The purpose of this study is to evaluate bone mineral density in adult subjects with hemophilia versus a comparator population without hemophilia (non-hemophilia age- and gender-matched database) by using the following diagnostic means: dual-energy X-ray absorptiometry (DXA) scanning, clinical scales, quality of life (QOL) scales and biomarkers. In addition to this osteoporosis study, hemophilic arthropathy of the knee with respect to loss of knee cartilage will also be explored by using magnetic resonance imaging (MRI substudy). No investigational product will be dispensed.