Diabetic foot ulcer

How to do diagnosis?

if you probe the wound and the probe hits the bone, it means that the patient has developed osteomyelitis. This "probe to bone test" has the highest specificity for the diagnosis of osteomyelitis. But if this test is negative, then you have to do an x-ray or MRI. MRI has the highest sensitivity among imaging modalities followed by a 3-phase bone scan. X-ray has the least sensitivity among all tests for diagnosis of osteomyelitis. 

CT scan also can be done but it is a less sensitive test than MRI.

if metal hardware interferes with MRI, then a nuclear scan (3-phase bone scan, tagged WBC scan) is done.

Let us say, there is one patient with a diabetic foot ulcer and underlying osteomyelitis. you had taken a wound swab and it revealed 3 bacteria with antibiotic sensitivity reports. Now, the question is can we rely that the same bacteria is causing osteomyelitis or the bacteria on the superficial might be contaminant as well?

The answer is we can't rely on the culture of superficial wounds. we must do a bone biopsy and culture for osteomyelitis because those bacteria do not correlate with the cause of osteomyelitis.