Efficacy of three-phase bone scans in evaluating diabetic foot ulcers

Current concepts of Charcot foot in diabetic patients

The Charcot foot is an uncommon complication of neuropathy in diabetes. It is a disabling and devastating condition. The etiology of the Charcot foot is unknown, but it is characterized by acute inflammation with collapse of the foot and/or the ankle. Although the cause of this potentially debilitating condition is not known, it is generally accepted that the components of neuropathy that lead to foot complications must exist. When it is not detected early, a severe deformity will result in a secondary ulceration, infection, and amputation. Immobilization in the early stages is the key for success, but severe deformity may still develop. When severe deformity is present, bracing may be attempted but often patients will need surgical intervention. Good success has been shown with internal and external fixation. In patients with concomitant osteomyelitis, severe deformity, and/or soft tissue infection, a high amputation may be the best treatment of choice.

Current concepts in the surgical management of acute diabetic foot infections

Diabetic foot complications are common, costly, and difficult to treat. Peripheral neuropathy, repetitive trauma, and peripheral vascular disease are common reasons that lead to ulcers, infection, and hospitalization. Individuals with diabetes presenting with foot infection require optimal medical and surgical management to accomplish limb salvage and prevent amputation; aggressive short-term and meticulous long-term care plans are required. Multiple classification systems have been recommended to ease the understanding and the management of these infections. Multi-disciplinary approach is the mainstay for a successful management. Such teams typically include multiple medical, surgical, and nursing specialties across a variety of public and private health care systems. This article is an overview in how to medically and surgically approach the diabetic foot infection with emphasis in soft tissue infection.

Indexing severity of diabetic foot infection with 99mTc-WBC SPECT/CT hybrid imaging

OBJECTIVE

Management of diabetic foot infection (DFI) has been hampered by limited means of accurately classifying disease severity. New hybrid nuclear/computed tomography (CT) imaging techniques elucidate a combination of wound infection parameters not previously evaluated as outcome prognosticators. Our aim is to determine if a novel standardized hybrid image-based scoring system, Composite Severity Index (CSI), has prognostic value in DFI.

RESEARCH DESIGN AND METHODS

Masked retrospective (99m)Tc-white blood cell (WBC) single photon emission CT (SPECT)/CT image interpretation and independent chart review of 77 patients (101 feet) suspected of DFI-associated osteomyelitis at a large municipal hospital between January 2007 and July 2009. CSI scores were correlated with probability of favorable outcome (no subsequent amputation/readmission after therapeutic intervention) during median 342-day follow-up.

RESULTS

CSI ranged from 0-13. Receiver operating characteristic accuracy for predicting favorable outcome was 0.79 (optimal cutoff CSI, ≤2; odds ratio of therapeutic failure for CSI >2, 15.1 [95% CI 4.4-51.5]). CSI of 0 had a 92% chance of favorable outcome, which fell progressively to 25% as indices rose to ≥7. Image-based osteomyelitis versus no osteomyelitis assessment was less accurate than CSI at predicting outcome (P = 0.016). In patients with intermediate severity (CSI 3-6), treatment failure decreased from 68 to 36% when antibiotic duration was extended to ≥42 days (P = 0.026).

CONCLUSIONS

(99m)Tc-WBC SPECT/CT hybrid image-derived wound infection parameters incorporated into a standardized scoring system, CSI, has prognostic value in DFI.

Current concepts in imaging diabetic pedal osteomyelitis

Diabetic pedal osteomyelitis is primarily a manifestation of vascular insufficiency with resultant tissue ischemia, neuropathy, and infection. Nearly all cases of pedal osteomyelitis arise from a contiguous ulcer and soft tissue infection. MR imaging is the modality of choice to assess for the presence of osteomyelitis and associated soft tissue complications, to guide patient management, and to aid in limited limb resection.

Surgical aspects of the diabetic foot

A comprehensive review of the literature relating to the pathology and management of the diabetic foot is presented. This should provide a guide for the treatment of ulcers, Charcot neuro-arthropathy and fractures involving the foot and ankle in diabetic patients.

