Expensive Hip Implants Show No Added Benefit

A new study finds no evidence that newer implants such as ceramic or uncemented implants are better than traditional cemented metal-on-plastic ones.

Researchers at the University of Bristol Medical School (United Kingdom) conducted a study that compared 24 different types of hip implants commonly used in clinical practice. To do so, they combined data from the U.K. National Joint Registry for England, Wales, and the Northern Ireland with the Swedish Hip Arthroplasty Register, analyzing in all over one million patients with total hip replacement in the two countries and with over 30 years follow-up. Implants, which are no longer recommended for use, such as metal-on-metal and resurfacing implants, were excluded from analyses.

The implants were then ranked by cost-effectiveness for each patient group of different sex and age profiles. The results revealed that small-head (less than 36 mm in diameter) cemented metal-on-plastic hip replacements are the most cost-effective in men and women older than 65 years. For adults younger than 65, small-head cemented ceramic-on-plastic hip replacements are more cost-effective. There was no evidence that uncemented or hybrid hip replacements are cost-effective options, while large-head implant sizes (more than 36 mm) are also not cost-effective. The study was published on November 1, 2018, in Value Health.

“Small-head cemented metal-on-plastic implants have the longest track-record of use; they are safe and the cheapest implant type on the market, but tend only to be favored for older patients,” said lead author Elsa Marques, PhD, of the University of Bristol Medical School Translational Health Sciences (THS). “Regardless of their bearing material, there is no effectiveness or cost-effectiveness evidence that uncemented implants last longer and avoid revision surgeries for any patient group.”

Modern uncemented ceramic-on-ceramic and uncemented ceramic-on-plastic are considerably more expensive than the older cemented metal-on-plastic hips, although there is little evidence that they avoid the need for revision surgeries in the longer term. But despite lack of cost-effectiveness evidence, uncemented or hybrid combinations are increasingly used in younger adults worldwide. Metal-on-plastic implants also remain the most commonly used bearing surface material in Sweden, Norway, Australia, and the United States.

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University of Bristol Medical School