UK community prevalence of knee chondrocalcinosis: evidence that correlation with osteoarthritis is through a shared association with osteophyte

Calcium Pyrophosphate Crystal Formation and Deposition: Where Do we Stand and What Does the Future hold?

PURPOSE OF THE REVIEW

Although calcium pyrophosphate deposition (CPPD) has been known since the 1960s, our understanding of its pathogenesis remains rudimentary. This review aims to illustrate the known mechanisms underlying calcium pyrophosphate (CPP) crystal formation and deposition and explore future directions in research. By examining various perspectives, from basic research to clinical and imaging assessments, as well as new emerging methodologies, we can establish a starting point for a deeper understanding of CPPD pathogenesis.

RECENT FINDINGS

Recent years have seen significant advances in CPPD research, particularly in the clinical field with the development of the 2023 ACR/EULAR classification criteria for CPPD disease, and in imaging with the introduction of the OMERACT ultrasonographic definitions and scoring system. However, progress in basic research has been slower. New laboratory approaches, such as Raman spectroscopy and omics sciences, offer promising insights that may help piece together the puzzle of CPPD. CPPD is a common yet understudied condition. As the population ages and CPPD becomes more prevalent, there is an urgent need to better understand the disease and the mechanisms involved in crystal formation and deposition, in order to improve diagnosis and therapeutic approaches.

Dual-Energy Computed Tomography Applications in Rheumatology

Dual-energy computed tomography (DECT) has emerged as a transformative tool in the past decade. Initially employed in gout within the field of rheumatology to distinguish and quantify monosodium urate crystals through its dual-material discrimination capability, DECT has since broadened its clinical applications. It now encompasses various rheumatic diseases, employing advanced techniques such as bone marrow edema assessment, iodine mapping, and collagen-specific imaging. This review article aims to examine the unique characteristics of DECT, discuss its strengths and limitations, illustrate its applications for accurately evaluating various rheumatic diseases in clinical practice, and propose future directions for DECT in rheumatology.

Calcium pyrophosphate deposition disease

Calcium pyrophosphate deposition (CPPD) disease is a consequence of the immune response to the pathological presence of calcium pyrophosphate (CPP) crystals inside joints, which causes acute or chronic inflammatory arthritis. CPPD is strongly associated with cartilage degradation and osteoarthritis, although the direction of causality is unclear. This clinical presentation is called CPPD with osteoarthritis. Although direct evidence is scarce, CPPD disease might be the most common cause of inflammatory arthritis in older people (aged >60 years). CPPD is caused by elevated extracellular-pyrophosphate concentrations in the cartilage and causes inflammation by activation of the NLRP3 inflammasome. Common risk factors for CPPD disease include ageing and previous joint injury. It is uncommonly associated with metabolic conditions (eg, hyperparathyroidism, haemochromatosis, hypomagnesaemia, and hypophosphatasia) and genetic variants (eg, in the ANKH and osteoprotegerin genes). Apart from the detection of CPP crystals in synovial fluid, imaging evidence of CPPD in joints by mainly conventional radiography, and increasingly ultrasonography, has a central role in the diagnosis of CPPD disease. CT is useful in showing calcification in axial joints such as in patients with crowned dens syndrome. To date, no treatment is effective in dissolving CPP crystals, which explains why control of inflammation is currently the main focus of therapeutic strategies. Prednisone might provide the best benefit-risk ratio for the treatment of acute CPP-crystal arthritis, but low-dose colchicine is also effective with a risk of mild diarrhoea. Limited evidence suggests that colchicine, low-dose weekly methotrexate, and hydroxychloroquine might be effective in the prophylaxis of recurrent flares and in the management of persistent CPP-crystal inflammatory arthritis. Additionally, biologics inhibiting IL-1 and IL-6 might have a role in the management of refractory disease.

Synovial Membrane Is a Major Producer of Extracellular Inorganic Pyrophosphate in Response to Hypoxia

Calcium pyrophosphate dehydrate (CPPD) crystals are found in the synovial fluid of patients with articular chondrocalcinosis or sometimes with osteoarthritis. In inflammatory conditions, the synovial membrane (SM) is subjected to transient hypoxia, especially during movement. CPPD formation is supported by an increase in extracellular inorganic pyrophosphate (ePPi) levels, which are mainly controlled by the transporter Ank and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). We demonstrated previously that transforming growth factor (TGF)-β1 increased ePPi production by inducing Ank and Enpp1 expression in chondrocytes. As the TGF-β1 level raises in synovial fluid under hypoxic conditions, we investigated whether hypoxia may transform SM as a major source of ePPi production. Synovial fibroblasts and SM explants were exposed to 10 ng/mL of TGF-β1 in normoxic or hypoxic (5% O2) culture conditions. Ank and Enpp1 expression were assessed by quantitative PCR, Western blot and immunohistochemistry. ePPi was quantified in culture supernatants. RNA silencing was used to define the respective roles of Ank and Enpp1 in TGF-β1-induced ePPi generation. The molecular mechanisms involved in hypoxia were investigated using an Ank promoter reporter plasmid for transactivation studies, as well as gene overexpression and RNA silencing, the respective role of hypoxia-induced factor (HIF)-1 and HIF-2. Our results showed that TGF-β1 increased Ank, Enpp1, and therefore ePPi production in synovial fibroblasts and SM explants. Ank was the major contributor in ePPi production compared to ENPP1. Hypoxia increased ePPi levels on its own and enhanced the stimulating effect of TGF-β1. Hypoxic conditions enhanced Ank promoter transactivation in an HIF-1-dependent/HIF-2-independent fashion. We demonstrated that under hypoxia, SM is an important contributor to ePPi production in the joint through the induction of Enpp1 and Ank. These findings are of interest as a rationale for the beneficial effect of anti-inflammatory drugs on SM in crystal depositions.

2023 EULAR recommendations on imaging in diagnosis and management of crystal-induced arthropathies in clinical practice

OBJECTIVE

To formulate evidence-based recommendations and overarching principles on the use of imaging in the clinical management of crystal-induced arthropathies (CiAs).

METHODS

An international task force of 25 rheumatologists, radiologists, methodologists, healthcare professionals and patient research partners from 11 countries was formed according to the EULAR standard operating procedures. Fourteen key questions on the role of imaging in the most common forms of CiA were generated. The CiA assessed included gout, calcium pyrophosphate deposition disease and basic calcium phosphate deposition disease. Imaging modalities included conventional radiography, ultrasound, CT and MRI. Experts applied research evidence obtained from four systematic literature reviews using MEDLINE, EMBASE and CENTRAL. Task force members provided level of agreement (LoA) anonymously by using a Numerical Rating Scale from 0 to 10.

RESULTS

Five overarching principles and 10 recommendations were developed encompassing the role of imaging in various aspects of patient management: making a diagnosis of CiA, monitoring inflammation and damage, predicting outcome, response to treatment, guided interventions and patient education. Overall, the LoA for the recommendations was high (8.46-9.92).

