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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.
CULTURE OF PER-WOUND BONE SPECIMEN: A SIMPLIFIED APPROACH FOR THE MEDICAL MANAGEMENT OF DIABETIC FOOT OSTEOMYELITIS.
Lesens O, Desbiez F, Vidal M, Robin F, Descamps S, Beytout J, Laurichesse H, Tauveron I. Clin Microbiol Infect. 2010 Feb 11
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Surgical percutaneous bone biopsy specimen after a 14-day antibiotic free period represents the gold standard of care for diabetic foot osteomyelitis but may be difficult to implement in many institutions. We evaluate a simplified strategy based on the results of per-wound bone specimen culture. For that purpose, we retrospectively reviewed the charts of 80 consecutive patients with diabetic osteomyelitis and bone sample obtained via the wound after a careful debridement. The outcome was defined as favourable if there was a complete healing of the wound with no sign of infection and stable or improved bone X-ray 6 months after antibiotic therapy completion. Culture of bone specimen was positive in 96% of patients although half of the patients did receive a course of antimicrobials within 14 days the bone specimen was obtained. 129 bacteria were found in bone culture with a mean of 1.6+/-1 bacteria per patient (S. aureus: 33%; CNS: 14%; streptococci: 9%; enterococci: 12%; corynebacteriae: 4%; Gram negative bacilli: 20%; anaerobes: 4%). 46% of cultures were monomicrobial. The mean duration of follow-up from diagnosis was 17+/-1 months. Six months after antibiotics discontinuation, 7.5% (6) had died, 9 were considered as failure and 65 as cured. 54 of these 65 had follow-up data available at one year and remained in remission. In conclusion, a simplified procedure based on the culture of bone sample obtained via the ulcer after a careful debridement of the wound is a good option in the medical management of diabetic foot osteomyelitis.
INTRODUCTION: There has been increasing evidence in favor of conservative management of diabetic foot osteomyelitis which requires targeted antibiotic therapy to the causative pathogen. But the method of reliable microbiological isolation is controversial.
AIMS AND OBJECTIVES: To study the concordance of superficial swab culture with bone biopsy specimen culture in patients with diabetic foot osteomyelitis.
MATERIALS AND METHODS: A prospective study was conducted from July 2008 to July 2010. All consecutive patients with suspected diabetic foot osteomyelitis were included in the study. Superficial swab and Percutaneous bone biopsy specimens were obtained for culture. The culture results in these two groups were compared for concordance.
RESULTS: A total of 144 patients were included in the study. 134 cases of bone biopsy specimen and 140 cases of superficial swab showed positive culture results. Mean number of isolate per sample were similar. Staphylococcus aureus was the commonest organism grown in both cultures. The bone pathogen was identified in the corresponding swab culture in only 55 cases (38.2%). Staphylococcus aureus had the highest concordance percentage of 46.5% which was not statistically significant.
CONCLUSION: Superficial swab culture may not be accurate in identifying all the organisms causing diabetic foot osteomyelitis. Bone biopsy specimen taken simultaneously would increase the accuracy of detecting the bacterial isolate.
It is important to accurately diagnose osteomyelitis, and bone biopsy is currently considered by many to be the gold standard diagnostic test for its identification. Microbiologic studies, namely culture and sensitivity tests, are also used to identify osteomyelitis. To our knowledge, no published reports exist that compare the diagnostic characteristics of bone biopsy to microbiology with regard to making the diagnosis of osteomyelitis. For these reasons, we undertook a matched case control study to test the null hypothesis that claimed there is no difference between histology and microbiology with regard to making the diagnosis of pedal osteomyelitis in diabetic patients. The sample population consisted of consecutive diabetic patients from a tertiary care hospital who were surgically treated for foot infection with suspected osteomyelitis. Each bone specimen was hemisected, and one half sent for microbiologic testing and the other half sent for histopathologic inspection. McNemar's test for correlated proportions was used to identify whether or not a statistically significant difference existed between the diagnostic methods. A total of 44 specimens were analyzed, and our results showed that a positive microbiologic and negative histologic result was just as likely as a negative microbiologic and positive histologic result (P > .05). In conclusion, based on the results of this investigation, microbiologic testing performed as well as did histopathologic testing when it came to identifying the presence of pedal osteomyelitis in the diabetic foot.
