Treatment and management of pseudogout: insights for the clinician

The patient with a painful knee

Knee pain encompasses a wide array of differential diagnoses and can often pose a diagnostic challenge, as it can have traumatic or non-traumatic causes. A good clinical history, assessment and anatomical knowledge gives a strong foundation to narrow down the diagnosis, and understanding the correct imaging modality and findings further informs correct and timely management. This article reviews various disease processes including fractures, inflammatory, infective and neoplastic causes, and discusses the assessment and various imaging modalities to aid diagnosis in both primary and secondary care.

Diagnosis, Treatment, and Outcomes of Crystalline Arthropathy in the Setting of Total Knee Arthroplasty: A Critical Analysis Review

» Emerging evidence suggests the prevalence of crystalline arthropathy (CA) in the setting of total knee arthroplasty (TKA) is increasing, and diagnosis of CA is often intricate because of symptom overlap with other common postoperative complications such as periprosthetic joint infection (PJI). Consequently, an accurate and timely diagnosis becomes pivotal in guiding the choice of treatment.» CA includes gout and calcium pyrophosphate deposition (CPPD) disease, and accurate diagnosis in patients with prior TKA requires a multifaceted approach. The diagnosis algorithm plays a critical role in determining the appropriate treatment approach.» Management of CA typically involves a conservative strategy, encompassing the administration of nonsteroidal anti-inflammatory drugs, colchicine, and steroids, regardless of whether patients have undergone prior TKA.» There is conflicting evidence on the effect CA has on the surgical outcomes in postoperative TKA patients. While these patients may expect excellent functional outcomes and pain relief, they may be at a higher risk of complications such as infections, medical complications, and revision procedures.» Additional research is required to fully comprehend the impact of CA on postoperative TKA outcomes and to establish effective strategies for enhancing patient care and optimizing long-term joint function.

Atypical Presentation of Gout: A Case Report

Gout is the most common inflammatory arthritis which is caused by the buildup of uric acid crystals in the joints, that leads to severe pain, swelling, and stiffness. The condition typically affects the first metatarsophalangeal joint but it can impact other joints in the body. We present a case in which a 43-year-old male with a past medical history of obesity, hypertension, osteoarthritis, and gout presented with bilateral leg pain and the inability to walk for the last two years. Labs showed persistent leukocytosis, elevated ESR (erythrocyte sedimentation rate), normal uric acid levels, with physical exam findings of bilateral tender nodular leg lesions. Chest X-ray, head CT without contrast, left hip X-ray and ultrasound of left lower extremity were performed which were all negative. Biopsy of the tender skin nodules confirmed the diagnosis of tophaceous gout. Acute and prophylactic treatment of tophaceous gout resulted in resolved inflammation and leukocytosis without any complications.

Diagnosis and Treatment of Calcium Pyrophosphate Deposition (CPPD) Disease: A Review

Calcium Pyrophosphate Dihydrate (CPPD) crystal-related arthropathies are a common cause of acute and chronic arthritis caused by the deposition of calcium pyrophosphate crystals in joints and soft tissues, resulting in inflammation and joint damage. They present with a wide spectrum of clinical manifestations and often present challenges to diagnosis and management as they commonly affect older co-morbid patients. The challenges are compounded by a lack of a well-defined description of CPPD. However, an international expert-driven process is underway to develop CPPD classification criteria. Treatment is also problematic as unlike gout, there are no agents available that decrease the crystal burden. Treatment options have often been extrapolated from gout treatment pathways without having extensive trials or a solid evidence base. It is hoped the new CPPD classification guidelines will contribute to large multicentre studies, with well-defined patient cohorts, which will facilitate the production of high-quality evidence to guide the management of this condition. Here, we discuss the barriers and facilitators in diagnosing and treating CPPD-related arthropathy.

Confusion With Presentations of Calcium Pyrophosphate Dihydrate Disease: A Report of Two Cases Mistaken for Cellulitis

Both pseudogout and cellulitis are diseases that may mimic one another in clinical practice. We discuss two cases of acute calcium pyrophosphate dihydrate (CPPD) arthritis mistaken for cellulitis in the emergency department. Both patients experienced significant improvement after management was changed to treat CPPD. These cases highlight how it is essential for physicians to consider CPPD as a differential diagnosis for a patient that is presenting with signs of inflammation in any joint.

