Theories concerning the pathogenesis of the acute charcot foot suggest future therapy

RANKL-RANK-OPG Pathway in Charcot Diabetic Foot: Pathophysiology and Clinical-Therapeutic Implications

Charcot Foot (CF), part of a broader condition known as Charcot Neuro-Osteoarthropathy (CNO), is characterized by neuropathic arthropathy with a progressive alteration of the foot. CNO is one of the most devastating complications in patients with diabetes mellitus and peripheral neuropathy but can also be caused by neurological or infectious diseases. The pathogenesis is multifactorial; many studies have demonstrated the central role of inflammation and the Receptor Activator of NF-κB ligand (RANKL)-Receptor Activator of NF-κB (RANK)-Osteoprotegerin (OPG) pathway in the acute phase of the disease, resulting in the serum overexpression of RANKL. This overexpression and activation of this signal lead to increased osteoclast activity and osteolysis, which is a prelude to bone destruction. The aim of this narrative review is to analyze this signaling pathway in bone remodeling, and in CF in particular, to highlight its clinical aspects and possible therapeutic implications of targeting drugs at different levels of the pathway. Drugs that act at different levels in this pathway are anti-RANKL monoclonal antibodies (Denosumab), bisphosphonates (BP), and calcitonin. The literature review showed encouraging data on treatment with Denosumab, although in a few studies and in small sample sizes. In contrast, BPs have been re-evaluated in recent years in relation to the high possibility of side effects, while calcitonin has shown little efficacy on CNO.

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.

Therapeutics of Charcot neuroarthropathy and pharmacological mechanisms: A bone metabolism perspective

Charcot neuroarthropathy (CN) is a chronic, destructive, and painless damage of the skeletal system that affects the life quality of patients. CN, with an unclear mechanism, is characterized with invasive destruction of bones and a serious abnormality of bone metabolism. Unfortunately, development of an effective prevention and treatment strategy for CN is still a great challenge. Of note, recent studies providing an insight into the molecular mechanisms of bone metabolism and homeostasis have propelled development of novel CN therapeutic strategies. Therefore, this review aims to shed light on the pathogenesis, diagnosis, and treatment of CN. In particular, we highlight the eminent role of the osteoprotegerin (OPG)-receptor activator of nuclear factor-κB (RANK)-RANK ligand (RANKL) system in the development of CN. Furthermore, we summarize and discuss the diagnostic biomarkers of CN as well as the potential pharmacological mechanisms of current treatment regimens from the perspective of bone metabolism. We believe that this review will enhance the current state of knowledge on the diagnosis, prevention, and therapeutic efficacy of CN.

Delayed Diagnosis of Bilateral Neuroarthropathy: Serious Impact on the Development of Charcot's Foot, a Case Report

Charcot neuroarthropathy (CN) is a destructive complication of the joints in patients with diabetes and should be managed from the onset of the first symptoms to avoid joint deformity and the risk of amputating the affected joint. Here, we describe the case of a young 24-year-old patient living with type I diabetes who developed active bilateral CN in both tarsal joints. This case of neuroarthropathy was uncommon due to the bilateral presentation at the same level of the joint. Despite the patient consulting from the beginning of the symptoms, none of the physicians suspected or diagnosed CN, leading to a delay in management and the aggravation of bone destruction by CN. This highlights the importance of early management of CN with the need to refer people with suspected CN to specialised diabetic foot care centres.

Coronal Hindfoot Alignment in Midfoot Charcot Neuroarthropathy

Coronal plane hindfoot malalignment produces abnormal compensatory forces within the midfoot and forefoot. The primary aim of this study is to compare radiographic hindfoot alignment in patients with a midfoot Charcot event, and identify patterns associated with breakdown. A retrospective review of 43 patients (48 limbs) with midfoot Charcot neuroarthropathy were compared between the coronal hindfoot alignments and Charcot joint involvement. Coronal hindfoot alignment was classified as neutral (n = 15), valgus (n = 16), and varus (n = 17) utilizing the Saltzman hindfoot alignment radiograph. Charcot joint breakdown was classified as isolated tarsometatarsal joint (n = 8), combination of tarsometatarsal and naviculocuneiform joints (n = 22), and midtarsal joints including talonavicular and calcaneocuboid joints (n = 18). Patients exhibiting varus hindfoot alignment had 5.8 times greater risk of breakdown at the tarsometatarsal and naviculocuneiform joints (odds ratio 5.8, 95% confidence interval 1.7-22.9, p < .01). Hindfoot varus induces external rotation of the talus, resulting in compensation through the naviculocuneiform and tarsometatarsal joint, which correlates with our findings of a 6-fold increase in naviculocuneiform and tarsometatarsal joint collapse. Patients exhibiting valgus hindfoot alignment had 27 times greater risk of breakdown at the midtarsal joint (odds ratio 27.0; 95% confidence interval 5.6-207.0, p < .01). Hindfoot valgus induces internal rotation of the talonavicular joint, which correlates with our findings of a 27-fold increase in midtarsal joint breakdown. Varus and valgus hindfoot alignment are associated with different midfoot injury patterns, which may have implications in surgical management and allow for focused surveillance in neuropathic patients presenting with early-stage clinical findings consistent with Charcot neuroarthropathy.

