Inflammatory and bone turnover markers in a cross-sectional and prospective study of acute Charcot osteoarthropathy

Brazilian Society of Angiology and Vascular Surgery 2023 guidelines on the diabetic foot

The diabetic foot interacts with anatomical, vascular, and neurological factors that challenge clinical practice. This study aimed to compile the primary scientific evidence based on a review of the main guidelines, in addition to articles published on the Embase, Lilacs, and PubMed platforms. The European Society of Cardiology system was used to develop recommendation classes and levels of evidence. The themes were divided into six chapters (Chapter 1 - Prevention of foot ulcers in people with diabetes; Chapter 2 - Pressure relief from foot ulcers in people with diabetes; Chapter 3 -Classifications of diabetic foot ulcers; Chapter 4 - Foot and peripheral artery disease; Chapter 5 - Infection and the diabetic foot; Chapter 6 - Charcot's neuroarthropathy). This version of the Diabetic Foot Guidelines presents essential recommendations for the prevention, diagnosis, treatment, and follow-up of patients with diabetic foot, offering an objective guide for medical practice.

The Differentiation Between Infection and Acute Charcot

The differentiation between acute Charcot neuroarthropathy and infection in the foot and ankle should be supported by multiple criteria. A detailed history and physical examination should always be completed. Plain radiographs should be performed, though advanced imaging, currently MRI, is more helpful in diagnosis. Scintigraphy and PET may become the standard imaging modalities once they are more clinically available due to their reported increased accuracy. Laboratory analysis can also act as a helpful diagnostic tool. Histopathology with culturing should be performed if osteomyelitis is suspected. The prompt diagnosis and initiation of treatment is vital to reducing patient morbidity and mortality.

Diagnosis and treatment of active charcot neuro-osteoarthropathy in persons with diabetes mellitus: A systematic review

BACKGROUND

There are uncertainties regarding the diagnostic criteria, optimal treatment methods, interventions, monitoring and determination of remission of Charcot neuro-osteoarthropathy (CNO) of the foot and ankle in people with diabetes mellitus (DM). The aims of this systematic review are to investigate the evidence for the diagnosis and subsequent treatment, to clarify the objective methods for determining remission and to evaluate the evidence for the prevention of re-activation in people with CNO, DM and intact skin.

METHODS

We performed a systematic review based on clinical questions in the following categories: Diagnosis, Treatment, Identification of Remission and Prevention of Re-Activation in people with CNO, DM and intact skin. Included controlled studies were assessed for methodological quality and key data from all studies were extracted.

RESULTS

We identified 37 studies for inclusion in this systematic review. Fourteen retrospective and observational studies relevant to the diagnosis of active CNO with respect to clinical examination, imaging and blood laboratory tests in patients with DM and intact skin were included. We identified 18 studies relevant to the treatment of active CNO. These studies included those focused on offloading (total contact cast, removable/non-removable knee high devices), medical treatment and surgical treatment in the setting of active CNO. Five observational studies were identified regarding the identification of remission in patients who had been treated for active CNO. We did not identify any studies that met our inclusion criteria for the prevention of re-activation in patients with DM and intact skin who had been previously treated for active CNO and were in remission.

CONCLUSIONS

There is a paucity of high-quality data on the diagnosis, treatment, and prognosis of active CNO in people with DM and intact skin. Further research is warranted to address the issues surrounding this complex disease.

Guidelines on the diagnosis and treatment of active Charcot neuro-osteoarthropathy in persons with diabetes mellitus (IWGDF 2023)

The International Working Group on the Diabetic Foot (IWGDF) has published evidence-based guidelines on the prevention and management of diabetic foot disease since 1999. This is the first guideline on the diagnosis and treatment of active Charcot neuro-osteoarthropathy in persons with diabetes published by the IWGDF. We followed the GRADE Methodology to devise clinical questions in the PACO (Population, Assessment, Comparison, Outcome) and PICO (Population, Intervention, Comparison, Outcome) format, conducted a systematic review of the medical literature, and developed recommendations with the rationale. The recommendations are based on the evidence from our systematic review, expert opinion when evidence was not available, and also taking into account weighing of the benefits and harms, patient preferences, feasibility and applicability, and costs related to an intervention. We here present the 2023 Guidelines on the diagnosis and treatment of active Charcot neuro-osteoarthropathy in persons with diabetes mellitus and also suggest key future topics of research.

Biomarkers for Early Detection of Charcot Arthropathy: A Prospective Study on Type 2 Diabetes Patients with Severe Neuropathy

BACKGROUND

Charcot arthropathy (CA) is a progressive noninfectious inflammatory disease that causes irreversible destruction to pedal architecture in diabetic neuropathy (DN) patients. The debilitating prognosis demands early detection to prevent the development and progression of this disorder. Dysregulated and persistent production of inflammatory cytokines is reported as the key element in initiating osteoclastogenesis in CA. The study analyzed the potential association of markers of inflammation and bone turnover of prediagnostic serum samples on CA.

METHODS

Seventy-one type 2 severe DN patients were selected based on inclusion-exclusion criteria. Serum samples of interleukin 6 (IL-6), osteoprotegerin (OPG), bone alkaline phosphatase (BALP), and C-reactive protein (CRP) were analyzed. These patients were followed for the development of symptoms of CA for 12 months. In the year of monitoring, 7 patients developed CA (group 1), whereas the remaining 64 patients did not develop CA (group 2).

