Concomitant Septic Arthritis and Crystalline Arthropathy Save

I joined a poster tour this morning on the topic of infections and was intrigued by an abstract titled, Coexistence of septic and crystal-induced arthritis: a diagnostic challenge (#0560, Y Garcia-Mira, et al).

The authors sought to describe the characteristics of patients with concurrent septic and crystal arthritis through a retrospective analysis of patients with the concomitant diagnoses between 1985-2015 at a university hospital in Spain.  

Out of 123 patients with septic arthritis, 20.3% (25) had concurrent crystalline arthritis. All patients had positive bacterial culture (blood and/or synovial fluid) and crystals in synovial fluid. The majority (68%) were males and average age was 67 years. Risk factors identified were diabetes in 24%, use of diuretics in 24%, and CKD in 16% including 2 on dialysis and 4 with history of kidney transplant. There was a delay to diagnosis on average of 14 days and the most commonly affected joint was the knee followed by the foot and hip.

As far as types of crystalline arthropathy, 60% had MUS, 20% CPPD and 8% hydroxyapatite. 32% had positive gram stain and 88% had positive synovial fluid culture. Blood cultures were positive in 32%. Surgical debridement was done in 32% and mortalitiy was 8%.

I found the 20% incidence of concurrent septic arthritis and crystal disease to be quite high, but nonetheless this is something to consider especially in elderly males with certain co-morbidities, and reminds us that synovial fluid should always be examined for crystals and infection.