Trends in the relation between hyperglycemia correction and active Charcot neuroarthropathy: results from the EPICHAR study

INTRODUCTION

The pathophysiology of Charcot neuroarthropathy (CN) remains unclear. There are a number of hypotheses but these are not exclusive. In its clinical presentation, this complication intersects with the semiology of diabetic-induced neuropathy, such as peripheral hypervascularization and the appearance of arteriovenous shunt. The EPICHAR study is as yet an unpublished cohort of people living with diabetes complicated by CN (in active or chronic phase). Based on the findings of the EPICHAR study, this study aimed to investigate whether a reduction in the rate of hyperglycemia accompanies the onset of an active phase of CN.

RESEARCH DESIGN AND METHODS

Hemoglobin A1c (HbA1c) levels were assessed 3 months (M3) and 6 months (M6) before the diagnosis of active CN (M0).

RESULTS

103 patients living with diabetes and presenting active CN were included between January and December 2019 from the 31 centers participating in this study (30 in France and 1 in Belgium). The mean age of the participants was 60.2±12.2 years; the vast majority were men (71.8%) living with type 2 diabetes (75.5%). Mean HbA1c levels significantly declined between M6 (median 7.70; Q1, Q3: 7.00, 8.55) and M3 (median 7.65; Q1, Q3: 6.90, 8.50) (p=0.012), as well as between M6 and M0 (median 7.40; Q1, Q3: 6.50, 8.50) (p=0.014). No significant difference was found between M3 and M0 (p=0.072).

CONCLUSIONS

A significant reduction in HbA1c levels seems to accompany the onset of the active phase of CN.

TRIAL REGISTRATION NUMBER

NCM03744039.

Impact of the Rapid Normalization of Chronic Hyperglycemia on the Receptor Activator of Nuclear Factor-Kappa B Ligand and the Osteoprotegerin System in Patients Living with Type 2 Diabetes: RANKL-GLYC Study

The RANKL-GLYC study aims to explore the impact of the rapid correction of chronic hyperglycemia on the receptor activator of nuclear factor-kappa B ligand (RANKL) and its antagonist osteoprotegerin (OPG). RANKL and OPG are considered the main factors in the pathophysiology of Charcot neuroarthropathy, a devastating complication of the joints that remains poorly understood. The study began recruiting patients in September 2021 and ends in June 2022; the final study results are scheduled for January 2023.

Fracture of the Bone Inducing Its Necrosis as the End Point in the Evolution of Untreated Neuroarthropathy

We describe here the case of a female patient with type I diabetes who developed active Charcot neuroarthropathy in the foot. Due to therapeutic noncompliance, talus necrosis was discovered 2 years after the presentation of neuroarthropathy. The impact of untreated neuroarthropathy on the bone is commonly described as fracture and joint dislocation, but we describe the complete disappearance of the bony structure and its necrosis associated with active neuroarthropathy in a patient who refused offloading.

Why the Risk of Developing Neuroarthropathy Is Higher After Simultaneous Kidney and Pancreatic Transplantation Compared to Kidney Transplantation Only: The Role of Euglycemia

Charcot’s neuroarthropathy is a destructive complication of the joint, which is often found in patients living with diabetes. Despite the fact that its description was published almost 100 years ago, its pathophysiology, diagnosis, and treatment remain areas that need to be updated. Its prevalence is low in patients living with diabetes, but this increases in particular situations such as peripheral neuropathy, as well as after simultaneous kidney-pancreas transplantation (SPKT) in patients living with type 1 diabetes. We suggest that the development of neuroarthropathy after SPK in not only due to glucocorticoid therapy, as described, but also to the rapid passage into euglycemia. The reduced prevalence of neuroarthropathy after only kidney transplantation compared to SPK seems to validate our hypothesis.

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.

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.

Rapid glycemic regulation in poorly controlled patients living with diabetes, a new associated factor in the pathophysiology of Charcot's acute neuroarthropathy

Objective

Aggressive antidiabetic therapy and rapid glycemic control are associated with diabetic neuropathy. Here we investigated if this is also the case for Charcot neuroarthropathy.

Research design and methods

HbA1c levels and other relevant data were extracted from medical databases of 44 cases of acute Charcot neuroarthropathy.

Results

HbA1c levels significantly declined from 8.25% (67mmol/mol) [7.1%–9.4%](54-79mmol/mol), at -6 months (M-6), to 7.40%(54mmol/mol) [6.70%–8.03%] (50–64 mmol/mol) during the six months preceding the diagnosis of Charcot neuroarthropathy (P <0.001).

