When Is the Best Time for a Knee Replacement?
Recent research suggests that waiting too
long may be counterproductive.
Replacing a knee joint with an artificial one—a procedure
called knee arthroplasty—is a common treatment for severe
arthritis: More than 350,000 knee replacements are performed
in the United States each year. Originally, the procedure was
considered most appropriate for people age 60 to 75. Doctors
thought that younger, more active patients would put too much
stress on the joint and require a second artificial joint in
10 to 20 years; older patients were believed to be too frail
to undergo the replacement procedure.
Over the past 20 years, however, researchers have concluded
that knee replacement can be appropriate for people of almost
any age. In 2003, a federal panel convened by the National Institutes
of Health (NIH) determined that joint replacement provided pain
relief and improved mobility in 90% of patients. The panel also
suggested that, rather than being a last resort, knee replacement
can be a valuable treatment option earlier in the course of arthritis.
Why the Procedure Is Often Delayed
Part of the reason that some patients wait a long time for joint
replacement is that the decision is up to the individual surgeon,
and there is no consensus as to the most appropriate time. Also,
patients may be reluctant to undergo the procedure for a variety
of reasons: they don’t want to believe that their arthritis
has become so serious; they fear the risks, pain, or cost associated
with the surgery; or they worry about taking time off from work
The panel reported that women (and minorities) have the surgery
less often than white men, even though women are more likely
than men to have arthritis. Also, women who have a knee replacement
have more pain and function loss than men at the time of the
procedure, suggesting that either women or their doctors tend
to delay surgery. However, these patients may be doing themselves
more harm than good.
Why Earlier May Be Better
Waiting until pain and function loss have become substantial
may chip away at the potential benefits of knee replacement.
For example, the NIH panel reported that after knee replacement,
patients with worse pain and function scores before the procedure
still had more pain and less function than people with better
scores before the procedure. In a similar finding, a 2002 study
of 222 people with osteoarthritis who underwent knee or hip replacement
reported that those with poorer function at the time of surgery
also had worse function two years after surgery, compared with
people with less pain and better function before surgery.
One problem with waiting too long is that bone as well as cartilage
may be worn away, making the procedure more difficult. Also,
being disabled for an extended period can affect the muscles
and make rehabilitation more difficult. Increased age may also
be correlated with an increased risk of surgical complications.
Another factor in favor of earlier joint replacement is improved
materials used in the artificial joint and refined surgical techniques.
Both of these advances mean that younger patients are not likely
to wear out the new joints, as was once feared. Ten years after
the procedure, only 10% of artificial joints are likely to need
replacement; after 20 years, the rate is 20%.
According to the NIH panel, candidates for knee replacement
• evidence on x-ray of joint damage;
moderate to severe persistent pain that is not relieved by
measures such as medication or lifestyle changes; and
significant functional limitation resulting in reduced quality
Conservative treatments—such as rest, ice, heat, muscle-strengthening
exercises, and pain medication—should always be attempted
first in the treatment of knee arthritis. If these measures fail,
however, joint replacement may be the best treatment option for