Diagnostic Imaging of Diabetic Foot Disorders

Imaging of the Diabetic Foot

Diabetic foot complications are increasingly prevalent in the world, leading to significant morbidity and driving up associated health care costs. Complex pathophysiology and suboptimal specificity of current imaging modalities have made diagnosis challenging, mainly in the evaluation of superimposed foot infection to underlying arthropathy or other marrow lesions. Recent advances in radiology and nuclear medicine have the potential to streamline the assessment of diabetic foot complications. But we must be aware of the specific strengths and weaknesses of each modality, and their applications. This review offers a comprehensive approach to the spectrum of diabetic foot complications and their imaging appearances in conventional and advanced imaging studies, including optimal technical considerations for each technique. Advanced magnetic resonance imaging (MRI) techniques are highlighted, illustrating their complementary role to conventional MRI, in particular their potential impact in avoiding additional studies.

Pilot study of the diagnostic value of CRP:albumin ratio for osteomyelitis in patients with diabetic foot ulcers

OBJECTIVE

Osteomyelitis may complicate diabetic foot ulcers (DFUs). As a new inflammation-based prognostic factor, CRP:albumin ratio's significance is not known in osteomyelitis among patients with or without diabetes.

METHOD

Patients with type 2 diabetes and DFUs were divided into two groups: group 1 (n=47) comprised patients without osteomyelitis, and group 2 (n=50) comprised patients with osteomyelitis.

RESULTS

Erythrocyte sedimentation rate (ESR) (88.5±23.0 versus 42.0±22.2), white blood cell count (WBC) (14.7±6.9x10³ versus 10.0±4.4x10³), C-reactive protein (CRP) level (15.6±9.9 versus 2.4±3.3) and CRP:albumin ratio (6.6±4.9 versus 0.7±1.0) were significantly higher, and albumin level was significantly lower in group 2 compared to group 1 (p<0.001 for all). The presence of osteomyelitis was significantly and positively correlated with ESR (r=0.721; p<0.001), WBC (r=0.380; p<0.001), CRP (r=0.667; p<0.001) and CRP:albumin ratio (r=0.638; p<0.001), and negatively correlated with albumin (r=-0.590; p<0.001). A CRP:albumin ratio of 1.74 or above could predict osteomyelitis with 92.0% sensitivity, 80.9% specificity, and the best area under the curve (AUC) score (AUC=0.957; 95% CI: 0.924-0.991). ESR (odds ratio (OR): 1.071 (1.025-1.119); p=0.02) and CRP:albumin ratio (OR: 2.65 (1.437-4.885); p=0.002) were independent predictors in the final model for stepwise linear regression analyses for the estimation of osteomyelitis.

CONCLUSION

CRP:albumin ratio is a cheap and repeatable inflammatory marker and can successfully detect osteomyelitis in patients with DFU.

Novel Application of 18F-NaF PET/CT Imaging for Evaluation of Active Bone Remodeling in Diabetic Patients With Charcot Neuropathy: A Proof-of-Concept Report

Charcot neuropathic osteoarthropathy (CN) is a serious and potentially limb-threatening complication for patients with diabetes mellitus and peripheral arterial disease. In recent decades, nuclear medicine-based approaches have been used for non-invasive detection of CN; however, to date, a positron emission tomography (PET) radionuclide specifically focused on targeted imaging of active bone remodeling has not been explored or validated for patients with CN. The radionuclide 18F-sodium fluoride (NaF) has historically been used as a bone imaging probe due to its high sensitivity for targeting hydroxyapatite and bone turnover, but has not been applied in the context of CN. Therefore, the present study focused on novel application of 18F-NaF PET/computed tomography (CT) imaging to three clinical cases of CN to evaluate active bone remodeling at various time courses of CN. PET/CT imaging in all 3 cases demonstrated focal uptake of 18F-NaF in the bones of the feet afflicted with CN, with bone retention of 18F-NaF persisting for up to 5 years following surgical reconstruction of the foot in two cases. On a group level, 18F-NaF bone uptake in the CN foot was significantly higher compared to the healthy, non-CN foot (p = 0.039). 18F-NaF PET/CT imaging may provide a non-invasive tool for monitoring active bone remodeling in the setting of CN, thereby offering novel opportunities for tracking disease progression and improving treatment and surgical intervention.

