Background Septic arthritis (SA) is the most rapidly destructive joint disease. The estimated incidence of septic arthritis is 2-10 cases per 100,000 per year. The incidence of septic arthritis appears to be increasing. This may be due to an aging population, the use of immunosuppressive therapies, and resistance to antibiotics.
Objectives To describe the changes in co-morbidities, bacterial etiology, treatment, and patient outcomes for SA over the past 2 decades.
Methods Medical records of all patients with a diagnosis recorded as SA admitted to two regional medical centers from 1988 to 2010 were reviewed. Data collected included age, sex, comorbidities, joint involvement, synovial fluid analysis, and relevant culture results. Patients mislabeled as SA or with incomplete medical data were excluded. The diagnosis of SA was defined as definite (clinically inflamed joint, positive synovial fluid culture), probable (clinically inflamed joint, negative synovial fluid culture but positive culture from another source), or possible (clinically inflamed joint, all cultures negative). In instances of missing data, statistics were performed based on the number of patients with data available. Data analysis was performed using SPSS 17.0.
Results A total of 601 patients were identified with a diagnosis of SA. Patients were divided into 3 groups by time periods: Group 1 (1988-95; n=100), Group 2 (1996-2000; n=271) and Group 3 (2003-10; n=230). P values compare Group 1 and 3. Significant demographic changes included a progressive increase in age of patients with SA (49, 57, 59 years for Groups 1, 2, and 3, respectively). The number of females affected remained stable at 45% over time. Length of hospital stay reduced from 12.4 days to 10.5 and 10.8 over time. Co-morbidities which increased over time in association with SA included CHF (3, 13, 15%; p=0.000), ESRD (8, 10, 14%; p=0.038), diabetes mellitus (18, 21, 36%; p=0.000), hepatitis C (2, 3.3, 21%; p=0.000), OA (9, 12, 37%; p=0.000) and prosthetic joint infections (8, 14, 19%; p=0.005). Co-morbidities which remained stable included CAD, cancer, and post-injection SA. Joint involvement remained stable with the knee being most commonly affected (51, 47, 48%), followed by shoulder, ankle, and wrist. Staphylococcus aureus was the most common organism (44, 42, 38%). The greatest change in bacterial etiology involved the extreme rarity of gonococcal arthritis in recent times (17, 1, 0.4%; p=0.000). Treatment trends included increased use of surgical drainage over serial aspirations (34, 55, 54%; p=0.001). More patients were sent to rehabilitation and skilled nursing facilities (25, 35, 38%; p=0.000) and a reduced number were discharged directly to home (54, 33, 25%; p=0.000). The incidence of death remained stable over time (8, 6.4, 8%).
Conclusions The incidence of SA is increasing in the general population, especially in older patients with CHF, hepatitis C, diabetes mellitus, OA and ESRD. The knee is most commonly involved, with Staphylococcus aureus being the most common organism, and gonococcal arthritis becoming extremely rare. More patients received surgical treatment and require inpatient rehabilitation before being discharged home over time. The incidence of death has remained stable.
Disclosure of Interest None Declared