A systematic trial of all major studies comparing metal on metal and other alternatives for artificial hip joints finds no good evidence to favor them. A test case for the FDA, the study bolsters the importance of a newly formed international consortium of orthopedic registries.
Newer metal on metal hip implants that many surgeons favor have no better long-term outcomes than traditional metal on ceramic devices. Nor do ceramic-on-ceramic or other novel bearings introduced and adopted widely over the past decade. These are the conclusions of a systematic review that analyzed 18 randomized comparative trials, involving more than 3,000 patients and 3,000 hips.
The comparative study of hip implants, authored by analysts from Harvard, New York's Weill Cornell Medical College, and the FDA, appears in the latest issue of the British Medical Journal. (Full text is available online for free.)
Both metal on metal and metal on ceramic bearings were more likely than traditional metal on polyethylene artificial joints to require revision, according to data from several national registries. Although surgeons prefer the metal on metal bearings for a purportedly lower risk of dislocation and a reputation for better quality of life among younger patients, the evidence suggests that quality of life is actually poorer for patients implanted with these bearings.
There was no noteworthy difference in Harris hip scores between any of the varous bearings.
Rapidly changing technology in orthopedics and the challenge of mounting sufficiently powerful clinical trials make it difficult to establish efficiently whether or not new devices are actually improvements, the authors observe. The solution, they contend, lies in the International Consortium of Orthopedic Registries, formed by the FDA last spring to facilitate collaboration between the existing registries in 15 countries. These already include data about more than 3.5 million procedures, involving all orthopedic devices on the market anywhere.
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