Health Alert: Pain and Artificial Joints

NBC—National—November 23, 2006

When a patient with an artificial joint has pain, X-rays may not be able to pinpoint the cause of the problem. And an MRI is rarely used because the magnet distorts the image. Now one MRI expert has found a way to bring the implants into focus.

Two years ago, Bill Heaton had both of his knees replaced. But he didn't have long-lasting relief: "I expected some pain, but this was kind of severe discomfort."

X-rays of the implants didn't reveal any problems. Dr. Geoffrey H. Westrich says: "We really didn't necessarily want to go and operate because we didn't know what we were operating on."

So Doctor Westrich asked Bill to get an MRI - even though the magnet usually makes a mess of the image: "What Hospital for Special Surgery MRI facility has done, really championed by Dr. Hollis G. Potter, is work on the MRI software to basically reduce the amount of artifact and enhance the detail."

Dr. Potter says, "The minute the patient goes into the magnet, that's when we start our work. And we change the whole protocol, the normal way that the images are obtained."

An MRI uses a strong magnet. When metal from an implant sits next to soft tissue from the body, it creates a "frequency shift." Dr. Potter explains, "That generates an artifact that looks like a big blob of black and a big blob of white."

After several years of research, Dr. Potter was finally able to manipulate the MRI's scanning settings for a clearer image.

That helps Dr. Westrich: "And so this MRI was very useful in telling me exactly what the problem is and making the specific diagnosis."

The MRI showed Bill's kneecap needed a new part and some rebalancing: "He was able to make a diagnosis that I felt really comfortable and confident about going into surgery."

Now, three weeks later, he's pain free.

This story originally appeared on wistv.com.