20 Years of Radiographic Imaging: Crystalline Deposits Causing Severe Arthropathy and Erosions

Urate crystal gout arthritis and calcium pyrophosphate deposition disease (CPPD) are crystalline arthropathies seen in middle age to elderly patients, but are also seen in the active duty military population. Flares of either can be identified by acute joint pain, associated swelling, tenderness, and warmth. Definitive diagnosis involves synovial analysis from arthrocentesis. Gout and CPPD are common inflammatory joint diseases. Both arthropathies presenting themselves in the same joint are rather rare. An elderly female with a history of gout presented to the hospital with severe hip pain. She was on urate-lowering therapy at the time, and uric acid levels on admission were not significantly elevated. Radiographic imaging of her hip demonstrated periarticular cartilage calcifications. A review of radiographic imaging over the last 20 years found significant erosive arthropathy in multiple joints and radiographic evidence of chondrocalcinosis, suggesting CPPD. Synovial analysis was not obtained during this admission as the patient declined procedures due to her elderly age. Her condition improved with oral steroids. Few literatures have demonstrated that gout and CPPD are common crystal arthropathies that can occur concomitantly in the same joint. A 20-year review of imaging in an elderly female with known gout arthropathy found that she had radiographic evidence of concomitant CPPD-associated damage to many of her joints. Clinicians should be aware of the different erosive arthropathies, their corresponding imaging findings, evaluation for underlying metabolic disorders if appropriate, and the possibility that they may occur in the same joint. Early prevention can reduce joint destruction later in life.

The use of Anakinra in treatment of calcium pyrophosphate crystal deposition disease: Analysis of own experience and a literature review

Calcium pyrophosphate crystal deposition disease (CPPD) is a disease caused by the deposition of calcium pyrophosphate crystals, mainly in the articular cartilage, and often manifests as severe acute or chronic arthritis. Therapy given in such cases with non-steroidal anti-inflammatory drugs, colchicine, methotrexate and glucocorticoids is often effective. In these cases, the possibility of prescribing biological drugs, primarily interleukin 1 (IL-1) inhibitors, is being considered. The article analyzes the experience of using Anakinra, an IL-1 receptor antagonist, registered in the Russian Federation in 2021, in 5 patients with persistent arthritis in CPPD. The article also presents an analysis of data from key studies on the use of the drug in patients with CPPD.

Windswept Deformity from pseudogout. A Diagnostic Challenge of an extreme presentation, a case report

Background: Twenty percent of the population globally is affected by musculoskeletal conditions. These conditions significantly impair mobility and dexterity. Pseudogout is similarly a debilitating disease that significantly increases morbidity and the disability adjusted life years. We report a case of pseudogout in its advanced stage, causing total joint destruction of the knees and shoulders, which manifested and presented as a windswept deformity. The Case: Our patient is a 69 year old man who complained of bilateral knee pain, shoulder pain during active flexion and an obvious knee deformity. His familial history was not significant, and there was no history of injuries, infection or congenital diseases. His knees were severely deformed, with extremely laxed collateral ligaments. Both of his shoulders had a limited range of movement with coarse crepitation on passive movement. X-ray of his knees showed a completely destroyed joint, reduced joint space, subchondral cysts and chondrocalcinosis. X-ray of his shoulder joint showed a subluxated joint, subchondral cyst and subchondral sclerosis. His joint aspirate had positive rhomboid crystals on the birefringence test, consistent with pseudogout. Joint replacement surgery is the definitive management, but the patient and caretaker were not able to afford the implants.  Conclusion: We discussed the diagnosis of pseudogout in this patient and how the policies in place do not provide adequate coverage for these populations. This marginalizes those who need surgery and limits their access to affordable surgical care when needed.

Orthopaedic Management of Gout

Gout is characterized by the deposition of monosodium urate crystals in patients with chronically elevated blood levels of uric acid. It is the most common form of inflammatory arthritis in the United States and is often comorbid with hypertension, obesity, and chronic kidney disease. Initial presentation is usually an acutely warm, swollen joint, most commonly the first metatarsophalangeal joint, but a variety of locations may be affected. The main treatment for gout is medical management of acute inflammation and chronic uric acid levels, but surgical treatment may be indicated in cases of damage to the surrounding soft tissue, concomitant septic arthritis, symptomatic cartilage loss, or neurologic deficits. Based on the literature to date, gout does not seem to independently affect outcomes after total hip, knee, and ankle arthroplasty, but associated comorbidities affecting outcomes in these patients should be considered.