Can Sequential 18F-FDG PET/CT Replace WBC Imaging in the Diabetic Foot?
Familiari D, Glaudemans AW, Vitale V, Prosperi D, Bagni O, Lenza A, Cavallini M, Scopinaro F, Signore A. J Nucl Med. 2011 Jun 16. [Epub ahead of print]
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White blood cell (WBC) scintigraphy is considered the nuclear medicine imaging gold standard for diagnosing osteomyelitis in the diabetic foot. Recent papers have suggested that the use of (18)F-FDG PET/CT produces similar diagnostic accuracy, but clear interpretation criteria have not yet been established. Our aim was to evaluate the role of sequential (18)F-FDG PET/CT in patients with a high suspicion of osteomyelitis to define objective interpretation criteria to be compared with WBC scintigraphy.
METHODS:
Thirteen patients whom clinicians considered positive for osteomyelitis (7 with ulcers, 6 with exposed bone) were enrolled. The patients underwent (99m)Tc-exametazime WBC scintigraphy with acquisition times of 30 min, 3 h, and 20 h and sequential (18)F-FDG PET/CT with acquisition times of 10 min, 1 h, and 2 h. A biopsy or tissue culture was performed for final diagnosis. Several interpretation criteria (qualitative and quantitative) were tested.
RESULTS:
At final biopsy, 7 patients had osteomyelitis, 2 had soft-tissue infection without osteomyelitis, and 4 had no infection. The best interpretation criterion for osteomyelitis with WBC scintigraphy was a target-to-background (T/B) ratio greater than 2.0 at 20 h and increasing with time. A T/B ratio greater than 2.0 at 20 h but stable or decreasing with time was suggestive of soft-tissue infection. A T/B ratio of no more than 2.0 at 20 h excluded an infection. Thus, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for osteomyelitis were 86%, 100%, 100%, 86%, and 92%, respectively. For (18)F-FDG PET/CT, the best interpretation criterion for osteomyelitis was a maximal standardized uptake value (SUVmax) greater than 2.0 at 1 and 2 h and increasing with time. A SUVmax greater than 2.0 after 1 and 2 h but stable or decreasing with time was suggestive of a soft-tissue infection. An SUVmax less than 2.0 excluded an infection. (18)F-FDG PET at 10 min was not useful. Using these criteria, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for osteomyelitis were 43%, 67%, 60%, 50%, and 54%, respectively. Combining visual assessment of PET at 1 h and CT was best for differentiating between osteomyelitis and soft-tissue infection, with a diagnostic accuracy of 62%.
CONCLUSION:
(18)F-FDG PET/CT, even with sequential imaging, has a low diagnostic accuracy for osteomyelitis and cannot replace WBC scintigraphy in patients with diabetic foot.
Bone biopsy is often referred to as the reference standard for the diagnosis of diabetic foot osteomyelitis (OM), and it also serves as an important interventional tool with respect to diabetic foot infections and limb salvage. However, the term “bone biopsy” lacks a standardized definition, and the statistical reliability of the pathologic diagnosis has not been previously examined. The objective of the present study was to quantify the reliability of the histopathologic analysis of bone with respect to the diagnosis of diabetic foot OM. Four pathologists, kept unaware of the previous pathology reports and specific patient clinical characteristics, retrospectively reviewed 39 consecutive tissue specimens and were informed only that it was “a specimen of bone taken from a diabetic foot to evaluate for OM.” As a primary outcome measure, the pathologists were asked to make 1 of 3 possible diagnoses: (1) no evidence of OM, (2) no definitive findings of OM, but cannot rule it out, or (3) findings consistent with OM. There was complete agreement among all 4 pathologists with respect to the primary diagnosis in 13 (33.33%) of the 39 specimens, with a corresponding kappa coefficient of 0.31. A situation of clinically significant disagreement, or in which at least 1 pathologist diagnosed “no evidence of OM,” but at least 1 other pathologist diagnosed “findings consistent with OM,” occurred in 16 (41.03%) of the specimens. These results indicate agreement below the level of a “reference standard” and emphasize the need for a more comprehensive diagnostic protocol for diabetic foot OM.
FDG PET/CT imaging in the diagnosis of osteomyelitis in the diabetic foot.
