When a skier skids on an icy patch, torques her knee, and gets a sudden ligament tear, is it the orthopedic equivalent of a myocardial infarction? Can rapid medical treatment in the knee damp down the resulting inflammatory, pathologic cascade and help preserve the knee’s long-term health, the same way that rapid restoration of coronary blood flow limits the extent of a myocardial infarct and long-term loss of cardiac function?
It’s an intriguing concept, and forms the rationale behind a new approach to acute management of traumatically injured knees that is starting clinical testing.
“The early phase of acute joint injury represents a window of opportunity to promote healing and prevent a subsequent cascade of joint destructive processes,” said Duke rheumatologist Virginia Byers Kraus last week at the World Congress on Osteoarthritis in Brussels.
“We think of osteoarthritis as a slow, chronic disease,” but that’s when it appears years after a traumatic knee injury, she said. “This is a curable type of osteoarthritis because you know when it starts. We should start to treat joint injury emergently, like an acute myocardial infarction.”
At the Congress, she presented early evidence supporting this approach. A single, knee-joint injection of a potent anti-inflammatory drug, the interleukin 1 receptor antagonist anakinra, produced dramatic improvements in short-term pain and function when administered roughly 2 weeks after traumatic injury in a pilot controlled study with 11 patients. The next step is to look at more patients, and to push the time of treatment even earlier, within a few hours after injury, Dr. Kraus said.
The time seems ripe for finding new ways to manage knee injuries, as middle-aged and elderly Americans are experiencing an epidemic of knee osteoarthritis that needs the ultimate treatment, total knee replacement. A second report at the Congress documented that the rate of total knee replacement surgeries soared during the decade ending in 2007. The number of knee replacements in Americans aged 45-64 tripled in that period, reaching 221,000 in 2007, with all U.S. knee replacements in 2007 reaching an all-time, 1-year high of 550,000.
—Mitchel Zoler (on Twitter @mitchelzoler)