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Diabetic foot osteomyelitis: usefulness of erythrocyte sedimentation rate in its diagnosis.
Malabu UH, Al-Rubeaan KA, Al-Derewish M. West Afr J Med. 2007 Apr-Jun;26(2):113-6.
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BACKGROUND: Recently, ESR was reported to have a useful diagnostic value in detecting diabetic osteomyelitis. The test has been performed in a limited number of patients. This laboratory parameter is simple and could be routinely performed in developing countries where diabetes and its complication are increasingly being encountered.
OBJECTIVE: To evaluate the reliability of erythrocyte sedimentation rate (ESR) in differentiating diabetic osteomyelitis from cellulitis, and to compare its diagnostic value with other hematological indices.
METHODS: In a one-year prospective study, forty -three adult diabetic patients with foot ulcers were assessed at King Abdulaziz University Hospital Diabetes Center Riyadh from 1st January to 31st December 2005. ESR was compared with other hematological profiles in differentiating osteomyelitis from cellulitis.
RESULTS: ESR, white blood cell count (WBC), platelet count, and red cell distribution width (RDW) were higher in patients with osteomyelitis than in patients with cellulitis (p<0.0001 for ESR; others p<0.05). In contrast, haematocrit and haemoglobin levels were lower in patients with osteomyelitis than in patients with cellulitis (p<0.0001). Overall, the efficiency of the haematological parameters in correctly diagnosing diabetic osteomyelitis from cellulitis was highest for ESR > 70 mm/hr (92%), followed by haematocrit < 36% (89%), haemoglobin < 12 g/dl (85%), platelet count > 400x10(9) (69%), RDW > 14.5 (65%), and WBC >11x10(9) (63%).
CONCLUSION: It is concluded that of the haematological parameters, ESR has the best diagnostic discrimination between diabetic foot osteomyelitis from cellulitis. Further studies on larger population in this environment are however indicated.
Unsuspected osteomyelitis is frequent in persistent diabetic foot ulcer and better diagnosed by MRI than by (18)F-FDG PET or (99m)Tc-MOAB.
Schwegler B, Stumpe KD, Weishaupt D, Strobel K, Spinas GA, von Schulthess GK, Hodler J, Böni T, Donath MY. J Intern Med. 2007 Nov 23; [Epub ahead of print]
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Aim. Prevalence, optimal diagnostic approach and consequences of clinically unsuspected osteomyelitis in diabetic foot ulcers are unclear. Early diagnosis of this infection may be crucial to ensure correct management.
Methods. We conducted a prospective study in 20 diabetic patients with a chronic foot ulcer (>8 weeks) without antibiotic pretreatment and without clinical signs for osteomyelitis to assess the prevalence of clinically unsuspected osteomyelitis and to compare the value of magnetic resonance imaging (MRI), (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) and (99m)Tc-labelled monoclonal antigranulocyte antibody scintigraphy ((99m)Tc-MOAB). Those with suggestive scans underwent bone biopsy for histology (n = 7).
Results. Osteomyelitis was confirmed by biopsy in seven of the 20 clinically unsuspected foot ulcers. Presence of osteomyelitis was not related to age, ulcer size, ulcer duration, duration of diabetes or HbA1c. C-reactive protein was slightly elevated in patients with osteomyelitis (35.1 +/- 16.0 mg L(-1) vs. 12.2 +/- 2.6 mg L(-1) in patients with and without osteomyelitis respectively; P = 0.07). MRI was positive in six of the seven patients with proven osteomyelitis, whereas (18)F-FDG PET and (99m)Tc-MOAB were positive only in (the same) two patients. Of the seven patients with osteomyelitis, five had lower limb amputation and in one patient the ulcer was persisting after 24 months of follow-up. In contrast, of the 13 patients without detectable signs of osteomyelitis on imaging modalities only two had lower limb amputation and two persisting ulcers.