CONCLUSIONS

These are the first recommendations that encompass the major forms of CiA and guide the use of common imaging modalities in this disease group in clinical practice.

[First classification criteria for diseases caused by calcium pyrophosphate deposition (CPPD)-Translation, explanation and assessment]

AIM

For diseases caused by calcium pyrophosphate deposition (CPPD), validated classification criteria were previously lacking. In this article the recently developed and validated classification criteria are translated, explained, and assessed.

METHODS

In recent years a multinational research group developed classification criteria for CPPD disease with the support by the European Alliance of Associations for Rheumatology (EULAR) and the American College of Rheumatology (ACR), following an established method. The developed criteria were finally validated in an independent cohort. The translation and annotation of the new first classification criteria were carried out in an iterative procedure in consensus with the authors.

RESULTS

The presence of a crowned dens syndrome or calcium pyrophosphate crystals in the synovial fluid in patients with pain, swelling or sensitivity of the joints (entry criterion) is sufficient for the classification as CPPD disease, where the symptoms cannot be completely explained by another rheumatic disease (exclusion criterion). If these symptoms are not present, a count of more than 56 points based on weighted criteria comprised of clinical features and the results of laboratory and imaging investigations can be included for classification as a CPPD disease. These criteria had a sensitivity of 92.2% and a specificity of 87.9% in the derivation cohorts (190 CPPD cases and 148 mimics), whereas the sensitivity was 99.2% and the specificity 92.5% in the validation cohorts (251 CPPD cases and 162 mimics).

CONCLUSION

The ACR/EULAR classification criteria 2023 of a CPPD disease will facilitate clinical research in this field. The use in the clinical routine will show how practical the criteria are.

Calcium pyrophosphate deposition disease: historical overview and potential gaps

CPPD disease can affect patients’ quality of life through its various clinical presentations. This mini-review discusses the evolution of CPPD from its discovery to current knowledge of its pathogenesis, genetic associations, diagnostics, and treatment options. Despite extensive research, the exact mechanisms of CPPD are not well understood, and there is a notable lack of knowledge about psychosocial impacts and patient experiences. This study aims to present a CPPD Disease Timeline identifying gaps in current knowledge and potential directions for future research. These findings contribute to a broader understanding of CPPD disease and emphasize the importance of continued research and innovation in this field.

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.

Pitfalls and pearls in diagnosing inflammatory arthritis in older patients

Given current demographic shifts, the number of older adults continues to grow, with almost half of patients over 65 being diagnosed with some form of arthritis. Rheumatic diseases pose unique diagnostic challenges in older patients due to the convergence of physiologic changes of aging, confounding difficulties to care, and atypical disease manifestations. This review summarizes the current published evidence to guide clinicians in evaluating geriatric patients with rheumatologic concerns, focusing on inflammatory arthritis. Using the background of epidemiologic data on various musculoskeletal diseases, clinical presentations, current diagnostic tests, and known physiologic changes of aging, this review highlights five diagnostic pitfalls in inflammatory polyarthritis among older patients. The pitfalls include: 1) broader differential diagnosis; 2) atypical presentations; 3) communication, cognitive, and social impairments; 4) the role of chronological vs. biological age; and 5) anchoring bias by assuming older adults are simply "older young adults". These pitfalls are discussed in the context of geriatric principles such as the "hallmarks of aging" and the expected pathophysiologic changes of organ systems. Furthermore, the review discusses the strengths and weaknesses of diagnostic tests used in arthritis and introduces some of the geriatric assessment tools that systematically evaluate multimorbidity and geriatric syndromes. With familiarity of the potential diagnostic pitfalls, knowledge of both normal and pathologic aging processes, awareness of the difference between biological and chronological age, and the ability to use geriatric assessment tools to better characterize older patients, clinicians will be better able to diagnose and manage rheumatic conditions in this population.

Anakinra for Refractory Pseudogout in Patients with End-stage Renal Disease on Haemodialysis

Calcium pyrophosphate deposition (CPPD) arthritis is the second most common type of crystal-induced arthritis after gout. Acute flares are commonly treated with non-steroidal anti-inflammatory drugs, intra-articular or short-term systemic glucocorticoids or colchicine. However, since there is no pharmacological treatment to reduce CPPD crystal burden, relapsing or chronic CPPD arthritis may be challenging to treat, particularly in patients with end-stage renal disease who are at risk for toxicity of the above medications. Since IL-1β appears to be driving CPPD arthritis, we treated two patients with chronic CPPD arthritis and end-stage renal disease on haemodialysis with the IL-1β receptor antagonist anakinra. In both patients, arthritis resolved quickly, while continuation of anakinra maintained remission and allowed complete glucocorticoid withdrawal. Therefore, anakinra may be a safe and effective option both for short and long-term treatment of CPPD arthritis in patients on chronic renal replacement therapy.

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.

Outcomes of total hip arthroplasty in calcium pyrophosphate deposition disease patients

OBJECTIVE

We aim to examine the demographics, clinical characteristics, outcomes, and resource utilization following total hip arthroplasty (THA) in patients with and without calcium pyrophosphate deposition (CPPD) disease.

METHODS

We queried the National Inpatient Sample database to identify patients who underwent THA between 2006 and 2014. The ICD-9 code 81.51 was used to determine the patients who underwent THA, and of those, we classified 2 groups of patients: (i) those with ICD-9 codes defining CPPD and (ii) those without any CPPD code. Data collection included patient demographics and comorbidities. Outcomes post-THA were mortality, length of stay (LOS), and costs. Associations between CPPD and specific morbidity were evaluated with chi-square tests. T tests were used for continuous variables.

RESULTS

Among the 4,111,808 patients who underwent THA, 6198 (0.15 %) had CPPD, with a mean age of 77 years and 64.2 % were females. CPPD patients were more likely to be older (mean age 77 vs 72.7 years; p<0.001) than non-CPPD patients. The Charlson Comorbidity Index score ≥ 2 was more frequently seen in CPPD, however, the mortality post-THA was lower in the CPPD patients (0.7 % vs 1.7 %, OR 0.35, 95 % CI 0.26- 0.47). THA in CPPD patients was associated with a longer mean length of stay (LOS) (6.04 vs 5.15 days, OR 1.15, 95 % CI 1.09-1.22) while mean total charges were not statistically different between the 2 groups (p = 0.344). CPPD patients were more likely to be discharged to rehabilitation or other nursing facilities (42.5 % vs 35.3 %, p<0.001). The number of THA procedures increased in both CPPD and non-CPPD patients over time.

CONCLUSIONS

CPPD patients who underwent THA were more likely to be older, with a greater comorbidity burden, longer LOS and discharged to a non-home setting.

Crystal arthropathies and osteoarthritis-where is the link?

