[Coxarthrosis--an update]

Degenerative osteoarthritis of the hip joint (coxarthrosis) is the most common disease of the hip joint in adults. The diagnosis is based on a combination of radiographic findings and characteristic clinical symptoms. The lack of a radiographic consensus definition has seemingly resulted in a variation of the published incidences and prevalence of degenerative osteoarthritis of the hip joint. The chronological sequence of degeneration includes the following basic symptoms on conventional radiographs and CT: joint space narrowing, development of osteophytes, subchondral demineralisation/sclerosis and cyst formation, as well as loose bodies, joint malalignment and deformity. MR imaging allows additional visualization of early symptoms and/or activity signs such as cartilage edema, cartilage tears and defects, subchondral bone marrow edema, synovial edema and thickening, joint effusion and muscle atrophy.The scientific dispute concerns the significance of (minimal) joint malalignment (e.g. impingement, dysplasia etc.) and forms of malpositioning which as possible prearthrosis have a high probability of leading to degenerative osteoarthritis. Moreover, without any question, the preservation of joint containment and gender differences are important additional basic diagnostic principles, which have gained great interest in recent years.In research different MR procedures such as Na and H spectroscopy, T2*-mapping etc. with ultrahigh field MR allow cartilage metabolism and its changes in early degenerative osteoarthritis ("biochemical imaging") to be studied. There is no doubt that even in a few years new profound knowledge is to be expected in this field.