Assessment and treatment of diabetic foot ulcer

BACKGROUND AND OBJECTIVES

Foot ulcers are one of the main complications in diabetes mellitus, with a 15% lifetime risk in all diabetic patients. The rate of lower extremity amputation among diabetic patients is 17-40 times higher than in non-diabetics. A critical triad of neuropathy, minor foot trauma and foot deformity was found in > 63% of diabetic foot ulcers (DFU). Peripheral vascular disease (PVD) has been identified in 30% of foot ulcers. We present a comprehensive assessment and the treatment of DFUs. We also want to notify physicians not to ignore foot assessment and examinations in patients with diabetes.

METHODS

We conducted this study on DFU on the basis of: pathogenesis and risk factors, assessment and physical examination, paraclinic assessment, treatment, cost and mortality and prevention.

RESULTS AND FINDINGS

Approximately 20% of hospital admissions among diabetic patients are the result of foot problems. Diabetic foot assessment should include dermatological, vascular, neurological and musculoskeletal systems. There are three basic treatments for management of DFU: (i) debridement; (ii) antibiotics and (iii) revascularization. The cost to treat one simple ulcer is $5000 to $8000.

CONCLUSION

Awareness of physicians about foot problems in diabetic patients, clinical examination and paraclinical assessment, regular foot examination, patient education, simple hygienic practices and provision of appropriate footwear combined with prompt treatment of minor injuries can decrease ulcer occurrence by 50%.

Potential role of FDG PET in the setting of diabetic neuro-osteoarthropathy: can it differentiate uncomplicated Charcot's neuroarthropathy from osteomyelitis and soft-tissue infection?

BACKGROUND

This paper is based on the results from an ongoing prospective trial designed to investigate the usefulness of FDG PET in the complicated diabetic foot.

AIM

To investigate the potential utility of FDG PET imaging in the setting of acute neuropathic osteoarthropathy (Charcot's foot).

PATIENTS AND METHODS

A total of 63 patients, in four groups, were evaluated. The groups were: (A) 17 patients with a clinical diagnosis of Charcot's neuroarthropathy (11 men, six women; mean age: 59.4+/-8.6 years); (B) 21 patients with uncomplicated diabetic foot (16 men, five women; mean age: 63+/-10 years); (C) 20 non-diabetic patients with normal lower extremities (12 men, eight women; mean age 54+/-19 years); and (D) five patients with proven osteomyelitis secondary to complicated diabetic foot (three men, two women; mean age: 61.2+/-13.9 years). Five patients in group A had foot ulcer and intermediate to high degree of suspicion for superimposed osteomyelitis. Each subject underwent FDG PET imaging of the lower extremities in addition to MRI and the findings were compared with the final diagnostic outcome based on histopathology and clinical follow-up. The images were examined visually for focal abnormalities. Regions of interest were assigned to the sites of abnormal FDG uptake for calculating maximum standardized uptake value (SUVmax). Two important clinical decision-making issues were explored: (1) whether FDG PET shows a definitive uptake pattern in Charcot's neuroarthropathy and if so whether that could be utilized to differentiate it from other complicated forms of diabetic foot like osteomyelitis and cellulitis, which is frequently a diagnostic challenge in this clinical setting; and (2) how accurate FDG PET is in detection soft tissue infection in patients with Charcot's foot. These issues were examined by utilizing FDG PET findings along with MRI results in the same patient.

