Background:Osteoporosis is an increasingly important health problem among patients with spondyloarthritis (SPA). The Measure of Bone Mineral Density BMD is routinely carried out in an anteroposterior (AP) view of the spine. However, the syndesmophytes, ligaments calcifications, and the posterior part of vertebrae affect AP scanning. A lateral spine view is a more sensitive tool in assessing bone loss in trabecular bone.Objectives:We aimed to evaluate the association between lateral lumbar DXA and syndesmophyte grading in patients with SPA.Methods:We conducted a retrospective study including 75 patients with SPA. Bone density of the hip and lumbar spine was measured with a GE Lunar Prodigy Advance Bone Densitometer equipment. All patients had lumbar lateral, AP, and proximal femur DXA scans. The T-score, which measures the difference between a patient’s BMD and young-normal subjects, was computed and age-matched.Results:The mean age of the patients was 36±11 years. Male predominance was noted with a sex ratio of 4.76. The mean BMI was 25±5 kg/m2. Eight percent were obese. Fifty-two percent had Vitamin D deficiency.Forty-eight percent of the patients had axial SPA, while 52% had axial and peripheral symptoms.The mean age of onset was 27±7 years. Fifty-two percent of the patients had high inflammatory biomarkers. The BASDAI, ASDAS-VS, and ASDAS-CRP mean levels were respectively: 3.5±2.4, 3.1±0.9, and 3±0.8. The mean BASRI and mass were respectively 8 + 4.8 and 16.4 + 19.4. Analyses of T-score values obtained over the femoral neck revealed osteoporosis in 18.7% of the cases and osteopenia in 32% of the cases. On the other hand, analyses of AP, spine views revealed osteoporosis in 25.3% and osteopenia in 45.3% of patients (p=0.028, r=0.254). We detected the highest percentage of osteoporosis in lateral lumbar view and T-scores matched more closely with femoral neck values; osteoporosis in 29.3%, and osteopenia in 22.7% of the patients (p<10-3, r=0.562). BMD measured in AP, and lateral views were in good agreement (p<10-3, p=0.592). Age was inversely but not significantly associated with BMD in lateral (p=0.442, r=-0.09), AP (p=0.319, r=-0.117) and femoral neck projections (p=0.179, r=-0.157). Femoral neck BMD was associated with the activity of SPA (ASDAS vs (p=0.027, r= -0.295), and the mobility limitation BASMI (p=0.032, r= -0.247). Coxitis, BASRI, or mSASS were independent of BMD.Conclusion:We conclude that spine lateral view in DXA accurately measures BMD exceeding the AP spine views and femoral neck values. Therefore, structural changes do not affect this measurementDisclosure of Interests:None declared.
Forearm (horizontal beam lateral view)
