Full endoscopic surgery for calcium pyrophosphate deposition disease (CPPD) in the cervical ligamentum flavum: report of two cervical myelopathy cases.

Calcium pyrophosphate deposition disease (CPPD), known as pseudogout, is characterized by the accumulation of calcium pyrophosphate crystals in musculoskeletal structures, primarily joints. While CPPD commonly affects various joints, involvement in the cervical spine leading to myelopathy is rare. Surgical intervention becomes necessary when conservative measures fail, but reports on full endoscopic surgeries are extremely rare. We present two successful cases where full endoscopic systems were used for CPPD removal in the cervical spine. The surgical technique involved a full endoscopic approach, adapting the previously reported technique for unilateral laminotomy bilateral decompression. Full-endoscopic removal of cervical CPPD inducing myelopathy were successfully removed with good clinical and radiologic outcomes. The scarcity of endoscopic cases for cervical ligamentum flavum CPPD is attributed to the condition's rarity. However, our successful cases advocate for endoscopic surgery as a potential primary treatment option for CPPD-induced cervical myelopathy, especially in elderly patients or those with previous cervical operation histories. This experience encourages the consideration of endoscopic surgery for managing cervical ligamentum flavum CPPD as a viable alternative.

Describing calcium pyrophosphate deposition: undoing the tower of Babel!

PURPOSE OF REVIEW: In 1977, McCarty astutely observed, 'The variety of names suggested for the condition associated with deposits of calcium pyrophosphate dihydrate crystals is exceeded only by the variations of its clinical presentation'. Fast forward to 2024, a standardized nomenclature for calcium pyrophosphate deposition (CPPD) is still lacking. This review aims to delineate the challenges in characterizing CPPD through nomenclature and imaging. RECENT FINDINGS: Despite the effort of nomenclature standardization in 2011 by the EULAR, confusion persists in the literature and clinical practice, with pseudo-forms and obscure abbreviations. The Gout, Hyperuricemia and Crystal-Associated Disease Network (G-CAN) has launched a project to redefine CPPD nomenclature and formulate a user-friendly language for effective communication with patients and other stakeholders. Additionally, recent advancements in imaging, have shed light on various aspects of the disorder. SUMMARY: Almost 60 years from the first description of a clinical manifestation related to calcium pyrophosphate crystals, a common language describing the disorder is still lacking. A redefined CPPD nomenclature, together with lay-friendly terminology, would significantly contribute to the uniformity of CPPD research, enhance public understanding and awareness and improve doctor-patient communication and therefore disease outcomes. Imaging can provide deep insights into CPPD elements, promoting comprehension of this disorder.

Crystal induced arthropathies-a comparative study of 40 patients with apatite rheumatism, chondrocalcinosis and primary synovial chondromatosis.

Introduction: Apatite rheumatism (AR), chondrocalcinosis (Ch-C), and primary synovial chondromatosis (prSynCh) are regarded as distinct clinical entities. The introduction of the non-staining technique by Bély and Apáthy (2013) opened a new era in the microscopic diagnosis of crystal induced diseases, allowing the analysis of MSU (monosodium urate monohydrate) HA (calcium hydroxyapatite), CPPD (calcium pyrophosphate dihydrate) crystals, cholesterol, crystalline liquid lipid droplets, and other crystals in unstained sections of conventionally proceeded (aqueous formaldehyde fixed, paraffin-embedded) tissue samples. The aim of this study was to describe the characteristic histology of crystal deposits in AR, Ch-C, and prSynCh with traditional stains and histochemical reactions comparing with unstained tissue sections according to Bély and Apáthy (2013). Patients and methods: Tissue samples of 4 with apatite rheumatism (Milwaukee syndrome), 16 with chondrocalcinosis, and 20 with clinically diagnosed primary synovial chondromatosis were analyzed. Results and conclusion: Apatite rheumatism, chondrocalcinosis, and primary synovial chondromatosis are related metabolic disorders with HA and CPPD depositions. The authors assume that AR and Ch-C are different stages of the same metabolic disorder, which differ from prSynCh in amorphous mineral production, furthermore in the production of chondroid, osteoid and/or bone. prSynCh is a defective variant of HA and CPPD induced metabolic disorders with reduced mineralization capabilities, where the deficient mineralization is replaced by chondroid and/or bone formation. The non-staining technique of Bély and Apáthy proved to be a much more effective method for the demonstration of crystals in metabolic diseases than conventional stains and histochemical reactions.

