Magnetic resonance imaging of the postoperative hip.

Magnetic resonance imaging (MRI) of the postoperative hip for delineation of various pathological conditions has been established in addition to conventional radiography and computed tomography. MRI provides superior soft-tissue contrast than the other imaging modalities, and it can be used for visualization of structures and pathological entities that cannot be depicted by conventional radiography and computed tomography. These entities include bone marrow changes such as bone marrow edema and avascular necrosis, and infiltration of the bone marrow by tumor recurrence or infections after insertion of metallic osteosynthetic material. The image quality of MRI, which is reduced as result of artifacts caused by metal alloys, can be optimized by using spin-echo or fast spin-echo sequences, and by adapting phase- and frequency-encoding directions in cases where metallic osteosynthetic materials were used. MRI, in addition to computed tomography and conventional radiography, appears to be a valuable tool for imaging the different pathological conditions of the postoperative hip, including after implantation of metallic osteosynthetic material.