Osteoarthritis (OA) is one of the leading causes of disability worldwide. As our understanding of OA progressively has moved from a purely mechanical "wear and tear" concept toward a complex multi-tissue condition in which inflammation plays a central role, the possible role of crystal-induced inflammation in OA incidence and progression may be relevant. In addition to gout, which affects 4% of the US population, basic calcium phosphate and calcium pyrophosphate deposition both may induce joint inflammation and may play a role in pain in OA. This narrative review article discusses the possible mechanisms underlying the associations between crystal-induced arthropathies and OA, and the important implications of these for clinical practice and future research.

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.

Compressive cervical myelopathy due to calcium pyrophosphate dihydrate deposition in ligamentum flavum: A case report and review of literature

INTRODUCTION

Symptomatic calcification of ligamentum flavum (CLF) is a rare condition of the cervical spine compared to other degenerative diseases. CLF manifests as myelopathic symptoms due to the compression of the spinal cord. Calcium pyrophosphate dihydrate (CPPD) deposition disease is the most prevalent cause of CLF. This is the first reported case of CLF caused by CPPD in the Middle East.

PRESENTATION OF CASE

A 75-year-old female patient presented with gait disturbance for two years. The imaging studies demonstrated two symmetric bulging masses with a density similar to bone between the inferior border of the C5 laminae and the superior border of the C6 laminae. Histologic evaluation of the resected tissue confirmed the CLF and CPPD disease pathology. The patient underwent a C5-C6 laminectomy. The symptoms resolved, and in a six-month follow-up period, the walking improved.

DISCUSSION

The diagnosis of CLF due to CPPD is based on the interpretation of the symptoms concurrent with MRI, CT scan, and histopathological examination. Due to the high reoccurrence rates of the condition following the pharmacological treatment and sub-optimal response in those with negative inflammatory markers, open decompression with either cervical laminectomy or laminoplasty is considered the gold-standard therapeutic option in CFL due to CPPD deposition disease.

CONCLUSION

CLF is a rare cervical spine disorder that compresses the spinal cord and manifests as myelopathic symptoms. Early surgical intervention, preferably in the first five months of the disease initiation, is associated with favorable outcomes.

A Rare Case of Acute Calcium Pyrophosphate Deposition Disease Following Zoledronic Acid Infusion

Calcium pyrophosphate deposition (CPPD) disease of the joints is a form of arthritis that can present in a severely debilitating form of pseudogout. Although mostly idiopathic, pseudogout has been reported following bisphosphonate therapy in only nine cases to date with a pathophysiology that remains unclear. We present the case of a 59-year-old postmenopausal woman who developed the rare onset of acute polyarticular CPPD disease following zoledronic acid infusion for the treatment of osteoporosis.

Prevalence of intra-articular mineralization on knee computed tomography: the multicenter osteoarthritis study

OBJECTIVE

The aim of this work was to report the prevalence of computed tomography (CT)-detected intra-articular mineralization.

DESIGN

We included participants from the Multicenter Osteoarthritis (MOST) Study. At the 12th year visit of the MOST study, bilateral knee CTs were first obtained. All participants also had posteroanterior and lateral radiographs of bilateral knees and completed standard questionnaires. Knee radiographs were assessed for Kellgren & Lawrence grade (KLG) and radiographic evidence of intra-articular mineralization. CT images were scored using the Boston University Calcium Knee Score (BUCKS) for cartilage, menisci, ligaments, capsule, and vasculature. Prevalence of intra-articular mineralization was computed for the total sample, and stratified by age, sex, race, Body Mass Index (BMI), presence of frequent knee pain, and KLG. We also determined distribution of mineralization in the cartilage and meniscus, and co-localization.

RESULTS

4140 bilateral knees from 2070 participants were included (56.7% female, mean age 61.1 years, mean BMI: 28.8 kg/m2). On radiographs 240 knees (5.8%) had intraarticular mineralization, while CT-detected mineralization was present in 9.8% of knees. Prevalence of hyaline articular and meniscus mineralization increased with age and KL grade, and was similar by sex, BMI categories, and comparable in subjects with and without frequent knee pain. Mineralization tended to be ubiquitous in the joint, most commonly involving all three (medial/lateral tibiofemoral and patellofemoral) compartments (3.1%), while the patellofemoral compartment was the most involved compartment in isolation (1.4%).

CONCLUSIONS

CT of the knee provides greater visualization of intra-articular mineralization than radiographs and allows better localization of the crystal deposition within the joint. Further studies should focus on the co-localization of intra-articular crystal deposition and corresponding magnetic resonance imaging (MRI)-features of knee osteoarthritis (OA).

Which are the most frequently involved peripheral joints in calcium pyrophosphate crystal deposition at imaging? A systematic literature review and meta-analysis by the OMERACT ultrasound – CPPD subgroup

Objectives

To identify the prevalence of calcium pyrophosphate crystal deposition (CPPD) using ultrasound and conventional radiology at peripheral joints in patients with suspected or definite CPPD.

Methods

A systematic literature search was performed in PubMed and Embase using pre-defined search strategies from inception to April 2021 to identify studies that evaluated conventional radiology and ultrasound in detecting CPPD at peripheral joints, including definite or suspected CPPD [Research question 1 (RQ1) and Research Question 2 (RQ2), respectively]. For the meta-analysis, the first, second, and third sub-analysis included studies with the knee, and knee or wrist as the index joint for CPPD (without restrictions on the reference standard) and synovial fluid analysis or histology as a reference standard (without restrictions on the index joint), respectively.

Results

One-thousand eight hundred and twenty-seven manuscripts were identified, of which 94 articles were finally included. Twenty-two and seventy-two papers were included in RQ1 and RQ2, respectively. The knee had the highest prevalence for RQ1 and RQ2 by both conventional radiology and ultrasound, followed by the wrist with the highest prevalence for RQ1. The hand had the lowest CPPD prevalence. The third sub-analysis showed a higher CPPD prevalence on ultrasound than conventional radiology at the knee (only data available).

Conclusion

Among all peripheral joints, the knees and wrists could be regarded as the target joints for CPPD detection by imaging. Furthermore, ultrasound seems to detect a higher number of calcium pyrophosphate deposits than conventional radiology, even when using a more restrictive reference standard.

Pseudogout of the lumbar spine

Calcium pyrophosphate deposition involves deposition of calcium pyrophosphate dihydrate crystals in various joints throughout the body. The term "pseudogout" refers to an acute attack of calcium pyrophosphate crystal-induced arthritis. Though clinical presentation and joint involvement vary, involvement of the lumbar spine is rare. We present the case of a 61-year-old male who presented with 3 days of worsening lower back pain. He had elevated inflammatory markers, leukocytosis, and spinal tenderness on exam. Magnetic resonance imaging of the lumbar spine showed likely L4-L5 osteomyelitis; however, biopsy of the disk space revealed extensive calcium pyrophosphate crystal deposition. The patient was treated with prednisone taper with alleviation of symptoms. Though pseudogout of the spine is rare, our report supports literature urging clinicians to consider pseudogout when assessing elderly patients with back pain for prompt and appropriate treatment.

