Axial spondyloarthritis is a chronic inflammatory disease affecting the spine, sacroiliac joints, entheses, and sometimes peripheral joints with a close link to HLAB27. Typical features include inflammatory back pain, limited spinal mobility, and sacroiliitis. The term axial spondyloarthritis (AxSpA) includes both Ankylosing Spondylitis (AS) where sacroiliitis is diagnosed by X-rays, and non-radiographic AxSpA, where sacroiliitis is diagnosed via magnetic resonance imaging (MRI). Osteoporosis is common in AS patients, and sarcopenia may also develop due to inflammation and immobilization. Osteosarcopenia, the co-occurrence of osteoporosis and sarcopenia, might have an impact on morbidity and mortality of AxSpA patients. This cross-sectional study aims to determine the frequency of osteosarcopenia in AxSpA patients and to investigate its relationship with various demographic and clinical factors. A control group with similar age and gender distribution will be recruited to evaluate osteosarcopenia. Our hypothesis is that osteosarcopenia will be more frequent in the AxSpA group compared to the control group. The study will also identify the demographic and clinical factors associated with osteosarcopenia in AxSpa.