RESULTS

The rate of development of CA in patients with severe DN was 9.8%. In this group, significantly increased median values of HbA1c (group 2: 8.00 [7.00-9.00], group 1: 10.00 [9.25-11.50], P = .013); IL-6 (group 2: 1.21 [0.72-2.16], group 1: 11.08 [6.65-63.64], P = .008); and CRP (group 2: 1.25 [0.78-3.20], group 1: 3.31 [1.18-41.33], P = .041) were found. The receiver operating characteristic analysis showed that IL-6 was more strongly associated with the onset of CA (IL-6: area under the curve = 0.808; P = .008) than CRP. Cut-off values of ≥6.6 for IL-6 show potential to rule out CA in high-risk patients, with a positive predictive value of 26.1%, a negative predictive value of 97.9%, a sensitivity of 85.7%, and a specificity of 73.4%.

CONCLUSION

In our study population, we found that an exacerbated inflammatory state, reflected by IL-6 values, generally occurred in DN patients before the clinical detection of CA.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Contralateral foot temperature monitoring during Charcot immobilisation: A systematic review

AIMS

Contralateral temperature difference (CTD) is a frequently used marker of healing in Charcot neuro-osteoarthropathy (CN). We aimed to determine whether there is a consistent approach to CTD measurement during healing and the decision-making process around cessation of immobilisation.

MATERIALS AND METHODS

Medline, Scopus, and Web of Science were searched until February 2022 for peer-reviewed studies using keywords, including (('arthropathy' OR 'osteoarthropathy' OR 'osteopathy' OR 'neuroarthropathy') AND 'Charcot' AND ('temperature')), which returned 789 results excluding duplicates. Included studies monitored CTD in those with active CN to (i) assess the healing process and (ii) assist in determining the transition from immobilisation.

RESULTS

Thirty four studies in total (n = 677 participants) were shortlisted and 19 were included after full paper review. Average CTD at presentation varied from 1.6 to 8.0°C with insufficient data to determine if CTD was proportional to severity of Charcot. Evidence of a relationship between CTD and radiographic or scintigraphy-based markers of healing varied depending on the methodology employed. Threshold CTD for the cessation of immobilisation ranged from <1°C to <2°C. Most frequently it was <2°C sustained for 2-3 visits. Temperature was monitored typically every 2-6 weeks using handheld thermometry at CN site(s) after resting the feet for 15 min. Device type, accuracy/reliability, and ambient temperature were rarely reported.

CONCLUSIONS

Further research on CTD and radiographic and radiotracer markers is needed involving larger cohorts. Standardisation in reporting of thermometry device type, accuracy and reliability, foot resting times, and ambient temperature controls is essential to facilitate the comparison of studies, meta-analysis, and evaluation of different immobilisation interventions.

Trends in the pathophysiology of Charcot neuroarthropathy

The pathophysiology of Charcot neuroarthropathy (CN) includes a number of gray areas, particularly regarding the onset of inflammation which induces the disruption of the bone remodeling factor responsible for the onset of bone lysis. This clinical insight highlights a potential link between this inflammation and the rapid correction of chronic hyperglycemia (Dardari et al., 2022), which is known to be responsible for a particular type of neuropathy known as treatment-induced neuropathy of diabetes (TIND). Our description makes an additional contribution to shed light on the mysterious physiopathology of CN.

Cartilage Damage Pathological Characteristics of Diabetic Neuropathic Osteoarthropathy

Background

Diabetic neuropathic osteoarthropathy (DNOAP) is a rare and easily missed complication for diabetes that leads to increased morbidity and mortality. DNOAP is characterized by progressive destruction of bone and joint, but its pathogenesis remains elusive. We herein aimed to investigate the pathological features and pathogenesis of the cartilages damage in DNOAP patients.

Methods

The articular cartilages of eight patients with DNOAP and eight normal controls were included. Masson staining and safranine O/fixed green staining (S-O) were used to observe the histopathological characteristics of cartilage. The ultrastructure and morphology of chondrocytes were detected by electron microscopy and toluidine blue staining. Chondrocytes were isolated from DNOAP group and control group. The expression of receptor activator of nuclear factor kappaB ligand (RANKL), osteoprotegerin (OPG), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and Aggrecan protein was evaluated by western blot. Reactive oxygen species (ROS) levels were measured using a 2',7'-dichlorofluorescin diacetate (DCFH-DA) probe. The percentage of apoptotic cells was determined by flow cytometry (FCM). The chondrocytes were cultured with different glucose concentrations to observe the expression of RANKL and OPG.

Results

Compared with the control group, the DNOAP group showed fewer chondrocytes, subchondral bone hyperplasia, and structural disorder, and a large number of osteoclasts formed in the subchondral bone area. Moreover, mitochondrial and endoplasmic reticulum swellings were observed in the DNOAP chondrocytes. The chromatin was partially broken and concentrated at the edge of nuclear membrane. The ROS fluorescence intensity of chondrocyte in DNOAP group was higher than that in normal control group (28.1 ± 2.3 vs. 11.9 ± 0.7; P < 0.05). The expression of RANKL, TNF-α, IL-1β, and IL-6 protein in DNOAP group was higher than that in normal control group, whereas OPG and Aggrecan protein were lower than that in normal control group (both P < 0.05). FCM showed that the apoptotic rate of chondrocyte in DNOAP group was higher than that in normal control group (P < 0.05). The RANKL/OPG ratio showed significant upward trend when the concentration of glucose was over than 15 mM.

Conclusions

DNOAP patients tend to have severe destruction of articular cartilage and collapse of organelle structure including mitochondrion and endoplasm reticulum. Indicators of bone metabolism (RANKL and OPG) and inflammatory cytokines (IL-1β, IL-6, and TNF-α) play an important role in promoting the pathogenesis of DNOAP. The glucose concentration higher than 15 mM made the RANKL/OPG ratio change rapidly.

