Because 72% of traditional implants have lasted only ten years surgeons, when dealing with patients younger than age 55, have explored hip resurfacing as an alternative to conventional total hip replacement, according to Todd Neale, writing in MedPage Today.
That has not worked out too well, reports a study conducted at the University of Bristol, England, and detailed in The Lancet. Researchers found that, for male patients with smaller femoral heads, the hip resurfacing was not as effective as total hip replacement. Implant survival was also poorer with hip resurfacing than with other surgical techniques when the femoral head was less than 54 mm. (For larger head sizes, implant survival was comparable.) For women the five-year implant survival was worse with hip resurfacing regardless of head size.
To assess implant survival, Ashley Blom, Ph.D. lead researcher and his colleagues, looked at data from the National Joint Registry for England and Wales. Their analysis included 434, 560 primary total hip replacements performed from 2003 through 2011. Of these, 7.3% were resurfacings.
An unadjusted analysis showed that five-year revision rates were higher for resurfacing than for stemmed total hip replacement (5.2% versus 2.8%). The unadjusted five-year revision rate was 8.5% for women and 3.6% for men, a difference not attributed to the smaller head sizes in women. “Women might have an increased risk of osteoporotic fractures of the femoral neck or a greater predisposition to reactions to metal debris, ” the authors suggested.
The median age of the patients who had a resurfacing was 55. The predicted five-year revision rates in 55-year-old women were 8.3% with a 42 mm resurfacing head, 6.1% with a 46 mm head, and 1.5% with a 28 mm cemented metal-on-polyethylene stemmed total hip replacement. That is the most common type of traditional implant. Similar differences were seen for 55-year-old men with smaller head sizes.
Blom recommended that resurfacing not be undertaken in women and that preoperative measurement be used to assess suitability in men. “Before further new implant technology is introduced we need to learn the lessons from resurfacing and metal-on-metal bearings, ” he said.
“Although our analysis focused on medium-term failure rates, other considerations need to be taken into account, ” the authors noted, including the conservation of femoral bone with resurfacing, differences in patient outcomes, and the release of metal into the patients’ tissues, which can cause end-organ damage and DNA changes.
