Do your knees make noise? There's probably no reason for concern. Popping and cracking sounds usually aren't signs that something's wrong.
“A lot of joints crack and the knees are a really common joint to crack,” says David McAllister, MD, director of the UCLA's Sports Medicine Program. “Most people have knees that crack when they squat down or go through the full arc of motion. We generally don’t worry about cracking or popping when it isn’t associated with pain or swelling.”
Knee pain is incredibly common. In the United States, it's responsible for about 1/3 of all doctor's visits for muscle and bone pain. Knee pain is a special problem for athletes -- over half of all athletes endure it every year.
Some of the most common reasons for knee pain are swollen or torn ligaments, meniscus (cartilage) tears, and runner's knee. But the knee is a complex joint, and there's plenty more that can go wrong.
Other conditions that cause knee pain include:
Curious why your healthy knees might be making noises? As we age, the tissue that covers the bones, called cartilage, can develop uneven areas. When we squat or stand, sounds come from these rougher surfaces gliding across each other. It could also be the tissue that connects bones to other bones, called ligaments, tightening as you move, or the joint lining moving over bones.
If you have cracking or popping that does cause pain or swelling, though, see a doctor. It can be a sign of:
Meniscus tears. The meniscus is a rubbery C-shaped disc that cushions your knee and acts as a shock-absorber. It also helps spread weight evenly so your bones don’t rub together. Tears to the meniscus are often caused by sudden twisting or other things you might do while playing sports. In young people, tears usually happen during a traumatic event, but as we age the meniscus can tear more easily.
Cartilage injury or wear. Sometimes the cartilage covering of our bones can be injured, causing a piece to break off and catch in our joint. Typically the knee will respond to this injury by swelling or catching. Cartilage in your knee can also wear thin or break down, commonly known as arthritis. Some people say it feels like their knees are grinding when they move. Osteoarthritis is the most common kind of arthritis. It usually affects middle-aged and older people.
Tips for Healthy Knees
Regular exercise can strengthen your legs and knees. Exercise with weights or resistance bands -- or do bodyweight moves, like squats and lunges -- at least twice a week. Walk up stairs or hills, or ride a stationary bicycle to build muscle to support your knees.
Warm up before you exercise. An intense workout with cold muscles and joints can cause injury.
Keep flexible. Before exercise, try dynamic stretches, in which you move a muscle through a full range of motion. After exercise, do static stretches, where you hold a stretch for 30 seconds. This helps prevent injury. Regularly stretch the muscles in the front and back of your thigh (quadriceps and hamstrings, respectively).
If you’re already exercising, slowly work up to harder, longer workouts.
Wear shoes that fit right and are in good condition.
Stay at a healthy weight. You’ll reduce stress on your knees. Being overweight is a major risk factor in developing early arthritis of the knee.
“The best thing is to keep the muscles around the knees strong,” McAllister says.