Conclusions

HbA1c levels significantly declined during the six months preceding the onset of Charcot neuroarthropathy. This decline seems to be a associated factor with the appearance of an active phase of Charcot neuroarthropathy in poorly controlled patients with diabetic sensitive neuropathy.

New Concepts in the Management of Charcot Neuroarthropathy in Diabetes

Charcot Neuroarthropathy (CN) is an uncommon, debilitating and often underdiagnosed complication of chronic diabetes mellitus though, it can also occur in other medical conditions resulting from nerve injury. Till date, the etiology of CN remains unknown, but enhanced osteoclastogenesis is believed to play a central role in the pathogenesis of CN, in the presence of neuropathy. CN compromises the overall health and quality of life. Delayed diagnosis can result in a severe deformity that can act as a gateway to ulceration, infection and in the worst case, can lead to limb loss. In an early stage of CN, immobilization with offloading plays a key role to a successful treatment. Medical therapies seem to have limited role in the treatment of CN.In case of severe deformity, proper footwear or bracing may help prevent further deterioration and development of an ulcer. In individuals with a concomitant ulcer with osteomyelitis, soft tissue infection and severe deformity, where conservative measures fall short, surgical intervention becomes the only choice of treatment. Early diagnosis and proper management at an early stage can help prevent the occurrence of CN and amputation.

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.

Charcot Pathogenesis: A Study of In Vivo Gene Expression

Charcot neuroarthropathy is a rare but often difficult to manage disease in the neuropathic patient. Early signs such as unremarkable edema, marginal trauma, or minor infection can activate a cascade of bony destruction and lead to gross prominence or deformity, with dire consequences. The exact molecular mechanism is poorly understood. Current theory states that an inflammatory reaction leads to the activation of osteoclasts mediated by specific cytokines. Our study sought to test the genetic expression of certain biomarkers in diabetic patients with and without Charcot neuroarthropathy compared with patients with and without diabetes or neuropathy. A total of 30 patients participated in the study, 17 (57%) males and 13 (43%) females. Peripheral blood samples were drawn, and gene expression was measured using real-time polymerase chain reaction. The expression levels of receptor activator of nuclear factor kappa-B ligand and osteoprotegerin showed no significant increase in the Charcot neuroarthropathy group compared with the healthy control group. We determined that the levels of receptor activator of nuclear factor kappa-B ligand and osteoprotegerin were not significantly increased in Charcot neuroarthropathy patients compared with healthy control patients. These results demonstrate a need for further investigation into alternative molecular pathways to determine the exact mechanism of the disease process.

Charcot Collapse: Does Collapse Pattern Dictate Osseous Metabolism?

Charcot fracture pattern (FP) and Charcot dislocation pattern (DP) are 2 distinct collapse patterns identified in Charcot neuroarthropathy of the foot and ankle. These patterns are believed to demonstrate relative differences in central bone mineral density (BMD), which has been theoretically extrapolated to describe local BMD. To assess variation in local bone composition of FP and DP patients, 10 patients, 5 DP and 5 FP were recruited. The patient's age, body mass index (BMI), radiographs, central BMD, local BMD, sRANKL (soluble receptor activator nuclear factor kappa-beta ligand), sRAGE (soluble receptors of advanced glycated end-products), and osteocalcin were measured to determined bone metabolic status and density. Central BMD was determined using DEXA (dual-energy X-ray absorptiometry) scans of the hip. peripheral BMD was determined using scans at the level of the ankle mortise and Chopart's joint, depending on the location of collapse. These scans were then compared with controls. Central and peripheral DEXA scans were significantly reduced in the FP ( P = .002 and P < .0001) when compared with healthy controls. Additionally, FP patients demonstrated statistically significant elevations in sRANKL ( P = .05) and sRAGE ( P = .002) when compared with DP. No significant difference was seen in osteocalcin ( P = 0.22); however, elevated values compared with normal reference ranges suggest increase bone production. These elevations combined with an osteoporotic profile may indicate difficulty of FP patients in repairing micro fracture. Results from this study emphasize the increased risk of nonunion during FP reconstruction, and highlight the variation in bone composition in these 2 Charcot subtypes.

LEVELS OF EVIDENCE

Level III.

