Clinical characteristics and predictors of outcomes in septic arthritis of the shoulder

Aims The incidence of septic arthritis is rising due to an increase in joint surgeries and life expectancy. Limited data exist on the characteristics and risk factors associated with septic arthritis of the shoulder. This study aimed to describe the clinical characteristics and identify predictors of unfavourable outcomes in affected patients. Methods This retrospective cohort study included patients aged > 19 years diagnosed with septic arthritis of the shoulder between June 2007 and June 2023 at a tertiary hospital in Korea. Patients who did not receive treatment at this hospital or had Mycobacterium tuberculosis isolated from synovial cultures were excluded. Demographic data, data on comorbidities, clinical history, imaging findings, laboratory results, and microbiological culture results were analyzed to determine their association with unfavourable outcomes. Results Among 99 patients, 49 had unfavourable outcomes. The most frequently identified microorganism was Staphylococcus aureus (39 cases), including methicillin-resistant S. aureus (MRSA) (11 cases), followed by Streptococcus and beta-haemolytic species (seven cases). Univariate analysis identified leukocytosis and an elevated CRP:albumin ratio at two weeks as significant factors, along with positive culture results, bloodstream infection, and MRSA isolation. In multivariate analysis, the CRP/albumin ratio at two weeks (odds ratio (OR) 1.05 (95% CI 1.01 to 1.10); p = 0.014) and a culture-confirmed strain (OR 3.38 (95% CI 1.20 to 10.33); p = 0.025) were significant predictors of unfavourable outcomes. Conclusion An elevated CRP:albumin ratio at two weeks and positive culture findings are significant predictors of unfavourable outcomes in septic arthritis of the shoulder. These findings emphasize the importance of close monitoring and timely intervention in high-risk patients. Cite this article: Bone Joint J 2025;107-B(12):1301–1308.