RESULTS

We observed a low degree of diffuse FDG uptake in the Charcot's joints. This was clearly distinguishable from the normal joints. The SUVmax in the Charcot's lesions varied from 0.7 to 2.4 (mean, 1.3+/-0.4) while those of midfoot of the normal control subjects and the uncomplicated diabetic foot ranged from 0.2 to 0.7 (mean 0.42+/-0.12) and from 0.2 to 0.8 (mean 0.5+/-0.16), respectively. The only patient with Charcot's foot with superimposed osteomyelitis had an SUVmax of 6.5. The SUVmax of the sites of osteomyelitis as a complication of diabetic foot was 2.9-6.2 (mean: 4.38+/-1.39). Unifactorial analysis of variance test yielded a statistical significance in the SUVmax between the four groups (P<0.01). The SUVmax between the normal control groups and the uncomplicated diabetic foot was not statistically significant by the Student's t-test (P>0.05). In the setting of concomitant foot ulcer FDG PET accurately ruled out osteomyelitis. Overall sensitivity and accuracy of FDG PET in the diagnosis of Charcot's foot was 100 and 93.8%, respectively; and for MRI were 76.9 and 75%, respectively. FDG PET showed foci of abnormally enhanced uptake in the soft tissue which was suggestive of inflammation in seven cases (43.75%) which were proven pathologically to be secondary to infection. In only two of these cases the features of soft tissue infection were noted on the magnetic resonance images.

CONCLUSION

The results support a valuable role of FDG PET in the setting of Charcot's neuroarthropathy by reliably differentiating it from osteomyelitis both in general and when foot ulcer is present.

Nuclear medicine imaging of diabetic foot infection: results of meta-analysis

BACKGROUND AND AIM

Osteomyelitis of the foot is the most commonly encountered complication in diabetic patients. Nuclear medicine techniques are usually complementary to radiology in the diagnosis of foot infections; they play an important role in various clinical situations. The aim of this study was to develop a practical guideline to describe the radiopharmaceuticals to be used for different clinical conditions and different aims in diabetic foot infection.

METHODS

In this study, we reviewed 57 papers (published between 1982 and 2004; 50 original papers and seven reviews) that described the imaging of the diabetic foot and examined a total of 2889 lesions. We performed data analysis to establish which imaging technique could be used as a 'gold standard' to diagnose infection, evaluate the extent of disease and monitor the efficacy of therapy.

RESULTS AND CONCLUSION

We provide a guideline to assist in the selection of the optimal radiopharmaceuticals for different clinical conditions and different aims.