Activation and Function of NLRP3 Inflammasome in Bone and Joint-Related Diseases

Inflammation is a pivotal response to a variety of stimuli, and inflammatory molecules such as cytokines have central roles in the pathogenesis of various diseases, including bone and joint diseases. Proinflammatory cytokines are mainly produced by immune cells and mediate inflammatory and innate immune responses. Additionally, proinflammatory cytokines accelerate bone resorption and cartilage destruction, resulting in the destruction of bone and joint tissues. Thus, proinflammatory cytokines are involved in regulating the pathogenesis of bone and joint diseases. Interleukin (IL)-1 is a representative inflammatory cytokine that strongly promotes bone and cartilage destruction, and elucidating the regulation of IL-1 will advance our understanding of the onset and progression of bone and joint diseases. IL-1 has two isoforms, IL-1α and IL-1β. Both isoforms signal through the same IL-1 receptor type 1, but the activation mechanisms are completely different. In particular, IL-1β is tightly regulated by protein complexes termed inflammasomes. Recent research using innovative technologies has led to a series of discoveries about inflammasomes. This review highlights the current understanding of the activation and function of the NLRP3 (NOD-like receptor family, pyrin domain-containing 3) inflammasome in bone and joint diseases.

Distinguishing Periprosthetic Crystalline Arthropathy from Infection in Total Knee Arthroplasty: A Systematic Review

Distinguishing periprosthetic crystalline arthropathy from periprosthetic joint infection (PJI) remains a diagnostic challenge as both symptom presentation and diagnostic tests overlap. Accurate differentiation is important as treatment plans vary significantly. We sought to systematically review all cases of total knee arthroplasty (TKA) periprosthetic crystalline arthropathy reported in the literature and summarize clinical, diagnostic, and operative findings in the context of guidelines for diagnosing PJI. The goal of this systematic review is to determine the amount of diagnostic overlap and to identify best practices for differentiating between these two diagnoses. MEDLINE and Google Scholar were searched to identify cases of crystalline arthropathy following TKA. Case reports were reviewed for patient characteristics, clinical symptoms, physical exam, laboratory results, and treatment outcomes. These findings were summarized across patients and dichotomized based on current thresholds for diagnosing PJI according to Musculoskeletal Infection Society criteria. Twenty-six articles were identified which included 42 cases of periprosthetic crystalline arthropathy (17 gout, 16 pseudogout, one both, and eight not specified). Of these cases, 25 presented over 1 year after their index arthroplasty and 15 had no prior history of crystalline arthropathy. Only six cases had a superimposed infection based on aspiration or intraoperative cultures. For cases without a culture-positive infection, several diagnostic tests overlap with PJI thresholds: 95% of patients had C-reactive protein greater than 1 mg/dL, 76% had an erythrocyte sedimentation rate greater than 30 mm/hour, 91% had a synovial white blood cell greater than 3,000 cells, and 76% had a synovial polymorphonuclear cells percent greater than 80%. Patients without co-infection were managed with non-steroidal anti-inflammatory drugs, colchicine, allopurinol, steroids, or a combination of these treatments and most had complete resolution of symptoms within 1 week. Commonly used markers of PJI fail to reliably distinguish periprosthetic crystalline arthropathy from infection. Though clinical judgement and consideration of the implications of delayed treatment for acute PJI remain paramount, in the setting of synovial crystals, surgeons may wish to consider this alternate etiology as the source of the patient's clinical symptoms.

Introducing variability in targeting the microtubules: Review of current mechanisms and future directions in colchicine therapy

Microtubules (MTs) are highly dynamic polymers that constitute the cellular cytoskeleton and play a role in multiple cellular functions. Variability characterizes biological systems and is considered a part of the normal function of cells and organs. Variability contributes to cell plasticity and is a mechanism for overcoming errors in cellular level assembly and function, and potentially the whole organ level. Dynamic instability is a feature of biological variability that characterizes the function of MTs. The dynamic behavior of MTs constitutes the basis for multiple biological processes that contribute to cellular plasticity and the timing of cell signaling. Colchicine is a MT‐modifying drug that exerts anti‐inflammatory and anti‐cancer effects. This review discusses some of the functions of colchicine and presents a platform for introducing variability while targeting MTs in intestinal cells, the microbiome, the gut, and the systemic immune system. This platform can be used for implementing novel therapies, improving response to chronic MT‐based therapies, overcoming drug resistance, exerting gut‐based systemic immune responses, and generating patient‐tailored dynamic therapeutic regimens.