Pseudogout After Total Knee Arthroplasty Meeting Minor Criteria for Infection Treated by Polyethylene Exchange

Case

Pseudogout in a total joint arthroplasty is rare and can be difficult to distinguish from a prosthetic joint infection (PJI). In this unique case, we present a patient who developed her first episode of pseudogout 17 years after her primary total knee arthroplasty at age 75.

Conclusion

With similar clinical and laboratory findings, it is important to distinguish the presence of PJI and inflammatory arthropathy. The use of diagnostic tools available, consideration of patient co-morbidities, and timing of symptoms can help guide surgeons' treatment.

Cartilage calcification in osteoarthritis: mechanisms and clinical relevance

Pathological calcification of cartilage is a hallmark of osteoarthritis (OA). Calcification can be observed both at the cartilage surface and in its deeper layers. The formation of calcium-containing crystals, typically basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate (CPP) crystals, is an active, highly regulated and complex biological process that is initiated by chondrocytes and modified by genetic factors, dysregulated mitophagy or apoptosis, inflammation and the activation of specific cellular-signalling pathways. The links between OA and BCP deposition are stronger than those observed between OA and CPP deposition. Here, we review the molecular processes involved in cartilage calcification in OA and summarize the effects of calcium crystals on chondrocytes, synovial fibroblasts, macrophages and bone cells. Finally, we highlight therapeutic pathways leading to decreased joint calcification and potential new drugs that could treat not only OA but also other diseases associated with pathological calcification.

Proton-Pump Inhibitors and Risk of Calcium Pyrophosphate Deposition in a Population-Based Study

OBJECTIVE

There are no proven effective medical treatments to prevent calcium pyrophosphate crystal deposition (CPPD). Hypomagnesemia is a known CPPD risk factor. The present study was undertaken to carry out a real-world epidemiologic study on proton-pump inhibitor (PPI) use, which can cause hypomagnesemia, and CPPD risk.

METHODS

We conducted a time-stratified, propensity score (PS)-matched cohort study using the UK-based IQVIA Medical Research Data. We compared risk of incident CPPD among PPI users versus H2 blocker users using Cox proportional hazards models. We used greedy matching of incident PPI users 1:1 to incident histamine receptor 2 (H2 ) blocker users in 1-year cohort accrual blocks. Subjects were censored at time of drug switch. We evaluated incident use of PPI and H2 blockers prior to incident CPPD using a nested case-control study within the same cohort, matched 1:4 by age and sex using risk-set sampling.

RESULTS

We identified 81,102 PPI and H2 blocker initiators, with 113 and 63 incident cases of CPPD, respectively. In the case-control study when compared with nonusers, both PPI and H2 B users had higher risk of incident CPPD, with odds ratios (ORs) of 1.79 (95% confidence interval [95% CI] 1.55-2.07) and 1.52 (95% CI 1.14-2.03), respectively. Incident PPI use was nonsignificantly associated with incident CPPD (hazard ratio 1.03 [95% CI 0.75-1.41]) compared with H2 blocker use.

CONCLUSION

In this study using real-world data, incident use of PPIs was not associated with a higher risk of CPPD compared with incident H2 blocker use, although use of PPI and H2 blockers had higher risk compared with nonuse.

Dual-Energy Computed Tomography Collagen Density Mapping of the Cranio-Cervical Ligaments-A Retrospective Feasibility Study

The objectives of this study were to investigate the mean collagen content of the atlanto-axial joint (AAJ) ligaments in a cohort without inflammatory disease and to analyze clinical confounders such as age, sex, and presence of ligamentous calcifications. A total of 153 patients who underwent dual-energy computed tomography (DECT) due to various reasons (e.g., suspected cancer or infection) were included in this retrospective study. Reconstruction of collagen density maps from the DECT dataset was performed. Region of interest (ROI) analysis was performed to assess densities in the following regions: ligamentum transversum atlantis (LTA), ligamenta alaria, fasciculi longitudinales, ligamentum nuchae, and retro-odontoid soft tissue (RDS). Osteoarthritis (OA) and the presence of calcifications were assessed by two experienced readers blinded to clinical data. Subgroup comparisons were performed using unpaired t-tests. The correlation of collagen density and clinical factors was investigated using Pearson's correlation coefficient. Mean LTA collagen density was 141.7 (SD 35.7). Ligamentous calcifications were rare (14.4 %). OA of the AAJ was common (91.5 %). LTA collagen density was not associated with age (Pearson's r of 0.109; p = 0.180) and was not significantly higher in patients with OA (p = 0.070). No correlations between RDS thickness, collagen density or calcifications were found. Our results show collagen density mapping of the cranio-cervical joint ligaments to be feasible; collagen densities are not significantly associated with age, sex, AAJ degeneration, or asymptomatic ligamentous calcification.

Calcium pyrophosphate dihydrate crystals in a 9-year-old with osteomyelitis of the knee: A case report

BACKGROUND

Calcium pyrophosphate dihydrate deposition disease (CPPD), or pseudogout, is an inflammatory arthritis common among elderly patients, but rarely seen in patients under the age of 40. In the rare cases presented of young patients with CPPD, genetic predisposition or related metabolic conditions were almost always identified.

CASE SUMMARY

The authors report the case of a 9-year-old boy with no past medical history who presented with acute knee pain and swelling after a cat scratch injury 5 d prior. Synovial fluid analysis identified calcium pyrophosphate dihydrate crystals. Further MRI analysis identified osteomyelitis and a small soft tissue abscess.

CONCLUSION

This case presents the extremely rare diagnostic finding of calcium pyrophosphate dihydrate crystals in a previously healthy pediatric patient. The presence of osteomyelitis presents a unique insight into the pathogenesis of these crystals in pediatric patients. More research needs to be done on the role of CPPD in pediatric arthritis and joint infection.

Imaging of Crystal Disorders:: Calcium Pyrophosphate Dihydrate Crystal Deposition Disease, Calcium Hydroxyapatite Crystal Deposition Disease and Gout Pathophysiology, Imaging, and Diagnosis

Crystal arthropathies are a group of joint disorders due to deposition of crystals in and around joints that lead to joint destruction and soft tissue masses. Clinical presentation is variable and diagnosis might be challenging. In this article the pathophysiology is addressed, the preferred deposition of crystal arthropathies and imaging findings. Case studies of calcium pyrophosphate dihydrate crystal deposition disease, hydroxyapatite crystal deposition disease, and gout are shown. Guidelines for the use of dual-energy computed tomography are given to enable the diagnosis and follow-up of gout.