A rare case of intervertebral disc calcification combined with ossification of the posterior longitudinal ligament in a child: a case report and literature review.

BACKGROUND: Intervertebral disc calcification (IDC) combined with calcification in children has been sporadically reported, while ossification of the posterior longitudinal ligament (OPLL) in the cervical spine in pediatric patients is exceedingly rare. The aim of this study is to investigate the potential prognosis and outcomes associated with this condition. CASE PRESENTATION: We present an unusual case involving a 10-year-old Chinese child diagnosed with calcified cervical disc herniation and ossification of the posterior longitudinal ligament. Conservative treatment measures were implemented, and at the 1-month and 6-month follow-up, the patient's pain exhibited significant improvement. Subsequent cervical MRI and CT scans revealed the complete disappearance of OPLL and substantial absorption of the calcified disc. During the three-month follow-up, CT demonstrated slight residual disc calcification, however, the patient remained asymptomatic with no discernible limitation in cervical motion. CONCLUSIONS: We conducted a comprehensive review of several cases presenting with the same diagnosis. It is noteworthy that IDC combined with OPLL in children constitutes a rare clinical entity. Despite imaging indications of potential spinal canal occupation, the majority of such cases demonstrate complete absorption following conservative treatment, with OPLL exhibiting a faster absorption rate than calcified discs.

A new perspective on intervertebral disc calcification-from bench to bedside.

Disc degeneration primarily contributes to chronic low back and neck pain. Consequently, there is an urgent need to understand the spectrum of disc degeneration phenotypes such as fibrosis, ectopic calcification, herniation, or mixed phenotypes. Amongst these phenotypes, disc calcification is the least studied. Ectopic calcification, by definition, is the pathological mineralization of soft tissues, widely studied in the context of conditions that afflict vasculature, skin, and cartilage. Clinically, disc calcification is associated with poor surgical outcomes and back pain refractory to conservative treatment. It is frequently seen as a consequence of disc aging and progressive degeneration but exhibits unique molecular and morphological characteristics: hypertrophic chondrocyte-like cell differentiation; TNAP, ENPP1, and ANK upregulation; cell death; altered Pi and PPi homeostasis; and local inflammation. Recent studies in mouse models have provided a better understanding of the mechanisms underlying this phenotype. It is essential to recognize that the presentation and nature of mineralization differ between AF, NP, and EP compartments. Moreover, the combination of anatomic location, genetics, and environmental stressors, such as aging or trauma, govern the predisposition to calcification. Lastly, the systemic regulation of calcium and Pi metabolism is less important than the local activity of PPi modulated by the ANK-ENPP1 axis, along with disc cell death and differentiation status. While there is limited understanding of this phenotype, understanding the molecular pathways governing local intervertebral disc calcification may lead to developing disease-modifying drugs and better clinical management of degeneration-related pathologies.

Calcified Chondroid Mesenchymal Neoplasms.

Calcified chondroid mesenchymal neoplasms (CCMN) represent a morphologic spectrum of related tumors. Historically, chondroid matrix or chondroblastoma-like features have been described in soft tissue chondroma, tenosynovial giant cell tumors (especially of the temporomandibular joint (TMJ) region), and in a subset of tophaceous pseudogout. Recently, these tumors have been found to share FN1-receptor tyrosine kinase (RTK) fusions. This review discusses the clinical, morphologic, immunohistochemical, and molecular genetic features of CCMN. The distinction from morphologic mimics is also discussed.

