MDCT is Better Than Plain Film in Diagnosing Hip Replacement Complications

May 7, 2004

06 May 2004

Multidetector CT (MDCT) is superior to plain film x-rays for detecting

problems that occur in patients who have undergone hip replacements, a new

study shows.

Hip prostheses generally last 10-15 years, said Farber, MD, vice

chair of clinical affairs at Indiana University Hospital in Indianapolis.

Then a series of complications can occur. Dr. Farber studied 45 patients who

had pain in their replaced hip, using both plain film x-rays and MDCT to

diagnose the problem. MDCT was 100% accurate in detecting bone loss near the

prosthesis, said Dr. Farber.

That compares to a 67% accuracy rate for plain films. MDCT had an added

benefit for these patients, in that it could pinpoint exactly where the bone

loss had occurred so the surgeon could more easily repair the problem, said

Dr. Farber.

MDCT was 100% accurate in detecting fractures near the prosthesis, compared

to 94% for plain films. In addition, MDCT was 61% accurate in detecting

whether the prosthesis had come loose, compared to 54% for plain films. The

ability to diagnose acetabular component loosening on MDCT was influenced by

the experience of the radiologists reading the examination, said Dr. Farber.

³When the most experienced radiologist read the examination, the accuracy

rate was 72%.²

Dr. Farber noted that they are currently comparing MDCT to plain film to

determine which is a better test for diagnosing wear on the plastic liner

between the metal components of the prosthesis and particle disease (as the

prosthesis wears down, particles get into the tissues near the prosthesis

and can cause an inflammation).

³As the population ages, we are seeing more of these types of patients. The

increase in obesity also plays a role in the increase in hip replacements,²

Dr. Farber said. ³At my institution we now do MDCT examinations on a

majority of these patients. We recommend that, at the very least, MDCT

should be performed if a patient has a plain film X-ray and the X-ray is

questionable. MDCT also should be performed if surgery is needed since it

provides a much better guide than plain film for the surgeon,² Dr. Farber

said.

The study will be presented on May 5 at the American Roentgen Ray Society

Annual Meeting in Miami Beach, FL.

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