Relative risk of knee chondrocalcinosis in siblings of index cases with pyrophosphate arthropathy

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.

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.

Association between chondrocalcinosis and osteoarthritis: A systematic review and meta-analysis

AIM

To systematically examine the existing literature on the associations between chondrocalcinosis (CC) and osteoarthritis (OA) at different joints, and to quantify such associations through meta-analysis.

METHODS

PubMed, Embase and Scopus databases were searched through from inception to June 2017. Cohort, case-control or cross-sectional studies were included if they examined the association between CC and OA. Data on the odds ratios (OR) and their 95% confidence intervals (CI) of the prevalence or progression of OA between the CC group and non-CC group with respect to the same joint were extracted.

RESULTS

A total of 14 studies were identified. Twelve studies were eligible for assessing the association between knee CC and knee OA. The combined data showed a positive association between them (OR = 2.84; 95% CI, 2.12-3.81; P < 0.001). Three studies were eligible for assessing the association between hip CC and hip OA. The data on the OR could only be extracted from one study (OR = 0.92; 95% CI, 0.68-1.24; P = 0.59). Two studies were eligible for assessing the association between hand CC and hand OA, and the data on the OR could only be extracted from one study which reported significant associations between CC and OA at the metacarpophalangeal joint (OR = 4.75; 95% CI, 2.12-10.64; P < 0.001) and the wrist joint (OR = 4.44; 95% CI, 3.56-5.54; P < 0.001).

CONCLUSION

This study established a strong association between knee CC and knee OA. However, the associations between CC and OA at the hip or hand still remain controversial and warrant further study.

Destructive pseudo-neuroarthropathy associated with calcium pyrophosphate deposition

BACKGROUND

Calcium pyrophosphate deposition (CPPD) disease is a metabolic disorder characterized by soft tissue calcific deposits formed primarily in articular cartilage. What can result is a crystal-induced arthropathy often referred to as pseudogout, which is variable in both presentation and severity. A particularly destructive and deforming arthritis is an uncommon but well-recognized subtype of this disease. Radiologically resembling the neuroarthropathy described by Charcot, a pattern of joint fragmentation and structural collapse occurs in the absence of peripheral neuropathy. This pseudo-neuroarthropathy is rarely reported in the foot and ankle.

METHODS

A total of 15 cases of pseudo-neuroarthropathy involving some previously unreported joints within the foot and ankle are described in this case series of 9 patients.

RESULTS

All patients presented with disease involving multiple joints. Clinical deformity was apparent in each case, and extensive joint destruction was seen on plain radiographs. In 6 patients, histopathological CPPD disease was confirmed on tissue biopsy of the affected joints. In the remaining 3 patients a clinical diagnosis was made on the basis of the classic appearance of pseudo-neuroarthropathy in the foot, with additional recognized features of CPPD. Operative management with deformity correction using joint arthrodesis produced satisfactory clinical and radiological results.

CONCLUSIONS

In the absence of peripheral neuropathy and systemic disease, the pseudo-neuroarthropathy of CPPD should be considered when a progressively deforming and destructive arthritis is seen in the foot and ankle.

LEVEL OF EVIDENCE

Level IV, case series.

Epidemiology of calcium pyrophosphate crystal arthritis and basic calcium phosphate crystal arthropathy

Calcium pyrophosphate crystal deposition (CPPD) is common and mainly associates with increasing age and osteoarthritis (OA). Recent studies suggest that CPPD occurs as the result of a generalized articular predisposition and may also associate with low cortical bone mineral density. The epidemiology of basic calcium phosphate (BCP) crystal deposition is poorly understood. Although periarticular BCP crystal deposits occurs at all ages and in both sexes, intra-articular BCP crystal deposition tends to associate with increasing age and OA. Calcium pyrophosphate and BCP crystals frequently coexist in joints with OA.

The association between ANKH promoter polymorphism and chondrocalcinosis is independent of age and osteoarthritis: results of a case-control study

Introduction

Chondrocalcinosis (CC) most commonly results from calcium pyrophosphate crystal deposition (CPPD). The objective of this study is to examine the association between candidate single-nucleotide polymorphisms (SNPs) and radiographic CC.