Pé diabético. Parte 1: Úlceras e Infecções*

Diabetes is a systemic disease that has achieved epidemic proportions in modern society. Ulcers and infections are common complications in the feet of patients with advanced stages of the disease, and are the main cause of amputation of the lower limb. Peripheral neuropathy is the primary cause of loss of the protective sensation of the feet and frequently leads to plantar pressure ulcers and osteoarticular disruption, which in turn develops into Charcot neuropathy (CN). Common co-factors that add to the morbidity of the disease and the risk of amputation in this population are obesity, peripheral arterial disease, immune and metabolic disorders. Orthopedic surgeons must be aware that the early detection and prevention of these comorbidities, through diligent medical care and patient education, can avoid these amputations.

Diabetic Foot. Part 2: Charcot Neuroarthropathy

Charcot neuroarthropathy (CN) is an unfortunate and common complication of patients with diabetes, most likely resulting from a lack of proper understanding of the disease, which leads to late diagnosis. It is commonly misdiagnosed as infection and treated with antibiotics and a frustrated attempt of surgical drainage, which will reveal only debris of the osteoarticular destruction. Proper education of diabetic patients and of the health care professionals involved in their treatment is essential for the recognition of the initial signs of CN. The general orthopedic surgeon is usually the first to treat these patients in the early stages of the disease and must be aware of the signs of CN in order to establish an accurate diagnosis and ensure proper treatment. In theory, this would make it possible to decrease the morbidity of this condition, as long as proper treatment is instituted early.

Financial Impact of Magnetic Resonance Imaging in the Surgical Treatment of Foot and Ankle Osteomyelitis

Magnetic resonance imaging (MRI) is generally considered the most sensitive imaging for diagnosis of osteomyelitis; however, it is associated with significant cost and is at times ordered as initial screening imaging when a less resource-intensive test would suffice. The purpose of this retrospective cohort study was to examine the differences between patients with osteomyelitis of the foot and ankle, and their subsequent treatment course, who underwent MRI compared with those who did not. Financial impact of MRI as it relates to clinical decision-making was also calculated. Patients treated for a diagnosis of osteomyelitis of the foot and ankle from 2009 to 2015 were retrospectively identified. Demographics, imaging modalities, and operative procedures for each patient were collected. An "impact MRI" was defined as one that led to a subsequent operative procedure within the same admission. The impact cost of an MRI was estimated using the equation: (average MRI cost) × (total MRIs/impact MRIs). A total of 144 patients underwent 220 MRIs, and 399 patients did not have MRIs. The operative rate between the 2 groups was similar (70.8% versus 70.4%, p = .93). Multiple linear regression showed that MRI was not a significant predictor of operation (p = .50). However, we found a significant correlation between MRI use and operative intervention for patients with increased comorbidities. From 2011 to 2015, there was a significant increase in impact cost, while controlling for average MRI cost ($8172 to $15,292, p ≤ .05). Over the study period, the impact cost of an MRI significantly increased from 1.8 to 5.0 times the average cost.

Surgical treatment of midfoot Charcot neuroarthropathy with osteomyelitis in patients with diabetes: a systematic review

OBJECTIVE

A wide range of clinical presentations of Charcot neuroarthropathy of the foot with concomitant osteomyelitis in patients with diabetes has been described. Existing literature provides an equally diverse list of treatment options. The purpose of this systematic review was to assess the outcomes specifically for the surgical management of midfoot Charcot neuroarthropathy with osteomyelitis in patients with diabetes.