High prevalence of chondrocalcinosis and frequent comorbidity with calcium pyrophosphate deposition disease in patients with seronegative rheumatoid arthritis

Background

The crystal-induced calcium pyrophosphate deposition disease (CPPD) clinically appearing as pseudogout differs from the mere radiographic finding of chondrocalcinosis (CC) but may cause symptoms resembling rheumatoid arthritis (RA).

Objective

To study the prevalence of CPPD and CC in rheumatic diseases focusing on differences between seropositive and seronegative RA.

Patients and methods

In a retrospective study design, we analysed records and radiographs of consecutive new patients presenting to our centre between January 2017 and May 2020. 503 patients were identified based on expert diagnoses: 181 with CPPD, 262 with RA, 142 seropositive (54.2%) and 120 seronegative RA, gout (n=30) and polymyalgia rheumatica (n=30), mean symptom duration <1 year in almost all patients.

Results

The majority of patients had only one rheumatological diagnosis (86.9%). Most patients with CPPD (92.6%) had radiographic CC, primarily in the wrists. The prevalence of CC was higher in seronegative (32.3%) than in seropositive RA (16.6%), respectively (p<0.001). Patients with CPPD were older (p<0.001) and had acute attacks more frequently than patients with RA (p<0.001), who had symmetric arthritis more often (p=0.007). The distribution pattern of osteoarthritic changes in radiographs of hands and wrists differs between patients with RA and CPPD. CC was present in more than one joint in 73.3% of patients with CPPD, 9.6% with seropositive and 18.7% with seronegative RA.

Discussion

CPPD and CC were more frequent in seronegative versus seropositive RA. Symmetry of arthritis and acuteness of attacks differentiated best between CPPD and RA but localisation of joint involvement did not. Co-occurrence of both diseases was frequently observed.

Outcomes and resource utilization in calcium pyrophosphate deposition disease patients who underwent total knee arthroplasty: a cross-sectional analysis

This cross-sectional study aims to evaluate the predictors, outcomes, and resource utilization of total knee arthroplasty (TKA) in calcium pyrophosphate deposition disease (CPPD) patients. We used the US National Inpatient Sample database to identify CPPD and non-CPPD who underwent TKA from 2006 to 2014. Data collection included patient demographics and comorbidities. Outcomes following TKA included in-hospital mortality, complications, length of hospitalization, hospital charges, and disposition. Among the 5,564,005 patients who have undergone TKA, 11,529 (0.20%) had CPPD, with a median age of 72 years, and 53.7% were females. Compared with non-CPPD, patients with CPPD were more likely to be older (mean 72 vs 66 years; p < 0.001), male, white, and have Medicare insurance. CPPD patients were more likely to have ≥ 2 comorbidities calculated by the Charlson Comorbidity Index and discharge to an inpatient/rehabilitation facility. Regarding inpatient complications, myocardial infarction and knee reoperation were significantly more common in CPPD patients. TKA in CPPD patients was associated with significantly higher odds of increased length of stay (> 3 days) than those without CPPD (OR 1.43, 95% CI 1.37-1.49). There was no significant difference in the in-hospital mortality even after adjusting for possible confounders. CPPD patients who underwent TKA were more likely to have a longer hospital stay and discharge to a non-home setting than non-CPPD. Also, CPPD patients had a higher comorbidity burden and risk for myocardial infarction and reoperation.Key Points• This is the largest study to analyze data of CPPD patients who underwent TKA and compare them with non-CPPD patients, using a large nationwide database.• Compared to non-CPPD patients, TKA in CPPD patients is associated with a greater length of stay and disposition to a nursing/rehabilitation facility.• In-hospital complications such as myocardial infarction and reoperation were more frequently observed in CPPD patients than non-CPPD.• The results of this study should alert healthcare providers to develop strategies in order to improve outcomes of CPPD patients undergoing TKA.

Chondrocalcinosis does not affect functional outcome and prosthesis survival in patients after total or unicompartmental knee arthroplasty: a systematic review

PURPOSE

There are contentious data about the role calcium pyrophosphate (CPP) crystals and chondrocalcinosis (CC) play in the progression of osteoarthritis (OA), as well as in the outcomes after knee arthroplasty. Hence, the purpose of this systematic review was to analyse the clinical and functional outcome, progression of OA and prosthesis survivorship after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) in patients with CC compared to patients without CC.

METHODS

A systematic review of the literature in PubMed, Medline, Embase and Web of Science was performed using the "Preferred Reporting Items for Systematic Reviews and Meta-Analysis" (PRISMA) guidelines. Articles which reported the outcome and survival rates of prosthesis after TKA or UKA in patients with CC were included.

RESULTS

A total of 3718 patient knees were included in eight selected publications, with a median sample sizes of 234 knees (range 78-1000) and 954 knees (range 408-1500) for publications including UKA and TKA, respectively. At time of surgery, the mean age was 69 years and the prevalence for CC ranged from 12.6 to 36%. Chondrocalcinosis did not significantly influence the functional and clinical outcome, the implant survival as well as the radiologic progression of OA disease after UKA and TKA.

CONCLUSION

The presence of CPP crystals in tissue samples, synovial fluid or evidence of calcifications on preoperative radiographs did not significantly influence the postoperative functional and activity scores. It also had no significant influence on prosthesis survival rate, whether it was a UKA or a TKA. This study shows that the impact of a subclinical form of chondrocalcinosis may not be of clinical relevance in the context of arthroplasty.

LEVEL OF EVIDENCE

IV.

Review: Outcome measures in calcium pyrophosphate deposition

This review highlights outcomes for patients with calcium pyrophosphate deposition (CPPD) reported in prior studies and underscores challenges to assessing outcomes of this condition. Prior clinical studies of interventions for CPPD focused on joint damage and calcification on imaging tests, joint pain, swelling, and inflammatory biomarkers. Qualitative interviews with patients with CPPD and healthcare providers additionally identified flares, overall function, and use of analgesic medications as important outcomes. Imaging evidence of joint damage and calcification is likely to be outcomes in future clinical studies of CPPD, though reliability and sensitivity to change in CPPD require further testing for several imaging modalities. Challenges to outcome measurement in CPPD include questions of attribution of signs and symptoms to CPPD versus co-existing forms of arthritis, lack of therapies to prevent or dissolve calcium pyrophosphate crystal deposition, absence of validated patient- or physician-reported CPPD outcome measures, and scarcity of large cohorts in which to study outcomes of different clinical presentations of CPPD.

A Phage Display-Identified Short Peptide Capable of Hydrolyzing Calcium Pyrophosphate Crystals-The Etiological Factor of Chondrocalcinosis

Chondrocalcinosis is a metabolic disease caused by the presence of calcium pyrophosphate dihydrate crystals in the synovial fluid. The goal of our endeavor was to find out whether short peptides could be used as a dissolving factor for such crystals. In order to identify peptides able to dissolve crystals of calcium pyrophosphate, we screened through a random library of peptides using a phage display. The first screening was designed to select phages able to bind the acidic part of alendronic acid (pyrophosphate analog). The second was a catalytic assay in the presence of crystals. The best-performing peptides were subsequently chemically synthesized and rechecked for catalytic properties. One peptide, named R25, turned out to possess some hydrolytic activity toward crystals. Its catalysis is Mg²⁺-dependent and also works against soluble species of pyrophosphate.

