Study: Bone Drugs May Increase Longevity of Replaced Joints

Dec. 6, 2011 -- New research may help hip and knee replacements last longer in patients who take commonly prescribed bone-loss drugs.

Joint replacement surgeries help millions live with less pain, but many people who have them eventually need repeat procedures when the implants loosen over time.

Now a new study suggests that commonly prescribed osteoporosis drugs may extend the life of replacement joints, but researchers say it is not yet clear which patients will benefit most from the treatment.

The study examined outcomes among patients in the U.K. who took oral osteoporosis drugs in the class known as bisphosphonates, such as Actonel, Atelvia, Boniva, and Fosamax.

Bone Drug Users Needed Fewer Surgeries

Bisphosphonate users who took the medication regularly for at least six months before hip or knee joint replacement surgeries were half as likely as non-users to need repeat surgeries after five years. Furthermore, use of the drugs was associated with an almost twofold increase in implant survival time.

“In the U.K., bisphosphonates are being increasingly used when a hip or knee replacement has already started to fail,” researcher Nigel K. Arden, University of Oxford professor of rheumatic diseases, tells WebMD. “What this study says is that we should use it for primary prevention.”

Joint Surgeries to Double in U.S. Over Next Decade

More than 700,000 hip and knee replacement surgeries are performed each year in the U.S. and this number is projected to double over the next decade, according to the American Academy of Orthopaedic Surgeons (AAOS).

More than 9 out of 10 joint replacement surgeries are in patients with osteoarthritis, and age and obesity are major risk factors for developing severe osteoarthritis.

Although several small studies have suggested that bisphosphonates might extend the life of hip and knee implants, Arden and colleagues were the first to follow patients over time to record their outcomes.

They did this by analyzing data from a health registry of more than 3 million people in the U.K.

The researchers identified all patients over the age of 40 who had knee or hip replacement surgeries in the U.K. between 1986 and 2006 for osteoarthritis.

Of the 42,000 patients who had joint replacement surgeries during this time, nearly 5% were classified as bisphosphonate users.

Just under 1% of bisphosphonate users followed for at least five years underwent repeat surgeries during the follow up, compared to just under 2% of non-users.

The study was published online in the journal BMJ.

Surgeon: Findings Promising, but Questions Remain

The most common cause of joint implant failure is loosening of the device due to weakening of the bone that supports it.

Arden says bisphosphonates may work by suppressing inflammation around the implant that accelerates bone weakening.

Orthopaedic surgeon Joseph M. Lane, MD, tells WebMD that while the research on bisphosphonates in joint replacement surgery is promising, many important questions remain, such as which patients will benefit from the drugs and when should they take them.

Lane is professor of orthopaedic surgery and chief of the Metabolic Bone Disease Service at the Weill Cornell College of Medicine Hospital for Special Surgery in New York City.

Bisphosphonates can cause gastrointestinal problems, and their use has also been associated with a rare but potentially serious jaw condition.

“These drugs are not without their side effects,” Lane says. “But this is a provocative study that should put pressure on the bone community to step up to the plate and answer these questions.”