MRI can predict failure of metal-on-metal hip implants

METAL-ON-METAL hip implants can cause inflammation of the joint lining (synovitis) long before symptoms appear, and magnetic resonance imaging (MRI) can be used to identify this inflammation, according to a new study by researchers at Hospital for Special Surgery. The study, which appears in an upcoming issue of the Journal of Bone & Joint Surgery, demonstrates that MRI can be used to identify implants that are going to fail before people become symptomatic.

The study shows that synovitis exists in asymptomatic people in a fairly high prevalence,” said Hollis Potter, M.D., chief of the Division of Magnetic Resonance Imaging at Hospital for Special Surgery, in New York City. “If that is the case, symptoms alone are insufficient to determine the health of an implant. You can’t wait for people to be sore before we evaluate them for this potential problem.” The researchers say that MRIs can help identify patients who need revision surgery before tissue sustains further damage that makes a revision more difficult.

Hip resurfacing, a surgical alternative to total hip replacement (THR), involves placing a metal cap over the head of the femur while a matching metal cup, similar to that used in a THR, is placed in the pelvic socket. The procedure preserves more of a patient’s thigh bone than a conventional hip replacement, but the implants can cause synovitis. Until now, no objective data has existed regarding just how much inflammation these implants can cause. To fill this knowledge gap, investigators set out to evaluate the ability of MRI to detect and quantify adverse synovial responses in symptomatic and asymptomatic subjects following metal-on-metal hip resurfacing.

The investigators included the first 69 consecutive subjects (74 hips) referred from three surgical practices to the Hospital for Special Surgery for an MRI after a metal-on-metal hip resurfacing arthroplasty. Patients were classified as asymptomatic, having unexplained pain, or symptomatic with a mechanical cause. This latter category included patients with pMen's Sneaker Hub Online