Colchicine in coronary artery disease

Coronary artery disease (CAD) is a major cause of morbidity and mortality worldwide. Inflammation has been seen to be a key feature of atherosclerosis and CAD, with a raised C-reactive protein being a marker of poor prognosis. Thus, the role of anti-inflammatory agents has been investigated in CAD. Colchicine is a well-known, inexpensive drug with marked anti-inflammatory effects. Here, we discuss the role of colchicine in stable CAD and post-acute coronary syndrome. We suggest that colchicine may play a key role in prevention of cardiovascular events in patients with stable and unstable CAD as colchicine is associated with a reduction in the rate of myocardial infarction and other major cardiovascular outcomes.

Synovial fluid analysis for the enhanced clinical diagnosis of crystal arthropathies in a tertiary care institution

INTRODUCTION/OBJECTIVES

Few studies have addressed the detection and clinical impact of different crystals in patients with diverse rheumatologic diagnoses in Latin America. The aim of this study was to assess the consistency between the clinical referring diagnosis and the identification of crystals, such as monosodium urate (MSU) and calcium pyrophosphate (CPP), in the synovial fluid (SF) of patients from a Mexican tertiary care institution.

METHODS

We reviewed the results of 264 SF analyses to identify any changes in diagnosis upon SF analysis. We reported patient medical file data on sex, age, diagnosis, and microscopic SF analysis results. We performed consistency analyses between referring diagnoses and SF findings with McNemar's test.

RESULTS

The prevalence of MSU crystals in SF was noted in 89.1% of gout cases and 9.09% of cases of calcium pyrophosphate disease (CPPD). CPP crystals were present in 54.5% of CPPD cases, 42.9% of osteoarthritis (OA) cases, and 7.27% of gout cases. Calcium hydroxyapatite (HA) crystals were identified in 5.45% of gout cases, 33.3% of rheumatoid arthritis (RA) cases, 57.1% of OA cases, and 63.6% of CPPD cases. Cholesterol and lipid crystals were present in small proportions in RA cases. Glucocorticoid crystals were observed in 1.85% of gout cases, 44.4% of RA cases, and 42.9% of OA cases. We observed an association of MSU identification with clinical suspicion of gout (P = 0.08), CPP with OA (P = 0.26) and CPPD (P = 0.50). An association was noted between HA and the diagnosis of CPPD (P = 0.84) and OA (P > 0.99). The number of initial diagnoses that changed upon SF analysis was 14.3%.

CONCLUSIONS

SF analysis has major diagnostic value regarding MSU crystals and gout. Our findings underscore the importance of SF crystal analysis in identifying the prevalence of crystals in the Mexican population. SF analysis provides for better diagnosis of crystal arthropathies and improves the quality of the medical care that the patient receives. Key Points • Synovial fluid analysis in laboratories from developing countries has been scarce. • In some cases, the initial diagnosis is modified after of synovial fluid analysis. • This study confirmed that synovial fluid analysis exhibits major diagnostic value for urate crystals and gout.

Interleukin-1 Blockade in Polygenic Autoinflammatory Disorders: Where Are We now?

Polygenic autoinflammatory diseases (AIDs), such as systemic juvenile idiopathic arthritis (sJIA), adult-onset Still's disease, Kawasaki disease, idiopathic recurrent pericarditis (IRP), Behçet’s Syndrome, Crystal-induced arthropatihes such as gout or Calcium pyrophosphate deposition disease are characterized by the overexpression of inflammasome-associated genes, leading to a dysregulation of the innate immune response. The IL-1 cytokine family (IL-1α, IL-1β, IL-1Ra, IL-18, IL-36Ra, IL-36α, IL-37, IL-36β, IL-36g, IL-38, IL-33) was defined to be principally responsible for the inflammatory nature of polygenic AIDs. Several clinical trials were initiated, and IL-1 blockade has been proven to cause a rapid reduction of clinical symptoms and normalization of laboratory parameters in the majority of cases. Randomized, placebo-controlled, clinical trials, together with registry-based clinical trials and open-label, retrospective and prospective observational studies, supported the efficacy and safety of IL-1 inhibitors in the treatment of polygenic AIDs. Most of the current data are focused on the therapeutic use of anakinra, an IL-1 receptor antagonist, canakinumab, an anti-IL-1β monoclonal antibody, and rilonacept, a soluble decoy receptor. However, other promising agents, such as gevokizumab, IL-1β blocking monoclonal antibody, tadekinig alfa, a human recombinant IL-18-binding protein, and tranilast, an analog of a tryptophan metabolite, are currently being tested. Anakinra, canakinumab and rilonacept caused impressive improvements in both systemic and musculoskeletal symptoms. Furthermore, the anti-IL-1 therapy allowed corticosteroid tapering and, in some cases, even withdrawal. This article reviews the current IL-1 inhibitors and the results of all clinical trials in which they have been tested for the management of broad spectrum of polygenic AIDs.