METHOD

A systematic review was conducted by three independent reviewers using the following databases and search engines: Cumulative Index of Nursing and Allied Health Literature (CINAHL), Cochrane Library, EMBASE (Excerpta Medica dataBASE), Google Scholar, Ovid, PubMed and Scopus. Search terms used were: Charcot neuroarthropathy, osteoarthropathy, neuro-osteoarthropathy, neurogenic arthropathy, osteomyelitis, midfoot, foot, ankle, diabetes mellitus, ulceration, wound, infection, surgical offloading, diabetic reconstruction, internal fixation, external fixation. Studies meeting the following criteria were included: English language studies, studies published from 1997-2017, patients with diabetes mellitus surgically treated for Charcot neuroarthropathy of the midfoot (specified location) with concomitant osteomyelitis, with or without internal and/or external fixation, follow-up period of six months or more postoperatively, documentation of healing rates, complications, and need for revisional surgery. Studies which were entirely literature reviews, descriptions of surgical-only technique and/or cadaveric studies, patients without diabetes, studies that did not specify location of osteomyelitis and Charcot neuroarthropathy, and treatment proximal to and including Chopart's/midtarsal joint specifically talonavicular, calcaneocuboid, subtalar, ankle were excluded.

RESULTS

A total of 13 selected studies, with a total of 114 patients with diabetes of which 56 had surgical treatment for midfoot Charcot neuroarthropathy with osteomyelitis, met the above inclusion criteria and were used for data extraction.

CONCLUSION

Surgical intervention for midfoot Charcot neuroarthropathy with osteomyelitis in patients with diabetes demonstrated a relatively high success rate for a range of procedures including debridement with simple exostectomy, arthrodesis with or without internal or external fixation, and advanced soft tissue reconstruction. However, this systematic review emphasises the need for larger, better designed studies to investigate the efficacy and failure rates of surgical treatment in this group of patients.

An Approach to Managing Midfoot Charcot Deformities

We present an approach to managing complex deformities in Charcot neuroarthropathy that typically present around the midfoot. This approach follows a stepwise progression from prevention, early detection, nonoperative through to operative management. It centers on multidisciplinary care with input from diabetologists, orthotists, plaster technicians, physiotherapists, orthopedic, vascular, and/or plastic surgeons. We discuss the timing of surgery with regard to Eichenholtz stage of disease and trends toward early surgical intervention. We review traditional and new surgical concepts. We evaluate the role of limited interventions. We aim to provide a template for deciding where future research priorities should be directed.

Nuclear Medicine for the Orthopedic Foot and Ankle Surgeon

Nuclear medicine has been widely applied as a diagnostic tool for orthopedic foot and ankle pathology. Although its indications have diminished with improvements in and the availability of magnetic resonance imaging, nuclear medicine still has a significant and valuable role. The present article offers a comprehensive and current review of the most common nuclear imaging modalities for the orthopedic foot and ankle surgeon. Methods discussed include bone scintigraphy, gallium citrate scintigraphy, labeled-leukocyte scintigraphy, and single-photon emission computed tomography (SPECT). We review the indications and utility of these techniques as they pertain to specific foot and ankle conditions, including osteomyelitis, stress fractures, talar osteochondral lesions, complex regional pain syndrome, oncology, plantar fasciitis, and the painful total ankle arthroplasty. We conclude with a discussion of our approach to nuclear medicine with illustrative cases. Level of Evidence: Level V, expert opinion.

Normal anatomic reference of pastern and coffin joints in Egyptian buffalo (Bubalus bubalis): A compared atlas of cross-sectional anatomy, magnetic resonance imaging and computed tomography

The purpose of this study was to describe normal magnetic resonance imaging and computed tomographic anatomy of pastern and coffin joints in Egyptian buffalo using cadaveric distal limbs. This study was achieved using twelve fresh cadaveric distal limbs from adult healthy buffaloes of both sexes. These cadaveric limbs were scanned using a 1 Tesla MRI scanner and CT scanner, injected with red latex, frozen at -20°C for 1 week, and then sectioned into sagittal, dorsal and transverse slices. The obtained MR and CT images were selected to be matched with their corresponding anatomical cross-sections for identification and evaluation of the clinically correlated anatomical structures of the pastern and coffin joints. The difference in signal intensities on CT and MRI scans amongst the tissues allowed clear differentiation of major bone and soft tissue structures of the pastern and coffin joints. CT provided a high spatial resolution of bone and soft tissue structures, however, MRI allowed a better and higher resolution and definition between soft tissues. The current study provided a normal CT and MRI anatomic reference which could help veterinary clinicians for interpretation and diagnosis of the clinically affected pastern and coffin joints in buffalo.

