What's new on the sacroiliac joint ?

Anatomical variation of the sacroiliac joint carries an increased risk for erosion and bone marrow oedema in axial spondyloarthritis

OBJECTIVES

To assess the impact of joint shape variations on inflammatory lesions on SI joint MRIs in patients with axial spondyloarthritis (axSpA).

METHODS

A total of 1194 patients from four different prospective cohorts were evaluated, with 684 (57.3%) having sufficient imaging data for inclusion (379 axSpA, 305 controls). All images were evaluated for joint form, erosion, sclerosis, fat metaplasia and bone marrow oedema (BMO) by two independent readers. Logistic regression analyses were used to assess the association of joint form and lesions on imaging for axSpA patients and controls.

RESULTS

Atypical joint forms were common in both axSpA (43.5% [154/354]) and control patients (44.2% [134/303]); both intra-articular variants and a crescent joint shape were significantly more common in axSpA patients (18.4% vs 11.6% and 11.0% vs 5.3.%, respectively; P < 0.001). The axSpA patients with intra-articular joint form variants had 2-fold higher odds of exhibiting erosions [odds ratio (OR) 2.09 (95% CI 1.18, 3.69)] and BMO [OR 1.79 (95% CI 1.13, 2.82)]; this association was not observed in controls. Accessory joints increased the odds for sclerosis in axSpA patients [OR 2.54 (95% CI 1.10, 5.84)] and for sclerosis [OR 17.91 (95% CI 6.92, 46.37)] and BMO [OR 2.05 (95% CI 1.03, 4.07)] in controls.

CONCLUSIONS

Joint form variations are associated with the presence of inflammatory lesions on SI joint MRIs of axSpA patients. This should be taken into consideration in future research on the interplay of mechanical strain and inflammation in axSpA.

Emerging therapies for the treatment of spondyloarthritides with focus on axial spondyloarthritis

INTRODUCTION

Spondyloarthritides (SpA) such as axial spondyloarthritis (axSpA) including ankylosing spondylitis (AS) and psoriatic arthritis (PsA) including psoriasis are chronic immune-mediated disorders with involvement of tumor necrosis factor (TNF), interleukin (IL)-17 cytokines, and janus kinases (JAK) in their pathogenesis, with IL-23 clearly also playing a role in psoriasis, PsA, and chronic inflammatory bowel diseases.

AREAS COVERED

In this narrative review, we focus on a biologic disease modifying anti-rheumatic drug (bDMARD), the bispecific IL-17A and IL-17 F inhibitor bimekizumab, and a targeted synthetic (ts) DMARD, the JAK inhibitor (i) filgotinib - emerging agents for the treatment of axSpA. Upadacitinib, another JAKi that has recently been reviewed intensively by us is already approved for axSpA and PsA in Europe.

EXPERT OPINION

In contrast to inhibition of IL-17, JAKi also work in rheumatoid arthritis (RA), while agents inhibiting IL-17 are not, even though some effect may be there. Indeed, 4 JAKi including filgotinib are approved for RA. There are several head-to-head trials with bimekizumab in plaque psoriasis. The last one showed that the bispecific inhibition of IL-17A and IL-17 F with bimekizumab may indeed be superior to inhibition of IL-17A alone with 300 mg secukinumab (usual dosage). Whether this is also the case for treatment of axSpA and PsA remains to be shown.

The influence of age on the prevalence of inflammatory and structural MRI lesions in the SIJ of patients with and without axSpA

OBJECTIVE

To compare the influence of age on inflammatory (bone marrow oedema. BME) and structural (fat lesions (FL), erosions and ankylosis) MRI lesions in the SIJ of patients with and without axial spondyloarthritis (axSpA).

METHODS

In a retrospective study, SIJ MRI (STIR/T1 sequences) of consecutive patients with chronic back pain diagnosed with axSpA or non-SpA were evaluated based on SIJ quadrants (SIJ-Q). Two blinded readers evaluated BME and structural lesions. Reader agreement was evaluated for prevalence of MRI lesions related to age.

RESULTS

MRIs of 309 (175 axSpA, 134 non-SpA) patients were evaluated. Their mean age was 38.5 ± 11.4 vs 43.4 ± 13.8 years (y), 67% and 36% were male, CRP 1.6 ± 2.4 vs 1.1 ± 2.1 mg/dl, median symptom duration 48 and 60 months, respectively. SIJ-Q with BME and erosions were significantly more frequent in axSpA vs non-SpA patients independent of age, while this difference was seen for FL only in patients ≥50 y. The proportion of patients with ≥1 or ≥ 3 BME or chronic lesions except for FL increased with age in both groups, and was constantly higher in axSpA vs non-SpA. In univariate analyses, only female sex was significantly associated with more FL.

CONCLUSIONS

The proportion of patients with MRI lesions was high in both, axSpA and non-SpA patients. However, the prevalence of BME and erosions was significantly more frequent in patients with axSpA, was independent of age and also allowed for discrimination. FL occurred more frequently only in older age groups and were less reliable for discrimination vs. non-SpA patients.