SLR - March 2011 - Nelida Dumitrache
Reference: Lozano, R., Fernandez, M., Hernandez, D., Montesinos, J., Jimenez, S., Jurado, M., (2010). Validating the Probe-to-Bone Test and Other Tests for Diagnosing Chronic Osteomyelitis in the Diabetic Foot. Diabetes Care, 33:2140–2145.
Scientific Literature Reviews
Reviewed by: Nelida Dumitrache, DPM, PGY-3
Residency Program: Southern Arizona VA Healthcare System
Podiatric Relevance:
Osteomyelitis of the diabetic foot is a leading cause of lower extremity amputations in diabetic patients. Having certainty in the diagnosis of osteomyelitis prevents both amputation of non-infected bone as well as waiting too long to amputate—which can result in progression of the infection and a greater amount of bone excision during the surgery. The probe to bone test is an especially useful method of diagnosing osteomyelitis because it can detect osteomyelitis before the two-week period required for x-ray detecting and is much cheaper than an MRI.
Methods:
This is a prospective observational study with 132 foot lesions with clinical signs of osteomyelitis. The mean ulcer duration was 42 weeks. The researchers used four methods to determine osteomyelitis: clinical signs, x-rays, culture of the soft tissues and the probe to bone test. The gold standard was the examination of infected bone by a pathologist after being removed in the OR. The probe to bone test was done by a single experienced physician.
Results:
The probe to bone test had the highest positive predictive value (PPV) of all the methods at 94.5% PPV with a sensitivity of 98.1%, and specificity of 77.78% (P<0.001). Radiographic signs had the next highest PPV of 81.74, with a sensitivity of 89.52% and specificity of 22.22%.
Conclusions:
In conclusion, the probe to bone test appears to have the best predictive value of all other methods performed in the study. It should be noted, however, that the sample consisted exclusively of foot ulcerations with clinical signs of infection. The probe to bone test has great value in detecting the presence of osteomyelitis in a clinically infected foot, which very beneficial as it may detect osteomyelitis earlier than X-rays, thus preventing the progression of osteomyelitis for two weeks.