Rheumatoid arthritis (RA) is the most common chronic inflammatory joint disease in adults and is characterized by chronic inflammation of the joints leading to their destruction, resulting in a major loss of function.||The investigators propose a pilot study for studying changes in bone microarchitecture with High Resolution peripheral micro Computerized Tomography (HR-pQCT) in patients with RA treated with anti-TNF(Tumor Necrosis Factor), with the measurement of micro-architectural parameters in subchondral area near an inflammatory joint during the first 12 months of initiation of an anti-TNF therapy (Infliximab®, Etanercept®, Adalimumab®).