Microanatomic studies to define predictive factors for the topography of periarticular erosion formation in inflammatory arthritis

Importance of tenosynovitis in preventing the progression through rheumatoid arthritis continuum

Rheumatoid arthritis (RA) has long been characterized by synovitis and bone erosions typically developing symmetrically in small joints. However, recent advances in imaging modalities have indicated frequent association of tenosynovitis with RA, and some consider tenosynovitis to be not just a complication but a major trait of RA. Furthermore, as there are cases with tenosynovitis preceding the clinical detection of inflammatory arthritis in predisposed individuals, tenosynovitis may constitute an important biomarker in defining the pre-RA phase of disease development. Tenosynovitis itself must be treated as it causes functional impairment and physical as well as socioeconomic burden, and its treatment may result in effective prevention of RA development at a pre-arthritic stage. Thus, further efforts need to be taken in detecting and treating tenosynovitis in the pre-RA stage, which can be facilitated by ultrasonography and magnetic resonance imaging.

The value of different involvement patterns of the knee "synovio-entheseal complex" in the differential diagnosis of spondyloarthritis, rheumatoid arthritis, and osteoarthritis: an MRI-based study

OBJECTIVES

To explore the different involvement patterns of the knee "synovio-entheseal complex (SEC)" on MRI in patients with spondyloarthritis (SPA), rheumatoid arthritis (RA), and osteoarthritis (OA).

METHODS

This study retrospectively included 120 patients (male:female, 55:65) with a mean age of 39.20 years diagnosed with SPA (n = 40), RA (n = 40), and OA (n = 40) at the First Central Hospital of Tianjin between January 2020 and May 2022. Six knee entheses were assessed by two musculoskeletal radiologists according to the SEC definition. Bone marrow lesions associated with entheses include bone marrow edema (BME) and bone erosion (BE), which were classified as entheseal or peri-entheseal based on their relationship to the entheses. Three groups (OA, RA, and SPA) were established to characterize the location of enthesitis and the different SEC involvement patterns. Inter-group and intra-group differences were analyzed using the ANOVA or chi-square tests, and the inter-class correlation coefficient (ICC) test was used to determine inter-reader agreement.

RESULTS

The study contained a total of 720 entheses. The SEC-based analysis revealed different involvement patterns in three groups. The OA group had the most abnormal signals in tendons/ligaments (p = 0.002). The RA group had considerably greater synovitis (p = 0.002). The majority of peri-entheseal BE was identified in the OA and RA groups (p = 0.003). Furthermore, entheseal BME in the SPA group was significantly different from those in the other two groups (p < 0.001).

CONCLUSIONS

SEC involvement patterns differed in SPA, RA, and OA, which is important for differential diagnosis. SEC should be used as a whole evaluation method in clinical practice.

KEY POINTS

• The "synovio-entheseal complex (SEC)" explained differences and characteristic alterations in the knee joint in patients with spondyloarthritis (SPA), rheumatoid arthritis (RA), and osteoarthritis (OA). • The various SEC involvement patterns are crucial for differentiating SPA, RA, and OA. • When "knee pain" is the only symptom, a detailed identification of characteristic alterations in the knee joint of SPA patients may help timely treatment and delay the structural damage.

Doppler Signal and Bone Erosions at the Enthesis Are Independently Associated With Ultrasound Joint Erosive Damage in Psoriatic Arthritis

OBJECTIVE

To explore the association of the Outcome Measures in Rheumatology ultrasound (US) entheseal abnormalities with the presence of US joint bone erosions in psoriatic arthritis (PsA).

METHODS

Consecutive patients with PsA were included in this cross-sectional study. Demographic and clinical variables were collected. A bilateral US assessment was carried out at the following entheses: plantar fascia, and the quadriceps, patellar (proximal and distal), and Achilles tendons. The following US entheseal abnormalities were registered: hypoechogenicity, thickening, Doppler signal < 2 mm from the bony cortex, calcification/enthesophyte, and bone erosion. The presence of US joint bone erosions was investigated at the second and fifth metacarpophalangeal joints, ulnar head, and fifth metatarsophalangeal (MTP) joint, bilaterally, as well as at the level of the most inflamed joint on physical examination. Multiple linear regression analysis was performed to identify clinical and/or US variables associated with US-detected joint bone erosions.

RESULTS

A total of 104 patients with PsA were enrolled. At least 1 joint bone erosion was found in 47 of 104 patients (45.2%). Bone erosions were most frequently detected at the fifth MTP joint level (42/208 joints [20.2 %] in 32/104 patients [30.8%]). In the multivariate model, only a power Doppler (PD) signal at the enthesis (P < 0.001, standardized β = 0.51), bone erosions at the enthesis (P = 0.02, standardized β = 0.20), PsA disease duration (P = 0.04, standardized β = 0.17), and greyscale joint synovitis (P = 0.03, standardized β = 0.42) were associated with US-detected joint bone erosions.

CONCLUSION

PD signal and bone erosions at the enthesis represent sonographic biomarkers of a more severe subset of PsA in terms of US-detected joint erosive damage.

