Bone marrow edema syndromes of the hip: MRI features in different hip disorders.

The objectives of this study were to describe the essential magnetic resonance imaging (MRI) features of bone marrow edema syndromes affecting the hip joint. In addition, to evaluate the role of MRI in the assessment of hip joint involvement in different clinical settings that may share similar clinical findings. Thirty-four patients who complained of hip pain were studied consecutively. Of these, 21 were men (61.8%) and 13 were women (38.2%). After clinical assessment of possible hip disease, plain radiograph and MRI study of both hips were performed. The literature was searched using keywords: bone marrow edema, hip, and MRI. All patients had antalgic gait and limping. Initial clinical examination revealed painful limited internal and external rotation of the affected hip/hips suspect for hip disease. Unilateral hip involvement was identified in 31 patients (91.2%), and bilateral hip involvement was found in three patients (8.8%), with a total of 37 hips evaluated by MRI. The final diagnoses in our patients were: reactive arthritis (1), transient osteoporosis (7), avascular necrosis (10), osteoarthritis (2), tuberculous arthritis (4), septic arthritis (2), osteomyelitis (2), sickle cell anemia (2), lymphocytic leukemia (1), and femoral stress fracture (3). Bone marrow edema affecting the hip is neither a specific MR imaging finding nor a specific diagnosis and may be encountered in a variety of hip disorders due to different etiologies. MR imaging is the modality of choice when clinical examination is suspect for hip disease and plain radiographs are normal or equivocal. Early diagnosis and treatment is important in many of the disorders. The literature is reviewed regarding bone marrow edema of the hip.