Prevalence of polymorphisms in OPG, RANKL and RANK as potential markers for Charcot arthropathy development

Charcot arthropathy is one of the most serious complications of diabetic foot syndrome that leads to amputation of the affected limb. Since there is no cure for Charcot arthropathy, early diagnosis and implementation preventive care are the best available treatment. However, diagnosis is hindered by obscure clinical picture of the disease and lack of molecular markers for its early detection. Results of recent research suggest that OPG-RANKL-RANK axis regulating bone metabolism can be associated with Charcot arthropathy and that SNPs in OPG gene are associated with the disease. Here we report the results of comprehensive analysis of ten SNPs in OPG, RANKL and RANK genes in 260 subjects divided into diabetes, neuropathy and Charcot arthropathy groups. Besides genotype analysis we performed linkage disequilibrium and hierarchical clustering to obtain information about correlation between SNPs. Our results show that OPG 245T/G (rs3134069) and OPG 1217C/T (rs3102734) polymorphisms co-occur in patients with Charcot arthropathy (r2 = 0.99). Moreover, hierarchical clustering revealed a characteristic profile of all SNPs in Charcot arthropathy and neuropathy, which is distinct from control group. Our results suggest that analysis of multiple SNPs can be used as potential marker of Charcot arthropathy and provide insight into possible molecular mechanisms of its development.

Foot bone density in diabetes may be unaffected by the presence of neuropathy

AIMS

Neuropathies are common complications of diabetes and are proposed to influence peripheral bone, principally via an altered vascular supply. This study aimed to determine the relationship between subtypes of neuropathy and vascular reactivity on foot bone density in people with diabetes.

METHODS

A case-control observational design was utilised with two groups: those with diabetic peripheral large fibre neuropathy (n=23) and a control group with diabetes but without neuropathy (n=23). Bone density in 12 foot bones was determined with computed tomography scanning. Additionally, post-occlusive reactive hyperemia, presence of small fibre neuropathy and heart rate variability were determined. T-tests and hierarchical regression were used to examine the relationships among the variables.

RESULTS

No difference in foot bone density was found between those with and those without large fibre neuropathy. Furthermore, no association between heart rate variability or reactive hyperemia and bone density was found. Small fibre neuropathy was associated with increased cuboid trabecular bone density (p=0.006) with its presence predictive of 14% of the variance.

CONCLUSIONS

This study found no clear association between presence of diabetic neuropathies and foot bone density. Furthermore, vascular reactivity appears to have no impact on bone density.

Neuropathic osteoarthropathy with and without superimposed osteomyelitis in patients with a diabetic foot

Soft tissue and bone infection involving the foot is one of the most common long-term complications of diabetes mellitus, implying a serious impairment in quality of life for patients in the advanced stages of the disease. Neuropathic osteoarthropathy often coexists and differentiating between these two entities is commonly challenging, but crucial, as the management may differ substantially. The importance of correct diagnosis cannot be understated and effective management requires a multidisciplinary approach owing to the complicated nature of therapy in such patients. A missed diagnosis has a high likelihood of major morbidity for the patient, including limb amputation, and over-diagnosis results in a great socioeconomic challenge for healthcare systems, the over-utilization of healthcare resources, and the unwise use of antibiotics. Diagnosis is largely based on clinical signs supplemented by various imaging modalities such as radiography, MR imaging, and hybrid imaging techniques such as F-18 fluorodeoxyglucose-positron emission tomography. In the interests of the management of diabetic foot complications, this review article is aimed on the one hand at providing radiologists with important clinical knowledge, and on the other hand to equip clinicians with relevant radiological semiotics.

[Tibiotalocalcaneal corrective arthrodesis in Charcot arthropathy of the ankle with a retrograde nail]

BACKGROUND

Involvement of the ankle joint in Charcot osteoarthropathy is most often associated with severe instability and fracture or collapse of the talus. Caused by malalignment, ulcerations over both malleoli are associated with increased risk of major amputation.

OBJECTIVE

The goal of the operation is to realign the hind foot, gain a stable osteosynthesis, and prevent major amputation.

INDICATIONS

Charcot osteoarthropathy of the ankle joint with instability, with or without soft tissue involvement, failure of the primary arthrodesis of the ankle or subtalar joint.

CONTRAINDICATIONS

Acute osteitis/osteomyelitis, severe malalignment of the distal tibia, soft tissue infection close to the ankle joint.

SURGICAL TECHNIQUE

Realignment of the hind foot, preparation of the joint surfaces using a transfibular approach. Bone grafting of the defects, stable osteosynthesis with an anatomically shaped retrograde locking nail.

POSTOPERATIVE MANAGEMENT

Walker or cast for at least 12 weeks, 6 weeks no weight bearing. Partial weight bearing starting from week 7. X-ray control at 2, 6, and 12 weeks. After 12 weeks, walking in an ankle brace until fully consolidated.