Calcium-Permeable Channels Cooperation for Rheumatoid Arthritis: Therapeutic Opportunities

Rheumatoid arthritis is a common autoimmune disease that results from the deposition of antibodies–autoantigens in the joints, leading to long-lasting inflammation. The main features of RA include cartilage damage, synovial invasion and flare-ups of intra-articular inflammation, and these pathological processes significantly reduce patients’ quality of life. To date, there is still no drug target that can act in rheumatoid arthritis. Therefore, the search for novel drug targets has become urgent. Due to their unique physicochemical properties, calcium ions play an important role in all cellular activities and the body has evolved a rigorous calcium signaling system. Calcium-permeable channels, as the main operators of calcium signaling, are widely distributed in cell membranes, endoplasmic reticulum membranes and mitochondrial membranes, and mediate the efflux and entry of Ca2+. Over the last century, more and more calcium-permeable channels have been identified in human cells, and the role of this large family of calcium-permeable channels in rheumatoid arthritis has gradually become clear. In this review, we briefly introduce the major calcium-permeable channels involved in the pathogenesis of RA (e.g., acid-sensitive ion channel (ASIC), transient receptor potential (TRP) channel and P2X receptor) and explain the specific roles and mechanisms of these calcium-permeable channels in the pathogenesis of RA, providing more comprehensive ideas and targets for the treatment of RA.

Topography of Bone Erosions at the Metatarsophalangeal Joints in Rheumatoid Arthritis: Bilateral Mapping by Computed Tomography

OBJECTIVES

To describe the bilateral anatomical location of bone erosions (BE) at the metatarsophalangeal joints in patients with rheumatoid arthritis using computed tomography.

MATERIALS AND METHODS

Eighteen consecutive patients with established rheumatoid arthritis prospectively underwent computed tomography of both forefeet. Each joint surface of the metatarsal heads (MTH) and the proximal phalangeal bases were divided into four quadrants: superior, plantar, tibial, and fibular. The number of BE was cumulatively counted per patient, side, joint, per joint surface, and quadrant. Descriptive statistics, paired and unpaired samples t-tests, Pearson's correlation coefficients, ANOVA 2, and variance component analysis were performed.

RESULTS

There were 288 BE at the MTH and 66 at the proximal phalanges. The number of BE in one forefoot was a poor predictor of the absolute number of BE on the contralateral foot "r=0.54" and was unrelated to symptoms. The superior quadrants were less frequently affected than other quadrants for both the MTH "p<0.0001" and proximal phalanges "p<0.001." The tibial quadrant showed a higher number of BE compared to all other quadrants for MTH "p<0.03," proximal phalanges "p<0.01, and for the metatarsophalangeal joint as a whole "p<0.0001." Plantar and fibular quadrants were equally affected "p<0.05."

CONCLUSION

BE were found more frequently on the tibial side of the MTH in patients with rheumatoid arthritis.

[Rheumatoid arthritis of the hand : Part 1: Clinical aspects]

BACKGROUND

All rheumatic autoimmune diseases are associated with arthritis of the hands, whereby it is possible to differentiate between typical and atypical arthritis patterns, which are key for diagnosis. Rheumatoid arthritis is commonly associated with synovitis of the hands. While patients with disease duration of less than 2 years were previously considered to have early disease, unfavorable prognosis with delayed initiation of therapy has reduced this time frame to 3 months after symptom onset.

OBJECTIVE

The aim is to provide radiologists with a systematic description of the clinical aspects of rheumatoid arthritis in order to better understand this entity so that they can confidently recognize arthritis patterns in the hands at an early stage.

MATERIALS AND METHODS

Narrative review based on the current literature on the subject from radiological and rheumatological point of view.

RESULTS

Synovitis of the hands is a common manifestation in rheumatoid arthritis. Knowledge of the epidemiology, prevalence, incidence, pathogenesis, genetics, etiology, biology and immunology, serology, histology, clinical presentation, the classification and diagnostic criteria, and therapy is essential for the radiologist to better understand the image-based morphologic changes associated with this complex disease and thereby gain greater confidence in the diagnosis of early stages.

CONCLUSIONS

For the diagnosis of rheumatoid arthritis, the radiologist must be familiar with basic clinical knowledge to confidently analyze the patterns present in arthritis of the hands at initial diagnosis and during the course of the disease, which are essential for therapy decisions.

DGEMRIC in the Assessment of Pre-Morphological Cartilage Degeneration in Rheumatic Disease: Rheumatoid Arthritis vs. Psoriatic Arthritis

Background: Even though cartilage loss is a known feature of psoriatic (PsA) and rheumatoid arthritis (RA), research is sparse on its role in the pathogenesis of PsA, its potential use for disease monitoring and for differentiation from RA. We therefore assessed the use of delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) to evaluate biochemical cartilage changes in metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints in PsA patients and compared these to RA patients. Materials and Methods: A total of 17 patients with active PsA and 20 patients with active RA were evaluated by high-resolution 3 Tesla dGEMRIC using a dedicated 16-channel hand coil. Images were analyzed by two independent raters for dGEMRIC indices and joint space width (JSW) at MCP and PIP joint levels. Results: No significant differences of dGEMRIC values could be found between both study populations (PsA 472.25 ms, RA 461.11 ms; p = 0.763). In all RA and most PsA patients, PIP joints showed significantly lower dGEMRIC indices than MCP joints (RA: D2: p = 0.009, D3: p = 0.008, D4: p = 0.002, D5: p = 0.002; PsA: D3: p = 0.001, D4: p = 0.004). Most joint spaces had similar widths in both disease entities and no significant differences were found. Conclusions: As evaluated by dGEMRIC, the molecular composition of the MCP and PIP joint cartilage of PsA patients is similar to that of RA patients, demonstrating the scientific and clinical feasibility of compositional magnetic resonance (MR) imaging in these disease entities. Patterns and severity of compositional cartilage degradation of the finger joints may therefore be assessed beyond mere morphology in PsA and RA patients.