Conclusions. Clinically unsuspected osteomyelitis is frequent in persisting foot ulcers and is a high risk factor for adverse outcome. MRI appears superior to (18)F-FDG PET and (99m)Tc-MOAB in detecting foot ulcer-associated osteomyelitis and might be the preferred imaging modality in patients with nonhealing diabetic foot ulcers.
"Diabetic foot osteomyelitis: usefulness of erythrocyte sedimentation rate in its diagnosis.
Malabu UH, Al-Rubeaan KA, Al-Derewish M.
West Afr J Med. 2007 Apr-Jun;26(2):113-6."
Has anyone got access to the full article? I'm interested to know how they made the diagnosis of osteomyelitis to compare the blood tests against.
Diagnostic Accuracy of the Physical Examination and Imaging Tests for Osteomyelitis Underlying Diabetic Foot Ulcers: Meta-Analysis.
Dinh MT, Abad CL, Safdar N. Clin Infect Dis. 2008 Jul 8. [Epub ahead of print]
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Accurate diagnosis of osteomyelitis underlying diabetic foot ulcers is essential to optimize outcomes. We undertook a meta-analysis of the accuracy of diagnostic tests for osteomyelitis in diabetic patients with foot ulcers. Pooled sensitivity and specificity, the summary measure of accuracy (Q*), and diagnostic odds ratio were calculated. Exposed bone or probe-to-bone test had a sensitivity of 0.60 and a specificity of 0.91. Plain radiography had a sensitivity of 0.54 and a specificity of 0.68. MRI had a sensitivity of 0.90 and a specificity of 0.79. Bone scan was found to have a sensitivity of 0.81 and a specificity of 0.28. Leukocyte scan was found to have a sensitivity of 0.74 and a specificity of 0.68. The diagnostic odds ratios for clinical examination, radiography, MRI, bone scan, and leukocyte scan were 49.45, 2.84, 24.36, 2.10, and 10.07, respectively. The presence of exposed bone or a positive probe-to-bone test result is moderately predictive of osteomyelitis. MRI is the most accurate imaging test for diagnosis of osteomyelitis.
Diagnostic Accuracy of the Physical Examination and Imaging Tests for Osteomyelitis Underlying Diabetic Foot Ulcers: Meta-Analysis.
Dinh MT, Abad CL, Safdar N. Clin Infect Dis. 2008 Jul 8. [Epub ahead of print]
Development of osteomyelitis of the foot is a potentially catastrophic event for a person with diabetes. The high success rates achieved with antimicrobial therapy for most infectious diseases have not yet been achieved for bone infections because of their unique physiological and anatomical characteristics [1]. When a foot ulcer becomes infected and the infection spreads to bone, the risk of limb amputation, with its substantial associated morbidity and mortality, is dramatically increased [2]. Furthermore, diabetic foot osteomyelitis often requires surgical therapy and/or prolonged antibiotic therapy. Because the key to successful management is early diagnosis, making an accurate diagnosis of this entity is crucial. Unfortunately, it is also difficult.
Two main issues complicate making a correct diagnosis of osteomyelitis in the diabetic foot [3]. First, as with other types of bone infection, it usually takes a couple of weeks before there is sufficient loss of bone to be apparent on plain radiographs. Second, patients with longstanding diabetes often have peripheral neuropathy, which may both obscure clinical symptoms of infection [4] and predispose to neuro-osteoarthropathy. This noninfectious entity, often called Charcot foot, can be difficult to differentiate from bone infection [5]. Examination of a bone sample, with microbiological or histopathologic evaluation, is generally accepted as the criterion standard for diagnosis of osteomyelitis [6, 7]. Unfortunately, this safe and relatively simple procedure is not widely used and can yield results that are either false positive (caused by specimen contamination during the procedure) or false negative (caused by prior antibiotic therapy or erroneous sampling of an uninfected area). Thus, many investigations have undertaken a search of clinical, laboratory, or imaging findings that may help in the diagnosis of osteomyelitis.
