| Objective To measure the bone mineral density (BMD) in patients with ankylosing spondylitis (AS), to analyze the relevant factors of bone mass changes, and to guide the clinical treatment. Methods Sixty-six patients with AS were selected and divided into study group. Twenty-six subjects received healthy examination were divided into control group. General information, duration of disease, and indexes including ESR, CRP, Bath AS functional index (BASFI), and HLA-B27 were all recorded. BMD of the lumbar vertebrae (L1-5) was measured using quantitative computed tomography (QCT). The correlation between BMD and the risk factors was analyzed. Results BMD of both lumbar cortical bone and spongy bone in study group was significantly lower than that in control group (269.1±39.8 vs 308.2±49.3mg/ml, 140.8±18.6 vs 190.1±15.7mg/ml, P<0.01, respectively). The loss of BMD of the lumbar spongy bone was significantly higher than that of the lumbar cortical bone in study group (25.9±10.3% vs 12.7±13.2%, P<0.01). The incidence of osteopenia and osteoporosis of the lumbar vertebra was 39.4% and 45.5%, respectively, in study group. The duration of the disease and the degree of the destruction of the sacroiliac joint were negatively correlated with BMD (r=-0.394, P<0.05; r=-0.674, P<0.01). Height, weight, BMI, BASFI, increase of CRP and/or ESR, and positive /negative of HLA-B27 had no correlation with BMD. Conclusion The decrease of the BMD of the lumbar vertebrae in patients with AS is significant. The incidence of osteoporosis in patients with AS is high. So BMD should be measured in patients at the early stage. Biological agents should be used to prevent and treat the loss of bone mass timely. |