Persistent inflammatory and non-inflammatory mechanisms in refractory rheumatoid arthritis

Despite nearly three decades of advances in the management of rheumatoid arthritis (RA), a substantial minority of patients are exposed to multiple DMARDs without necessarily benefitting from them; a group of patients variously designated as having 'difficult to treat', 'treatment-resistant' or 'refractory' RA. This Review of refractory RA focuses on two types of patients: those for whom multiple targeted therapies lack efficacy and who have persistent inflammatory pathology, which we designate as persistent inflammatory refractory RA (PIRRA); and those with supposed refractory RA who have continued disease activity that is predominantly independent of objective evidence of inflammation, which we designate as non-inflammatory refractory RA (NIRRA). These two types of disease are not mutually exclusive, but identifying those individuals with predominant PIRRA or NIRRA is important, as it informs distinct treatment and management approaches. This Review outlines the clinical differences between PIRRA and NIRRA, the genetic and epigenetic mechanisms and immune pathways that might contribute to the immunopathogenesis of recalcitrant synovitis in PIRRA, and a possible basis for non-inflammatory symptomatology in NIRRA. Future approaches towards the definition of refractory RA and the application of single-cell and integrated omics technologies to the identification of refractory RA endotypes are also discussed.

Arthritis and the role of endogenous glucocorticoids

Rheumatoid arthritis and osteoarthritis, the most common forms of arthritis, are chronic, painful, and disabling conditions. Although both diseases differ in etiology, they manifest in progressive joint destruction characterized by pathological changes in the articular cartilage, bone, and synovium. While the potent anti-inflammatory properties of therapeutic (i.e., exogenous) glucocorticoids have been heavily researched and are widely used in clinical practice, the role of endogenous glucocorticoids in arthritis susceptibility and disease progression remains poorly understood. Current evidence from mouse models suggests that local endogenous glucocorticoid signaling is upregulated by the pro-inflammatory microenvironment in rheumatoid arthritis and by aging-related mechanisms in osteoarthritis. Furthermore, these models indicate that endogenous glucocorticoid signaling in macrophages, mast cells, and chondrocytes has anti-inflammatory effects, while signaling in fibroblast-like synoviocytes, myocytes, osteoblasts, and osteocytes has pro-inflammatory actions in rheumatoid arthritis. Conversely, in osteoarthritis, endogenous glucocorticoid signaling in both osteoblasts and chondrocytes has destructive actions. Together these studies provide insights into the role of endogenous glucocorticoids in the pathogenesis of both inflammatory and degenerative joint disease.

Differentiating Rheumatoid and Psoriatic Arthritis of the Hand: Multimodality Imaging Characteristics

Accurate diagnosis and therapeutic intervention at an early stage is paramount for the management of rheumatoid arthritis (RA) and psoriatic arthritis (PsA), which are the two major types of inflammatory arthritis that involve the hand joints. As more disease-specific medications are developed, medication selection according to the correct diagnosis becomes more important. A delay in diagnosis and inappropriate medication selection may result in poor functional prognosis. However, clinical differentiation between RA and PsA can be challenging and may become largely dependent on imaging interpretation results. Although there is substantial overlap in the imaging findings of RA and PsA, there are differences in the affected primary target sites, reflected by the various patterns of joint involvement, and different microanatomic localization of abnormalities within a single joint in each disease. Therefore, appropriate use of various imaging modalities and accurate image interpretation add significant value to the diagnosis and treatment process. The synovio-entheseal complex is an important concept for understanding the imaging features of PsA. The authors review the different features of RA and PsA of the hands seen with various imaging modalities, including radiography, US, MRI, and dual-energy CT, with updates on the contemporary role of imaging in diagnosis and treatment. The radiologist should have sufficient knowledge to interpret imaging findings and understand the strengths and weaknesses of each modality to recommend the appropriate imaging method and differentiate both diseases accurately. ^©RSNA, 2020.

Proteoglycan loss in the articular cartilage is associated with severity of joint inflammation in psoriatic arthritis-a compositional magnetic resonance imaging study

Background

Even though cartilage loss is a known feature of psoriatic arthritis (PsA), little is known about its role in the pathogenesis of PsA. Using delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) as a non-invasive marker of the tissue’s proteoglycan content, such early (i.e., pre-morphological) changes have been associated with inflammation in rheumatoid arthritis (RA). Yet, this association has not been studied before in PsA.

Methods

The metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints of 17 patients with active PsA were evaluated by high-resolution clinical standard morphological and dGEMRIC sequences using a 3T MRI scanner (Magnetom Skyra, Siemens) and a dedicated 16-channel hand coil. Images were analyzed by two independent raters for dGEMRIC indices, PsA MRI scores (PsAMRIS), and total cartilage thickness (TCT). Kendall tau correlation coefficients (τ) were calculated.

Results

We found significant negative correlations between dGEMRIC indices and total PsAMRIS (τ = − 0.5, p = 0.012), synovitis (τ = − 0.56, p = 0.006), flexor tenosynovitis (τ = − 0.4, p = 0.049), and periarticular inflammation (τ = − 0.72, p < 0.001). Significant positive correlations were found between TCT and dGEMRIC indices at all joint levels (τ = 0.43, p < 0.001). No significant correlations were determined between dGEMRIC indices and bone erosion, bone edema, or bone proliferation.

Conclusion

In PsA, proteoglycan loss as assessed by dGEMRIC is associated with periarticular inflammation, synovitis, and flexor tenosynovitis, but not with bone erosion or proliferation. Thereby, these findings contribute to in vivo concepts of the disease’s pathophysiology. Beyond morphology, advanced MRI techniques may be used to assess cartilage composition in PsA and to identify early changes in the cartilage as an imaging biomarker with potential application in detection, monitoring, and prediction of outcomes of PsA.

