Background/Purpose:

Polyarticular septic arthritis (polySA) is rare, but clinically important, with reported mortality rates approaching 30% even with appropriate therapy. Little is known regarding how patients with polySA differ from those with monoarticular septic arthritis (mSA). In addition, there is little known regarding outcomes of patients with polySA who have surgery compared with those who do not. We describe one of the largest cohorts of patients with culture-proven polySA with the aim of characterizing differences in clinical features and outcomes between those with polySA and mSA and between those with polySA treated conservatively or with surgery.

Methods:

We conducted a retrospective study of patients 18 years and older admitted to a single tertiary care center from 1998 to 2015 with culture-positive polySA. Only patients for whom synovial fluid cultures were available for each affected joint were included. Patients with polySA were stratified into operatively managed and conservatively managed groups and compared in aggregate to those with mSA. Microbial profiles, predisposing factors, sites of joint involvement, length of hospital stay (LOS), and 60-day readmission rates were determined.

Results:

Of 41 patients with polySA, 35 received surgical intervention. The most common organisms isolated from synovial fluid were methicillin-sensitive Staph aureus, group B Strep, and methicillin-resistant Staph aureus. The knee was most frequently involved (n = 27), followed by the shoulder (n = 12), wrist (n = 10), hip (n = 8) and elbow (n = 5). Patients with polySA managed surgically had a higher mean ESR (p < 0.01), CRP (p = 0.02), and synovial polymorphonuclear (PMN) leukocyte % (p = 0.01) and a longer mean LOS (18.1 vs. 4.7 days; p = 0.04), and a higher rate of discharge to a rehabilitation facility (p < 0.01) than their conservatively managed peers. Compared to those with mSA, patients with polySA were more likely to have rheumatoid arthritis (p = 0.02), malignancy (p = 0.02), or immunosuppression (p = 0.05) and had a higher mean peripheral white blood cell (WBC) count (p < 0.01), CRP (p = 0.05), and frequency of associated sepsis (p = 0.01). While rates of surgery were similar between the polySA and mSA groups, those with polySA required more repeat surgeries during the same admission (p < 0.01).

Conclusion:

In this large, retrospective cohort, patients with polySA were more medically complex and more likely to have systemic infection at presentation than those with mSA, but ultimately experienced similar outcomes, with the exception of requiring repeat surgery more often. Increased markers of systemic and synovial inflammation were found in patients with polySA managed surgically as compared to their conservatively managed peers. Future research should identify whether the observed differences between patients with polySA and mSA and between surgically or medically managed patients with polySA can be used to guide optimal management.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-characteristics-and-outcomes-of-polyarticular-septic-arthritis/