Methods

SNPs in ankylosis human (ANKH), high ferritin (HFE), tissue non-specific alkaline phosphatase (TNAP), ecto-neucleotide pyrophosphatase 1 (ENPP1), and transferrin (TE) genes were genotyped in participants of the Genetics of Osteoarthritis and Lifestyle (GOAL) and Nottingham Osteoarthritis Case-Control studies. Adjusted genotype odds ratio (aOR_GENOTYPE), the OR for association between one additional minor allele and CC, was calculated and adjusted for age, gender, body mass index (BMI), and osteoarthritis (OA) by using binary logistic regression. Statistical significance was set at P ≤0.003 after Bonferroni correction for multiple tests.

Results

The -4bpG > A polymorphism in the 5′ untranslated region (5′ UTR) of ANKH associated with CC after Bonferroni correction. This was independent of age, gender, OA, and BMI; aOR_GENOTYPE (95% confidence interval, or CI) was 1.39 (1.14-1.69) (P = 0.001). rs3045 and rs875525, two other SNPs in ANKH, associated with CC; aOR_GENOTYPE (95% CI) values were 1.31 (1.09-1.58) (P = 0.005) and 1.18 (1.03-1.35) (P = 0.015), respectively; however, this was non-significant after Bonferroni correction.

Conclusions

This study validates the association between a functional polymorphism in the 5′ UTR of ANKH and CC and shows for the first time that this is independent of age and OA – the two key risk factors for CC. It shows that other SNPs in ANKH may also associate with CC. This supports the role of extracellular inorganic pyrophosphate in the pathogenesis of CC. The findings of this hospital-based study require replication in a community-based population.

Diagnosis and clinical presentation of osteoarthritis

Osteoarthritis (OA), the commonest arthropathy, targets the knees, hips, finger interphalangeal joints, thumb bases, first metatarsophalangeal joints, and spinal facet joints, and displays marked heterogeneity of clinical presentation. Signs of OA include coarse crepitus, bony enlargement, reduced range of movement, and joint-line tenderness. Muscle wasting and joint deformity occur with severe OA. Painful periarticular disorders often coexist with OA. Inflammation is absent or only modest, although mild-moderate effusions are common at the knee. The diagnosis of OA may be made without recourse to radiographic or laboratory investigations in the at-risk age group with typical symptoms and signs.

Comparison of three imaging techniques in diagnosis of chondrocalcinosis of the knees in calcium pyrophosphate deposition disease

OBJECTIVE

To study the role of different imaging modalities, ultrasonography, conventional radiography (CR) and CT, in visualization of chondrocalcinosis of the knees in patients with CPDD.

METHODS

Twenty-five patients (14 males and 11 females) with CPDD were enrolled in the study. Diagnosis was made according to D.J. McCarty classification criteria. All patients had arthritis of the knee and underwent aspiration of SF from the knee and microscopic investigation of SF samples. Diagnosis of CPDD was crystal proven. Three imaging methods were performed in patients: CR, CT and US of the knees.

RESULTS

CR of the knee confirmed cartilage calcification (CC) in 13 patients, CT in 18 patients and US in 25 patients. No difference in age or disease duration between patients with CC detected by different imaging methods was found.

CONCLUSION

US appeared to be a helpful tool, possibly better than CR or CT, in revealing CC in patients with CPDD. Informativity of CT and CR in the detection of CC is almost equal.

Risk factors for pseudogout in the general population

Objective. To evaluate the association between the purported risk factors for chondrocalcinosis and gout and the risk of pseudogout in the general population. Methods. We conducted a case-control study nested within a UK general practice database (The Health Improvement Network) by identifying incident cases of pseudogout between 1986 and 2007 and up to 10 control subjects matched to each case, based on age, sex and follow-up time. We evaluated the purported risk factors for chondrocalcinosis (i.e. OA, RA, hyperparathyroidism and diuretics) and established risk factors for gout (as comparison exposures) using conditional logistic regression analysis. Results. We identified 795 cases of pseudogout and 7770 matched control subjects. The risk of pseudogout was associated with hyperparathyroidism [odds ratio (OR) 4.87; 95% CI 2.10, 11.3], OA (OR 2.91; 95% CI 2.48, 3.43) and loop diuretic use (OR 1.35; 95% CI 1.09, 1.67). RA, thiazide diuretic use, BMI and other gout risk factors were not associated with the risk of pseudogout, except for chronic renal failure (OR 2.29; 95% CI 1.30, 4.01). Conclusion. This general population study based on physician-recorded pseudogout suggests that most of the previously observed associations with chondrocalcinosis are replicable with the risk of pseudogout, but there are notable differences, such as thiazide diuretics, RA and chronic renal failure, highlighting the need to study the clinical outcome, pseudogout. Avoiding loop diuretics may help individuals with recurrent pseudogout.