Ultrasound reveals a high prevalence of CPPD in consecutive patients with knee pain.

The objective of this study is to estimate the prevalence of US findings indicative of calcium pyrophosphate deposition (CPPD) in patients with knee pain. Consecutive patients with knee pain, equally distributed among males and females in seven different age-decades (21-90 years), were enrolled in a cross-sectional study. The presence of US OMERACT-defined CPPD (medial and lateral menisci and femoral hyaline cartilage) and osteophytes (medial and lateral compartments of the tibiofemoral joint) was scored as presence/absence in both knees. Four hundred twenty participants were enrolled (210 men/210 women). Fibrocartilage and hyaline cartilage CPPDs were detected by US in 94/420 (22.4%) and 41/420 (9.8%) participants, respectively. No significant sex differences were noted. The prevalence and the extent of CPPD increased with age. Fibrocartilage and hyaline cartilage CPPDs were identified in 0/60 participants in the third decade, and in 28/60 (46.7%) and 14/60 (23.3%) participants in the ninth decade, respectively (p for trend < 0.01). While fibrocartilage and hyaline cartilage CPPD is virtually absent in subjects younger than 40 and 50 years old, their prevalence steeply increases above from these age groups. Age (aIRR, 1.03; 95% CI, 1.02-1.05), osteophyte score (aIRR, 1.40; 95% CI, 1.22-1.60), and hyaline cartilage CPPD score (aIRR, 2.68; 95% CI, 2.06-3.49) were associated with fibrocartilage CPPD score, whereas age (aIRR, 1.02; 95% CI, 1.01-1.05) and fibrocartilage CPPD score (aIRR, 2.92; 95% CI, 2.29-3.72) were associated with hyaline cartilage CPPD score in multivariable negative binomial regression analyses. In conclusion, we report the US prevalence of CPPD in patients with knee pain. Fibrocartilage CPPD occurs at a younger age and is more prevalent than hyaline cartilage CPPD. Key points • Fibrocartilage CPPD occurs at a younger age and is more prevalent than hyaline cartilage CPPD. • Fibrocartilage and hyaline cartilage CPPDs are virtually absent in subjects younger than 40 and 50 years old. • In subjects older than 80 years, fibrocartilage and hyaline cartilage CPPD prevalence rises up to 46.7% and 23.3%, respectively.

Acute calcium pyrophosphate crystal arthritis is associated with an increased rate of hip and knee joint surgery.

OBJECTIVE: Acute calcium pyrophosphate (CPP) crystal arthritis is a distinct manifestation of calcium pyrophosphate crystal deposition (CPPD). No studies have specifically examined whether acute CPP crystal arthritis is associated with progressive structural joint damage. The objective of this retrospective cohort study was to evaluate the relative rate of hip and knee joint arthroplasties as an estimate of structural joint damage accrual, in a population of patients with acute CPP crystal arthritis. METHODS: Data were collected from Waikato District Health Board (WDHB) to identify an acute CPP crystal arthritis cohort with clinical episodes highly characteristic of acute CPP crystal arthritis. Data on hip and knee joint arthroplasties were collected from the New Zealand Orthopaedic Association's Joint Registry. The rate of arthroplasties in the cohort was compared with the age-ethnicity-matched New Zealand population. Additional analysis was performed for age, obesity (BMI) and ethnicity. RESULTS: The acute CPP crystal arthritis cohort included 99 patients; 63 were male and the median age was 77 years (interquartile range, 71-82). The obesity rate was 36% with a median BMI of 28.4 kg/m2 (interquartile range, 25.8-32.2), comparable to the New Zealand population. The standardized surgical rate ratio in the cohort vs the age-ethnicity-matched New Zealand population was 2.54 (95% CI: 1.39, 4.27). CONCLUSION: Our study identified a considerable increase in the rate of hip and knee joint arthroplasties in patients with episodes of acute CPP crystal arthritis. This suggests CPP crystal arthritis may be a chronic condition, leading to progressive joint damage.

