Diagnostic value of magnetic resonance imaging and the outcomes of medical therapy in histologically confirmed diabetes-related foot osteomyelitis

<b>Background</b>: The preferred imaging modality in diabetes-related foot osteomyelitis is magnetic resonance imaging; however the test characteristics of magnetic resonance imaging have not been well evaluated in histologically confirmed disease. Although there is reasonably strong evidence of the effectiveness of medical therapy in the treatment of diabetes-related foot osteomyelitis, there is limited evidence in histologically confirmed cases. <b>Methods</b>: A retrospective review of episodes in which diabetes-related foot osteomyelitis was suspected was performed among patients who had both magnetic resonance imaging and bone histology. Magnetic resonance images were reviewed by a musculoskeletal trained radiologist using guideline criteria. Cases were subsequently followed for need for amputation at 1 year. <b>Results</b>: Among 84 episodes, the sensitivity of magnetic resonance imaging in histologically confirmed diabetes-related foot osteomyelitis was 96 %, specificity 38.2 %, positive predictive value 69.6 %, negative predictive value 86.7 %, positive likelihood ratio 1.15, and negative likelihood ratio 0.1. Of 15 cases in which the histology specimen revealed osteomyelitis from a diagnostic biopsy, 10 responded to medical management without the need for an amputation. <b>Conclusions</b>: Magnetic resonance imaging is useful excluding diabetes-related foot osteomyelitis but is of limited diagnostic value in confirming its presence. Most cases of histologically confirmed diabetes-related foot osteomyelitis responded to medical management without the need for amputation.