Tests for Diagnosing Chronic Osteomyelitis in the Diabetic Foot. Part 4

The mean time of ulcer duration was 44 weeks, the median being 16 weeks (range 1–74 weeks). When we examined ulcer duration according to the results of the different diagnostic methods, in patients in whom osteomyelitis was biopsy proven, ulcer duration was 41.67 ± 75.52 weeks, and in those with a negative biopsy result, it was 52.19 ± 104.32 weeks (P = 0.554). Corresponding ulcer durations in weeks recorded for a positive versus a negative test result, respectively, were PTB 41.15 ± 74.19 vs. 56.48 ± 112.74 (P = 0.417), ulcer specimen culture 45.83 ± 85.14 vs. 33.19 ± 62.55 (P = 0.519), radiography signs 42.08 ± 72.97 vs. 55.59 ± 129.61 (P = 0.528), and clinical signs 44.26 ± 89.51 vs. 42.83 ± 62.99 (P = 0.926).

Test efficiencies (percentage of patients correctly diagnosed as positive or negative) were PTB 93.89% (88–99.1%), ulcer specimen culture 71.97% (63.4–79.7%), radiographic signs 75.76% (67.4–82.6%), and clinical signs 59.09% (50.2–67.4%). To try to improve the capacity for diagnosing osteomyelitis, we assessed the use of two of the clinical diagnostic methods compared with bone histology and found that only when the PTB test was one of the two methods was the result significant. Thus, the pair of methods, clinical signs plus PTB, showed a sensitivity of 64.8%, specificity of 77.8%, positive predictive value (PPV) of 91.9%, and negative predictive value (NPV) of 36.2% (P < 0.001, κ 0.298); for radiography signs plus PTB the values recorded were sensitivity 88.6%, specificity 66.7%, PPV 91.2%, and NPV 60% (P < 0.001, κ 0.530); and for culture plus PTB they were sensitivity 84.8%, specificity 77.8%, PPV 93.8%, and NPV 56.8% (P < 0.001, κ 0.550). The test revealed by this analysis as most accurate was the PTB with a PPV of 94.5%. According to the decision tree, a correct diagnosis was made in 98.4% of the neuropathic ulcers vs. 88% of the neuroischemic ulcers. The correlation between ulcer duration and risk of having osteomyelitis was only significant for the neuroischemic ulcers such that 100% of ulcers <9 weeks old were positive for osteomyelitis. In this study we sought to provide data on the validity of the tests used in current clinical practice to diagnose chronic osteomyelitis in diabetic foot ulcers. There is still much controversy regarding the best way to detect bone infection in patients with diabetes, and there is also confusion about which is the most efficient treatment. Although most researchers consider that the histopathological study of bone specimens is the criterion standard for diagnosing osteomyelitis, this method is not systematically used because clinicians feel that surgically obtaining bone tissue is an aggressive procedure and puts patients at risk. Moreover, qualified medical staff are needed to undertake the surgical procedure. Buy avandia online
Few studies have validated the use of clinical signs as a diagnostic tool for infection of the diabetic foot. Cutting and White and Gardner et al. performed a series of studies on chronic foot ulcers, but their patients had different systemic diseases including diabetes. Our findings indicate that assessment of clinical signs of infection in diabetic patients, although valid, provides limited information for a prompt diagnosis of osteomyelitis. There is an obvious need for a more detailed and precise definition of clinical indicators in chronic diabetic ulcers.