Acute monoarticular hip joint pseudogout masquerading as septic arthritis.

Monoarticular pseudogout of the hip joint is rare and to the best of our knowledge only four other cases exist in the literature. We present a case of primary monoarticular pseudogout affecting the right hip in a patient in his 50s. The diagnosis was confirmed through ultrasound-guided synovial fluid aspiration and crystal analysis. The patient was treated conservatively with analgesia and after hip joint aspiration resulted in dramatic symptomatic resolution. Acute attack of pseudogout is a rare cause of acute hip pain. The clinical features may mimic hip joint septic arthritis and should be considered in the differential diagnosis of any presentation of acute joint pain. Diagnosis is important to avoid unnecessary medical and surgical intervention reducing hospital stay.

Lateral meniscus with tears or with histologic calcification does not increase the risk of lateral osteoarthritis after medial unicompartmental arthroplasty.

PURPOSE: Meniscal tears or histological meniscal calcifications (in the absence of radiological chondrocalcinosis) are frequent in osteoarthritis. Whether lateral meniscal lesions influence clinical outcomes after medial unicompartmental knee arthroplasty (UKA) is unknown. METHODS: We analyzed 130 patients (130 knees) with medial unicompartmental knee arthroplasties between 2005 and 2015. These 130 knees had full articular cartilage thickness in the lateral compartment and no radiological chondrocalcinosis on preoperative radiographs. The lateral meniscus was analyzed with preoperative MRI and a biopsy of the anterior horn at the time of surgery. Synovial fluid was collected and analyzed for calcium pyrophosphate dihydrate crystal deposition (CPPD crystals). Lateral meniscal tears were untreated when detected on MRI or during surgery, with the hypothesis that these tears on the opposite compartment would remain asymptomatic in medial UKA. At average 10-year follow-up, patients were evaluated with clinical and radiographic outcome, with a focus on the risk of joint space narrowing of the lateral femorotibial compartment. RESULTS: CPPD crystals were present in the synovial fluid of 70 knees. Lateral meniscal tears were seen on MRI in 34 (49%) normal meniscuses of the 60 knees without CPPD crystals and in six other knees without histological meniscal calcification despite CPPD crystals. Histological calcification was present on 61 lateral meniscuses with 53 meniscal tears. The results showed no significant differences in the clinical outcomes between knees with lateral meniscal tears or lateral meniscal histological chondrocalcinosis or both lesions and those without these conditions. Additionally, radiographic progression of osteoarthritis in the opposite femorotibial compartment of the knee was not more frequent in patients with these meniscal issues. The ten year cumulative survival rates, measured by the need for total knee arthroplasty, were 91% for knees without meniscal lesions and 92% for knees with these lesions. CONCLUSION: On this basis, treatment of meniscal tears of the lateral compartment and routine aspiration of the knee to assess for birefringent crystals in the planning of medial UKA do not appear necessary.

The 2023 ACR/EULAR Classification Criteria for Calcium Pyrophosphate Deposition Disease.

OBJECTIVE: Calcium pyrophosphate deposition (CPPD) disease is prevalent and has diverse presentations, but there are no validated classification criteria for this symptomatic arthritis. The American College of Rheumatology (ACR) and EULAR have developed the first-ever validated classification criteria for symptomatic CPPD disease. METHODS: Supported by the ACR and EULAR, a multinational group of investigators followed established methodology to develop these disease classification criteria. The group generated lists of candidate items and refined their definitions, collected de-identified patient profiles, evaluated strengths of associations between candidate items and CPPD disease, developed a classification criteria framework, and used multi-criterion decision analysis to define criteria weights and a classification threshold score. The criteria were validated in an independent cohort. RESULTS: Among patients with joint pain, swelling, or tenderness (entry criterion) whose symptoms are not fully explained by an alternative disease (exclusion criterion), the presence of crowned dens syndrome or calcium pyrophosphate crystals in synovial fluid are sufficient to classify a patient as having CPPD disease. In the absence of these findings, a score >56 points using weighted criteria, comprising clinical features, associated metabolic disorders, and results of laboratory and imaging investigations, can be used to classify as CPPD disease. These criteria had a sensitivity of 92.2% and specificity of 87.9% in the derivation cohort (190 CPPD cases, 148 mimickers), whereas sensitivity was 99.2% and specificity was 92.5% in the validation cohort (251 CPPD cases, 162 mimickers). CONCLUSION: The 2023 ACR/EULAR CPPD disease classification criteria have excellent performance characteristics and will facilitate research in this field.

