The study is a cross sectional observational multicenter study. It is established in collaboration with the Egyptian college of rheumatology study group (ECRsg). It is conditioned that all the study participants had either mono- or oligo-arthritis with effusion of the knee or the first metatarsophalangeal (MTP) joint in patients with a known history of gout or at high risk. Patients with any known chronic arthritis, comprising rheumatoid arthritis, Sjogren's syndrome, systemic lupus erythematosus, scleroderma, neuropathic arthritis, seronegative spondyloarthropathy, will be excluded from the study. None of the participants had a history of intra-articular injection or aspiration in the scanned joints for 3 months prior to the inclusion in the study. The sonographers will be blinded for clinical data and the EULAR scanning protocol for the knee and 1st MTP will be considered [2]. Further, scanning of the double contour sign over the femur condyles anteriorly and posteriorly in sagittal planes will be assessed. All the sonographers in the study had an experience between 5 and 10 years in the field of musculoskeletal ultrasound.

Inclusion Criteria:

• mono- or oligo-arthritis with effusion of the knee or the first metatarsophalangeal
• patients with a known history of gout or at high risk

Exclusion Criteria:

• Patients with any known chronic arthritis, comprising rheumatoid arthritis, Sjoegren's syndrome, systemic lupus erythematosus, scleroderma, neuropathic arthritis, seronegative spondyloarthropathy
• History of intra-articular injection in the last 3 months.

The study population will be collected from several university clinics all over Egypt. All are aged 40 or more with a history of definite gouty arthritis or at high risk and they have active arthritis of at least one joint.