Trial registration

2014123117, December 2014.

A Comparative Study of High-Resolution Chemical-Shift-Eliminated Magnetic Resonance Imaging of Finger Specimens with Microcomputed Tomography

Objective:

High-resolution images of finger joints with chemical-shift elimination can be obtained using an interleaved water-fat (IWF) sequence. This study assessed IWF imaging of finger joints in the delineation of bone structures by comparing images of cadaver fingers with those of microcomputed tomography (CT) that served as a standard reference.

Materials and Methods:

IWF images with spatial resolution of 176 µ × 176 µ × 300 µ were obtained from the distal and proximal interphalangeal joints of two cadaver finger specimens using a custom-built radiofrequency receive coil at 1.5T. Regular three-dimensional gradient-echo (GRE) images were also acquired with similar parameters and compared with the IWF images to evaluate the effects of chemical shift. Micro-CT scans were obtained and served as the standard reference. The image data were reviewed by two experienced musculoskeletal radiologists in consensus. The delineation of normal joint structures and abnormalities in the finger specimens as revealed by the magnetic resonance imaging (MRI) and micro-CT images were compared. The IWF and regular GRE images were assigned scores 0–3 for the depiction of apparent marginal bone defects, with zero being the same in appearance to the micro-CT image and three as having minimal resemblance to it. Statistical analysis of the scoring results was conducted to compare the two MRI techniques.

Results:

The high-resolution IWF images provided accurate delineation of bone and calcified structures as seen in micro-CT. The thickness of subchondral bone was depicted similarly on the IWF water + fat and the micro-CT images but not on the regular GRE images. The regular GRE sequence showed false marginal bone defects not observed with IWF and micro-CT. In addition, the IWF water-only images facilitated the identification of bone cyst by revealing its water content.

Conclusion:

High-resolution IWF imaging should be useful for the early diagnosis and treatment assessment of arthritis and should also benefit basic research in the pathophysiology of the disease.

The ageing joint-standard age- and sex-related values of bone erosions and osteophytes in the hand joints of healthy individuals

OBJECTIVE

To analyze the age-related changes of the physiological hand joint architecture.

METHOD

To address this concept, healthy individuals (each 10 women and 10 men in six different age decades spanning from 21 to 80 years) were recruited through a field campaign, investigated for the absence of rheumatic diseases and other comorbidities and received high-resolution quantitative computed tomography (HR-pQCT) examination of the hand joints. Number and extent of erosions and osteophytes were quantified across the ages and different sexes.

RESULTS

Bone erosions [median (Q1-Q3), 1 (0-2)] and osteophytes [2 (1-4)] were found in healthy women and men with no significant sex differences. Structural changes however accumulated with age: the overall incidence rate ratio (IRR) for the number of erosions and osteophytes per age were 1.04 (95% CI: erosions 1.03-1.06; osteophytes: 1.03-1.05). This means a 4% increase in the number of erosions and osteophytes per year. Using third decade as reference, healthy individuals in the age decades from 50 years had higher IRR for erosion numbers (sixth, seventh, eigth decade: 4.87 (2.20-11.75), 6.81 (3.08-16.46) and 6.92 (3.11-16.79)) compared to younger subjects (fourth, fifth decade: 1.80 (0.69-4.87), 1.53 (0.59-4.10)). The IRRs of osteophytes also indicate a gradual increase after the fifth decade, with IRRs of 2.32 (1.32-4.17), 4.17 (2.38-7.49) and 6.86 (3.97-12.20) for the sixth, seventh and eigth decades, respectively.

CONCLUSIONS

Structural changes in the hand joints of healthy individuals are age dependent. While being rare under 50 years of age, erosions and osteophytes accumulate above the age of 50, suggesting that the threshold between "normal" and "pathological" is shifted with the increase of age.

Development of a scoring method to visually score cortical interruptions on high-resolution peripheral quantitative computed tomography in rheumatoid arthritis and healthy controls

Objectives

To develop a scoring method to visually score cortical interruptions in finger joints on High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT), determine its intra- and inter-reader reliability and test its feasibility.

Methods

The scoring method was developed by integrating results from in-depth discussions with experts, consensus meetings, multiple reading experiments and the literature. Cortical interruptions were scored by two independent readers in an imaging dataset with finger joints from patients with rheumatoid arthritis (RA) and healthy controls and assessed for adjacent trabecular distortion. Reliability for the total number of cortical interruptions per joint and per quadrant was calculated using intraclass correlation coefficient (ICC). Feasibility was tested by recording the time to analyze one joint.

Results

In 98 joints we identified 252 cortical interruptions, 17% had trabecular distortion. Mean diameter of the interruptions was significantly larger in patients with RA compared with healthy controls (0.88 vs 0.47 mm, p = 0.03). Intra-reader reliability was ICC 0.88 (95% CI 0.83;0.92) per joint and ICC 0.69 (95% CI 0.65;0.73) per quadrant. Inter-reader reliability was ICC 0.48 (95% CI 0.20;0.67) per joint and ICC 0.56 (95% CI 0.49;0.62) per quadrant. The time to score one joint was mean 9.2 (SD 4.9) min.

Conclusions

This scoring method allows detection of small cortical interruptions on HR-pQCT imaging of finger joints, which is promising for use in clinical studies.

Skeletal complications of rheumatoid arthritis

Rheumatoid arthritis (RA) is associated with local and systemic inflammation that induces many changes in the skeletal health. Locally, periarticular bone loss and juxta-articular bone erosions may occur while joint ankylosis, generalized bone loss, osteoporosis, and fractures may develop secondary to inflammation. The aim of this narrative review is to summarize the clinical evidence for abnormal skeletal health in RA, the effects of disease modifying anti-rheumatic drugs (DMARDS) on bone health, and the effects of drugs for the prevention or treatment of osteoporosis in the RA population.