Biochemical predictors of diabetic foot osteomyelitis: A potential diagnostic role for parathormone

AIMS

The aims of this study were to evaluate parathormone (PTH) levels in people with diabetic foot ulcers (DFU) and investigate the relationship between PTH levels and osteomyelitis (OM) in this population.

MATERIALS AND METHODS

Eighty-eight patients were admitted for DFU in a tertiary-care centre from October 2021 to May 2022. OM was diagnosed by clinical, laboratory, and radiological evaluations. Laboratory measurements and clinical parameters were collected from medical records. Participants in the study were divided into two groups according to the diagnosis of OM (patients with OM, group 1 [n = 54] and patients without OM, group 2 [n = 34]).

RESULTS

Compared with group 2, patients in group 1 were younger and had a longer duration of diabetes. Erythrocyte sedimentation rate and fibrinogen were significantly higher in group 1 compared with group 2. PTH levels were significantly lower (group 1 vs. group 2, median [interquartile range] 16.2 (11.6, 31.0) vs. 23.7 (17.0, 38.1), p = 0.008) and alkaline phosphatase was significantly higher (97.0 (79.0, 112.0) vs. 88.0 (63.0, 107.0), p = 0.031) in group 1. In multiple linear regression analysis, the only independent predictors of PTH concentrations were alkaline phosphatase levels (β-coefficient 0.441, p < 0.001) and the presence of OM (β-coefficient -0.290, p = 0.038).

CONCLUSIONS

In a population of patients with diabetes and OM admitted to a tertiary university centre, PTH levels were lower as compared with diabetic individuals without OM. The OM and alkaline phosphatase levels were independent predictors of PTH levels in this selected population.

Novel Biomarkers Predictive of Diabetic Charcot Foot-An Overview of the Literature

Background: Although Charcot diabetic foot (CDF) is a frequent complication of diabetic neuropathy, less is known about the possibility of its early prevention. Methods: A review of the original articles published in English, using the "biomarkers AND Charcot's foot" criterion, resulted in 33 articles from the PubMed database and seven articles from the Web of Science database. The five duplicates were eliminated, and two independent reviewers selected the most relevant articles, leaving a total of 21 articles. Results: The biomarkers identified are exhaustively described, related to the system of advanced glycation end products (AGEs) and their soluble receptors (sRAGE), inflammatory cascade, osteoclastogenesis, and, respectively, osteoblastic activity. Conclusions: This article highlights the importance of potential early identifiable biomarkers that can lead to microstructural changes in the affected bones.

Etiology, Epidemiology, and Outcomes of Managing Charcot Arthropathy

Surgical intervention for Charcot arthropathy is becoming more common; this is driven by an increased prevalence, better understanding of the cause, identifying patient risk factors that influence outcomes, and how to best optimize these. This article aims to summarize the cause of Charcot, look at the factors that influence the outcomes, and the financial cost of managing what is a very challenging condition.

The Charcot Foot Reflects a Response to Injury That Is Critically Distorted by Preexisting Nerve Damage: An Imperfect Storm

It has been recognized since comprehensive descriptions by Jean-Martin Charcot in 1868 and 1883 that development of what is usually known as neuropathic osteoarthropathy (or the Charcot foot) requires the coincidence of neuropathy and inflammation. Despite this, detailed understanding of the causes has remained remarkably limited in the succeeding century and a half. The aim of this descriptive account is to draw particular attention to the processes involved in both the onset and resolution of the inflammation that is an essential component of active disease. The principal observation is that while neuropathy is common in people with diabetes, the inflammation and secondary skeletal damage that characterize neuropathic osteoarthropathy are observed in only a small minority of people with diabetes and with neuropathy. We therefore argue that the key to understanding the causes of the Charcot foot is to focus equally on those who have active disease as well as those who do not. Although neuropathy is essential for development of the disorder, neuropathy also has an adverse impact on the mechanisms involved in the onset of inflammation, and these may be critically affected in the majority of those who are susceptible. The Charcot foot is uncommon in people with diabetes (or any other cause of neuropathy) because the large majority of those with neuropathy may have also lost the capacity to mount the specific inflammatory reaction that is essential for its development.

Neurologic Disorders Affecting the Foot and Ankle

The neurologic causes of foot and leg dysfunction are reviewed. Disorders causing foot and ankle pain, weakness, or other sensorimotor disturbances often cause difficulty with ambulation and prompt patients to seek medical evaluation. Physical signs and symptoms along with targeted diagnostic testing are needed to come to the correct diagnosis and treatment plan. An overview of peripheral nerve, muscle, and central nervous system disorders affecting the foot and leg are discussed.

Long-term foot outcomes following differential abatement of inflammation and osteoclastogenesis for active Charcot neuroarthropathy in diabetes mellitus

AIMS

Inflammatory osteolysis is sine-qua-non of active Charcot neuroarthropathy (CN) causing decreased foot bone mineral density (BMD) and fractures. We aimed to explore the effect of anti-inflammatory or anti-resorptive agents for effect on foot bone mineral content (BMC) and consequent long-term outcomes of foot deformities, fractures and amputation.

METHODS

Forty-three patients with active CN (temperature difference >2°C from normal foot) were evaluated. Patients were off-loaded with total contact cast and randomized to receive either methylprednisolone (1gm) (group A), zoledronate (5mg) (group B) or placebo (100ml normal saline) (group C) once monthly infusion for three consecutive months. Change in foot BMC was assessed at 6 months or at remission and followed subsequently up to 4 years for the incidence of new-onset fracture, deformities, or CN recurrence.