The 2023 ACR/EULAR classification criteria for calcium pyrophosphate deposition disease.

OBJECTIVE: Calcium pyrophosphate deposition (CPPD) disease is prevalent and has diverse presentations, but there are no validated classification criteria for this symptomatic arthritis. The American College of Rheumatology (ACR) and EULAR have developed the first-ever validated classification criteria for symptomatic CPPD disease. METHODS: Supported by the ACR and EULAR, a multinational group of investigators followed established methodology to develop these disease classification criteria. The group generated lists of candidate items and refined their definitions, collected de-identified patient profiles, evaluated strengths of associations between candidate items and CPPD disease, developed a classification criteria framework, and used multi-criterion decision analysis to define criteria weights and a classification threshold score. The criteria were validated in an independent cohort. RESULTS: Among patients with joint pain, swelling, or tenderness (entry criterion) whose symptoms are not fully explained by an alternative disease (exclusion criterion), the presence of crowned dens syndrome or calcium pyrophosphate crystals in synovial fluid are sufficient to classify a patient as having CPPD disease. In the absence of these findings, a score>56 points using weighted criteria, comprising clinical features, associated metabolic disorders, and results of laboratory and imaging investigations, can be used to classify as CPPD disease. These criteria had a sensitivity of 92.2% and specificity of 87.9% in the derivation cohort (190 CPPD cases, 148 mimickers), whereas sensitivity was 99.2% and specificity was 92.5% in the validation cohort (251 CPPD cases, 162 mimickers). CONCLUSION: The 2023 ACR/EULAR CPPD disease classification criteria have excellent performance characteristics and will facilitate research in this field.

Crowned dens syndrome: A rare form of acute neck pain and headache that can be misdiagnosed or missed.

Crowned dens syndrome (CDS) occurs due to the deposition of calcium pyrophosphate (CPP) in the ligament tissue around the odontoid process of the axis. CDS is characterized by acute neck pain, stiffness, fever, and elevated inflammatory markers. It is a rare cause of neck pain among older people. We report a 71-year-old female patient who presented with acute neck pain, headache, with dizziness. Body temperature showed normal, with elevated C-reactive protein and ESR in the blood. Over the past 5 years, the patient has experienced neck and head pain several times.MRI of the head and CT scan of the neck showed calcification of the transverse atlantoaxial and cruciate ligament in combination with mild compression of the medulla oblongata. The patient was given non-steroidal anti-inflammatory drugs (NSAIDs) and colchicine for 10 days, with significant symptom improvement and no recurrence at 10 months of follow-up.

Patient-Reported Outcomes in Calcium Pyrophosphate Deposition Disease Compared to Gout and Osteoarthritis.