Kagna O, Srour S, Melamed E, Militianu D, Keidar Z. Eur J Nucl Med Mol Imaging. 2012 Jul 17.
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PURPOSE:
Osteomyelitis, the most serious complication of the diabetic foot, occurs in about 20 % of patients. Early diagnosis is crucial. Appropriate treatment will avoid or decrease the likelihood of amputation. The objective of this study was to assess the value of FDG PET/CT in diabetic patients with clinically suspected osteomyelitis.
METHODS:
Enrolled in this prospective study were 39 consecutive diabetic patients (29 men and 10 women, mean age 57 years, range 28-71 years) with 46 suspected sites of foot infection. Of these 39 patients, 38 had type 2 and 1 type 1 diabetes for 4-25 years, and 28 were receiving treatment with insulin. FDG PET/CT was interpreted for the presence, intensity (SUVmax) and localization of increased FDG foci. Final diagnosis was based on histopathology and bacteriology of surgical samples, or clinical and imaging follow-up.
RESULTS:
Osteomyelitis was correctly diagnosed in 18 and excluded in 21 sites. Of 20 lesions with focal bone FDG uptake, 2 were false-positive with no further evidence of osteomyelitis. Five sites of diffuse FDG uptake involving more than one bone on CT were correctly diagnosed as diabetic osteoarthropathy. FDG PET/CT had a sensitivity, specificity and accuracy of 100 %, 92 % and 95 % in a patient-based analysis and 100 %, 93 % and 96 % in a lesion-based analysis, respectively, for the diagnosis of osteomyelitis in the diabetic foot.
CONCLUSION:
FDG PET/CT was found to have high performance indices for evaluation of the diabetic foot. The PET component identified FDG-avid foci in sites of acute infection which were precisely localized on fused PET/CT images allowing correct differentiation between osteomyelitis and soft-tissue infection.
Interobserver and Intraobserver Reproducibility of Plain X-Rays in the Diagnosis of Diabetic Foot Osteomyelitis
Francisco J. Álvaro-Afonso, Jose L. Lázaro-Martínez, Javier Aragón-Sánchez, Esther García-Morales, Almudena Cecilia-Matilla, Juan V. Beneit-Montesinos International Journal of Lower Extremity Wounds February 1, 2013
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The purpose of this study was to analyze the interobserver and intraobserver variability in plain radiography in the diagnosis of diabetic foot osteomyelitis. A prospective observational study was performed from October 1, 2009, to July 31, 2011, on patients with diabetic foot ulcers, with clinically suspected osteomyelitis who were admitted to the Diabetic Foot Unit of the Complutense University of Madrid. Two professional groups examined 123 plain X-rays, each group comprising 3 different levels of clinical experience. To analyze intraobserver variability, 2 months later plain X-rays were reanalyzed by one of the clinical groups. When using only plain radiography for the diagnosis of osteomyelitis in the diabetic foot, low concordance rates were observed for clinicians with a similar level of experience: experienced clinicians (K11AB = .35, P < .001), moderately experienced clinicians (K22AB = .39, P < .001), and inexperienced clinicians (K33AB = .40, P < .001). Intraobserver agreement was highest in experienced clinicians (K11A = .75, P < .001), followed by moderately experienced clinicians (K22A = .61, P < .001) and inexperienced clinicians (K33A = .57, P < .001). Plain radiography for the diagnosis of diabetic foot osteomyelitis is operator dependent and shows low association strength, even among experienced clinicians, when interpreted in isolation without knowing the clinical characteristics of the lesion.
The purpose of this study was to analyze the interobserver and intraobserver variability in plain radiography in the diagnosis of diabetic foot osteomyelitis. A prospective observational study was performed from October 1, 2009, to July 31, 2011, on patients with diabetic foot ulcers, with clinically suspected osteomyelitis who were admitted to the Diabetic Foot Unit of the Complutense University of Madrid. Two professional groups examined 123 plain X-rays, each group comprising 3 different levels of clinical experience. To analyze intraobserver variability, 2 months later plain X-rays were reanalyzed by one of the clinical groups. When using only plain radiography for the diagnosis of osteomyelitis in the diabetic foot, low concordance rates were observed for clinicians with a similar level of experience: experienced clinicians (K 11AB = .35, P < .001), moderately experienced clinicians (K 22AB = .39, P < .001), and inexperienced clinicians (K 33AB = .40, P < .001). Intraobserver agreement was highest in experienced clinicians (K 11A = .75, P < .001), followed by moderately experienced clinicians (K 22A = .61, P < .001) and inexperienced clinicians (K 33A = .57, P < .001). Plain radiography for the diagnosis of diabetic foot osteomyelitis is operator dependent and shows low association strength, even among experienced clinicians, when interpreted in isolation without knowing the clinical characteristics of the lesion.