In this issue of Clinical Infectious Diseases, Dinh et al. [8] present the results of a meta-analysis of studies examining the diagnostic accuracy of various clinical and imaging methods for diabetic patients with a foot ulcer. They elected to include only studies that used histopathologic examination or culture of a bone specimen as the reference for diagnosis of osteomyelitis. Although this criterion adds rigor to their findings, it allowed them to select only 9 studies for their analysis. By contrast, a systematic review of diagnostic tests for diabetic foot osteomyelitis (published since the submission of the article by Dinh et al. [8]) that included some patients from whom no bone specimen was obtained reported data from 21 publications [9]. This study and the one by Dinh et al. [8] are otherwise very similar, seeking articles addressing the same question for the same types of patients over the same period. Surprisingly and for unclear reasons, only 4 of the same studies were selected by both groups for inclusion in their analyses.
Thus, which evidence is useful for diagnosis of diabetic foot osteomyelitis? Both Dinh et al. [8] and Butalia et al. [9] concluded that the presence of exposed or visible bone correlated with bone infection, but this conclusion was based on only 2 studies. There was insufficient data to support the value of any other clinical finding, except perhaps the presence of a foot ulcer with a size >2 cm2. Butalia at al. [9] reviewed the value of laboratory tests and concluded-again based on only 2 studies-that an erythrocyte sedimentation rate >70 mm/h significantly increased the probability of osteomyelitis. With regard to imaging studies, both reviews concluded that MRI is the most accurate of the available tests. Plain radiography and WBC radionuclide scans are moderately helpful, but bone scans are too nonspecific to be useful. It is not easy to directly compare the findings of the 2 studies, because the systematic review by Butalia et al. [9] reported likelihood ratios for the various diagnostic tests, and the meta-analysis by Dinh et al. [8] provided pooled diagnostic ORs and Q* values (i.e., a summary receiver operating characteristic that is less affected by heterogeneity).
It is worth considering diagnostic methods that neither study discussed, because these methods have not been subject to rigorous investigation. Experienced clinicians have advocated some clinical findings that may suggest osteomyelitis. These include the presence of a break in the skin-especially a chronic ulcer that is overlying a bony prominence-that affects the forefoot (or the heel) rather than the midfoot and that is deep [3]. Similarly, an ulcer that is not healing (or especially, deepening) despite appropriate care and pressure off-loading suggests underlying osteomyelitis [10]. Although both reviews recommended the probe-to-bone test, the test must be performed as described in the studies demonstrating its usefulness (i.e., after debridement of the soft-tissue wound and with a sterile metal-not a wooden or plastic-probe). Also, as with other diagnostic tests, the performance characteristics of the probe-to-bone test depend on the pretest probability of osteomyelitis in the tested population [11]. With regard to available laboratory tests, leukocytosis is infrequent in patients with diabetic foot osteomyelitis [12], but C-reactive protein measurement may be useful, because the C-reactive protein level is often elevated in patients with bone infection but is normal in patients with Charcot foot [13, 14]. More recently, the serum procalcitonin level has been shown to be a useful diagnostic marker of diabetic foot infection [15, 16], but additional investigations are required to determine the value of this test, especially for diagnosis of osteomyelitis. With regard to imaging tests, there are some promising diagnostic approaches. It may be possible to overcome the lack of sensitivity of negative plain radiograph findings for a patient with an acute soft-tissue wound by providing appropriate treatment (including for any infection) and then repeating the radiography assessment a few weeks later. Negative follow-up radiograph findings make the presence of osteomyelitis unlikely, and the development of new findings of bony erosion suggests that is osteomyelitis present [10]. Of course, newer diagnostic methods are continually being evaluated. One method that is particularly promising is the positron emission tomography scan with 18F-fluorodeoxyglucose imaging [17]. Studies have revealed that this method can detect clinically unsuspected osteomyelitis [14] and can accurately distinguish osteomyelitis from Charcot foot [18].
