[Differential diagnoses of avascular necrosis of the femoral head. Articular groin pain in adults].

Early diagnosis and therapy of hip joint complaints in the young adult are often crucial for the prognosis of the joint. Besides avascular necrosis of the femoral head several differential diagnoses are possible, which if left untreated frequently lead to early osteoarthritis. The necessity of joint replacement in middle age often could be avoided by initiating adequate therapy as early as possible. The early diagnosis of aseptic necrosis of the femoral head at an early stage is possible with MRI. Especially in consideration of decreasing budgets MRI is dispensable for other diagnosis, e.g. hip dysplasia, femoroacetabular impingement or coxitis. On the other hand para-articular causes and non-orthopaedic diseases must also be considered, which remain hidden to classic orthopaedic diagnostics. Important differential diagnoses of groin pain in the adult, with emphasis on articular illnesses, are described.