Objective: The aim of this study was to evaluate bone mineral density, osteoporosis and fractures in patients with ankylosing spondylitis (AS) along with related factors like depression, fatigue and quality of life. 
 

Materials and Methods: In this prospective, controlled study 38 patients with ankylosing spondylitis and 30 healthy controls were evaluated 
densitometrically by DXA and quantitative ultrasonography (QUS) of the heel was performed. With the use of DXA, bone mineral densities (BMD) of the proximal femur, tibia and lateral lumbar vertebrae were  determined. Dorsal and lumbar radiographs were obtained for morphometric measurements. Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), fatigue scale, Beck Depression Scale and SF-36 were used. 
 

Results: In patients L3 t values were significantly lower than controls (p<0.05) with lower femoral  neck and total BMD values (in terms of g/cm2  and  t-scores) (p<0.01) but similar tibial measurements (p>0.05). Femoral and tibial BMD were moderately correlated with calcaneal QUS (r: 0.427; p<0.05). Vertebral fractures were diagnosed in 21% of patients without any correlation with BMD. Osteoporosis was strongly associated with CRP, BASMI, duration of disease, age and sedimentation rate. Physical role difficulty subgroup of SF-36 was correlated with BMD of  the femoral neck (p<0.05). 
 

Conclusion: Calcaneal QUS and tibial BMD values also inform about femoral bone mass. Vertebral fractures can develop independently from BMD. CRP levels, sedimentation rate, and limitation in mobility play significant roles in development of osteoporosis in AS.