Early Changes of the Cortical Micro-Channel System in the Bare Area of the Joints of Patients With Rheumatoid Arthritis

OBJECTIVE

To characterize the specific structural properties of the erosion-prone bare area of the human joint, and to search for early microstructural changes in this region during rheumatoid arthritis (RA).

METHODS

In the initial part of the study, human cadaveric hand joints were examined for exact localization of the bare area of the metacarpal heads, followed by detection of cortical micro-channels (CoMiCs) in this region by high-resolution peripheral quantitative computed tomography (HR-pQCT) and, after anatomic dissection, validation of the presence of CoMiCs by micro-computed tomography (micro-CT). In the second part of the study, the number and distribution of CoMiCs were analyzed in 107 RA patients compared to 105 healthy individuals of similar age and sex distribution.

RESULTS

Investigation by HR-pQCT combined with adaptive thresholding allowed the detection of CoMiCs in the bare area of human cadaveric joints. The existence of CoMiCs in the bare area was additionally validated by micro-CT. In healthy individuals, the number of CoMiCs increased with age. RA patients showed significantly more CoMiCs compared to healthy individuals (mean ± SD 112.9 ± 54.7/joint versus 75.2 ± 41.9/joint; P < 0.001), with 20-49-year-old RA patients exhibiting similar numbers of CoMiCs as observed in healthy individuals older than age 65 years. Importantly, CoMiCs were already found in RA patients very early in their disease course, with enrichment in the erosion-prone radial side of the joint.

CONCLUSION

CoMiCs represent a new form of structural change in the joints of patients with RA. Although the number of CoMiCs increases with age, RA patients develop CoMiCs much earlier in life, and such changes can even occur at the onset of the disease. CoMiCs therefore represent an interesting new opportunity to assess structural changes in RA.

Heterogeneity of Cortical Breaks in Hand Joints of Patients with Rheumatoid Arthritis and Healthy Controls Imaged by High-resolution Peripheral Quantitative Computed Tomography

Objective.

Conventional radiographs (CR) of the hands are the gold standard for imaging bone erosions. The presence of bone erosions, reflected by the presence of cortical breaks, is a poor prognostic factor in patients with rheumatoid arthritis (RA). The availability of high-resolution peripheral quantitative computed tomography (HR-pQCT) enables detailed investigation of cortical breaks in rheumatic diseases. The aim of this image review is to show HR-pQCT images of the spectrum of cortical breaks with and without underlying trabecular bone changes in metacarpophalangeal (MCP) joints of healthy controls (HC) and patients with RA, with corresponding images on CR and magnetic resonance imaging (MRI).

Methods.

Second and third MCP joints of 41 patients (of which 10 were early RA with ≤ 2 years and 24 longstanding RA with ≥ 10 years of disease duration) and 38 HC were imaged by CR, MRI, and HR-pQCT (XtremeCT1, Scanco Medical AG). Representative images of the spectrum of cortical breaks were selected.

Results.

Cortical breaks were found in early and longstanding RA, but also in HC. They were heterogeneous in size, location, and number per joint, with a variety of surrounding cortical and underlying trabecular bone characteristics.

Conclusion.

Using HR-pQCT images of MCP joints, heterogeneous cortical breaks with and without surrounding trabecular bone changes were found, not only in RA but also in HC. The underlying mechanisms and significance of this spectrum of cortical breaks as found with high 3-D resolution needs further investigation.

Analysis of periarticular bone changes in patients with cutaneous psoriasis without associated psoriatic arthritis

Objectives

To search for structural bone changes in the joints of psoriasis patients without psoriatic arthritis (PsA).

Methods

55 psoriasis patients without any current or past symptoms of arthritis or enthesitis and 47 healthy controls were examined by high-resolution peripheral quantitative CT scans of the metacarpophalangeal joints. Number, size and exact localisation of erosions and enthesiophytes were recorded by analysing axial scans of the metacarpal heads and phalangeal bases and were confirmed in additional coronal and/or sagittal sections. In addition, we collected demographic and clinical data including subtype, duration and severity of psoriasis.

Results

Psoriasis patients showed a larger and significantly increased number of enthesiophytes (total number 306; mean±SD/patient 5.62±3.30) compared with healthy controls (total number 138; mean±SD/patient 3.04±1.81, p<0.001). Enthesiophytes were typically found at the dorsal and palmar sides of the metacarpal heads where functional entheses related to extensor and flexor tendons are localised. Bone erosions were rare and not significantly different between psoriasis patients and healthy controls. If present, erosions were almost exclusively found at the radial side of the second metacarpal head in both psoriasis patients and healthy controls.

Conclusions

Psoriasis patients without PsA show substantial signs of enthesiophyte formation compared with healthy controls. These changes represent new bone formation at mechanically exposed sites of the joint and substantiate the concept of the existence of a ‘Deep Koebner Phenomenon’ at enthesial sites in psoriasis patients.

Role of vascular channels as a novel mechanism for subchondral bone damage at cruciate ligament entheses in osteoarthritis and inflammatory arthritis

OBJECTIVES

The purpose of this work was to test whether normal peri-entheseal vascular anatomy at anterior and posterior cruciate ligaments (ACL and PCL) was associated with distribution of peri-entheseal bone erosion/bone marrow lesions (BMLs) in inflammatory arthritis (IA) and osteoarthritis (OA).