RESULTS

Thirty-six participants (24 male, 12 female) were randomized (11 in group A, 12 group B, 13 group C). The mean age was 57.7± 9.9 years, duration of diabetes 12.3± 5.8 years and symptom duration 6.5± 2.8 weeks. BMC increased by 36% with zoledronate (p = 0.02) but reduced by 13% with methylprednisolone (p = 0.03) and 9% (p = 0.09) with placebo at remission. There were no incident foot fractures, however, two patients sustained ulcers, and 3 had new-onset or worsening deformities and none required amputation during 3.36 ± 0.89 years of follow-up.

CONCLUSION

Bisphosphonate for active CN is associated with an increase in foot bone mineral content as compared to decrease with steroids or total contact cast but long-term outcomes of foot deformities, ulceration and amputation are similar.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03289338.

Effect of Recombinant Human Parathyroid Hormone (1-84) on Resolution of Active Charcot Neuro-osteoarthropathy in Diabetes: A Randomized, Double-Blind, Placebo-Controlled Study

OBJECTIVE

Fractures in Charcot neuro-osteoarthropathy (CN) often fail to heal despite prolonged immobilization with below-knee casting. The aim of the study was to assess the efficacy of recombinant human parathyroid hormone (PTH) in reducing time to resolution of CN and healing of fractures.

RESEARCH DESIGN AND METHODS

People with diabetes and acute (active) Charcot foot were randomized (double-blind) to either full-length PTH (1-84) or placebo therapy, both in addition to below-knee casting and calcium and vitamin D3 supplementation. The primary outcome was resolution of CN, defined as a skin foot temperature difference >2°C at two consecutive monthly visits.

RESULTS

Median time to resolution was 5 months (95% CI 4, 12) in intervention and 6 months (95% CI 2, 9) in control. On univariate mixed Cox and logistic regression, there was no significant difference in time to resolution between the groups (P = 0.64) or in the likelihood of resolution (P = 0.66). The hazard ratio of resolution was 0.84 (95% CI 0.41, 1.74; P = 0.64), and the odds ratio of resolution by 12 months was 0.80 (95% CI 0.3, 2.13; P = 0.66) (intervention vs. control). On linear regression analysis, there were no significant differences in the effect of treatment on fracture scores quantitated on MRI scans (coefficient 0.13 [95% CI -0.62, 0.88]; P = 0.73) and on foot and ankle X-rays (coefficient 0.30 [95% CI -0.03, 0.63]; P = 0.07).

CONCLUSIONS

This double-blind placebo-controlled trial did not reduce time to resolution or enhance fracture healing of CN. There was no added benefit of daily intervention with PTH (1-84) to below-knee casting in achieving earlier resolution of CN.

Association between Osteoprotegerin and Charcot Neuroarthropathy: a systematic review

AIMS

Osteoprotegerin (OPG) has been associated with Charcot Neuroarthropathy (CN); however, three studied OPG polymorphisms (1181C > G, 245A > C and 950 T > C) have yielded conflicting results. Therefore, this meta-analysis was conducted to determine the difference in serum OPG concentrations between healthy controls and diabetics with and without CN and the effect OPG polymorphisms have on CN development.

METHODS

PubMed, LILAC, SCOPUS, and EBSCO databases and retrieved publications' bibliographies were searched for studies that examined for OPG and CN. Depending on the heterogeneity, fixed or random effects were used to calculate the pooled odds ratio (OR) or standard difference in means (SDM) with 95% confidence intervals (95%CI) for 5 genetic models (heterozygous, homozygous, dominant, recessive, and allelic) and serum concentrations, respectively.

RESULTS

Seven publications (12 studies) demonstrated that serum OPG concentrations were more elevated in subjects with CN (SDM = 0.719, 95%CI = 0.555-0.883, p < 0.001). When CN was compared to healthy controls or diabetics, the difference was more prominent for healthy controls (SDM = 1.043, 95%CI = 0.676-1.409, p < 0.001) than diabetics (SDM = 0.639, 95%CI = 0.456-0.821, p < 0.001) and the SDM difference was significant (p = 0.013). Using 6 publications (9 studies), neither the 1181C > G or the 950 T > C polymorphisms showed any significant associations for any genetic model. For the 245A > C polymorphism, only the homozygous genetic model showed a significant association between the polymorphism and CN (OR = 2.850, 95%CI: 1.051-7.729, p = 0.040).

CONCLUSIONS

Here, we determined a potential correlation between the CN and serum OPG concentrations and that only the CC genotype of the 245A > C polymorphism showed an increased risk of developing CN.

The Role of Bone Scintigraphy with SPECT/CT in the Characterization and Early Diagnosis of Stage 0 Charcot Neuroarthropathy

We describe the use of Single Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) in the investigation and diagnosis of Charcot neuroarthropathy (CN) in patients with a hot swollen foot but normal radiographs and clinical suspicion of CN, usually termed Stage 0. This was a retrospective cohort review of 46 diabetes patients who underwent 3 phase bone scintigraphy with “High Resolution” SPECT/CT. The imaging demonstrated that Stage 0 Charcot foot has a distinct bone pathology, which can be classified into three groups: (1) fractures on Computed Tomography (CT) with accompanying focal uptake of tracer on SPECT, (2) bony abnormalities apart from fracture on CT with focal uptake of tracer on SPECT, and (3) normal CT but focal bony uptake of tracer on SPECT. The CT component of SPECT/CT detected bony fractures in 59% of patients. Early treatment with below knee cast and follow-up for 24 months showed only 4 patients who developed Stage 1 Eichenholtz Charcot foot. Our findings support the use of 3 phase bone scintigraphy with SPECT/CT in the characterization and early diagnosis of CN. Stage 0 Charcot foot has a distinct bone pathology which requires urgent treatment to prevent progression to Stage 1 Eichenholtz Charcot foot. If SPECT/CT is unavailable, CT alone will detect bone fracture in 59% patients.

