New MRI can 'see through' metal screws after hip surgery

Medical Device Daily—March 17, 2014

People who sustain the most common type of hip fracture, known as a femoral neck fracture, are at increased risk of complications. A special type of MRI developed at Hospital for Special Surgery (New York) in collaboration with GE Healthcare (Chalfont, UK) can show a detailed image following fracture repair, without the distortion caused by metal surgical screws that are problematic in standard MRIs.

According to the researchers, the femoral neck, the area just below the ball of the hip's ball-and-socket joint, is the most common site of fracture, accounting for 45% to 53% of cases. People with this type of injury are at high risk of complications because the blood supply to the fractured portion of the bone is often disrupted. The concern is that the decreased blood supply will lead to non-healing or the death of bone cells, known as osteonecrosis.

Researchers at Hospital for Special Surgery developed a specially sequenced, contrast-enhanced MRI to identify potential problems so doctors can intervene early and prevent further damage to the joint.

"This new MRI greatly improves the visualization of bone and soft tissue when there is metal in a joint, such as the screws used to repair a hip fracture," said Hollis Potter, MD, chairman of the Department of Radiology and Imaging at HSS.

A study on this subject, "Femoral Head Osteonecrosis Following Anatomic Stable Fixation of Femoral Neck Fractures: An in-vivo MRI Study" was presented at the annual meeting of the American Academy of Orthopaedic Surgeons (AAOS; Rosemont, Illinois) in New Orleans last week.

"The concept was that the standard risk of osteonecrosis is traditionally assessed by radiograph, which is essentially a two-dimensional view of a three-dimensional problem," Potter told Medical Device Daily during a phone interview from AAOS. MRI is a more sensitive and accurate means of assessing osteonecrosis, she said, but then the problem becomes distortion caused by the metal surgical screws.

The Department of Radiology and Imaging at HSS is known internationally as a premier center for world class musculoskeletal clinical and research imaging. "Imaging is a vital component of the integrated care system provided by HSS," Potter said. "Our team is constantly optimizing the ability to image the earliest signs of a musculoskeletal condition, disease progression and/or healing."

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