METHODS

Normal microanatomy was defined histologically in mice and by 3 T MRI and histology in 21 cadaveric knees. MRI of 89 patients from the Osteoarthritis Initiative and 27 patients with IA was evaluated for BMLs at ACL and PCL entheses. Antigen-induced arthritis (AIA) in mice was evaluated to ascertain whether putative peri-entheseal vascular regions influenced osteitis and bone erosion.

RESULTS

Vascular channels penetrating cortical bone were identified in knees of non-arthritic mice adjacent to the cruciate ligaments. On MRI of normal cadavers, vascular channels adjacent to the ACL (64% of cases) and PCL (71%) entheses were observed. Histology of 10 macroscopically normal cadaveric specimens confirmed the location of vascular channels and associated subclinical changes including subchondral bone damage (80% of cases) and micro-cyst formation (50%). In the AIA model, vascular channels clearly provided a site for inflammatory tissue entry and osteoclast activation. MRI showed BMLs in the same topographic locations in both patients with early OA (41% ACL, 59% PCL) and IA (44%, 33%).

CONCLUSION

The findings show that normal ACL and PCL entheses have immediately adjacent vascular channels which are common sites of subtle bone marrow pathology in non-arthritic joints. These channels appear to be key determinants in bone damage in inflammatory and degenerative arthritis.

Anatomical location of erosions at the metatarsophalangeal joints in patients with rheumatoid arthritis

OBJECTIVE

The aim of this study was to identify the anatomical location of erosions at the MTP joints in patients with RA using high-resolution 3T MRI.

METHODS

In 24 patients with RA, the more symptomatic forefoot was imaged using 3T MRI. T1-weighted, intermediate-weighted and T2-weighted fat-suppressed sequences were acquired through the MTP joints, together with three-dimensional volumetric interpolated breath-hold examination (3D VIBE) and T1-weighted fat-suppressed post-gadolinium contrast sequences. Images were scored for bone erosion in the distal and proximal part of the MTP joints using the RA MRI scoring (RAMRIS) system. The base of the proximal phalanx and the head of the metatarsal were divided into quadrants to determine the location of erosions (octants) in the dorsal-medial, dorsal-lateral, plantar-medial and plantar-lateral regions.

RESULTS

Seventeen females and seven males with a mean age of 55.5 years and disease duration of 10.6 years (range 0.6-36) were included. Eighteen patients were RF positive, the mean 44-joint DAS for CRP and ESR (DAS44CRP and DAS44ESR) were 2.5 (s.d. 0.8) and 2.6 (s.d. 0.9), respectively. In this cohort of patients with RA, irrespective of MTP joint location, octants located in the proximal part (metatarsal) of the joint and the plantar aspect of the joint were more eroded.

CONCLUSION

This is the first study to report the anatomical location of erosions at the MTP joints in patients with RA. We noted that erosions were more commonly seen on the plantar aspect of the metatarsal head in RA, supporting the hypothesis of a relationship between biomechanical demands and bone changes in the forefoot.

The specificity of ultrasound-detected bone erosions for rheumatoid arthritis

BACKGROUND

Bone erosion is one of the hallmarks of rheumatoid arthritis (RA), but also seen in other rheumatic diseases. The objective of this study was to determine the specificity of ultrasound (US)-detected bone erosions (including their size) in the classical 'target' joints for RA.

METHODS

Patients fulfilling the diagnostic criteria for RA, psoriatic arthritis, osteoarthritis or gout in addition to healthy volunteers were included. The following areas were examined by US: distal radius and ulna, 2nd, 3rd and 5th metacarpophalangeal (MCP), 2nd and 3rd proximal interphalangeal (PIP) and 1st and 5th metatarsophalangeal (MTP) joints. All joints were scanned in four quadrants using both semiquantitative (0-3) and quantitative (erosion diameter) scoring systems.

RESULTS

310 subjects were recruited. The inter-reader and intrareader agreements were good to excellent. US-detected bone erosions were more frequent but not specific for RA (specificity 32.9% and sensitivity 91.4%). The presence of erosions with semiquantitative score ≥2 in four target joints (2nd, 5rd MCP, 5th MTP joints and distal ulna) was highly specific for RA (specificity 97.9% and sensitivity 41.4%). Size of erosion was found to be associated with RA. Erosions of any size in the 5th MTP joint were both specific and sensitive for RA (specificity 85.4% and sensitivity 68.6%).

CONCLUSIONS

The presence of US-detected erosions is not specific for RA. However, larger erosions in selected joints, especially 2nd and 5rd MCP, 5th MTP joints and distal ulna, were highly specific for and predictive of RA.

Prospective assessment of bone texture parameters at the hand in rheumatoid arthritis

OBJECTIVE

Fractal bone analysis (Hmean) is a texture parameter reflecting bone microarchitecture. The BMA device (D3A™ Medical Systems, Orléans, France) is a high-resolution X-ray device that allows assessment of bone texture analysis. We aimed to measure Hmean in rheumatoid arthritis patients at the second and third metacarpal bones, at baseline and after 1 year of follow-up, and to assess the relationship of Hmean and rheumatoid arthritis disease parameters.

METHODS

Patients with rheumatoid arthritis according to ACR criteria were included. They were assessed over 1 year, in the context of a prospective study conducted in Maastricht. For this substudy, activity of the disease was assessed by erythrocyte sedimentation rate, C-reactive protein and Disease Activity Score 28 performed at each visit. Radiographic bone damage was assessed using hand and feet radiographs at baseline and on a 1-year basis. The bone texture parameters were evaluated on the second and third metacarpal heads of the left hand using BMA device.