Novel use of a Dektak 150 surface profiler unmasks differences in resorption pit profiles between control and Charcot patient osteoclasts

We hypothesized that newly formed osteoclasts from patients with acute Charcot osteoarthropathy can resorb surfaces of bone more extensively compared with controls. Peripheral blood monocytes, isolated from eight Charcot patients and nine controls, were cultured in vitro on 24-well plates and bovine bone discs in duplicate with macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor κβ ligand (RANKL). Osteoclast formation was assessed by tartrate-resistant acid phosphatase staining (TRAcP) at day 17. Resorption was measured at day 21 after toluidine blue staining by two methods: (1) area of resorption at the surface by image analysis (%) and (2) area of resorption under the surface (μm(2)) measured by a Dektak 150 Surface Profiler. Ten 1,000 μm-long scans were performed per disc. Pits were classified as unidented, bidented, and multidented according to their shape. Although the number of newly formed TRAcP positive multinucleated cells (>3 nuclei) was similar in M-CSF + RANKL-treated cultures between controls and Charcot patients, the latter exhibited increased resorbing activity. The area of resorption on the surface by image analysis was significantly greater in Charcot patients compared with controls (21.1 % [14.5-26.2] vs. 40.8 % [35.4-46.0], median [25-75th percentile], p < 0.01), as was the area of resorption under the surface (2.7 x 10(3) μm(2) [1.6 x 10(3)- 3.9 x 10(3)] vs. 8.3 x 10(3) μm (2) [5.6 x 10(3)- 10.6 x 10(3), [corrected] p < 0.01) after profilometry. In Charcot patients pits were deeper and wider and more frequently presented as multidented pits. This application of the Dektak 150 Surface Profiler revealed novel differences in resorption pit profile from osteoclasts derived from Charcot patients compared with controls. Resorption in Charcot patients was mediated by highly aggressive newly formed osteoclasts from monocytes eroding large and deep areas of bone.

The effect of diabetic neuropathy on foot bones: a systematic review and meta-analysis

AIMS

It is proposed that diabetic neuropathy may affect peripheral bone. Direct innervation of bone as well as neural control over its vascular supply and muscular influences may be affected by diabetes-induced peripheral neuropathies. Associated changes to bone may contribute to the occurrence of foot bone pathology in this population. This systematic review aims to examine the literature related to the effect of diabetic neuropathy on foot bones.

METHODS

Studies examining relationships between neuropathy and indicators of bone health (e.g. bone mineral density) in populations with diabetes were sought. Relevant publications were obtained from searches in MEDLINE, CINAHL and Embase in the period up to March 2013. Meta-analysis was performed using a random effects model in the statistical package Stata version 12.1.

RESULTS

Ten studies met the inclusion criteria and were included in the narrative synthesis. All studies were cross-sectional or case-control in design. Four of the 10 included studies found results indicating poorer bone health in those with diabetes and neuropathy compared with those with diabetes without neuropathy. Seven of the 10 studies were able to be included in a meta-analysis. The mean pooled effect was -0.36 (95% CI -0.76 to 0.04; P = 0.08), indicating a non-significant trend towards poorer bone health in those with diabetic neuropathy.

CONCLUSIONS

We did not find a significant relationship between presence of neuropathy in those with diabetes and poorer peripheral bone health. However, methodological limitations of the included studies mean further research is required to investigate this theoretical relationship.

Charcot neuroarthropathy of the foot and ankle: diagnosis and management strategies

This article reviews current literature discussing the etiology, pathophysiology, diagnosis and imaging, and conservative and surgical treatment of Charcot osteoarthropathy. The treatment of Charcot osteoarthropathy with concurrent osteomyelitis is also discussed.

Charcot foot and ankle with osteomyelitis

This paper presents a review of the current literature discussing topics of Charcot osteoarthropathy, osteomyelitis, diagnosing osteomyelitis, antibiotic management of osteomyelitis, and treatment strategies for management of Charcot osteoarthropathy with concurrent osteomyelitis.

The Charcot foot

The diabetic Charcot foot is rare, but a life-changing event affecting quality of life, and it risks amputation of the limb. There is no high quality evidence base governing treatment, causing clinicians to rely on low-quality, underpowered studies and expert opinion. However, CN is a treatable condition and, with lifestyle modifications and proper footwear, it does not shorten the life span of those afflicted.

Charcot neuroarthropathy of the foot and ankle: a review

Charcot neuroarthropathy is a limb-threatening, destructive process that occurs in patients with neuropathy associated with medical diseases such as diabetes mellitus. Clinicians' treating diabetic patients should be vigilant in recognizing the early signs of acute Charcot neuroarthropathy, such as pain, warmth, edema, or pathologic fracture in a neuropathic foot. Early detection and prompt treatment can prevent joint and bone destruction, which, if untreated, can lead to morbidity and high-level amputation. A high degree of suspicion is necessary. Once the early signs have been detected, prompt immobilization and offloading are important. Treatment should be determined on an individual basis, and it must be determined whether a patient can be treated conservatively or will require surgical intervention when entering the chronic phase. If diagnosed early, medical and conservative measures only will be required. Surgery is indicated for patients with severe or unstable deformities that, if untreated, will result in major amputations. A team approach that includes a foot and ankle surgeon, a diabetologist, a physiotherapist, a medical social councilor, and, most importantly, the patient and immediate family members is vital for successful management of this serious condition.

