Evidence library

Recommends diagnosing soft-tissue infection clinically and grading its severity with the IWGDF/IDSA classification, a structured work-up for suspected osteomyelitis (probe-to-bone, plain radiographs, inflammatory markers and MRI where uncertain), deep tissue or bone sampling for culture rather than superficial swabs, and shorter, targeted antibiotic courses.

Major criteria (sinus tract communicating with the joint, or two positive cultures of the same organism) confirm infection; otherwise weighted minor criteria (serum CRP, D-dimer, ESR; synovial WCC, leucocyte esterase, alpha-defensin, neutrophil percentage, synovial CRP) give a score where 6 or more indicates infection and 2-5 is inconclusive. The new definition showed higher sensitivity than the 2011 MSIS criteria with very high specificity.

Defined confirmatory criteria (fistula, sinus or wound breakdown communicating with bone or implant; purulent drainage or pus; the same pathogen in at least two deep tissue samples; microorganisms on histology) and suggestive criteria (clinical signs, raised markers, imaging, single positive culture) that should prompt further investigation.

Fever was the strongest single predictor and raised CRP was an independent predictor; combining CRP with the Kocher criteria increased the probability of septic arthritis as more predictors were present.

The probability of septic arthritis rose steeply with the number of predictors present, being very high when all four were present and very low when none were.