THE QUESTION Might taking medication that helps maintain strong bones make a difference in how long a knee or hip replacement lasts?
THIS STUDY involved 41,995 people (average age, 70) who had a total knee or hip replacement, including 1,912 who had taken oral bisphosphonates — alendronate (Fosamax), risedronate (Actonel, Atelvia), ibandronate (Boniva) or etidronate (Didronel, EHDP) — for at least six months before their surgery. Five years later, about 3 percent of those who had had a hip replacement and 4 percent of those with a knee replacement required revision surgery, an operation to replace the original implant. The revision rate for those taking bisphosphonates was about half that of the others, and their original implants lasted nearly twice as long. Among people with osteoarthritis, the life of the original implant was about three times longer for those who took bisphosphonates.
WHO MAY BE AFFECTED? People who have knee or hip replacement surgery, a group that is estimated to include nearly 775,000 each year in the United States. By some estimates, about 10 percent of those who have a joint replaced will need revision surgery. Most often this is caused by loosening, which can occur if the bone supporting the joint has weakened.
CAVEATS People considered nonusers of bisphosphonates included some who started taking the medication after their joint replacement surgery. The effect of other types of bone drugs was not assessed. The study was funded in part by grants from pharmaceutical companies that market bisphosphonates, and three of the seven authors had accepted fees from the companies.
FIND THIS STUDY Dec. 6 online issue of BMJ (www.bmj.com).
The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.