OBJECTIVE: Calcium pyrophosphate deposition (CPPD) disease prevalence is similar to that of gout and osteoarthritis (OA), yet CPPD outcomes research greatly lags behind research in these other forms of arthritis. We compared validated patient-reported outcome measures in patients with CPPD vs gout and OA. METHODS: Patients with CPPD were recruited from Brigham and Women's Hospital from 2018 to 2022. Presence of CPPD manifestations (acute calcium pyrophosphate [CPP] crystal arthritis, chronic CPP inflammatory arthritis, and/or OA with CPPD) was confirmed by medical record review. Baseline surveys included the Gout Assessment Questionnaire version 2.0, modified to ask about "pseudogout" rather than "gout"; Routine Assessment of Patient Index Data 3 (RAPID-3); and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). We compared responses in patients with CPPD against published gout and OA cohort studies. RESULTS: Among 47 patients with CPPD, the mean age was 71.9 years and 51% were female. Sixty-eight percent had at least 1 episode of acute CPP crystal arthritis, 40% had chronic CPP inflammatory arthritis, and 62% had OA with CPPD. Pain visual analog scale scores during a flare were similar in CPPD (mean 6.8 [SD 1.9]) and gout (mean 6.7 [SD 2.6]; P = 0.78). Patients with CPPD reported significantly greater unmet treatment need than patients with gout (P = 0.04). RAPID-3 scores in CPPD (mean 8.1 [SD 5.6]) were lower than in gout (mean 12.1 [SD 6.2]; P < 0.01) and similar in OA (mean 6.8 [SD 6.1]; P = 0.30). Patients with CPPD had significantly worse WOMAC stiffness scores than patients with mild OA, and significantly better WOMAC function scores than patients with severe OA. CONCLUSION: Patients with CPPD may experience pain comparable to that in gout and OA and reported substantial unmet treatment needs.

Dynamic assessment of the double contour sign by ultrasonography helps to distinguish between gout and calcium pyrophosphate deposition disease.

OBJECTIVE: To test whether the double contour (DC) sign has a different dynamic behaviour in gout and calcium pyrophosphate deposition (CPPD) and whether the dynamic assessment of the DC sign increases its accuracy in gout diagnosis. METHODS: This cross-sectional analysis included patients with gout meeting the 2015 ACR/EULAR classification criteria and patients with crystal-proven diagnosis of CPPD. Hyaline cartilages were explored by ultrasound (US) to detect the DC sign (ie, abnormal hyperechoic band over the superficial margin of hyaline cartilages) and its dynamic behaviour during joint movement was evaluated ((ie, movement of the DC sign together with subchondral bone (DC sign), or in the opposite direction (pseudo DC sign)). RESULTS: Eighty-one patients with gout and 84 patients with CPPD underwent US assessment. Among them, 47 patients with gout and 9 patients with CPPD had evidence of the DC sign. During dynamic assessment, in all 47/47 patients with gout there was a DC sign. Conversely, in 7/9 (77.8%) patients with CPPD, there was a pseudo DC sign (p<0.01).The presence of DC sign during static assessment had a sensitivity, specificity and accuracy of 58.0% (95% CI 46.5% to 68.9%), 89.3% (95% CI 80.6% to 95.0%) and 73.9% (95% CI 66.5% to 80.5%) for gout, respectively. The dynamic evaluation improved the DC sign's diagnostic performance (p=0.01) as the specificity (97.6% (95% CI 91.7% to 99.7%)) and the accuracy (78.2% (95% CI 71.1% to 84.2%)) increased without loss in sensitivity. CONCLUSION: The dynamic US assessment of the DC sign may help to differentiate the DC sign due to MSU crystals from the pseudo DC sign seen in CPPD, as they move in opposite directions.

How can ultrasonography help in the management of CPPD? From diagnosis to clinical subset identification.

PURPOSE OF REVIEW: Clinical manifestations of calcium pyrophosphate deposition (CPPD) disease are quite heterogeneous, ranging from asymptomatic presentation to severe forms of arthritis. In recent years, imaging, particularly ultrasound (US) has gained a central role for the diagnosis of CPPD. However, many questions are still open. Aim of this review is to present how US could be a key tool in the diagnosis and assessment of CPPD and for the identification of subsets of the disease. RECENT FINDINGS: awareness and research interest around CPPD is increasing in the recent years, as several international taskforces are working on the validation of outcome measures and classification criteria for CPPD, but many pieces of the puzzle are still missing. Recent studies demonstrated that CPPD is an underdiagnosed disease, frequently misdiagnosed as rheumatoid arthritis or polymyalgia rheumatica. US has been increasingly used in the past decade for the diagnosis of CPPD and US definitions have been validated by the OMERACT US working group in the recent years, making of US a valuable tool for diagnosis. SUMMARY: The most challenging aspects of CPPD are the differential diagnosis with other form of arthritis of the elderly, and the classification of patients in clinical subsets. In this review, we will present the available data for the use of US in the diagnosis of CPPD and we will provide a mainly experienced-based approach to the potential role of the technique in differential diagnosis and phenotypization of patients.