An overview of Charcot's neuroarthropathy

Charcot's neuroarthropathy is a destructive complication of the joints, which is often found in people with diabetes with peripheral neuropathy. Despite the fact that its description was published almost 130 years ago, its pathophysiology, diagnosis, and treatment remain areas that need to be described. Thanks to the use of bone remodelling, new therapeutic classes have emerged, we hope that this review will shed light on the pathology from its discovery through to the current state of knowledge on its classification, diagnosis and treatment methods.

Infrared dermal thermometry is highly reliable in the assessment of patients with Charcot neuroarthropathy

BACKGROUND

Charcot neuroarthropathy (Charcot foot) is a serious limb-threatening complication most commonly seen in individuals with diabetic peripheral neuropathy. Although dermal thermometry is widely used by clinicians to assist in the diagnosis, monitoring, and management of the disease, there is limited high-quality evidence to support its reliability. Therefore, this study investigated the intra-rater and inter-rater reliability of infrared dermal thermometry in patients with Charcot neuroarthropathy.

METHODS

We collected clinical, demographic, health status, and foot examination information on 32 adults with Charcot neuroarthropathy from a metropolitan high-risk foot service in Melbourne, Australia. Infrared dermal thermometry assessments were conducted by two independent raters at 10 anatomical sites of the Charcot foot using both a (i) touch and (ii) non-touch technique. Intra-rater and inter-rater reliability of the two assessment techniques were evaluated using intra-class correlation coefficients (ICCs), limits of agreement, standard error of measurement, and minimal detectable change statistics.

RESULTS

Mean age was 59.9 (standard deviation [SD], 10.5) years, 68.8% were male, average duration of diabetes was 20.6 (SD, 15.1) years, 71.9% had type 2 diabetes, 93.8% had peripheral neuropathy, 43.8% had peripheral arterial disease, and 50% had previous foot ulceration. Charcot foot most commonly affected the tarsometatarsal joints (38.9%), had a median duration of 2.8 (interquartile range [IQR], 1.3 to 5.9) months, and a large proportion were being treated with total contact casting (69.4%). Overall, there was good to excellent intra-rater and inter-rater relative reliability for the 'touch' technique (ICC, 0.87 to 0.99; ICC, 0.83 to 0.98, respectively), and excellent intra-rater and inter-rater relative reliability for the 'non-touch' technique (ICC, 0.93 to 0.99; ICC, 0.91 to 0.99, respectively). In addition, measurement error was found to be relatively low across the 10 anatomical sites.

CONCLUSIONS

Infrared dermal thermometry can now be used with confidence in clinical and research settings to provide a reliable assessment of skin temperature in patients with Charcot neuroarthropathy, using either a touch or non-touch technique at 10 commonly used testing sites. A non-touch technique, however, was observed to have slightly higher reliability indicating it may be associated with less measurement error than the touch technique.

The role of genetic factors and monocyte-to-osteoclast differentiation in the pathogenesis of Charcot neuroarthropathy

Charcot neuroarthropathy is a chronic, progressive condition of the skeletal system that affects some patients with diabetic neuropathy. It results in progressive destruction of bones of the foot and disorganisation of pedal joints and ligaments. Effective prevention and treatment for Charcot neuroarthropathy remain a challenge. Currently, there are no reliable repeatable markers to identify patients with diabetes who are at higher risk of developing Charcot neuroarthropathy. The pathogenesis underlying the development of Charcot neuroarthropathy also remains unclear. In this review, we provide an overview of the history, prevalence, symptoms, risk factors, diagnostics and treatment of Charcot neuroarthropathy. We also discuss the potential for OPG and RANKL gene variants to act as predictive markers for the development of Charcot neuroarthropathy. Finally, we summarise the latest research on the role of monocyte-to-osteoclast differentiation in the development of acute Charcot neuroarthropathy.

Current concepts underlying the pathophysiology of acute Charcot neuroarthropathy in the diabetic foot and ankle

INTRODUCTION

With a complex and often misunderstood etiology, acute Charcot neuroarthropathy (ACN) is a devastating complication of peripheral neuropathy. In patients with diabetes, timely diagnosis of ACN in the foot and ankle is essential to prevent loss of both limb and life.

AREAS COVERED

Herein, the authors evaluate the growing body of evidence in identifying targeted pathways for future therapeutic interventions. A literature search was conducted through the PubMed research database. Searched terms included 'Charcot,' 'foot and ankle,' 'neuroarthropathy,' 'pathophysiology,' 'arthropathy,' 'diabetic foot,' and 'Charcot foot.'

EXPERT OPINION

The interplay between the acute inflammatory response, cytokine signaling, and bone metabolism equilibrium can now be better understood with the aid of several novel immunobiologic mechanisms. The more recently elucidated roles of advanced glycation end-products, neuropeptides, monocyte differentiation, and genomics combine with classical Charcot pathophysiology to aid researchers and clinicians alike in combatting this often puzzling consequence of peripheral neuropathy.