Accuracy of synovial fluid analysis compared to histology for the identification of calcium pyrophosphate crystals: an ancillary study of the OMERACT US Working Group - CPPD subgroup

The aim of this study was to evaluate the accuracy of synovial fluid analysis in the identification of calcium pyrophosphate dihydrate crystals compared to microscopic analysis of joint tissues as the reference standard. This is an ancillary study of an international, multicentre cross-sectional study performed by the calcium pyrophosphate deposition disease (CPPD) subgroup of the OMERACT Ultrasound working group. Consecutive patients with knee osteoarthritis (OA) waiting for total knee replacement surgery were enrolled in the study from 2 participating centres in Mexico and Romania. During the surgical procedures, synovial fluid, menisci and hyaline cartilage were collected and analysed within 48 hours from surgery under transmitted light microscopy and compensated polarised light microscopy for the presence/absence of calcium pyrophosphate crystals. All slides were analysed by expert examiners on site, blinded to other findings. A dichotomic score (absence/ presence) was used for scoring both synovial fluid and tissues. Microscopic analysis of knee tissues was considered the gold standard. Sensitivity, specificity, accuracy, positive and negative predictive values of synovial fluid analysis in the identification of calcium pyrophosphate crystals were calculated. 15 patients (53% female, mean age 68 yo ± 8.4) with OA of grade 3 or 4 according to Kellgren-Lawrence scoring were enrolled. 12 patients (80%) were positive for calcium pyrophosphate crystals at the synovial fluid analysis and 14 (93%) at the tissue microscopic analysis. The overall diagnostic accuracy of synovial fluid analysis compared with histology for CPPD was 87%, with a sensitivity of 86% and a specificity of 100%, the positive predictive value was 100% and the negative predictive value was 33%. In conclusion synovial fluid analysis proved to be an accurate test for the identification of calcium pyrophosphate dihydrate crystals in patients with advanced OA.

The role of Interleukin-1 receptor antagonist as a treatment option in calcium pyrophosphate crystal deposition disease

Calcium Pyrophosphate Crystal Deposition (CPPD) disease is characterized by the deposition of calcium pyrophosphate crystals in the cartilage. In most cases, it can manifest as a subclinical condition named chondrocalcinosis, often revealed by joint x-ray examination. In other cases, deposition can cause flares of arthritis, known as acute CPP crystal arthritis. In the last few years, many pathogenic pathways have been discovered. Interleukin-1 (IL-1) plays a key role in the pathogenesis of CPPD disease, both as a mediator of inflammatory response to crystals and as a promoter of damage to articular cartilage. In this review, we investigated the role of IL-1R inhibitor, such as Anakinra, as an alternative to the various therapeutic strategies for CPPD disease, especially among patients resistant to traditional treatment with NSAIDs, corticosteroids and colchicine.

Ultra-high resolution 3D MRI for chondrocalcinosis detection in the knee-a prospective diagnostic accuracy study comparing 7-tesla and 3-tesla MRI with CT

OBJECTIVES

To test the diagnostic accuracy of a 3D dual-echo steady-state (DESS) sequence at 7-T MRI regarding the detection of chondral calcific deposits of the knee in comparison to 3-T MRI, using CT as cross-sectional imaging reference standard.

METHODS

CT and 7-T MRI (DESS) of knee joints in 42 patients with radiographically known chondrocalcinosis (13 of 42 bilateral) were prospectively acquired for all included patients (n = 55 knee joints). Additionally, 3-T MRI (DESS) was performed for 20 of these 55 knee joints. Two fellowship-trained musculoskeletal radiologists scored eight cartilage regions of each knee joint separately regarding presence of cartilage calcification, diagnostic confidence level, and sharpness of calcific deposits. In an explorative subanalysis, micro-CT of the menisci was evaluated after knee arthroplasty in one patient. Diagnostic performance metrics and nonparametric tests were used to compare between modalities. p values < 0.05 were considered to represent statistical significance.

RESULTS

Sensitivity for chondrocalcinosis detection was significantly higher for 7-T MRI (100%) compared to 3-T MRI (reader 1: 95.9%, p = 0.03; reader 2: 93.2%, p = 0.002). The diagnostic confidence was significantly higher for both readers at 7 T compared to both 3-T MRI (p < 0.001) and to CT (p = 0.03). The delineation of chondral calcifications was significantly sharper for 7-T compared to both 3-T MRI and CT (p < 0.001, both readers). Micro-CT in one patient suggested that 7-T MRI may potentially outperform standard CT in diagnosing chondral calcifications.

CONCLUSION

3D-DESS imaging at 7-T MRI offers a significantly higher sensitivity in detection of chondral calcific deposits compared to 3-T MRI.

KEY POINTS

• 3D dual-echo steady-state (DESS) MRI at 7 T has a higher sensitivity in detection of chondral calcific deposits compared to 3-T MRI (p ≤ 0.03). • 3D DESS MRI at 7 T yields no false-negative cases regarding presence of chondral calcific deposits. • 3D DESS MRI at 7 T offers better delineation and higher diagnostic confidence in detection of chondral calcific deposits compared to 3-T MRI (p < 0.001).

Risk Factors for Knee Osteoarthritis in Retired Professional Footballers: A Cross-Sectional Study

OBJECTIVE

To determine risk factors for 3 knee osteoarthritis (KOA) outcomes, knee pain (KP), radiographic KOA (RKOA), and total knee replacement (TKR) in professional footballers.

DESIGN

This was a cross-sectional study involving a postal questionnaire, followed by radiographic assessment in a subcohort of responders.

SETTINGS AND PARTICIPANTS

Four thousand seven hundred seventy-five questionnaires were sent to retired professional footballers, who had played in the English football league, and 1207 responded. Of these, 470 underwent knee radiographs.

ASSESSMENT OF RISK FACTORS

Potential factors include age, body mass index (BMI), knee alignment, a history of football-related knee injury, and training hours (during career) were collected through the questionnaire.

MAIN OUTCOME MEASURES

Knee osteoarthritis outcomes were current KP (pain for most days of the previous month), TKR (self-reported), and RKOA (observed through radiographs).

RESULTS

Football-related injury was the strongest risk factor for KP [adjusted odds ratio (aOR), 4.22; 95% confidence interval (CI), 3.26-5.48], RKOA [aOR, 2.88; 95% CI, 1.81-4.59], and TKR [aOR, 4.83; 95% CI, 2.87-8.13]. Footballers had a 7% increased risk of RKOA for every 1000 hours trained. Although age and gout were associated with all 3 KOA outcomes, BMI, nodal osteoarthritis (OA), a family history of OA, knee malalignment, and 2D:4D ratio were associated with one or another of these 3 KOA outcomes.

