Diagnosis of Osteomyelitis in the Distal Phalanx of the Finger

Initial Clinical Assessment

The Infectious Diseases Society of America recommends suspecting osteomyelitis when an open wound or ulcer overlies the distal phalanx and fails to heal after 6 weeks of appropriate care, or when the finger appears swollen, erythematous, and lacks normal contours, or when there is visible bone or a draining sinus tract 1, 2, 3
The American College of Clinical Infectious Diseases suggests performing probe-to-bone (PTB) testing if an open wound is present, as a positive test substantially increases the likelihood of osteomyelitis with a positive likelihood ratio of 7.2 in high-prevalence settings 4, 1, 2, 5

The Infectious Diseases Society of America recommends ordering inflammatory markers, such as erythrocyte sedimentation rate (ESR), to support the diagnosis, as an ESR >70 mm/h increases the likelihood of osteomyelitis (positive LR of 11) 4

The American College of Radiology recommends obtaining plain radiographs of the affected finger in all cases, looking for cortical erosion, periosteal reaction, mixed lucency and sclerosis, or bone destruction, with a sensitivity of 54% and specificity of 68% 1, 2, 7, 5
The Infectious Diseases Society of America suggests ordering MRI when plain radiographs are equivocal or negative but clinical suspicion remains high, or when surgical planning requires precise anatomic definition, with a sensitivity of ~90-97% and specificity of ~85-93% 1, 2, 7, 5

The Infectious Diseases Society of America recommends that the gold standard for diagnosis is bone culture plus histology showing inflammatory cells and osteonecrosis, and obtaining bone biopsy when the diagnosis remains uncertain after imaging, or when antibiotic-resistant organisms are suspected 1, 2, 7, 5, 3