A new study published in The Lancet, examined data from 434,650 hip operations done between April 2003 and September 2011, of which 7.3 percent were resurfacings. The study viewed the amount of resurfacing implants that failed in the initial seven years after surgery and whether the head size of the implant played a role in the failure. Patients who underwent resurfacing were compared with those who had undergone hip replacements using other bearing surfaces.
Hip resurfacing differs from regular hip replacement because the top section of the thigh bone (femoral head), is not totally removed. Alternatively, the superficial bone is removed and changed for a metal cap. Hip replacements can use a variety of materials such as plastic, metal, and ceramic, while hip resurfacings always use metal-on-metal bearings. Used commonly in older patients, hip resurfacing is normally recommended as a different option for younger patients.
The investigators found that smaller head sizes were connected to higher failure rates, and in the majority of cases resurfacing bearings failed more rapidly than bearings of other materials. The one exception to this was men with a large femoral head, that showed similar rates of implant success with those who had total hip replacement. This particular group accounted for only 23 percent of all resurfacing operations in men during the duration of the study. On the other hand, women who endured hip resurfacing had an exceptionally poor implant survival rate, with failures over five times more common than any other bearing surfaces.
According to Ashley Blom, Professor of Orthopaedic Surgery in the University of Bristol's School of Clinical Sciences:
"Resurfacing failure rates in women were unacceptably high. In view of these findings, we recommend that resurfacing procedures are not undertaken in women. The National Joint Registry for England and Wales has the biggest joint replacement database in the world, allowing us to analyze over 30,000 hip resurfacings up to seven years after surgery. Our findings show that resurfacings with smaller head sizes are prone to early failure, and in particular that resurfacing in women has much worse implant survival, irrespective of head size."
Previous research has stated hip resurfacing failure may be due to excessive sports or physical activity. The researchers recognize that surgeons will need to factor in other important elements, such as the relative benefits of total hip replacement and resurfacing surgery on the patient's quality of life and function, to determine whether hip resurfacing is a logical option.
According to Professor Art Sedrakyan, of Weill Cornell Medical College in New York, and author of a linked comment accompanying the article:
"Regulators and surgeons need to make proper recommendations for patients, such as not using resurfacing in women, and developing decision aids for patients to convey the benefits and harms of hip implants. It is also vital to prevent use of the marketing term "young and active"; few patients, even if elderly and inactive, will refuse a device that is intended for the young and active. Communication with patients on all these issues should be more specific and evidence based."
Written by Kelly Fitzgerald