CONCLUSION

This study is the first to examine KOA risk factors in retired professional footballers. The study has identified several risk factors, both specific (eg, knee injury and training dose) and nonspecific (eg, age and gout) to footballers. This may be used to develop prevention strategies to reduce the risk of KOA in professional footballers after retirement.

The Incidence and Significance of Calcium Pyrophosphate Dihydrate Deposits in Histologic Examinations of Total Hip, Knee, and Shoulder Joint Arthroplasties

CONTEXT.—

The incidence, distribution, and significance of calcium pyrophosphate dihydrate deposition (CPPD) disease have not been extensively compared among various total joint resections.

OBJECTIVE.—

To investigate and define the clinical and pathologic features of CPPD in hip, shoulder, and knee arthroplasties.

DESIGN.—

We retrospectively reviewed consecutive total hip, knee, and shoulder arthroplasty cases (N = 3195) confirmed pathologically between January 1, 2017, and October 10, 2018, comparing clinical and pathologic data.

RESULTS.—

Among 2004 hip arthroplasties, 61 (3%) had CPPD on pathologic examination; the majority had a histologic diagnosis of osteoarthritis followed by fracture and avascular necrosis. Of 1113 knee arthroplasties, 98 (9%) had CPPD; all had a histologic diagnosis of osteoarthritis. Among 78 shoulder arthroplasties, 10 (13%) had CPPD; all but one had a histologic diagnosis of osteoarthritis. Patients with hip and knee CPPD were significantly older than those without CPPD. Of the 169 pathologically detected CPPD cases, only 35 (21%) were documented on preoperative radiologic images or by other clinical means; radiology reports were significantly more likely to document chondrocalcinosis in the knees than in the hips. Histologically, CPPD were noted almost exclusively in the separately submitted soft tissues/joint capsule, concomitantly involving the articular cartilage surface in only 3.0% (5 of 169) of cases.

CONCLUSIONS.—

Calcium pyrophosphate dihydrate deposition is more than twice as likely to occur in the knees and shoulders compared with the hips. Patients with CPPD in the knees or hips are usually not recognized preoperatively/radiologically and constitute a significantly older population. Reliably establishing the diagnosis of CPPD requires pathologic examination of the submitted soft tissue/joint capsule.

Infective endocarditis initially manifesting as pseudogout

Infective endocarditis is a commonly encountered disease in which diagnosis is often challenging due to the variety of clinical manifestations. Early identification is key due to risk of mortality without treatment. In this case, a 31-year-old man presented with pseudogout of the right ankle and COVID-19 infection. Further workup showed blood cultures growing Staphylococcus aureus, and the diagnosis of infective endocarditis was confirmed by echocardiography. Independently, pseudogout and infective endocarditis result in activation of the innate immune system and can manifest with joint inflammation. Their co-occurrence likely resulted in an augmented inflammatory response due to overlap in their pathophysiologic pathways.

Imaging of Joints and Bones in Autoinflammation

Autoinflammatory disorders are commonly characterized by seemingly unprovoked systemic inflammation mainly driven by cells and cytokines of the innate immune system. In many disorders on this spectrum, joint and bone involvement may be observed and imaging of these manifestations can provide essential diagnostic information. This review aimed to provide a comprehensive overview of the imaging characteristics for major diseases and disease groups on the autoinflammatory spectrum, including familial Mediterranean fever (FMF), Behçet disease (BD), crystal deposition diseases (including gout), adult-onset Still's disease (AoSD), and syndromatic synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO)/chronic recurrent multifocal osteomyelitis (CRMO). Herein, we discuss common and distinguishing imaging characteristics, phenotypical overlaps with related diseases, and promising fields of future research.

A critical review of the available evidence on the diagnosis and clinical features of CPPD: do we really need imaging?

Imaging has been playing an important role in the pathogenetic and clinical characterisation of many rheumatic diseases, especially in the most recent years with the advent of many new, highly technological and promising techniques. Calcium pyrophosphate deposition disease (CPPD) benefited also from these new techniques, most of which can readily identify calcium crystals. Nowadays, imaging is used mainly to identify crystals in joints but given the complexity of CPPD, imaging should be used with an "holistic" approach in order to gain insights in the pathogenesis, spectrum of clinical manifestations and natural history of the disease. Furthermore, overlap or association of CPPD with other prevalent diseases of the elderly makes the differential diagnosis challenging. In this review, we provide a critical review of the current knowledge on the use of imaging both for the identification of crystals and for its application in clinical practice as an aid for determining the impact of the disease on patients.Key Points• CPPD is a complex disease with a wide spectrum of clinical manifestations and understanding of pathogenetic mechanisms and clinical phenotypes is essential for correct characterisation• Imaging has made important advances regarding identification of CPPD in recent years, and new, more sophisticated techniques are under investigation• Imaging has the potential to improve our knowledge on pathogenesis and clinical phenotypes of CPPD• Imaging techniques have to be tested thoroughly for reliability, discrimination and sensitivity to change before they can be implemented in clinical trials.

Cartilage calcification is associated with histological degeneration of the knee joint: a highly prevalent, age-independent systemic process

OBJECTIVES

To investigate if cartilage calcification (CC) is a systemic process, the purpose of this study was to determine the prevalence and the amount of meniscal/hyaline CC of the knee joint in the general population by high-resolution imaging (DCR) and to evaluate the association between CC with cartilage degeneration and age.

METHODS

Cross-sectional DCR-study of 180 knee joints of 90 donors (42 female/48 male, mean age 62.3y). Histological hyaline (OARSI) and meniscal (Krenn) cartilage degeneration was determined of all knees.

RESULTS

CC was observed in 100% of the donors (bilaterally in 98%), hyaline cartilage calcification (HCC) in 92% and meniscal calcification (MC) in 100%. CC was detected in more than three out of six distinct cartilage areas in 84.4% of all knees. The mean amount of CC correlated between both sides of donors, the different analyzed areas of the knee joint and between the various types of cartilage structures. There was more calcification in meniscal than in hyaline cartilage (factor 5.3) and in the medial than the lateral compartment (factor 1.2). HCC/MC were already detectable with only mild cartilage lesions and the amount correlated with histological cartilage degeneration, but not with age.

CONCLUSIONS

The present study provides evidence that meniscal and hyaline CC occurs in a pattern that is compatible with CC being a systemically driven process and that meniscal fibrocartilage is more prone to calcification than hyaline cartilage. Furthermore, the age-independent association between the amount of CC and the grade of degeneration in both hyaline and meniscal cartilage, suggests that CC is an obligatory early event in initiating cartilage degeneration.