Crowned Dens Syndrome Occurring after Endoscopic Submucosal Dissection for Early Gastric Cancer

Crowned dens syndrome (CDS) is a rare form of pseudogout which causes acute neck pain due to calcium pyrophosphate dehydrate deposition surrounding the odontoid process, commonly causing neck pain with rigidity. While invasive procedures such as surgery are known to present a risk of acute pseudogout, reports of occurrence after endoscopic procedures are scarce. We report the case of a 75-year-old man who presented with sudden neck pain after endoscopic submucosal dissection (ESD) for gastric cancer. He could nod but could not rotate his head. Computed tomography showed calcifications surrounding the odontoid process consistent with CDS. Prolonged dietary restrictions and proton pump inhibitor use following the ESD procedure may have caused hypomagnesemia, a precipitating factor for CDS. We prescribed colchicine 1 mg/day and symptoms resolved completely in 3 days. This is the first report of CDS after ESD. CDS should be included in the differential diagnosis of neck pain after endoscopic procedures.

Tophaceous pseudogout in a 12-year-old dog, with a review of applicable laboratory tests

Pseudogout, also known as calcium pyrophosphate dihydrate (CPPD) deposition disease or chondrocalcinosis, is caused by crystalline deposits of CPPD within the extracellular matrix of articular hyaline cartilage and fibrocartilage, and within articular and periarticular connective tissue. Using a variety of laboratory techniques, we diagnosed pseudogout in the right hindlimb digit V of a 12-y-old Standard Poodle. Histologically, the joint, bone, tendon, and dermis were expanded and effaced by masses of mineralized, rhomboid crystals surrounded by macrophages, multinucleate giant cells, fibrous connective tissue, and chondroid and osseous matrix. Rhomboid crystals exhibiting weak-positive birefringence were identified under polarized light using a first-order red compensator filter. Scanning electron microscopy with energy-dispersive x-ray analysis (SEM-EDXA) revealed that the rhomboid crystals were composed of calcium, phosphorus, and oxygen. Fourier-transform infrared (FTIR) microspectroscopy confirmed the presence of calcium pyrophosphate. In dogs, tophaceous pseudogout, which was the variant of pseudogout in our case, occurs as a single, tumor-like periarticular mass that can be invasive and mimic neoplasia. Having ancillary confirmatory testing (SEM-EDXA and FTIR), particularly in unusual histologic scenarios, such as tophaceous pseudogout in dogs, is desirable for confirming the correct diagnosis, even though it is available only at certain reference centers. The pathogenesis of pseudogout is unknown.

Calcium crystal deposition diseases - beyond gout

The most common types of calcium-containing crystals that are associated with joint and periarticular disorders are calcium pyrophosphate dihydrate (CPP) and basic calcium phosphate (BCP) crystals. Several diverse but difficult-to-treat acute and chronic arthropathies and other clinical syndromes are associated with the deposition of these crystals. Although the pathogenic mechanism of calcium crystal deposition is partially understood, much remains to be investigated, as no drug is available to prevent crystal deposition, permit crystal dissolution or specifically target the pathogenic effects that result in the clinical manifestations. In this Review, the main clinical manifestations of CPP and BCP crystal deposition are discussed, along with the biological effects of these crystals, current therapeutic approaches and future directions in therapy.

Acute pseudogout – Measure serum magnesium

We report a 49-year-old woman with an acute swollen left knee due to acute pseudogout with chondrocalcinosis as a presenting feature of Gitelman syndrome due a novel homozygous mutation of the SLC12A3 gene. This report highlights the under-recognized importance of excluding metabolic disease, including Gitelman syndrome, in younger patients whose sole presenting feature may be chondrocalcinosis with or without pseudogout, as this may impact on management and risk of further episodes. We also suggest that chondrocalcinosis and hypomagnesaemia with or without hypokalaemia are diagnostic of Gitelman syndrome.

