Don't Ignore Buckling Knees

Going “weak in the knees”—that is, having your knees give way when you put weight on them—is a sign of knee instability. Knee buckling increases your risk of falling, and it’s particularly common in people who have arthritis or knee pain. But you don’t have to have arthritis to have a knee give way.

You may have had a knee buckle at one time or another. If you were lucky, you were able to regain your balance and steady yourself before you took a tumble. But you might not be so lucky next time around: Your risk of falling, and possibly incurring serious injuries, when your knee unpredictably buckles could increase within two years of your first knee-buckling incident, according to a new study.

Until recently, the consequences of knee buckling had not received much attention in the medical literature and scientific research. But the new study, in last February’s Arthritis Care and Research, takes a closer look at knee instability and its role in causing falls. The authors conclude that doctors should be paying closer attention to patients’ complaints of knee weakness.

Fear of falling

Knee buckling may be a result of balance difficulties and muscle weakness, particularly in the quadriceps, the group of muscles that runs down the front and sides of the thigh. Some studies estimate that knee instability during weight-bearing activities, such as going up or down stairs or simply walking, occurs most commonly in people with knee osteoarthritis or knee pain.

To measure the little-studied consequences of knee buckling, researchers asked 1,842 people, ages 55 to 84, who either had, or were at high risk for, knee osteoarthritis if they recalled an episode of knee buckling any time within the past three months. Nearly 17 percent of the participants recalled their knees buckling, and 20 percent of those participants reported they fell as a result.

The researchers checked back with the participants two years later to determine whether they had experienced any additional knee-buckling episodes. They found that those who reported knee buckling at baseline were four and a half times more likely to have fallen at least once more during the previous year, twice as likely to be significantly injured from a fall, and three times as likely to be injured enough to cause disability. Those who had a knee-buckling incident but didn’t fall were twice as likely to fall within two years because of a knee giving way.

Of major concern among the researchers was the number of people—69 percent—who told them that, after they fell, they lost confidence in their balance and gained a fear of falling—so much so that they compensated by limiting their daily activities. But curtailing activity to avoid falling isn’t a good solution: It will most certainly lead to a downward health spiral.

“Avoiding physical activity can result in further decline in muscle strength and general overall physical condition, putting you at even greater risk of falling,” says John A. Flynn, M.D., M.Ed., medical director of the Spondyloarthritis Center at Johns Hopkins University School of Medicine in Baltimore. “This deconditioning will eventually lead to loss of mobility and function and will likely have a psychological impact in the form of depression, anxiety, dependency, and social isolation.”

Speak up before you fall down

Such consequences, say the researchers, are preventable in people whose buckling knees are caused by muscle weakness or poor balance with interventions that include quadriceps-strengthening exercises and balance and agility training. Doctors must do their part in first identifying these patients and patients should bring up the subject if their doctors don’t.

Unless prompted by their doctors, most patients don’t mention incidences of their knees giving way. The researchers suspect that doctors don’t always consider knee buckling and its consequences in their arthritis patients because they’re more focused on pain relief and regaining function. As a result, the researchers are encouraging doctors to routinely ask patients whether they’ve experienced any knee buckling or instability.

“Don’t wait for your doctor to ask about these symptoms,” Flynn says. “Since pain is the most common knee-arthritis symptom, other symptoms like buckling can sometimes be overlooked. Ask your doctor about options that can help you stay active and reduce your fall risk. In addition to recommending exercise, he or she may suggest losing excess weight that could be putting strain on your knees; upgrading your footwear to shoes or slippers with low heels and thin, slip-resistant soles; and using a walking aid such as a cane.”

Exercise to get you steady on your feet

Ask your doctor to refer you to a physical therapist who can develop an exercise program for you. A typical exercise program should include:

• Range-of-motion exercises, such as yoga or tai chi (an exercise that involves gentle
stretching movements), to keep your joints and muscles flexible.

• Aerobic exercise that’s easy on the joints, such as swimming, walking, and bicycling,
to keep your heart and lungs healthy and control your weight.

• Strengthening exercises, especially ones that target your quadriceps.

• Balance and agility exercises to reduce your risk of falling.

(Originally published Aug. 25, 2016; updated Feb. 24, 2017)

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HealthAfter50 was published by the University of California, Berkeley, School of Public Health, providing up-to-date, evidence-based research and expert advice on the prevention, diagnosis, and treatment of a wide range of health conditions affecting adults in middle age and beyond. It was previously part of Remedy Health Media's network of digital and print publications, which also include HealthCentral; HIV/AIDS resources The Body and The Body Pro; the UC Berkeley Wellness Letter; and the Berkeley Wellness website. All content from HA50 merged into in 2018.