A systematic review assessed historical features, physican examination, laboratory investigations, and plain radiographs in the diagnosis of lower extremity osteomyelitis in patients with diabetes mellitus. The gold standard was culture or histological results from bone biopsy. An ulcer area larger than 2 cm², (positive LR 7.2, 95% CI 1.1 to 49), negative LR 0.48, 95% CI 0.31 to 0.76) and a positive probe-to-bone test result (positive LR 6.4, 95% CI 3.6 to 11; negative LR 0.39, 95% CI 0.20 to 0.76) were the best clinical findings. An erythrocyte sedimentation rate of more than 70 mm/h increases the probability of a diagnosis of ostemyelitis (LR 11, 95% CI 1.6 to 79) An abnormal plain radiograph doubles the odds of osteomyelitis (LR 2.3, 95% CI 1.6 to 3.3). A positive MRI result makes increases the likelihood of osteomyelitis (LR 3.8, 95% CI 3.8, 95% CI 2.5 to 5.8) A normal MRI result makes osteomyelitis much less likely (LR 0.14, 95% CI 0.08 to 0.26). The overall accuracy (ie, the weighted average of the sensitivity and specificity) of the MRI is 89% (95% CI, 83.0 to 94.5).
Comment: Many of the studies were of poor quality. The majority of studies were of retrospective design and had unblinded protocols.