Pathophysiology of articular chondrocalcinosis--role of ANKH

Calcium pyrophosphate (CPP) crystal deposition (CPPD) is associated with ageing and osteoarthritis, and with uncommon disorders such as hyperparathyroidism, hypomagnesemia, hemochromatosis and hypophosphatasia. Elevated levels of synovial fluid pyrophosphate promote CPP crystal formation. This extracellular pyrophosphate originates either from the breakdown of nucleotide triphosphates by plasma-cell membrane glycoprotein 1 (PC-1) or from pyrophosphate transport by the transmembrane protein progressive ankylosis protein homolog (ANK). Although the etiology of apparent sporadic CPPD is not well-established, mutations in the ANK human gene (ANKH) have been shown to cause familial CPPD. In this Review, the key regulators of pyrophosphate metabolism and factors that lead to high extracellular pyrophosphate levels are described. Particular emphasis is placed on the mechanisms by which mutations in ANKH cause CPPD and the clinical phenotype of these mutations is discussed. Cartilage factors predisposing to CPPD and CPP-crystal-induced inflammation and current treatment options for the management of CPPD are also described.

Genetic factors in the pathogenesis of CPPD crystal deposition disease

Crystal deposition is a very complex process ruled by numerous factors. A small but important proportion of cases of chondrocalcinosis are monogenic, and many of the genes involved have been identified. These genetic findings strongly point to control of the level of extracellular inorganic pyrophosphate as the primary mechanism for their association with either calcium pyrophosphate dihydrate or hydroxyapatite deposition. However, effects on extracellular inorganic pyrophosphate levels do not explain the mechanism of association in all of these monogenic diseases. Further, there are likely to be several as yet unidentified genes that are important in this common condition. This review highlights what genetic studies have demonstrated about the processes involved in these diverse but related disorders.

Angiogenesis in the synovium and at the osteochondral junction in osteoarthritis

OBJECTIVES

We hypothesised that osteochondral and synovial angiogenesis in osteoarthritis (OA) are independent processes. We investigated whether indices of osteochondral and synovial angiogenesis display different relationships with synovitis, disease severity and chondrocalcinosis in patients with OA.

DESIGN

Synovium and medial tibial plateaux were obtained from 62 patients undergoing total knee joint replacement for OA (18 [29%] had chondrocalcinosis) and from 31 recently deceased people with no evidence of joint pathology post-mortem (PM). Vascular endothelium, proliferating endothelial cells (ECs) and macrophages were quantified by immunohistochemistry for CD34, CD31/Ki67 and CD14, respectively. Grades were assigned for radiographic and histological OA disease severity, clinical disease activity and histological synovitis (based on cellular content of the synovium).

RESULTS

Blood vessels breached the tidemark in 60% of patients with OA and 20% of PM controls. Osteochondral vascular density increased with increasing cartilage severity and clinical disease activity scores, but not with synovitis. Synovial EC proliferation, inflammation and macrophage infiltration were higher in OA than in PM controls. Synovial angiogenesis indices increased with increasing histological synovitis, but were not related to osteochondral vascular density or other indices of OA disease severity. OA changes were more severe in patients with concurrent chondrocalcinosis. Chondrocalcinosis was not associated with increased angiogenesis or histological synovitis beyond that seen in OA alone.

CONCLUSION

Osteochondral and synovial angiogenesis appear to be independent processes. Osteochondral vascularity is associated with the severity of OA cartilage changes and clinical disease activity, whereas synovial angiogenesis is associated with histological synovitis. Modulation of osteochondral and synovial angiogenesis may differentially affect OA disease.

