OBJECTIVE: To compare the diagnostic characteristics of tests used for a prompt 
diagnosis of chronic osteomyelitis in the diabetic foot, using bone histology as 
the criterion standard. The tests assessed were probe-to-bone (PTB), clinical 
signs of infection, radiography signs of osteomyelitis, and ulcer specimen 
culture.
RESEARCH DESIGN AND METHODS: A prospective study was performed on patients with 
foot ulcers referred to our diabetic foot clinic. Ulcer infection was diagnosed 
by recording clinical signs of infection and taking specimens for culture. The 
presumptive diagnosis of osteomyelitis was based on these results and the 
findings of a plain X-ray and PTB test. All patients with a clinical suspicion 
of bone infection were subjected to surgical treatment of the affected bone. 
During surgery, bone specimens were obtained for a histological diagnosis of 
osteomyelitis.
RESULTS: Over 2.5 years, 210 foot lesions were consecutively examined and 132 of 
these wounds with clinical suspicion of infection selected as the study sample. 
Of these, 105 (79.5%) lesions were diagnosed as osteomyelitis. Among the tests 
compared, the best results were yielded by the PTB test including an efficiency 
of 94%, sensitivity of 98%, specificity of 78%, positive predictive value of 
95%, and negative predictive value of 91% (P < 0.001, κ 0.803); the positive 
likelihood ratio was 4.41, and the negative likelihood ratio was 0.02 (95% CI).
CONCLUSIONS: In our outpatient population with a high prevalence of 
osteomyelitis, the PTB test was of greatest diagnostic value, especially for 
neuropathic ulcers, and proved to be efficient for detecting osteomyelitis in 
the diabetic foot.