Diagnosis and treatment of diabetic foot infections

EXECUTIVE SUMMARY: 1. Foot infections in patients with diabetes cause substantial morbidity and frequent visits to health care professionals and may lead to amputation of a lower extremity. 2. Diabetic foot infections require attention to local (foot) and systemic (metabolic) issues and coordinated management, preferably by a multidisciplinary foot-care team (A-II). The team managing these infections should include, or have ready access to, an infectious diseases specialist or a medical microbiologist (B-II). 3. The major predisposing factor to these infections is foot ulceration, which is usually related to peripheral neuropathy. Peripheral vascular disease and various immunological disturbances play a secondary role. 4. Aerobic Gram-positive cocci (especially Staphylococcus aureus) are the predominant pathogens in diabetic foot infections. Patients who have chronic wounds or who have recently received antibiotic therapy may also be infected with Gram-negative rods, and those with foot ischemia or gangrene may have obligate anaerobic pathogens. 5. Wound infections must be diagnosed clinically on the basis of local (and occasionally systemic) signs and symptoms of inflammation. Laboratory (including microbiological) investigations are of limited use for diagnosing infection, except in cases of osteomyelitis (B-II). 6. Send appropriately obtained specimens for culture before starting empirical antibiotic therapy in all cases of infection, except perhaps those that are mild and previously untreated (B-III). Tissue specimens obtained by biopsy, ulcer curettage, or aspiration are preferable to wound swab specimens (A-I). 7. Imaging studies may help diagnose or better define deep, soft-tissue purulent collections and are usually needed to detect pathological findings in bone. Plain radiography may be adequate in many cases, but MRI (in preference to isotope scanning) is more sensitive and specific, especially for detection of soft-tissue lesions (A-I). 8. Infections should be categorized by their severity on the basis of readily assessable clinical and laboratory features (B-II). Most important among these are the specific tissues involved, the adequacy of arterial perfusion, and the presence of systemic toxicity or metabolic instability. Categorization helps determine the degree of risk to the patient and the limb and, thus, the urgency and venue of management. 9. Available evidence does not support treating clinically uninfected ulcers with antibiotic therapy (D-III). Antibiotic therapy is necessary for virtually all infected wounds, but it is often insufficient without appropriate wound care. 10. Select an empirical antibiotic regimen on the basis of the severity of the infection and the likely etiologic agent(s) (B-II). Therapy aimed solely at aerobic Gram-positive cocci may be sufficient for mild-to-moderate infections in patients who have not recently received antibiotic therapy (A-II). Broad-spectrum empirical therapy is not routinely required but is indicated for severe infections, pending culture results and antibiotic susceptibility data (B-III). Take into consideration any recent antibiotic therapy and local antibiotic susceptibility data, especially the prevalence of methicillin-resistant S. aureus (MRSA) or other resistant organisms. Definitive therapy should be based on both the culture results and susceptibility data and the clinical response to the empirical regimen (C-III). 11. There is only limited evidence with which to make informed choices among the various topical, oral, and parenteral antibiotic agents. Virtually all severe and some moderate infections require parenteral therapy, at least initially (C-III). Highly bioavailable oral antibiotics can be used in most mild and in many moderate infections, including some cases of osteomyelitis (A-II). Topical therapy may be used for some mild superficial infections (B-I). 12. Continue antibiotic therapy until there is evidence that the infection has resolved but not necessarily until a wound has healed. Suggestions for the duration of antibiotic therapy are as follows: for mild infections, 12 weeks usually suffices, but some require an additional 12 weeks; for moderate and severe infections, usually 24 weeks is sufficient, depending on the structures involved, the adequacy of debridement, the type of soft-tissue wound cover, and wound vascularity (A-II); and for osteomyelitis, generally at least 46 weeks is required, but a shorter duration is sufficient if the entire infected bone is removed, and probably a longer duration is needed if infected bone remains (B-II). 13. If an infection in a clinically stable patient fails to respond to 1 antibiotic courses, consider discontinuing all antimicrobials and, after a few days, obtaining optimal culture specimens (C-III). 14. Seek surgical consultation and, when needed, intervention for infections accompanied by a deep abscess, extensive bone or joint involvement, crepitus, substantial necrosis or gangrene, or necrotizing fasciitis (A-II). Evaluating the limb's arterial supply and revascularizing when indicated are particularly important. Surgeons with experience and interest in the field should be recruited by the foot-care team, if possible. 15. Providing optimal wound care, in addition to appropriate antibiotic treatment of the infection, is crucial for healing (A-I). This includes proper wound cleansing, debridement of any callus and necrotic tissue, and, especially, off-loading of pressure. There is insufficient evidence to recommend use of a specific wound dressing or any type of wound healing agents or products for infected foot wounds. 16. Patients with infected wounds require early and careful follow-up observation to ensure that the selected medical and surgical treatment regimens have been appropriate and effective (B-III). 17. Studies have not adequately defined the role of most adjunctive therapies for diabetic foot infections, but systematic reviews suggest that granulocyte colony-stimulating factors and systemic hyperbaric oxygen therapy may help prevent amputations (B-I). These treatments may be useful for severe infections or for those that have not adequately responded to therapy, despite correcting for all amenable local and systemic adverse factors. 18. Spread of infection to bone (osteitis or osteomyelitis) may be difficult to distinguish from noninfectious osteoarthropathy. Clinical examination and imaging tests may suffice, but bone biopsy is valuable for establishing the diagnosis of osteomyelitis, for defining the pathogenic organism(s), and for determining the antibiotic susceptibilities of such organisms (B-II). 19. Although this field has matured, further research is much needed. The committee especially recommends that adequately powered prospective studies be undertaken to elucidate and validate systems for classifying infection, diagnosing osteomyelitis, defining optimal antibiotic regimens in various situations, and clarifying the role of surgery in treating osteomyelitis (A-III).

