[Osteoarthritis: value of imaging and biomarkers]

"Osteoarthritis (OA) is one of the most common disorders of joints. The joints most frequently affected are the hip, knee and the hand, notably the base of the thumb. Use of imaging to diagnose OA, whatever its localization should be limited to plain X-Rays in the majority of cases. It is particularly useful for the diagnosis, the assessment of the severity of structural changes and follow-up. The four main radiographic features of OA are joint space narrowing, subchondral sclerosis, subchondral cyst formation and osteophyte. MRI, CT scanner and Ultrasound have no role in the diagnosis of OA in the vast majority of OA patients. However, US is useful to guide intra-articular injection, mostly in the hip, and to diagnose a baker cyst. There is no blood or urine biomarker validated at the individual level for the diagnosis of OA."