Etiology, pathophysiology and classifications of the diabetic Charcot foot

In people with diabetes mellitus, the Charcot foot is a specific manifestation of peripheral neuropathy that may involve autonomic neuropathy with high blood flow to the foot, leading to increased bone resorption. It may also involve peripheral somatic polyneuropathy with loss of protective sensation and high risk of unrecognized acute or chronic minor trauma. In both cases, there is excess local inflammatory response to foot injury, resulting in local osteoporosis. In the Charcot foot, the acute and chronic phases have been described. The former is characterized by local erythema, edema, and marked temperature elevation, while pain is not a prominent symptom. In the latter, signs of inflammation gradually recede and deformities may develop, increasing the risk of foot ulceration. The most common anatomical classification describes five patterns, according to the localization of bone and joint pathology. This review article aims to provide a brief overview of the diabetic Charcot foot in terms of etiology, pathophysiology, and classification.

Inhibition of matrix metalloproteinase 9 expression in rat dermal fibroblasts using small interfering RNA

BACKGROUND

Matrix metalloproteinases (MMPs) degrade extracellular matrix components. Increased MMP-9 content in diabetic skin contributes to skin vulnerability and refractory foot ulcers. To identify ways to decrease MMP-9 levels in skin, inhibition of MMP-9 expression in dermal fibroblasts using small interfering RNA was investigated in vitro.

METHODS

A full-thickness wound was created on the midback of streptozotocin-induced diabetic rats; skin biopsies were performed 3 days later. Skin MMP-9 expression was observed by immunohistochemical analysis. Dermal fibroblasts from 1-day-old normal Sprague Dawley rats cultured with high glucose and homocysteine concentrations were transfected with small interfering RNA complexes. Cells were collected 30, 48, and 72 hours after transfection, and reverse transcription-polymerase chain reaction, Western blot analysis, and gelatin zymography for MMP-9 were performed.

RESULTS

Expression of MMP-9 was increased in diabetic rat skin, especially around wounds. After 30-, 48-, and 72-hour transfection with each MMP-9-specific small interfering RNA, reverse transcription-polymerase chain reaction showed markedly decreased MMP-9 messenger RNA expression, protein abundance, and activity. Of four MMP-9 small interfering RNAs, one sequence had a stable high inhibition rate (>70% at 30 and 48 hours after transfection).

CONCLUSIONS

Expression of MMP-9 was increased in diabetic rat skin, especially around wounds, and was markedly inhibited after MMP-9 small interfering RNA transfection in vitro (P < .05). These findings may provide new treatments for diabetic skin wounds.

Factors associated with nonunion, delayed union, and malunion in foot and ankle surgery in diabetic patients

The incidence of bone healing complications in diabetic patients is believed to be high after foot and ankle surgery. Although the association of hyperglycemia with bone healing complications has been well documented, little clinical information is available to show which diabetes-related comorbidities directly affect bone healing. Our goal was to better understand the risk factors associated with poor bone healing in the diabetic population through an exploratory, observational, retrospective, cohort study. To this end, 165 diabetic patients who had undergone arthrodesis, osteotomy, or fracture reduction were enrolled in the study to assess the risk factors associated with nonunion, delayed union, and malunion after elective and nonelective foot and/or ankle surgery. Bivariate analyses showed that a history of foot ulcer, peripheral neuropathy, and surgery duration were statistically significantly associated with bone healing complications. After adjusting for other covariates, only peripheral neuropathy, surgery duration, and hemoglobin A1c levels >7% were significantly associated statistically with bone healing complications. Of the risk factors we considered, peripheral neuropathy had the strongest association with bone healing complications.

Expression of antimicrobial peptides in diabetic foot ulcer

BACKGROUND

Foot ulcers are one of the main diabetes complications due to its high frequency and difficulty of complete healing. There are several factors that participate in diabetic ulcers development and limited information exists about the role of antimicrobial peptides (AMP) in its pathogenesis.

OBJECTIVE

The aim of this study was to analyze the expression pattern of the main AMPs: Human Neutrophil Peptide (HNP)-1, Human β-defensin (HBD)-1, HBD-2, HBD-3, HBD-4 and cathelicidin LL-37 in biopsies from diabetic foot ulcers (DFU).

METHODS

20 biopsies from DFU grade 3 according to Wagner's classification and 20 biopsies from healthy donors were obtained. Real time PCR, immunohistochemistry and primary cell cultures were performed.

RESULTS

β-Defensins were overexpressed in DFU, whereas LL-37 has low or none expression in comparison with healthy skin. When primary cell culture from these biopsies were performed and infected with Staphylococcus aureus, epidermal cell from diabetic ulcers showed lower LL-37 expression compared with cell cultures from healthy donors skin.

