331 - Septic arthritis: when is the joint clean enough?

Background: Septic arthritis is an orthopedic emergency that requires debridement. Previous authors reported that patients with inflammatory arthropathy, diabetes, infection with S. aureus, involvement of a large joint, and synovial fluid WBC >85,000 are associated with >1 debridements. The purpose of this study was to determine factors associated with 1 vs >1 debridements.

Methods: This is a retrospective cohort of adult patients hospitalized at Denver Health Medical Center with large joint septic arthritis between 7/1/2012 and 4/13/20. Patients with implanted orthopedic material, osteomyelitis, and recurrent septic arthritis were excluded. Septic arthritis was defined as a patient presenting with acute arthritis and positive culture OR negative culture and no other etiology. Both electronic capture and manual chart review were performed. Descriptive statistics were used to characterize the population. Statistical analyses included bivariate and multivariate analyses. 

Results: Forty-four cases were included (26 knee [59.1%], 4 hip [9.1%], 6 elbow [13.6%], and 8 shoulder [18.2%]. The median age was 55.7 years (41.3-64.1], and 79.5% were male. The most common organisms were S. aureus (n=20, 45.5%) and beta-hemolytic Streptococcus (n=10, 22.7%). Three patients had no surgical debridement, 21 had 1 debridement, and 20 had >1 debridements.
As compared to those who had 1 debridement, those with >1 debridements were more likely to be male (95% vs 61.9%, p=0.02) and to have a higher synovial fluid leukocyte count (102,761 vs 49,154, p=0.001), CRP at admission (162.5 vs 97.7, p=0.039), and WBC the day prior to debridement (13.4 vs 9.8, p=0.007). Intra-operative purulence trended to association with >1 debridements. Pre- to post-operative changes in opiate use, temperature, and ability to work with physical therapy were not associated with 1 vs >1 debridements. Both higher synovial fluid leukocyte counts and CRP value at admission were independently associated with >1 debridements (OR 2.31, p=0.015; OR 1.01, p=0.036 respectively).

Conclusion: Patients with higher synovial fluid leukocytes and CRP at admission were more likely to have >1 debridements. Additional studies with functional outcome scores are necessary to determine if >1 debridements are associated with better clinical outcomes.