Cardiovascular Disease Risk in Calcium Pyrophosphate Deposition Disease: A Nationwide Study of Veterans.

OBJECTIVE: Calcium pyrophosphate deposition (CPPD) disease represents a common crystalline arthritis with a range of manifestations. Our goal was to investigate risks for cardiovascular events in patients with CPPD. METHODS: We performed a retrospective matched cohort analysis in the Veterans Health Administration Corporate Data Warehouse, 2010-2014. CPPD was defined by ≥1 International Classification of Diseases, Ninth Revision codes for chondrocalcinosis or calcium metabolism disorder. CPPD patients were age- and sex-matched to approximately 4 patients without codes for CPPD; we excluded patients with a cardiovascular event during the 365 days prior to the index date. Demographic information, traditional cardiovascular risk factors, medications, and health care utilization were assessed at baseline. The primary outcome was a major adverse cardiovascular event (MACE: myocardial infarction, acute coronary syndrome, coronary revascularization, stroke, or death). Secondary outcomes included individual components of MACE. Cox proportional hazards models estimated fully adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs). RESULTS: We identified 23,124 CPPD patients matched to 86,629 non-CPPD patients with >250,000 person-years of follow-up. The study population was 96% male, mean age was 78 years, and 75% were White. The frequency of traditional cardiovascular risk factors was similar between the 2 cohorts. CPPD was not significantly associated with risk for MACE (HR 0.98 [95% CI 0.94-1.02]) in fully adjusted models, though risks of myocardial infarction, acute coronary syndrome, and stroke were significantly higher in the CPPD cohort compared to the non-CPPD cohort. CONCLUSION: CPPD did not confer an increased risk for MACE, a composite end point including all-cause mortality. Our results propose CPPD as a novel risk factor for MACE components, including myocardial infarction, acute coronary syndrome, and stroke.

Imaging Features of Calcium Pyrophosphate Deposition Disease: Consensus Definitions From an International Multidisciplinary Working Group.

OBJECTIVE: To develop definitions for imaging features being considered as potential classification criteria for calcium pyrophosphate deposition (CPPD) disease, additional to clinical and laboratory criteria, and to compile example images of CPPD on different imaging modalities. METHODS: The American College of Rheumatology and European Alliance of Associations for Rheumatology CPPD classification criteria Imaging Advisory Group (IAG) and Steering Committee drafted definitions of imaging features that are characteristic of CPPD on conventional radiography (CR), conventional computed tomography (CT), dual-energy CT (DECT), and magnetic resonance imaging (MRI). An anonymous expert survey was undertaken by a 35-member Combined Expert Committee, including all IAG members. The IAG and 5 external musculoskeletal radiologists with expertise in CPPD convened virtually to further refine item definitions and voted on example images illustrating CR, CT, and DECT item definitions, with ≥90% agreement required to deem them acceptable. RESULTS: The Combined Expert Committee survey indicated consensus on all CR definitions. The IAG and external radiologists reached consensus on CT and DECT item definitions, which specify that calcium pyrophosphate deposits appear less dense than cortical bone. The group developed an MRI definition and acknowledged limitations of this modality for CPPD. Ten example images for CPPD were voted acceptable (4 CR, 4 CT, and 2 DECT), and 3 images of basic calcium phosphate deposition were voted acceptable to serve as contrast against imaging features of CPPD. CONCLUSION: An international group of rheumatologists and musculoskeletal radiologists defined imaging features characteristic of CPPD on CR, CT, and DECT and assembled a set of example images as a reference for future clinical research studies.