Objectives To study the association between MRI inflammation of the lumbar spine (LS), sacroiliac joints (SIJs) and hip joints (HJs) and bone mineral density (BMD) in LS and femoral neck (FN) in early axial spondyloarthritis (axSpA) patients.
Methods 150 patients with axSpA and <5 years duration of inflammatory back pain (ASAS 2009 criteria) were examined. Median age – 27.0 (24.0 – 33.0) y., median disease duration – 21.0 (7.0 – 28.0) mo. 119 (79.3%) patients were HLA-B27 positive. Median BASDAI – 4.3 (2.2 – 6.0), ASDAS-CRP – 2.2 (1.3 – 3.3), BASFI – 1.9 (0.9 – 5.0). Median ESR – 8 (5-24) mm/h, CRP – 4.3 (1.0-20.6) mg/L. The patients fulfilled ASAS criteria. MRI of LS, SIJs and HJs (in case of hip joint pain and limitation of movement) was performed on Signa Ovation 0.35 T scanner (matrix 288x192). BMD was measured using dual energy x-ray absorptiometry (DXA) of the femoral neck (FN) and lumbar spine (LS) (L2–4). BMD reduction was defined as Z score ≤-2 (at at least one site)
Results MRI inflammation of LS and/or SIJ, and/or HJs has been found in 117 (78.2%) patients. Among the 117 patients of this group 21 (17.9%) had BMD reduction in LS and/or FN. And in the group of patients without MRI inflammation (n=33; 22.0%) low BMD was found in 6 (4.0%) patients (p=0.96). MRI-sacroiliitis was documented in 102 (68.6%) patients. Among them BMD reduction was found in 17.8%. While in the group of patients without MRI inflammation of SIJs low BMD has been found in 22.5% (p=0.73). MRI-coxitis was observed in 24 (22.5%) patients, and was associated with low BMD in 12.5% of cases. In the group of patients without inflammatory lesion in HJs, BMD reduction was found in 22.9% patients (p=0.27). Lumbar spine MRI-spondylitis was observed in 27 (19%) patients, and was associated with low BMD in 33.3% of cases. Meanwhile among the group of patients without MRI-spondylitis of the LS, BMD reduction was documented in 15.2% of cases (p=0.03). MRI findings and DEXA data are shown in the Table.
Conclusions Correlation has been detected between active MRI-spondylitis of the LS and BMD reduction in LS and/or FN. This demonstrates that in patients with early axSpA low BMD is a result of inflammation.
Disclosure of Interest None declared