Bone marrow oedema in axial spondyloarthritis: different patterns identified

Retrospective data on the distribution of bone marrow oedema (BMO) in axial spondyloarthritis (axSpA) identified 3 distinct patterns in the sacroiliac joints (SIJ): predominantly upper, predominantly lower, and symmetrical. Each pattern was linked to different clinical and immunogenic traits.

Using data from patients with axSpA confirmed by the Assessment of SpondyloArthritis international Society (ASAS) criteria, a retrospective study aimed to investigate whether distinct patterns of BMO distribution in the SIJ may be associated with specific demographic and/or clinical factors [1].

Between 2002 and 2024, 203 patients with axSpA who underwent SIJ MRI at Leeds Teaching Hospital were included. Participants had a mean age of 40.4 years, and 60.1% were men. BMO was found in 80.8%, 72.4% were positive for the HLA-B27 antigen, and nearly 60% had radiographic sacroiliitis. Moreover, 20.3% had psoriasis and 19.7% had uveitis.

The Leeds axSpA MRI Scoring system scores BMO in each SIJ quadrant (upper or lower sacral and upper or lower iliac) from 1 to 3. Patients were grouped into 3 categories: 50 had predominant-upper (pU) BMO, 88 had predominant-lower (pL) BMO, and 26 had symmetrical upper-and-lower pattern.

Table: Disease-related factors associated with BMO localisation in SIJ [1]



BMO, bone marrow oedema; M/F, male/female; MRI, magnetic resonance imaging; SD, standard deviation.

Comparing the 2 non-symmetrical groups revealed differences in clinical features. The pU group was older (42.6 vs 35.8; P=0.002), had higher body mass index (30.3 vs 26.2; P=0.005), longer disease duration (5.8 years vs 2; P=0.002), lower HLA-B27 positivity (54% vs 80.2%; P=0.001), more frequent concomitant psoriasis (38.8% vs 13.6%; P<0.001) and less common uveitis (12% vs 28.4%; P=0.026) compared to the pL group. Other interesting, but not statistically significant, results of the comparison between pU BMO and pL BMO arms included the proportion of men (56% vs 68.2%; P=0.15) and the mean CRP levels (11.6 vs 15.4 mg/L; P=0.263).

Several disease-related factors were associated with the regional BMO types (see Table). The upper SIJ BMO scores were positively associated with body mass index (P<0.001) and inversely with uveitis (P<0.001). In the lower combined SIJ BMO scores, significant associations included younger age (P=0.005) and HLA-B27 positivity (P=0.002).

The investigators concluded that the topographic differences in BMO may reflect divergent biomechanical and inflammatory pathways converging on the SIJ. Recognising these patterns may enhance phenotypic stratification and inform future studies aimed at personalised management in axSpA.

1. Abacar K, et Two distinct patterns of sacroiliac joint bone marrow oedema in axial spondyloarthritis are associated with HLA-B27 status, Body Mass Index and/ psoriasis. POS0126, EULAR 2025, 11–14 June, Barcelona, Spain.

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Posted on 8 August 202522 August 2025