CONCLUSION

These results suggest that though most AMPs are expressed in DFU, this production is not appropriate to promote wound healing and contain secondary infections.

Charcot osteoarthropathy in diabetes: A brief review with an emphasis on clinical practice

Charcot osteoarthropathy (COA) is a potentially limbthreatening condition that mainly affects diabetic patients with neuropathy. In everyday practice, it presents as a red, hot, swollen foot, usually painless, and is frequently triggered by trivial injury. Its etiology is traditionally attributed to impairment of either the autonomic nervous system, leading to increased blood flow and bone resorption, or of the peripheral nervous system, whereby loss of pain and protective sensation render the foot susceptible to repeated injury. More recently, excessive local inflammation is thought to play a decisive role. Diagnosis is based on clinical manifestation and imaging studies (plain X-rays, bone scan, Magnetic Resonance Imaging). The mainstay of management is immediate off-loading, while surgery is usually reserved for chronic cases with irreversible deformities and/or joint instability. The aim of this review is to provide an overview of COA in terms of pathogenesis, classification and clinical presentation, diagnosis and treatment, with an emphasis on the high suspicion required by clinicians for timely recognition to avoid further complications.

An overview of conservative treatment options for diabetic Charcot foot neuroarthropathy

Conservative management of Charcot foot neuroarthropathy remains efficacious for certain clinical scenarios. Treatment of the patient should take into account the stage of the Charcot neuroarthopathy, site(s) of involvement, presence or absence of ulceration, presence or absence of infection, overall medical status, and level of compliance. The authors present an overview of evidence-based non-operative treatment for diabetic Charcot neuroarthropathy with an emphasis on the most recent developments in therapy.

Charcot arthropathy of the foot and ankle: modern concepts and management review

Charcot arthropathy (Charcot neuroarthropathy, diabetic neuropathic osteoarthropathy, or neuropathic arthropathy) remains a poorly understood disease, although recent research has improved our level of knowledge regarding its etiology and treatment. The effects of Charcot arthropathy are almost exclusively seen in the foot and ankle, and the diagnosis is commonly missed upon initial presentation. It has been well established that this complication of diabetes mellitus severely reduces the overall quality of life and dramatically increases the morbidity and mortality of patients. However, there are few high-level evidence studies to support management and treatment options at this point in time. The goal of this study is to evaluate the modern concepts of Charcot arthropathy through a review of the available literature and to integrate a perspective of management from the authors' extensive experience.

The management of Charcot joint disease affecting the ankle and foot by arthrodesis controlled by an Ilizarov frame

Charcot osteoarthropathy of the foot is a chronic and progressive disease of bone and joint associated with a risk of amputation. The main problems encountered in this process are osteopenia, fragmentation of the bones of the foot and ankle, joint subluxation or even dislocation, ulceration of the skin and the development of deep sepsis. We report our experience of a series of 20 patients with Charcot osteoarthropathy of the foot and ankle treated with an Ilizarov external fixator. The mean age of the group was 30 years (21 to 50). Diabetes mellitus was the underlying cause in 18 patients. Five had chronic ulcers involving the foot and ankle. Each patient had an open lengthening of the tendo Achillis with excision of all necrotic and loose bone from the ankle, subtalar and midtarsal joints when needed. The resulting defect was packed with corticocancellous bone graft harvested from the iliac crest and an Ilizarov external fixator was applied. Arthrodesis was achieved after a mean of 18 weeks (15 to 20), with healing of the skin ulcers. Pin track infection was not uncommon, but no frame had to be removed before the arthrodesis was sound.

Every patient was able to resume wearing regular shoes after a mean of 26.5 weeks (20 to 45).

Charcot neuroarthropathy of the foot and ankle

Charcot neuroarthropathy is a common cause of morbidity in persons with diabetes mellitus and sensory neuropathy. Although Charcot neuroarthropathy is rare, it likely will become more prevalent in conjunction with increased incidence of diabetes mellitus. Prevention of disease progression remains the mainstay of treatment, with surgical intervention usually reserved for refractory cases. Late deformities are often complicated by chronic ulceration, infection, and osteomyelitis. The clinical presentation is best summarized with the Eichenholtz classification, and progression often follows a predictable pattern. Although Charcot neuroarthropathy is a clinical diagnosis, recent advances in diagnostic imaging have eased the clinical challenge of deciphering infection from Charcot changes. Advances in surgical treatment have demonstrated new options for limb salvage. Pharmacologic therapies directed toward decreasing bone resorption have also shown promise for treatment, but clinical application remains theoretical.