Diagnosing Diabetic Foot Osteomyelitis in Patients Without Signs of Soft Tissue Infection by Coupling Hybrid 67Ga SPECT/CT With Bedside Percutaneous Bone Puncture.
Aslangul E, M'bemba J, Caillat-Vigneron N, Coignard S, Larger E, Boitard C, Lipsky BA. Diabetes Care. 2013 Mar 20.
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OBJECTIVESuccessful treatment of osteomyelitis is more likely with accurate diagnosis and identification of the causative pathogens. This typically requires obtaining a specimen of bone, usually by image-guided biopsy. We sought to develop a simpler bedside method for definitively diagnosing osteomyelitis.
RESEARCH DESIGN AND METHODSOver two years we enrolled consecutive patients presenting to our diabetic foot clinic with a foot ulcer and clinically suspected osteomyelitis but without soft tissue infection. Each underwent hybrid 67Ga single-photon emission computed tomography and X-ray computed tomography (SPECT/CT) imaging; those with a positive scan underwent bedside percutaneous bone puncture. Patients with a positive bone culture received culture-guided antibiotic therapy. Patients with negative 67Ga SPECT/CT imaging or with positive imaging but negative bone culture were not treated with antibiotics. All patients were followed up for ≥1 year.
RESULTSAmong 55 patients who underwent 67Ga SPECT/CT imaging, 13 had negative results and all of their foot ulcers resolved without antibiotic therapy. Among 42 with positive imaging, 2 were excluded (for recent antibiotic therapy) and 40 had bone punctures (3 punctured twice): 19 had negative results, 3 of which were likely false-negatives, and 24 had positive results (all gram-positive cocci). At follow-up, 3 patients had died, 3 had undergone amputation, 47 had no evidence of foot infection. The sensitivity and specificity of this combined method were 88.0 and 93.6%, respectively, and the positive and negative predictive values were 91.7 and 90.7%, respectively.
CONCLUSIONSCoupling of 67Ga SPECT/CT imaging and bedside percutaneous bone puncture appears to be accurate and safe for diagnosing diabetic foot osteomyelitis in patients without signs of soft tissue infection, obviating the need for antibiotic treatment in 55% of suspected cases.
Deep wound cultures and bone biopsy in diabetic foot osteomyelitis.
Malone M, Bowling FL, Gannass A, Jude EB, Boulton AJ. Diabetes Metab Res Rev. 2013 May 7
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BACKGROUND:
Osteomyelitis is a major complication in patients with diabetic foot ulceration. Accurate pathogenic identification of organisms can aid the clinician to a specific antibiotic therapy thereby preventing the need for amputation.
METHODS:
All diabetic patients with bone biopsy- confirmed osteomyelitis were included into the study: biopsies were performed either during surgical removal of infected bone, or percutaneously under guided fluoroscopy through non-infected tissue. The depth and extent of the ulcer was assessed using a sterile blunt metal probe. Deep wound cultures were taken from the wound base after sharp debridement.
RESULTS:
Of 66 cases of suspected Osteomyelitis in 102 joints, 34 patients had both bone biopsies and deep wound cultures over the study period. Thirty two of 34 (94%), had a history of preceding foot ulceration, and in 25 of the cases a positive probe to bone test was recorded. In a high proportion of patients, at least one similar organism was isolated from both the deep wound culture and bone biopsy procedures (n = 25, 73.5% of cases; p < 0.001). When organisms were isolated from both wound cultures and bone biopsies, the identical strain was identified in both procedures in a significant proportion of cases (n = 14, 56% of cases; p < 0.001.
CONCLUSIONS:
Deep wound cultures correlate well with osseous cultures and provide a sensitive method in assessing and targeting likely pathogens that cause osseous infections. This will help aid the clinician in guiding antibiotic therapy in centers where bone biopsies may not be readily available.
Diagnosing osteomyelitis
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