RESULTS

One hundred and sixty-five rheumatoid arthritis patients were included in this study. At baseline, Hmean was negatively correlated with age [r=-0.22 (P=0.013)] and erythrocyte sedimentation rate [r=-0.16 (P=0.039)]. No significant correlation was found between Hmean and Disease Activity Score, disease activity Visual Analog Scale, daily corticosteroid dose and C-reactive protein. There was a significant increase in Hmean of second and third metacarpal bones over 1 year (1.6% and 1.3%, P<0.01) except in patients with local second and third metacarpal bones erosion.

CONCLUSION

The bone texture parameter Hmean is influenced by age, inflammation and local erosions in rheumatoid arthritis.

Bone erosion in rheumatoid arthritis: mechanisms, diagnosis and treatment

Bone erosion is a central feature of rheumatoid arthritis and is associated with disease severity and poor functional outcome. Erosion of periarticular cortical bone, the typical feature observed on plain radiographs in patients with rheumatoid arthritis, results from excessive local bone resorption and inadequate bone formation. The main triggers of articular bone erosion are synovitis, including the production of proinflammatory cytokines and receptor activator of nuclear factor κB ligand (RANKL), as well as antibodies directed against citrullinated proteins. Indeed, both cytokines and autoantibodies stimulate the differentiation of bone-resorbing osteoclasts, thereby stimulating local bone resorption. Although current antirheumatic therapy inhibits both bone erosion and inflammation, repair of existing bone lesions, albeit physiologically feasible, occurs rarely. Lack of repair is due, at least in part, to active suppression of bone formation by proinflammatory cytokines. This Review summarizes the substantial progress that has been made in understanding the pathophysiology of bone erosions and discusses the improvements in the diagnosis, monitoring and treatment of such lesions.

The role of RANK ligand/osteoprotegerin in rheumatoid arthritis

In the complex system of bone remodeling, the receptor activator of nuclear factor κB ligand (RANKL)/osteoprotegerin (OPG) pathway is the coupling factor between bone formation and bone resorption. RANKL binds to the RANK receptor of pre-osteoclasts and mature osteoclasts and stimulates their activation and differentiation. The production of RANKL/OPG by osteoblasts is influenced by hormones, growth factors and cytokines, which each have a different effect on the production of RANKL and OPG. Ultimately, the balance between RANKL and OPG determines the degree of proliferation and activity of the osteoclasts. In rheumatoid arthritis (RA), bone erosions are the result of osteoclastic bone resorption at the sites of synovitis, where RANKL expression is also found. Furthermore, magnetic resonance imaging (MRI) bone edema in RA indicates the presence of active inflammation within bone and the presence of osteitis, which is also associated with the expression of RANKL. Bone loss has been documented in the cortical and trabecular bone in the joints of the hand of RA patients. Both synovitis and periarticular bone involvement (osteitis and bone loss) are essential components of RA: they occur early in the disease and both are predictive for the occurrence and progression of bone damage. RANKL knockout mice and mice treated with OPG did not develop focal bone loss, in spite of persistent joint inflammation. Inhibition of osteoclasts by denosumab, a humanized antibody that selectively binds RANKL, has revealed in patients with RA that the occurrence of erosions and periarticular bone loss can be halted, however without affecting synovial inflammation. This disconnect between inflammation and bone destruction opens new ways to separately focus treatment on inflammation and osteoclastogenesis for preventing and/or minimizing the connection between joints and subchondral bone and bone marrow.

Joint appendages: the structures which have historically been overlooked in arthritis research and therapy development

Rheumatologists have largely conceptualised joint disease in inflammatory and degenerative arthritis in terms of bone, cartilage and the synovial lining, but have tended to overlook other integral components of the joints which are attached close to joint margins. We discuss these structures under the umbrella term of 'appendages'. These structures include ligaments, tendons, entheses or joint insertions, regional fibrocartilages, bursae and other peri-articular joint structures including fat pads and nails. In this review, we highlight how these structures play key pathophysiological roles in inflammatory arthritis and we emphasise how an understanding of these structures is collectively important for both clinical practice and future rheumatological research.

Osteoimmunology and osteoporosis

The concept of osteoimmunology is based on growing insight into the links between the immune system and bone at the anatomical, vascular, cellular, and molecular levels. In both rheumatoid arthritis (RA) and ankylosing spondylitis (AS), bone is a target of inflammation. Activated immune cells at sites of inflammation produce a wide spectrum of cytokines in favor of increased bone resorption in RA and AS, resulting in bone erosions, osteitis, and peri-inflammatory and systemic bone loss. Peri-inflammatory bone formation is impaired in RA, resulting in non-healing of erosions, and this allows a local vicious circle of inflammation between synovitis, osteitis, and local bone loss. In contrast, peri-inflammatory bone formation is increased in AS, resulting in healing of erosions, ossifying enthesitis, and potential ankylosis of sacroiliac joints and intervertebral connections, and this changes the biomechanical competence of the spine. These changes in bone remodeling and structure contribute to the increased risk of vertebral fractures (in RA and AS) and non-vertebral fractures (in RA), and this risk is related to severity of disease and is independent of and superimposed on background fracture risk. Identifying patients who have RA and AS and are at high fracture risk and considering fracture prevention are, therefore, advocated in guidelines. Local peri-inflammatory bone loss and osteitis occur early and precede and predict erosive bone destruction in RA and AS and syndesmophytes in AS, which can occur despite clinically detectable inflammation (the so-called 'disconnection'). With the availability of new techniques to evaluate peri-inflammatory bone loss, osteitis, and erosions, peri-inflammatory bone changes are an exciting field for further research in the context of osteoimmunology.