There is no difference in postoperative pain, function and complications in patients with chondrocalcinosis in the outcome of total knee arthroplasty for end-stage osteoarthritis

PURPOSE

Chondrocalcinosis is the radiographic appearance of calcium crystals in cartilage and other soft tissue. It is suggested that preoperative chondrocalcinosis predicts a worse outcome after total knee arthroplasty and it is unclear if chondrocalcinosis leads to more postoperative complications. This study aimed to compare function, pain, postoperative complications, postoperative signs of acute arthritis and revision rates between patients with and without chondrocalcinosis undergoing total knee arthroplasty for osteoarthritis.

METHODS

In this retrospective cohort study performed in 2017, 408 knees in 392 patients (16 bilateral total knee arthroplasties) were included. None of the patients received additional synovectomy. PROMs were evaluated after 1 year (n = 294) and 5 years (n = 308). The follow-up for clinical data was 5 years (n = 408). The range of final follow-up was 57-84 months. All preoperative radiographs were scored for chondrocalcinosis and Oxford Knee Score, Knee Society Score and Algofunctional Index were used to assess outcome. All clinical records were screened for postoperative complications (excessive wound discharge, infection, loosening, PAO, stiffness), arthritis after surgery and reoperation or revision for any reason.

RESULTS

Sixty-three knees (15.4%) showed signs of chondrocalcinosis. Male gender, higher age and lower BMI were risk factors for chondrocalcinosis. No difference was found in Oxford Knee Score, Knee Society Score and Algofunctional Index, nor in postoperative complications, postoperative signs of acute arthritis and revision rate.

CONCLUSION

Patients with and without chondrocalcinosis have the same outcome after total knee arthroplasty related to pain, functionality, complications, arthritis and revision after surgery for end-stage osteoarthritis. Chondrocalcinosis is not a contraindication for total knee arthroplasty and additional synovectomy is unnecessary.

LEVEL OF EVIDENCE

III.

Bone status and aortic calcifications in chondrocalcinosis patients

Aim: We aimed to examine the association between several circulating bone turnover markers [ osteocalcin (OC), osteoprotegerin (OPG), beta-CrossLaps (β-CTx)], hip and spine bone mineral density (BMD) and abdominal aortic calcification (AAC) in patients with chondrocalcinosis (CC).

Methods: Thirty-six patients with CC and thirty-seven controls were consecutively enrolled in this pilot case-control, cross-sectional study. The following parameters were assessed: serum levels of OC, OPG and β-CTx by enzyme-linked immunosorbent assay (ELISA); hip and spine BMD by dual-energy X-ray absorptiometry and AAC score by lateral radiography.

Results: Patients with CC had higher levels of serum bone turnover markers and AAC score than the control group: OC [6.5 (3.5-9.9) vs 4.5 (2.6-7.2) ng/ml; p=0.05], OPG [(7.7 (6.2-9.4) vs 6.5 (5.5-8.12) pmol/ml; p=0.02], β-CTx [6078 (5870-6171) vs 5851 (5465-6109) pg/ml; p=0.02] and AAC score (3.6±6.2 vs 0.5±2; p=0.006). Conversely, even if statistical significance was not reached, hip and spine BMD was lower in patients with CC. Additionally, we found a positive correlation between OPG and AAC, but also between OPG and osteoporosis in patients with CC.

Conclusion: Patients with CC are characterized by higher circulating OC, OPG and β-CTx. The presence of AAC was more common in patients with CC, being only associated with serum OPG.

Calcium pyrophosphate deposition disease: A case report with bilateral involvement of the temporomandibular joints and concurrence of psoriatic arthritis

Calcium pyrophosphate dehydrate deposition (CPDD) disease very rarely affects the temporomandibular joint (TMJ). It may resemble synovial chondromatosis, chondrosarcoma, chondroblastoma, or a parotid tumor. Clinical examination, CT, and MRI are important in making the correct diagnosis. Surgical removal of CPDD is necessary with or without excision of the TMJ.

Prevalence and incidence of non-gout crystal arthropathy in southern Sweden

Objective

To estimate the prevalence and incidence of non-gout crystal arthropathy in relation to socioeconomic factors in southern Sweden.

Methods

All patients (age ≥ 18 years) with at least one visit to a physician with the diagnosis of interest in the Skåne region (population of 1.3 million) in 1998–2014 were identified. Non-gout crystal arthropathy (ICD-10 codes M11.0–M11.9) was subclassified in four different groups: calcium pyrophosphate crystal deposition related arthropathy (CPPD), unspecified non-gout arthropathies, chondrocalcinosis, and hydroxyapatite crystal deposition disease. The crude and age-adjusted point prevalence on December 31, 2014, and the cumulative incidence during 2014 were calculated for all non-gout crystal arthropathies, CPPD, and other unspecified non-gout arthropathies overall and in relation to occupation, income, and level of education.

Results

The crude 2014 point prevalence (95% CI) and 2014 cumulative incidence (95% CI) of all non-gout crystal arthropathies were 0.23% (0.23–0.24) and 21.5 (19–25) cases/100,000 persons. Mean age (range) among all prevalent cases in 2014 was 71 (20–102) years and 56% were males. The point prevalence and cumulative incidence of CPPD were 0.09% (0.08–0.09) and 8 (7–10)/100,000 persons, respectively. The corresponding data for unspecified non-gout crystal deposition disease was 0.16% (0.16–0.17) and 15.6 (13–18)/100,000 persons, respectively. The prevalence and incidence of CPPD and unspecified non-gout crystal arthropathies were slightly higher in men and increased with age irrespective of gender. Unspecified non-gout crystal arthropathy but not CPPD was less prevalent in persons with ≥ 15 years of education, whereas there were no clear associations with occupation and income.

Conclusion

The prevalence of all diagnosed non-gout crystal arthropathies was 0.23%, thus considerably less prevalent than gout in southern Sweden. CPPD and other unspecified non-gout crystal arthropathies are the predominant diagnoses, increasing with age and in men. With the exception for unspecified non-gout crystal arthropathies being inversely correlated to a higher level of education, no convincing association with the socioeconomic factors was found.

Crowned dens syndrome presenting as pyrexia of unknown origin (PUO)

BACKGROUND

Deposition of calcium pyrophosphate crystals in the cervical spine around the odontoid process may lead to neck pain and fever. This condition is called crowned dens syndrome (CDS).

CASE REPORT

An 89-year-old female presented with complaints of fever for one-month duration and recent onset neck pain. During her admission, she developed right knee pain with evidence of chondrocalcinosis on X-ray. Considering her clinical presentation in setting of pseudogout, she had a CT scan of her neck that revealed erosion of the dens and hyperdense soft tissue surrounding the odontoid process. Based on her clinical and radiologic presentation, she was diagnosed with crowned dens syndrome and started on NSAIDs. Unfortunately, she did not respond to NSAIDs and was switched to Colchicine, which resulted in immediate improvement in her symptoms.

CONCLUSIONS

We present this case to stress the importance of keeping crowned dens syndrome as one of the differentials in an elderly patient presenting with fever and neck pain.

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.