A different approach to this diagnostic dilemma is to develop a consensus scheme that integrates the results of a range of clinical, laboratory, and imaging findings. This technique has been used in several clinical situations, such as the Duke criteria for endocarditis, in which there is not a single criterion sufficiently reliable for making a diagnosis. To that end, the International Working Group on the Diabetic Foot appointed an expert advisory group to suggest criteria for the diagnosis of diabetic foot osteomyelitis that could be used in future research [19]. The group stratified levels of diagnostic certainty, based on the posttest probabilities of various diagnostic tests (depending on their relative values), into 4 categories of likelihood: definite (>90%), probable (51%-90%), possible (10%-50%), and unlikely (<10%). In addition to using an individual criterion, they proposed combinations of test results that would determine the diagnostic category. The scheme may be useful for initial decisions regarding whether additional diagnostic testing is needed or whether initiation of empirical antibiotic therapy is appropriate. It also allows for changing the level of diagnostic certainty over time as the course of infection evolves. Of course, this proposed scheme should currently only be used for research purposes and must undergo validation for use in clinical trials.
The meta-analysis by Dinh et al. [8] is a useful review of the current methods for diagnosis of osteomyelitis of the foot in patients with diabetes. Make no bones about it, with the combination of some promising new diagnostic tests, the systematic review by Butalia et al. [9], and the proposed research consensus scheme from the International Working Group on the Diabetic Foot, we are finally approaching the point of having the ability to accurately diagnose this relatively frequent and potentially devastating infection.
Full editorial with references
Clinical Infectious Diseases 2008;47:000–000
This article is in the public domain, and no copyright is claimed.
Needle Puncture and Transcutaneous Bone Biopsy Cultures are Inconsistent in Patients with Diabetes and Suspected Osteomyelitis of the Foot.
Senneville E, Morant H, Descamps D, Dekeyser S, Beltrand E, Singer B, Caillaux M, Boulogne A, Legout L, Lemaire X, Lemaire C, Yazdanpanah Y. Clin Infect Dis. 2009 Feb 19. [Epub ahead of print]
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Background. Needle puncture has been suggested as a method for identifying bacteria in the bones in patients with diabetes with osteomyelitis of the foot. However, no studies have compared needle puncture with concomitant transcutaneous bone biopsy, which is the current standard recommended in international guidelines.
Methods. We conducted a prospective study in 2 French diabetes foot clinics. Transcutaneous bone biopsy specimens, needle puncture specimens, and swab samples were collected on the same day for each patient.
Results. Overall, 31 patients were included in the study from July 2006 through February 2008. Twenty-one bone biopsy specimens (67.7%), 18 needle puncture specimens (58%), and 30 swab samples (96.7%) had positive culture results. Staphylococcus aureus was the most common type of bacteria that grew from bone samples, followed by Proteus mirabilis and Morganella morganii. The mean number of bacteria types per positive sample were 1.35, 1.32, and 2.51 for bone biopsy specimens, needle puncture specimens, and swab samples, respectively. Among the 20 patients with positive bone biopsy specimens (69%), 13 had positive needle puncture samples. Overall, the correlation between microbiological results was 23.9%, with S. aureus showing the strongest correlation (46.7%). Results of cultures of bone biopsy and needle puncture specimens were identical for 10 (32.3%) of 31 patients. Bone bacteria were isolated from the needle punctures in 7 (33.3%) of the 21 patients who had positive bone biopsy specimen culture results. If the results of cultures of needle puncture specimens alone had been considered, 5 patients (16.1%) would have received unnecessary treatment, and 8 patients (38.1%) who had positive bone culture results would not have been treated at all.
Conclusions. Our results suggest that needle punctures, compared with transcutaneous bone biopsies, do not identify bone bacteria reliably in patients with diabetes who have low-grade infection of the foot and suspected osteomyelitis.