Update in calcium deposition diseases

PURPOSE OF REVIEW

Calcium pyrophosphate dihydrate and basic calcium phosphate crystals are common components of osteoarthritic synovial fluids and define subsets of patients with inflammatory or rapidly destructive arthritis. Recent literature concerning clinical and etiologic aspects of calcium pyrophosphate dihydrate and basic calcium phosphate crystal arthritis are reviewed.

RECENT FINDINGS

Recent literature reminds us of the propensity of calcium pyrophosphate dihydrate deposition disease to mimic other syndromes affecting the elderly. Several new studies reinforce the prevalence and significance of extra-articular calcium pyrophosphate dihydrate deposits, and demonstrate the presence of basic calcium phosphate-like whitlockite crystals in intervertebral discs. Current work serves to increase our appreciation for the complex role of the putative pyrophosphate transporter, ANKH, in healthy and diseased cartilage. The application of newer radiographic techniques to the diagnosis of calcium pyrophosphate dihydrate deposition disease holds promise for easier and more accurate identification of these crystal deposits in vivo. Work demonstrating the efficacy of a crystal poison in an animal model of osteoarthritis provides good evidence for a pathogenic role of calcium crystals in osteoarthritis, and hope for new therapies for these diseases.

SUMMARY

Continued work will further our understanding of these common crystals and their associated clinical syndromes.

Ectopic calcification among families in the Azores: clinical and radiologic manifestations in families with diffuse idiopathic skeletal hyperostosis and chondrocalcinosis

OBJECTIVE

Twelve families that were multiply affected with diffuse idiopathic skeletal hyperostosis (DISH) and/or chondrocalcinosis, were identified on the island of Terceira, The Azores, potentially supporting the hypothesis that the 2 disorders share common etiopathogenic factors. The present study was undertaken to investigate this hypothesis.

METHODS

One hundred three individuals from 12 unrelated families were assessed. Probands were identified from patients attending the Rheumatic Diseases Clinic, Hospital de Santo Espírito, in The Azores. Family members were assessed by rheumatologists and radiologists. Radiographs of all family members were obtained, including radiographs of the dorsolumbar spine, pelvis, knees, elbows, and wrists, and all cases were screened for known features of chondrocalcinosis.

RESULTS

Ectopic calcifications were identified in 70 patients. The most frequent symptoms or findings were as follows: axial pain, elbow, knee and metacarpophalangeal (MCP) joint pain, swelling, and/or deformity, and radiographic enthesopathic changes. Elbow and MCP joint periarticular calcifications were observed in 35 and 5 patients, respectively, and chondrocalcinosis was identified in 12 patients. Fifteen patients had sacroiliac disease (ankylosis or sclerosis) on computed tomography scans. Fifty-two patients could be classified as having definite (17%), probable (26%), or possible (31%) DISH. Concomitant DISH and chondrocalcinosis was diagnosed in 12 patients. Pyrophosphate crystals were identified from knee effusions in 13 patients. The pattern of disease transmission was compatible with an autosomal-dominant monogenic disease. The mean age at which symptoms developed was 38 years.

CONCLUSION

These families may represent a familial type of pyrophosphate arthropathy with a phenotype that includes peripheral and axial enthesopathic calcifications. The concurrence of DISH and chondrocalcinosis suggests a shared pathogenic mechanism in the 2 conditions.

Genetic studies of chondrocalcinosis

PURPOSE OF REVIEW

Our understanding of the causation of the chondrocalcinosis and other disorders characterized by ectopic mineralization is rapidly increasing, and genetic studies have contributed substantially to recent major advances in the field. This review will discuss what is known about the genetics of chondrocalcinosis and what we have learned from genetic studies to date.

RECENT FINDINGS

Chondrocalcinosis is one of a family of conditions associated with ectopic mineralization. This family also includes disorders of mineralization of bone and spinal and other ligaments, and vascular calcification. There has been increasing evidence of the key role of transport and metabolism of inorganic pyrophosphate (PPi) in control of mineralization, and as the likely explanation for the association of a variety of genetic variants with chondrocalcinosis and ectopic mineralization elsewhere. This may be an overly simplistic view of this family of conditions, with recent evidence suggesting that, for example, ANKH variants may not all predispose to chondrocalcinosis by effects on PPi transport, but may also influence chondrocyte maturation.

SUMMARY

Understanding the control of the process of mineralization and its tissue specificity are important steps in the search for rational therapies for these conditions.