MR findings of synovial disease in children and young adults: Part 1

Synovial diseases in children can be classified into normal structures as potential sources of pathology (synovial folds: plicae, infrapatellar fat pad clefts); noninfectious synovial proliferation (juvenile idiopathic arthritis, hemophilic arthropathy, lipoma arborescens, synovial osteochondromatosis, pigmented villonodular synovitis, reactive synovitis), and infectious synovial proliferation, deposition disease, vascular malformations, malignancy (including metastasis) and intra-articular/periarticular cysts and cyst-like structures (ganglia). Familiarity with characteristic MR imaging findings of synovial diseases in children and young adults will enable a more confident diagnosis for earlier intervention and directed therapy. The first part of this paper will cover potential pathology of normal synovial structures as well as noninfectious synovial proliferation.

Use of tomosynthesis for erosion evaluation in rheumatoid arthritic hands and wrists

PURPOSE

To compare tomosynthesis with radiography for the detection of hand and wrist bone erosions in patients with rheumatoid arthritis (RA), using multidetector computed tomography (CT) as the reference method.

MATERIALS AND METHODS

The study was approved by the local ethics committee, and written consent was obtained from all patients. From December 2008 to April 2009, 30 consecutive patients with RA were included in this prospective study. They underwent radiography, tomosynthesis, and CT of the most symptomatic hand and wrist on the same day. Two radiologists and one rheumatologist independently read images from the three imaging modalities.

RESULTS

A total of 232 erosions were detected with CT, while 199 and 140 erosions, respectively, were detected with tomosynthesis and radiography. More erosions were revealed with CT than with tomosynthesis and radiography (P < .0001); significantly more erosions were shown with tomosynthesis than with radiography (P < .0001). With CT as the reference method for bone erosions, the overall sensitivity, specificity, and accuracy of tomosynthesis were, respectively, 77.6%, 89.9%, and 83.1%. The corresponding values for radiography were 53.9%, 92%, and 70.9%. The sensitivity of each reader increased by roughly 20% with use of tomosynthesis.

CONCLUSION

The depiction of bone erosions of the hands and wrists is significantly greater with tomosynthesis than with radiography.

MRI for the assessment and monitoring of RA--what can it tell us?

The past 15 years has seen an exponential rise in the use of MRI for the assessment of rheumatoid arthritis (RA). In this Perspectives article, we review the current and potential future role of MRI in the diagnosis, prognosis and monitoring of RA. We also review the impact of MRI research on the understanding of disease mechanisms. In our view, the pivotal role of synovitis in RA and its predilection for sonographically accessible joints makes it likely that MRI will be used diagnostically in joints that are inaccessible to ultrasonography or where the differential diagnosis is unclear. Additionally, MRI will probably assume an even more prominent role in clinical trials where the aim of therapy is the complete ablation of synovitis. Given the ever-increasing sophistication of MRI, we anticipate that it will continue to be a key research tool in the coming years.

Psoriatic arthritis: correlation between imaging and pathology

Psoriatic arthritis (PsA) is an archetypal type of spondyloarthritis, but may have some features of rheumatoid arthritis, namely a small joint polyarthritis pattern. Most of these features are well demonstrated on imaging, and as a result, imaging has helped us to better understand the pathophysiology of PsA. Although the unique changes of PsA such as the "pencil-in-cup" deformities and periostitis are commonly shown on conventional radiography, PsA affects all areas of joints, with enthesitis being the predominant pathology. Imaging, especially magnetic resonance imaging (MRI) and ultrasonography, has allowed us to explain the relationships between enthesitis, synovitis (or the synovio-entheseal complex) and osteitis or bone oedema in PsA. Histological studies have complemented the imaging findings, and have corroborated the MRI changes seen in the skin and nails in PsA. The advancement in imaging technology such as high-resolution "microscopy" MRI and whole-body MRI, and improved protocols such as ultrashort echo time, will further enhance our understanding of the disease mechanisms. The ability to demonstrate very early pre-clinical changes as shown by ultrasonography and bone scintigraphy may eventually provide a basis for screening for disease and will further improve the understanding of the link between skin and joint disease.

The anatomical basis for a novel classification of osteoarthritis and allied disorders

Osteoarthritis (OA) has historically been classified as 'primary' where no discernible cause was evident and 'secondary' where a triggering factor was apparent. Irrespective of the triggering events, late-stage OA is usually characterized by articular cartilage attrition and consequently the anatomical basis for disease has been viewed in terms of cartilage. However, the widespread application of magnetic resonance imaging in early OA has confirmed several different anatomical abnormalities within diseased joints. A key observation has been that several types of primary or idiopathic OA show ligament-related pathology at the time of clinical presentation, so these categories of disease are no longer idiopathic - at least from the anatomical perspective. There is also ample evidence for OA initiation in other structures including menisci and bones in addition to articular cartilage. Therefore, a new classification for OA is proposed, which is based on the anatomical sites of earliest discernible joint structural involvement. The major proposed subgroups within this classification are ligament-, cartilage-, bone-, meniscal- and synovial-related, in addition to disease that is mixed pattern or multifocal in origin. We show how such a structural classification for OA provides a useful reference framework for staging the magnitude of disease. For late-stage or end-stage/whole organ disease, the final common pathway of these different scenarios, joint replacement strategies are likely to remain the only viable option. However, for younger subjects in particular, near the time of clinical disease onset, this scheme has implications for therapy targeted to specific anatomical locations. Thus, in the same way that tumours can be classified and staged according to their tissue of origin and extent of involvement, OA can likewise be anatomically classified and staged. This has implications for therapeutic strategies including regenerative medicine therapy development.