second, elevated PMN% and synovial WBC were determined to be the strongest indicators of PJI in a patient who was treated with antibiotics before diagnosis, although CRP and ESR were more likely to normalize. This suggests that patients with strong clinical suspicion for PJI on antibiotics should be aspirated regardless of normalized ESR and CRP.