The diagnosis of diabetic foot osteomyelitis: Examination findings and laboratory values.
Ertugrul BM, Savk O, Ozturk B, Cobanoglu M, Oncu S, Sakarya S. Med Sci Monit. 2009 Jun;15(6):CR307-312.
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Background: This study aimed to demonstrate how much examination findings and laboratory values can be helpful in the diagnosis of osteomyelitis in patients with diabetic foot infections.
Material/Methods: Data of 46 consecutive inpatients prospectively followed up according to a specially designed "Diabetic Foot Follow-up Form" were analyzed. Following diagnostic interventions, clinical and laboratory findings of patients with and without a diagnosis of osteomyelitis were compared. In these patients with and without osteomyelitis confirmed by histopathology and/or microbiology and/or MRI the sensitivity and specificity of ESR (erythrocyte sedimentation rate) and wound size were also determined.
Results: There was no significant differences in the duration of diabetes or the existence of nephropathy or vascular disease, while the other findings (ESR, C-reactive protein, wound size, history of diabetic foot ulcer, and retinopathy) were significantly different. It is found that ESR >/=65 mm/h together with a wound size >/=2 cm2 had a sensitivity of 83%, specificity of 77%, positive predictive value of 80%, and negative predictive value of 81% in the diagnosis of osteomyelitis.
Conclusions: This study demonstrated that simple clinical evaluation and laboratory findings without using expensive imaging methods may be important indicators of osteomyelitis.
Diagnostic Performance of FDG-PET, MRI, and Plain Film Radiography (PFR) for the Diagnosis of Osteomyelitis in the Diabetic Foot.
Nawaz A, Torigian DA, Siegelman ES, Basu S, Chryssikos T, Alavi A. Mol Imaging Biol. 2009 Oct 9. [Epub ahead of print]
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BACKGROUND: The early and accurate diagnosis of osteomyelitis in the diabetic foot is essential to provide appropriate treatment and obviate long-term complications of the disease. The currently employed non-invasive imaging modalities such as plain film radiography (PFR) lack the sensitivity to accurately exclude osteomyelitis, while magnetic resonance imaging (MRI) is limited by its low specificity and contraindications in certain patients. Therefore, accurate non-invasive detection of osteomyelitis in the diabetic foot remains a challenge. [18F]-2-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) has been proven useful in other settings to detect infection. In this ongoing prospective study, we assessed the diagnostic performance of FDG-PET to diagnose osteomyelitis in the diabetic foot and compared it with that of MRI and PFR.
METHODS: Patients who met the prespecified criteria for complicated diabetic foot underwent FDG-PET, MRI, and PFR of the feet. Each imaging study was then interpreted in a blinded fashion for presence of osteomyelitis or other abnormalities. The gold standard for diagnosis in each patient was based on surgical, microbiological, and clinical follow-up results.
RESULTS: One hundred ten consecutive patients have been enrolled to date into this prospective project. FDG-PET correctly diagnosed osteomyelitis in 21 of 26 patients and correctly excluded it in 74 of 80, with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 81%, 93%, 78%, 94%, and 90%, respectively. MRI correctly diagnosed osteomyelitis in 20 of 22 and correctly excluded it in 56 of 72, with sensitivity, specificity, PPV, NPV, and accuracy of 91%, 78%, 56%, 97%, and 81%, respectively. PFR correctly diagnosed osteomyelitis in 15 of 24 and correctly excluded it in 65 of 75, with sensitivity, specificity, PPV, NPV, and accuracy of 63%, 87%, 60%, 88%, and 81%, respectively.
CONCLUSION: FDG-PET is a highly specific imaging modality for the diagnosis of osteomyelitis in diabetic foot and, therefore, should be considered to be a useful complimentary imaging modality with MRI. In the setting where MRI is contraindicated, the high sensitivity and specificity of FDG-PET justifies its use after a negative or inconclusive PFR to aid an accurate diagnosis.
Diagnosing osteomyelitis
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