Molecular Imaging of Diabetic Foot Infections: New Tools for Old Questions

Diabetic foot infections (DFIs) are a common, complex, and costly medical problem with increasing prevalence. Diagnosing DFIs is a clinical challenge due to the poor specificity of the available methods to accurately determine the presence of infection in these patients. However, failure to perform an opportune diagnosis and provide optimal antibiotic therapy can lead to higher morbidity for the patient, unnecessary amputations, and increased healthcare costs. Novel developments in bacteria-specific molecular imaging can provide a non-invasive assessment of the infection site to support diagnosis, determine the extension and location of the infection, guide the selection of antibiotics, and monitor the response to treatment. This is a review of recent research in molecular imaging of infections in the context of DFI. We summarize different clinical and preclinical methods and the translational implications aimed to improve the care of patients with DFI.

Clinical Applications for Radiotracer Imaging of Lower Extremity Peripheral Arterial Disease and Critical Limb Ischemia

Peripheral arterial disease (PAD) is an atherosclerotic occlusive disease of the non-coronary vessels that is characterized by lower extremity tissue ischemia, claudication, increased prevalence of lower extremity wounds and amputations, and impaired quality of life. Critical limb ischemia (CLI) represents the severe stage of PAD and is associated with additional risk for wound formation, amputation, and premature death. Standard clinical tools utilized for assessing PAD and CLI primarily focus on anatomical evaluation of peripheral vascular lesions or hemodynamic assessment of the peripheral circulation. Evaluation of underlying pathophysiology has traditionally been achieved by radiotracer-based imaging, with many clinical investigations focusing on imaging of skeletal muscle perfusion and cases of foot infection/inflammation such as osteomyelitis and Charcot neuropathic osteoarthropathy. As advancements in hybrid imaging systems and radiotracers continue to evolve, opportunities for molecular imaging of PAD and CLI are also emerging that may offer novel insight into associated complications such as peripheral atherosclerosis, alterations in skeletal muscle metabolism, and peripheral neuropathy. This review summarizes the pros and cons of radiotracer-based techniques that have been utilized in the clinical environment for evaluating lower extremity ischemia and common pathologies associated with PAD and CLI.

What Is the Best Method to Differentiate Acute Charcot Foot From Acute Infection?

RECOMMENDATION

Differentiation between acute Charcot neuroarthropathy (CN) and acute infection/osteomyelitis is complex and requires multiple (>1) diagnostic criteria. These criteria include an emphasis on the presence of neuropathy, history, and physical examination. The absence of skin wounds and resolution of swelling/erythema with elevation makes the likelihood of infection very low. In unclear cases, laboratory testing, histologic examination and culturing of bone specimens, scintigraphy, and imaging, especially magnetic resonance imaging (MRI), may be of benefit.

LEVEL OF EVIDENCE

Moderate.

DELEGATE VOTE

Agree: 100%, Disagree: 0%, Abstain: 0% (Unanimous, Strongest Consensus).

A Clinical Review of Diabetic Foot Infections

"Diabetic foot infections (DFIs) are a common cause of morbidity and mortality. This article summarizes current knowledge regarding DFI epidemiology, disease pathogenesis, and the impact of antimicrobial resistance among DFI. An evidence-based approach to clinical assessment, diagnosing osteomyelitis, as well as medical and surgical treatment is discussed, including a review of empiric and directed antibiotic treatment recommendations. The current state and needs of the clinical literature are identified throughout, with a discussion of the supporting role of infectious diseases specialists as well as future directions of the field."

Diabetic Foot Infections: Update on Management

PURPOSE OF REVIEW

Diabetic foot infections (DFIs) are common in patients with diabetes mellitus complicated by foot ulcers and can be classified in different categories based on their severity. In this report, we present the diagnosis and management of DFIs according to their classification.

RECENT FINDINGS

While appropriate antibiotic regiments and surgical techniques for the treatment of DFIs are well established, new technologies and techniques for example in medical imaging, wound care modalities, and supplementary therapy approaches show potentially promising results in preventing DFIs. As with every complex disease, fine tuning DFI management can be challenging as it requires careful evaluation of different parameters. It demands timely action, close collaboration of different specialties, and patient cooperation.