Charcot Neuroarthropathy Advances: Understanding Pathogenesis and Medical and Surgical Management

Understanding new theories of the epidemiology of Charcot neuroarthropathy is practice changing. Treatment of Charcot neuroarthropathy is evolving from a passive approach to one that sees the urgency of proactive, early recognition, thereby avoiding the cascading events that lead to the complex, limb-threatening deformities. Preventive medicine is the most efficient at avoiding severe deformity, with prolonged offloading and immobilization as the current mainstay of treatment. However, with recent advancements in medical and surgical modalities, this may become the treatment of the past as clinicians begin to favor medical management and early surgical intervention.

Microscopic study of chronic charcot arthropathy foot bones contributes to understanding pathogenesis - A preliminary report

INTRODUCTION

Charcot arthropathy (CA) is non-infective, chronic destructive condition affecting the pes architecture of long standing diabetic patients with neuropathy. Even though several theories have emerged to disclose its pathogenesis, inflammatory cytokine induced osteoclastogenesis stands as the chief culprit. Studies on micro-architecture of foot bones of acute stage CA patients, describes mainly destructive phase of bone remodelling. Increased osteoclast cell activity is reported in all studies communicated. No study has to the best of our knowledge detailed the microscopic structure of chronic stage CA foot bones.

AIM

To study the microscopic structure of foot bones in patients with chronic CA.

MATERIALS AND METHODS

Foot bones were collected from the feet of chronic CA patients (six in number) who underwent corrective foot surgery in the Department of Podiatric Surgery of a tertiary care hospital. Control samples were collected from the feet of age matched non-diabetic controls (2 in number). The samples were fixed in formalin, decalcified in 10% nitric acid, processed, sectioned and stained with haematoxylin and eosin. Histopathology and histomorphometry analysis were performed by two different pathologists.

RESULTS

Trabeculae of chronic CA foot bones exhibited mainly a lamellar architecture, with reduced number of osteocytes and plenty of empty lacunae. Trabecular connectivity was lost and trabeculae showed considerable thinning. Trabecular osteoids lined by active osteoblast cells was a remarkable observation. Bone area was also considerably reduced in chronic CA foot bones.

CONCLUSION

Chronic stage CA foot bones presented features of both healing and fragile bone. The compromised bone quality may be due to thin and fragmented trabecular structure and reduced cellularity.

A review of bone metabolism and developments in medical treatment of the diabetic Charcot foot

Charcot foot is a rare but severe, and possibly limb-threatening, complication to neuropathy and diabetes mellitus. The current treatment consists of long-term off-loading, and has a large negative impact on the patient's life. Much research has gone into understanding the condition and its biochemical mechanisms, however, the underlying pathogenesis of a Charcot foot is not yet fully understood. In the recent decades several key advances in our understanding of the Charcot foot have been made, both in regards to the changes in bone metabolism and structure an acute Charcot foot can cause, and to the molecular pathways involved in this. This review summerizes the available research into the bone metabolism around a Charcot foot, with an emphasis on the biochemical profile. The existing data regarding attempts at medical treatment is also reviewed, including novel trials targetting specific inflammatory pathways upregulated in the acute diabetic Charcot foot.

Neuroarthropathy in diabetes: pathogenesis of Charcot arthropathy

Charcot neuroarthropathy is a rare but serious complication of diabetes, causing progressive destruction of the bones and joints of the foot leading to deformity, altered biomechanics and an increased risk of ulceration.

Management is complicated by a lack of consensus on diagnostic criteria and an incomplete understanding of the pathogenesis. In this review, we consider recent insights into the development of Charcot neuroarthropathy.

It is likely to be dependent on several interrelated factors which may include a genetic pre-disposition in combination with diabetic neuropathy. This leads to decreased neuropeptides (nitric oxide and calcitonin gene-related peptide), which may affect the normal coupling of bone formation and resorption, and increased levels of Receptor activator of nuclear factor kappa-B ligand, potentiating osteoclastogenesis.

Repetitive unrecognized trauma due to neuropathy increases levels of pro-inflammatory cytokines (interleukin-1β, interleukin-6, tumour necrosis factor α) which could also contribute to increased bone resorption, in combination with a pre-inflammatory state, with increased autoimmune reactivity and a profile of monocytes primed to transform into osteoclasts - cluster of differentiation 14 (CD14).

Increased blood glucose and loss of circulating Receptor for Advanced Glycation End-Products (AGLEPs), leading to increased non-enzymatic glycation of collagen and accumulation of AGLEPs in the tissues of the foot, may also contribute to the pathological process.

An understanding of the relative contributions of each of these mechanisms and a final common pathway for the development of Charcot neuroarthropathy are still lacking.

Cite this article: S. E. Johnson-Lynn, A. W. McCaskie, A. P. Coll, A. H. N. Robinson. Neuroarthropathy in diabetes: pathogenesis of Charcot arthropathy. Bone Joint Res 2018;7:373–378. DOI: 10.1302/2046-3758.75.BJR-2017-0334.R1.

Bone mineral density and markers of bone turnover and inflammation in diabetes patients with or without a Charcot foot: An 8.5-year prospective case-control study

BACKGROUND AND AIMS

Charcot foot is a rare but severe complication to diabetes and peripheral neuropathy. It is still unclear if an acute Charcot foot has long-term effects on the bone metabolism. To investigate this, we conducted a follow-up study to examine if a previously acute Charcot foot has any long-term effects on bone mineral density (BMD) or local or systemic bone metabolism.

METHODS

An 8.5-year follow-up case-control study of 44 individuals with diabetes mellitus, 24 of whom also had acute or chronic Charcot foot at the baseline visit in 2005-2007, who were followed up in 2015 with DXA scans and blood samples.