Clinical Presentation, Management, and Prognosis of Pseudogout in Joint Arthroplasty: A Retrospective Cohort Study

Introduction: Calcium pyrophosphate deposition disease (CPPD), or pseudogout, is rare in prosthetic joints, but can mimic prosthetic joint infection (PJI) according to case reports. The purpose of this case series is to describe the demographics, presentation, management, and outcomes of a cohort of these patients seen at our academic medical center. Methods: Patients with post-implant pseudogout, who were evaluated at our medical center between January 1, 2000 and June 30, 2016, were identified from our EHR. Data pertaining to demographics, presentation, management, and outcomes were abstracted, and patients were categorized into two groups based on presence of concomitant infection along with positive CPDD findings in synovial fluid. Results: 22 patients were included. 90.9% of cases involved a TKA. The most common indication for arthroplasty was degenerative joint disease. Only four patients had a history of previous gout or pseudogout, three of which belonged to the group with no evidence of concomitant joint infection. Clinical features for patients without concomitant infection included pain (100%), swelling at the joint (88.9%), redness (33.3%), fever (22.2%), and decreased range of motion (100%). 45.5% of patients received antibiotics prior to joint aspiration (44.4% of patients with negative synovial fluid cultures, 46.2% of patients with concomitant infection). Conclusion: Our study suggests similar clinical presentation between post-implant pseudogout and PJI. Among patients with pseudogout as well as in those with PJI, the first dose of antibiotics should not be given before sampling for synovial culture. Unfortunately, many patients receive antibiotics prior to culture ascertainment, which raises concern for antibiotic overuse.

Cartilage diseases

Hyaline cartilages, fibrocartilages and elastic cartilages play multiple roles in the human body including bearing loads in articular joints and intervertebral discs, providing joint lubrication, forming the external ears and nose, supporting the trachea, and forming the long bones during development and growth. The structure and organization of cartilage's extracellular matrix (ECM) are the primary determinants of normal function. Most diseases involving cartilage lead to dramatic changes in the ECM which can govern disease progression (e.g., in osteoarthritis), cause the main symptoms of the disease (e.g., dwarfism caused by genetically inherited mutations) or occur as collateral damage in pathological processes occurring in other nearby tissues (e.g., osteochondritis dissecans and inflammatory arthropathies). Challenges associated with cartilage diseases include poor understanding of the etiology and pathogenesis, delayed diagnoses due to the aneural nature of the tissue and drug delivery challenges due to the avascular nature of adult cartilages. This narrative review provides an overview of the clinical and pathological features as well as current treatment options available for various cartilage diseases. Late breaking advances are also described in the quest for development and delivery of effective disease modifying drugs for cartilage diseases including osteoarthritis, the most common form of arthritis that affects hundreds of millions of people worldwide.

Severe calcium pyrophosphate dihydrate deposition disease of the metacarpophalangeal joints

We report a case of calcium pyrophosphate deposition disease (CPPD) with an unusual presentation of severe chondrocalcinosis with atypical large burden deposited in the metacarpophalangeal joints as well as more typical deposition in wrists and knees as demonstrated on plain radiographs. A 77-year-old African-American woman 1-year status post parathyroidectomy for hyperparathyroidism initially presented to the rheumatology clinic to treat suspected rheumatoid arthritis given her pattern of joint involvement but was found to have CPPD. The patient’s history is notable for end-stage renal disease which complicates medical management. This case illustrates radiographic findings of CPPD and explores the challenges of treating CPPD in the setting of comorbid conditions.

Mechanistic immunological based classification of rheumatoid arthritis

The classical autoimmunity paradigm in rheumatoid arthritis (RA) is strongly supported by immunogenetics suggesting follicular helper T-cell responses driving high titre specific autoantibodies that pre-dates disease onset. Using the immunological disease continuum model of inflammation against self with "pure" adaptive and innate immune disease at opposite boundaries, we propose a novel immune mechanistic classification describing the heterogeneity within RA. Mutations or SNPs in autoinflammatory genes including MEFV and NOD2 are linked to seronegative RA phenotypes including some so called palindromic RA cases. However, just as innate and adaptive immunity are closely functionally integrated, some ACPA+ RA cases have superimposed "autoinflammatory" features including abrupt onset attacks, severe attacks, self-limiting attacks, relevant autoinflammatory mutations or SNPs and therapeutic responses to autoinflammatory pathway therapies including colchicine and IL-1 pathway blockade. An emergent feature from this classification that non-destructive RA phenotypes, both innate and adaptive, have disease epicentres situated in the extracapsular tissues. This mixed innate and adaptive immunopathogenesis may be the key to understanding severe disease flares, resistant disease subsets that are unresponsive to standard therapy and for therapies that target the autoinflammatory component of disease that are not currently considered by expert therapeutic recommendations.

