Imaging the painful hip.

With the advent of magnetic resonance imaging and, subsequently, magnetic resonance arthrography, the imaging algorithm for hip pain has evolved considerably. Magnetic resonance imaging has supplanted bone scintigraphy as the first line imaging test after conventional radiographs in the setting of suspected occult fracture, transient marrow edema, and osteonecrosis. Computed tomography scanning and magnetic resonance imaging are invaluable for the evaluation of monarticular arthropathies such as pigmented villonodular synovitis and synovial osteochondromatosis. By combining conventional magnetic resonance imaging with capsular distention afforded by arthrography, magnetic resonance arthrography has become the imaging examination of choice for disorders of the acetabular labrum and for the evaluation of articular cartilage at the hip.