[Bone marrow edema-differential diagnosis of the femoral head necrosis].

In patients with hip pain, clinical examination is of only restricted value in the differential diagnosis. Besides a patient's age, their medical history is often helpful in finding the correct diagnosis. Additionally, imaging can give valuable hints for excluding or validating a differential diagnosis. Nowadays, magnetic resonance imaging (MRI) is often used as a primary imaging modality in Germany. These MRIs show a bone marrow edema (BME) in many different pathologies. BME occurs in transitory bone marrow edema and outside of the atraumatic femoral head necrosis, concomitant with coxarthrosis, arthritis, herniation pit, and osteoid osteoma, amongst other conditions. This article describes several frequent differential diagnoses and gives hints on how to find the correct diagnosis.