Emergent nanotherapies in microcrystal-induced arthritis

The anti-inflammatory and immunomodulatory effects of nanoparticles in several chronic diseases have been extensively researched. The aim of this review is to examine how nanoparticles modulate the inflammatory pathways that characterize the most prevalent forms of microcrystal-induced arthritis, including gout, pseudogout, and BCP-induced arthritis. The nanoparticles of chitosan-coated calcium phosphate, uricase, aceclofenac, and gold have been investigated in crystal-inducedarthritis. The most important results of the studies outlined in this review show that nanoparticles can inhibit the expression and the release of some pro-inflammatory mediators and proteolytic enzymes, and the activity of different transcriptional factors in vitro, as well as decrease the uric acid levels in several studies of in vitro and in vivo models of gout, which show interesting results in terms of decreasing the amount of crystals and tissue damage, respectively. In view of their multiple beneficial effects, nanoparticles can be considered a valuable therapy that contributes to the pharmacological treatment in crystalinduced arthritis.

Pseudogout of the cervical and thoracic spine mimicking infection after lumbar fusion: case report

Pseudogout is a form of acute calcium pyrophosphate deposition (CPPD) disease that typically afflicts the elderly. CPPD commonly involves larger joints, such as the knees, wrists, shoulders, and hips, and has been known to involve the spine. The authors report the case of a 66-year-old woman with a recent history of lumbar laminectomy and fusion who presented 5 weeks postprocedure with a clinical and radiographic picture consistent with multilevel skip lesions involving the cervical and thoracic spine, thoracic discitis, and epidural abscess. Serial blood cultures and repeat biopsy samples were sterile. Subsequent wrist and ankle erythema, pain, and swelling led to synovial fluid analysis, and pseudogout was diagnosed. She was treated with an interleukin-1 inhibitor with immediate symptom relief. To the authors' knowledge, this is only the second report of spinal pseudogout presenting with a clinical and radiographic picture consistent with discitis and epidural abscess. This report is the first to report skip lesions of pseudogout occurring throughout the spine that are uniquely remote from a recent lumbar surgery.

Calcium pyrophosphate deposition disease in the ankle joint: a case report

OBJECTIVE

To detail the presentation of calcium pyrophosphate deposition disease (CPPD) in the ankle joint. The aim of this case report is to inform health-care practitioners about the presentation of this condition in an uncommon location and discuss the diagnosis, potential treatment, and management strategies for a patient with CPPD.

CLINICAL FEATURES

A 36-year-old male patient presented to a chiropractic clinic with an acute, painful, and swollen ankle, which was later diagnosed by plain film radiograph as CPPD. A rheumatology follow-up was recommended and at-home treatment was prescribed to treat acute symptoms and monitor progress.

OUTCOME

No chiropractic treatment was provided and the patient has been referred to a rheumatologist for further assessment. The diagnosis of CPPD was confirmed and he was advised to take an anti-inflammatory if symptoms recurred and booked for further follow-up in six months.

SUMMARY

Although the presentation is less common, CPPD can present in the ankle joint and mimic other inflammatory disorders. Conservative treatment can be applied to treat acute symptoms and referral to a rheumatologist is suggested to monitor progress of this condition.

Bidentate iminodiacetate modified dendrimer for bone imaging

A new dendrimer probe was designed for bone imaging. Bidentate iminodiacetate groups were introduced to the probe to obtain strong bind to bones. The assembled dendrimeric probe, with four iminodiacetate moieties and a fluorescent tag, displayed good selectivity to hydroxyapatite, calcium oxalate and calcium phosphate salts. In mice, the probe offered vivid skeletal details after intravenous delivery.

Calcium Pyrophosphate Dihydrate Deposition Disease in Young Patients: Two Case Reports

Calcium pyrophosphate deposition disease (CPDD) is a type of arthritis caused by the deposition of calcium pyrophosphate crystals, and may present as either acute or chronic arthritis. Development of CPPD crystal deposition disease in young people may be associated with metabolic diseases such as hemochromatosis, hyperparathyroidism, hypomagnesemia, Wilson's disease, hypothyroidism, gout, acromegaly, and X-linked hypophosphatemic rickets. Therefore, investigations for a predisposing metabolic condition are advised in young-onset polyarticular CPPD crystal deposition disease. In this article, we report two young patients who were investigated for recurrent joint pain due to CPPD disease.