Charcot neuro-osteoarthropathy

The classical neurotraumatic and neurotrophic theories for the pathogenesis of the acute Charcot neuro-osteoarthropathy (CN) in diabetes, do not address certain key features of the disease. These features include the facts that the condition usually affects just one side, that it is self-limiting, and that it is also very uncommon. Similarly, it is not known to what extent the condition may depend, as suggested by Jean-Martin Charcot, on pre-morbid osteopenia. Recent advances in understanding the mechanisms underlying the pathogenesis of osteopenia and osteoporosis and the central role of the RANKL/OPG signalling system have, however, suggested the possible involvement of other factors in the evolution of the disease. Specifically, it has been suggested that acute CN may be triggered in a susceptible individual by any event that leads to localized inflammation in the affected foot. This local inflammation leads to a vicious cycle in which there is increasing inflammation, increasing expression of RANKL, and increasing bone breakdown. The likely central role for the RANKL/OPG pathway suggests new possibilities for future treatments.

Foot structure and footwear prescription in diabetes mellitus

Foot structure abnormalities such as foot deformity and limited joint mobility are common and well established components of the diabetic foot which are associated with increased levels of mechanical stress on the foot and the development of ulcers. Our understanding of foot structure abnormality in diabetes has improved recently, mainly through the findings from in vivo imaging studies. Several examples will be discussed in this review. A limited understanding, however, still exists about several aspects related to the assessment, etiology, and consequences of change in foot structure in diabetes. Knowledge on these matters is needed if we are to better deal with the implications of foot structure change in diabetes. Diabetic patients with neuropathy and foot deformity are commonly prescribed with custom footwear, in particular after ulcer healing. The goal of this footwear is to redistribute and reduce plantar foot pressures, and to prevent ulcer recurrence. However, the available evidence for the effectiveness of custom footwear in secondary ulcer prevention is not yet strong. This may be associated with several factors, including a lack of standardized or systematic approach (a set of guidelines) in footwear prescription and evaluation or with the significant variability that exists across patients in the offloading effect of different footwear interventions, which increases the difficulty of predicting what works for a given patient. Objective evaluation tools such as in-shoe plantar pressure analysis can be helpful in this regard in order to ensure efficacy of an intervention. This provides a more optimal footwear solution that may lower the risk for ulceration.

The diabetic foot: Charcot joint and osteomyelitis

Foot problems are common causes of disability in diabetic patients with as many as 25% expected to develop severe foot or leg problems during their lifetimes. Although skin ulceration is the most frequent problem, bones may also be involved in two different clinical conditions: osteomyelitis and Charcot osteoarthropathy. Osteomyelitis causes complications in up to one third of diabetic foot infections and is due to direct contamination from a soft-tissue ulcer. Osteoarthropathy Charcot foot is a chronic and progressive disease of the bone and joints. Both osteomyelitis and Charcot joint are conditions with an increased risk of lower limb amputation, both may have a successful outcome when recognized and treated in the early stages. The major diagnostic difficulty is in distinguishing bone infection (osteomyelitis) from non-infectious neuropathic bony disorders as in osteoarthropathy Charcot foot. An additional difficulty is found when a bone infection superimposes a Charcot osteopathy. This condition, which can be clinically suspected when foot ulceration appears in Charcot foot, needs to be diagnosed because it implies a different therapeutic strategy. This article aims to summarize both these two clinical conditions and give indications to make a timely and correct diagnosis.

Risk factors for foot infections in individuals with diabetes

OBJECTIVE

To prospectively determine risk factors for foot infection in a cohort of people with diabetes.

RESEARCH DESIGN AND METHODS

We evaluated then followed 1,666 consecutive diabetic patients enrolled in a managed care-based outpatient clinic in a 2-year longitudinal outcomes study. At enrollment, patients underwent a standardized general medical examination and detailed foot assessment and were educated about proper foot care. They were then rescreened at scheduled intervals and also seen promptly if they developed any foot problem.

RESULTS

During the evaluation period, 151 (9.1%) patients developed 199 foot infections, all but one involving a wound or penetrating injury. Most patients had infections involving only the soft tissue, but 19.9% had bone culture-proven osteomyelitis. For those who developed a foot infection, compared with those who did not, the risk of hospitalization was 55.7 times greater (95% CI 30.3-102.2; P < 0.001) and the risk of amputation was 154.5 times greater (58.5-468.5; P < 0.001). Foot wounds preceded all but one infection. Significant (P < 0.05) independent risk factors for foot infection from a multivariate analysis included wounds that penetrated to bone (odds ratio 6.7), wounds with a duration >30 days (4.7), recurrent wounds (2.4), wounds with a traumatic etiology (2.4), and presence of peripheral vascular disease (1.9).

CONCLUSIONS

Foot infections occur relatively frequently in individuals with diabetes, almost always follow trauma, and dramatically increase the risk of hospitalization and amputation. Efforts to prevent infections should be targeted at people with traumatic foot wounds, especially those that are chronic, deep, recurrent, or associated with peripheral vascular disease.