RESULTS

21 of the 44 baseline participants participated in the follow-up. There were no difference in the change in total hip BMD from baseline to follow-up in either the Charcot or the control group (p = 0.402 and 0.517), and no increased risk of osteoporosis in the previous Charcot feet either. From baseline to follow-up, there was a significant difference in the change in levels of fsRANK-L in the Charcot group, but not in the control group (p = 0.002 and 0.232, respectively). At follow-up, there were no differences in fsRANK-L between the groups. The fsRANK-L/OPG ratio also significantly decreased from baseline to follow-up in the Charcot group (3.4 versus 0.5) (p = 0.009), but not in the control group (1.3 versus 1.1) (p = 0.302).

CONCLUSION

We found that diabetes patients with an acute Charcot foot have an elevated fsRANK-L/OPG ratio, and that the level decreased from baseline to follow-up to be comparable to the level in diabetes patients without previous or current Charcot foot. We found no permanent effect of an acute Charcot foot on hip or foot BMD.

Markers of Local Inflammation and Bone Resorption in the Acute Diabetic Charcot Foot

OBJECTIVE

Due to the localized nature of Charcot foot, systemically altered levels of inflammation markers can be difficult to measure. The aim of this study was to investigate whether it is possible to detect an arteriovenous (A-V) flux in any locally produced inflammatory biomarkers from an acute Charcot foot by comparing local and systemic measurements.

METHODS

We included patients with acute diabetic Charcot foot. Blood was sampled from the vena saphena magna on the distal part of the crus bilaterally as well as from the arteria radialis. To minimize the A-V shunting effect, the feet were externally cooled with ice water prior to resampling.

RESULTS

Both before and after cooling, the A-V flux of interleukin-6 (IL-6) between the Charcot feet and the arterial level was significantly higher than the flux between the healthy feet and the arterial level (Δvalue_before: 7.25 versus 0.41 pg/mL, resp., p = 0.008; Δvalue_after: 10.04 versus 1.68 pg/mL, resp., p = 0.032). There were no differences in the fluxes for other markers of inflammation.

CONCLUSION

We have found an increased A-V flux of IL-6 in the acute diabetic Charcot foot compared to the healthy foot in the same patients.

Circulating microparticles in acute diabetic Charcot foot exhibit a high content of inflammatory cytokines, and support monocyte-to-osteoclast cell induction

Circulating microparticles (MPs) are major mediators in cardiovascular complications of type 2 diabetes (T2D); however, their contribution to Charcot foot (CF) disease is not known. Here, we purified and assessed the origin, concentration and content of circulating MPs from 33 individuals: 11 with T2D and acute CF, 11 T2D patients with equivalent neuropathy and 11 non-diabetic controls. First, we demonstrated that there were no differences in the distribution of MPs of endothelial, platelet origin among the 3 groups. However, MPs from leukocytes and monocytes origin were increased in CF patients. Moreover, we demonstrated that monocytes-derived MPs originated more frequently from intermediate and non-classical monocytes in CF patients. Five cytokines (G-CSF, GM-CSF, IL-1-ra, IL-2 and IL-16) were significantly increased in MPs from acute CF patients. Applying ingenuity pathways analysis, we found that those cytokines interacted well and induced the activation of pathways that are involved in osteoclast formation. Further, we treated THP-1 monocytes and monocytes sorted from healthy patients with CF-derived MPs during their differentiation into osteoclasts, which increased their differentiation into multinucleated osteoclast-like cells. Altogether, our study suggests that circulating MPs in CF disease have a high content of inflammatory cytokines and could increase osteoclast differentiation in vitro.

Diabetic osteoarthropathy care in Sweden - Need for improvement: A national inventory

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79% of the clinics had no guidelines for managing patients with osteoarthropathy.

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Only two clinics presented acceptable guidelines.

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Plain X-ray, was the common diagnostic method.

Aims

Osteoarthropathy, a rare foot complication in patients with diabetes mellitus, calls for immediate and optimal management to prevent irreversible bone/joint destruction and risk of amputation. Awareness of the condition and adequate guidelines would minimize the consequences and the costs, both for the patient and for the society. We investigated the diabetic osteoarthropathy care in Swedish orthopedic clinics.

Methods

A questionnaire was distributed to 63 Swedish hospitals with emergency department for orthopedic patients. There was a 95% response rate.

Results

Most of the respondents (79%) specified absence of established procedures including guidelines for managing patients with osteoarthropathy. The most common diagnostic method was clinical diagnosis and plain X-ray (95%). MRI or scintigraphy was used by 19% and 10.5% respectively. As treatment method, 84% used a total contact cast, while 38% used orthoses. Treatment duration <3 months was reported in 4%, 3–6 months in 53% and 6–12 months in 28% of the clinics. Four clinics reported treatment duration >12 months and two clinics provided no treatment.

Conclusion

Our national inventory indicates a need for improvement in knowledge as well as guidance and organization at orthopedic clinics regarding optimal care of patients with diabetic osteoarthropathy.

MECHANISMS IN ENDOCRINOLOGY: Diabetes mellitus, a state of low bone turnover - a systematic review and meta-analysis

OBJECTIVE

To investigate the differences in bone turnover between diabetic patients and controls.

DESIGN

A systematic review and meta-analysis.

METHODS

A literature search was conducted using the databases Medline at PubMed and EMBASE. The free text search terms 'diabetes mellitus' and 'bone turnover', 'sclerostin', 'RANKL', 'osteoprotegerin', 'tartrate-resistant acid' and 'TRAP' were used. Studies were eligible if they investigated bone turnover markers in patients with diabetes compared with controls. Data were extracted by two reviewers.