Acute calcium pyrophosphate deposition arthropathy

Acute calcium pyrophosphate deposition (CPPD) arthropathy, also called pseudogout, is common, and becomes more prevalent as patients age. The presenting symptoms are similar to both gout and septic arthritis but may be treated differently. This article describes a typical patient presentation and management from an emergency medicine and orthopedic surgery standpoint.

Recurrent Craniocervical Pseudogout: Indications for Surgical Resection, Surveillance Imaging, and Craniocervical Fixation

BACKGROUND

Calcium pyrophosphate dihydrate (CPPD) crystallization is known to occur in the spine, leading to the development of visible calcification as seen by imaging. Occasionally, the deposition of this material can lead to larger accumulations that are seen as masses in the articular processes, intervertebral discs, and posterior longitudinal ligaments. A particularly significant manifestation of this process is at the craniocervical junction, where symptomatic presentations can arise.

CLINICAL PRESENTATION

 A 74-year-old woman presented after several falls from standing, complaining of leg and arm weakness. Imaging revealed a mass arising from the C1-C2 articulation dorsal to the dens, extending to the clivus. The mass compressed the medulla and cervicomedullary junction.

INTERVENTION

The patient underwent a left, far lateral craniotomy with C1 laminectomy to approach the cervicomedullary junction. The mass was cyst-like and contained scattered crystals and amorphous material consistent with pseudogout. There were no cells with an elevated Ki-67 index. The patient's symptoms and exam improved at follow-up two months later. However, seven months after surgery, she declined once again and was found to have a recurrence.

CONCLUSION

A subtotal resection of pseudogout may lead to recurrence. The recurrence can occur in a rapid fashion. Serial MRIs are indicated following resection. Occipitocervical fusion could reduce the likelihood of recurrence in such cases.

From crystalline to amorphous calcium pyrophosphates: A solid state Nuclear Magnetic Resonance perspective

Hydrated calcium pyrophosphates (CPP, Ca2P2O7·nH2O) are a fundamental family of materials among osteoarticular pathologic calcifications. In this contribution, a comprehensive multinuclear NMR (Nuclear Magnetic Resonance) study of four crystalline and two amorphous phases of this family is presented. (1)H, (31)P and (43)Ca MAS (Magic Angle Spinning) NMR spectra were recorded, leading to informative fingerprints characterizing each compound. In particular, different (1)H and (43)Ca solid state NMR signatures were observed for the amorphous phases, depending on the synthetic procedure used. The NMR parameters of the crystalline phases were determined using the GIPAW (Gauge Including Projected Augmented Wave) DFT approach, based on first-principles calculations. In some cases, relaxed structures were found to improve the agreement between experimental and calculated values, demonstrating the importance of proton positions and pyrophosphate local geometry in this particular NMR crystallography approach. Such calculations serve as a basis for the future ab initio modeling of the amorphous CPP phases.

STATEMENT OF SIGNIFICANCE

The general concept of NMR crystallography is applied to the detailed study of calcium pyrophosphates (CPP), whether hydrated or not, and whether crystalline or amorphous. CPP are a fundamental family of materials among osteoarticular pathologic calcifications. Their prevalence increases with age, impacting on 17.5% of the population after the age of 80. They are frequently involved or associated with acute articular arthritis such as pseudogout. Current treatments are mainly directed at relieving the symptoms of joint inflammation but not at inhibiting CPP formation nor at dissolving these crystals. The combination of advanced NMR techniques, modeling and DFT based calculation of NMR parameters allows new original insights in the detailed structural description of this important class of biomaterials.

Comorbidities in patients with crystal diseases and hyperuricemia

Crystal arthropathies are among the most common causes of painful inflammatory arthritis. Gout, the most common example, has been associated with cardiovascular and renal disease. In recent years, evidence for these associations and those involving other comorbidities, such as the metabolic syndrome, have emerged, and the importance of asymptomatic hyperuricemia has been established. In this review, an update on evidence, both experimental and clinical, is presented, and associations between hyperuricemia, gout, and several comorbidities are described. Causality regarding calcium pyrophosphate arthropathy and associated comorbidities is also reviewed.