Evidence-Based Protocol for Diabetic Foot Ulcers

BACKGROUND

Diabetic foot ulcers are the single biggest risk factor for nontraumatic foot amputations in persons with diabetes. Foot ulcers occur in 12 to 25 percent of persons with diabetes and precede 84 percent of all nontraumatic amputations in this growing population. Because of the high incidence of foot ulcers, amputations remain a source of morbidity and mortality in persons with diabetes. Strict adherence to evidence-based protocols as described herein will prevent the majority of these amputations.

METHODS

The collective experience of treating patients with neuropathic diabetic foot ulcers in four major diabetic foot programs in the United States and Europe was analyzed.

RESULTS

The following protocol was developed for patients with diabetic foot ulcers: (1) establishment of good communication among the patient, the wound healing team, and the primary medical doctor; (2) comprehensive, protocol-driven care of the entire patient, including hemoglobin A1c, microalbuminuria, and cholesterol as well as early treatment of retinopathy, nephropathy, and cardiac disease; (3) weekly objective measurement of the wound with digital photography, planimetry, and documentation of the wound-healing process using the Wound Electronic Medical Record, if available; (4) objective evaluation of blood flow in the lower extremities (e.g., noninvasive flow studies); (5) débridement of hyperkeratotic, infected, and nonviable tissue; (6) use of systemic antibiotics for deep infection, drainage, and cellulitis; (7) off-loading; (8) maintenance of a moist wound bed; (9) use of growth factor and/or cellular therapy if the wound is not healing after 3 weeks with this protocol; and (10) consideration of the use of vacuum-assisted therapy in complex wounds.

CONCLUSIONS

In diabetic foot ulcers, availability of the above modalities, in combination with early recognition and comprehensive treatment, ensures rapid healing, minimizes morbidity and mortality rates, and eliminates toe and limb amputations in the absence of ischemia and osteomyelitis.

Protocol for treatment of diabetic foot ulcers

Each year, 82,000 limb amputations are performed in patients with diabetes mellitus. The majority of these amputations could be avoided by following strict protocols. The collective experience treating patients with neuropathic diabetic foot ulcers of 4 major diabetic foot programs in the United States and Europe were analyzed. The following protocol has been developed for patients with diabetic foot ulcers: (1) measurement of the wound by planimetry; (2) optimal glucose control; (3) surgical debridement of all hyperkeratotic, infected, and nonviable tissue; (4) systemic antibiotics for deep infection, drainage, and cellulitis; (5) offloading; (6) moist-wound environment; and (7) treatment with growth factors and/or cellular therapy if the wound is not healing after 2 weeks with this protocol and a new epithelial layer is not forming. In addition, the pathogenesis of diabetic foot ulcers is discussed, as well as the associated costs and complications, including amputation. Debridement, wound-bed preparation, antibiotics, various types of dressings, biological therapies, growth factors, and offloading are described as treatment modalities for patients with diabetic foot ulcers. In diabetic foot ulcers, availability of the above modalities, in combination with early recognition and comprehensive treatment, ensure rapid healing and minimize morbidity, mortality, and costs, as well as eliminate amputation in the absence of ischemia and osteomyelitis.

Prognostic value of 99m Tc leukocyte scintigraphy in diabetic pedal osteomyelitis

While leukocyte scintigraphy is accurate in detection of pedal osteomyelitis, there has been little data relating the technique to outcomes. We designed a trial to examine the prognostic value of sequential 99m Tc labeled leukocyte scans to establish the diagnosis of osteomyelitis and after three to four weeks of culture-guided antibiotic therapy. Twenty-three diabetic patients with proven pedal osteomyelitis (21/23) or persistent uptake (2/23) on the sequence of scans were studied. Five additional episodes of osteomyelitis developed in the group over the period of the study. Eleven patients demonstrated persistent uptake in the sequential scans. Nine progressed to amputation. The remaining two patients were biopsy-negative for infection, did not have cutaneous ulceration and were thought to have rapidly progressive arthropathy. Sequential leukocyte scintigraphy accurately predicts the need for amputation and can circumvent ineffective prolonged antibiotic therapy.