RESULTS

A total of 2881 papers were identified of which 66 studies were included. Serum levels of the bone resorption marker C-terminal cross-linked telopeptide (-0.10 ng/mL (-0.12, -0.08)) and the bone formation markers osteocalcin (-2.51 ng/mL (-3.01, -2.01)) and procollagen type 1 amino terminal propeptide (-10.80 ng/mL (-12.83, -8.77)) were all lower in patients with diabetes compared with controls. Furthermore, s-tartrate-resistant acid phosphatase was decreased in patients with type 2 diabetes (-0.31 U/L (-0.56, -0.05)) compared with controls. S-sclerostin was significantly higher in patients with type 2 diabetes (14.92 pmol/L (3.12, 26.72)) and patients with type 1 diabetes (3.24 pmol/L (1.52, 4.96)) compared with controls. Also, s-osteoprotegerin was increased among patients with diabetes compared with controls (2.67 pmol/L (0.21, 5.14)).

CONCLUSIONS

Markers of both bone formation and bone resorption are decreased in patients with diabetes. This suggests that diabetes mellitus is a state of low bone turnover, which in turn may lead to more fragile bone. Altered levels of sclerostin and osteoprotegerin may be responsible for this.

Charcot shoulder and elbow: a review of the literature and update on treatment

Charcot arthropathy of the shoulder and elbow is a rare disease process initially described in the 1700s; however, it was not until the 19th century that physicians understood its association with other disease processes such as cervical spine pathology and diabetes. A primary complaint is painful or painless joint dysfunction, meaning the orthopedic surgeon is regularly the first physician to evaluate the patient. Frequently, the condition of these patients is misdiagnosed. Although the pathogenesis of the disease is controversial, the etiology is commonly due to syringomyelia. The key to successful management is a thorough history and examination along with a workup including specific laboratory testing and imaging to rule out other disease processes. Most neuropathic shoulders and elbows have historically been managed conservatively because of poor outcomes with operative interventions. Newer data have emerged hinting that early neurosurgical intervention can stabilize this degenerative process. If clinical and radiographic stabilization occurs, recent studies have outlined surgical indications that can provide surgeons with a guide as to patients in whom successful operative outcomes can be achieved in the face of failed conservative management.

Conservative and Pharmacologic Treatments for the Diabetic Charcot Foot

Charcot neuroarthropathy is a disabling complication of diabetic neuropathy. Prolonged immobilization in a total contact cast (TCC) is among the main treatments. Education of health care professionals in the application of TCC together with well-conducted clinical trials are required to overcome its frequent underuse. There are no established pharmacologic therapies to treat this condition; however, there is an overwhelming need for a new therapeutic approach. Novel targeted drug delivery systems are required to prevent the pathologic bone and joint destruction of the Charcot neuroarthropathy and this may lead to an improved outcome in diabetic patients with this condition.

Challenges in diagnosing infection in the diabetic foot

Diagnosing the presence of infection in the foot of a patient with diabetes can sometimes be a difficult task. Because open wounds are always colonized with microorganisms, most agree that infection should be diagnosed by the presence of systemic or local signs of inflammation. Determining whether or not infection is present in bone can be especially difficult. Diagnosis begins with a history and physical examination in which both classic and 'secondary' findings suggesting invasion of microorganisms or a host response are sought. Serological tests may be helpful, especially measurement of the erythrocyte sedimentation rate in osteomyelitis, but all (including bone biomarkers and procalcitonin) are relatively non-specific. Cultures of properly obtained soft tissue and bone specimens can diagnose and define the causative pathogens in diabetic foot infections. Newer molecular microbial techniques, which may not only identify more organisms but also virulence factors and antibiotic resistance, look very promising. Imaging tests generally begin with plain X-rays; when these are inconclusive or when more detail of bone or soft tissue abnormalities is required, more advanced studies are needed. Among these, magnetic resonance imaging is generally superior to standard radionuclide studies, but newer hybrid imaging techniques (single-photon emission computed tomography/computed tomography, positron emission tomography/computed tomography and positron emission tomography/magnetic resonance imaging) look to be useful techniques, and new radiopharmaceuticals are on the horizon. In some cases, ultrasonography, photographic and thermographic methods may also be diagnostically useful. Improved methods developed and tested over the past decade have clearly increased our accuracy in diagnosing diabetic foot infections.

Inhibition of TNF-α Reverses the Pathological Resorption Pit Profile of Osteoclasts from Patients with Acute Charcot Osteoarthropathy

We hypothesised that tumour necrosis factor-α (TNF-α) may enhance receptor activator of nuclear factor-κβ ligand- (RANKL-) mediated osteoclastogenesis in acute Charcot osteoarthropathy. Peripheral blood monocytes were isolated from 10 acute Charcot patients, 8 diabetic patients, and 9 healthy control subjects and cultured in vitro on plastic and bone discs. Osteoclast formation and resorption were assessed after treatment with (1) macrophage-colony stimulating factor (M-CSF) and RANKL and (2) M-CSF, RANKL, and neutralising antibody to TNF-α (anti-TNF-α). Resorption was measured on the surface of bone discs by image analysis and under the surface using surface profilometry. Although osteoclast formation was similar in M-CSF + RANKL-treated cultures between the groups (p > 0.05), there was a significant increase in the area of resorption on the surface (p < 0.01) and under the surface (p < 0.01) in Charcot patients compared with diabetic patients and control subjects. The addition of anti-TNF-α resulted in a significant reduction in the area of resorption on the surface (p < 0.05) and under the surface (p < 0.05) only in Charcot patients as well as a normalisation of the aberrant erosion profile. We conclude that TNF-α modulates RANKL-mediated osteoclastic resorption in vitro in patients with acute Charcot osteoarthropathy.