Hearing occasional pops, snaps, and crackles when you bend your knees doesn’t necessarily mean you have arthritis. Other joints might even make these noises now and then, too. However, the sounds are common in those with arthritis.
Doctors call this sound “crepitus” (KREP-ih-dus). This term usually refers to the joints, but can be used to describe lung sounds as well.
The knee works like a large hinge. It joins the thighbone (femur) to the long bone of the lower leg (tibia). The fibula, a bone in the lower leg, is also connected to the joint. The kneecap (patella) is the small, convex bone that sits at the front of the knee, shielding the joint.
Two thick pads of cartilage called the menisci cushion the tibia and femur and reduce friction where they meet. A fluid-filled capsule called the synovium encloses and lubricates the joint. Four ligaments — tough, flexible bands that stretch across the uneven surface of the joint — connect the bones.
Over time, gas can build up in the areas surrounding the joint, forming tiny bubbles in the synovial fluid. When you bend your knee, some of the bubbles burst, and ligaments may snap or pop. This is normal, and happens to everyone from time to time.
Arthritis, on the other hand, damages cartilage and bone. As the damaged knee joint moves, it may crackle and crunch.
Crepitus also may be a result of an injury.
Crepitus in the knee is common and usually painless. There’s no need to be concerned about it. However, pain that accompanies the crackling and popping sounds could indicate a problem.
Knee crepitus is one of the common symptoms of osteoarthritis (OA). It also can be one of the symptoms of rheumatoid or infectious arthritis, and may accompany several different types of knee injuries.
See your doctor as soon as possible if your knee creaks, crackles, and hurts.
Around 27 million Americans have OA, according to the Arthritis Foundation. This type of arthritis mainly affects people over the age of 65. Also known as “wear and tear” arthritis, OA commonly affects the joints used most often, such as the joints in the hands. It also affects weight-bearing joints such as the knees and hips.
Mechanical stress or biochemical changes slowly break down the cartilage that cushions the joint, causing inflammation and pain. Over time, the cartilage is destroyed and the bones grind together. When crepitus is accompanied by pain, it’s usually caused by OA.
Crepitus in the knees may be caused by knee injuries such as meniscus tears. These are fairly common in people who play sports, jog, or run. A meniscus tear can cause crepitus as the joint moves.
Chondromalacia patella is a dull ache behind the kneecap, usually caused by overuse or injury. It’s also known as “runner’s knee” or patellofemoral pain syndrome. If you have this condition, you’ll feel and hear a painful crunching and grating when the knee is moved.
Other knee injuries and types of arthritis can also cause crepitus.
Crepitus is harmless and needs no treatment when it’s painless and isn’t caused by disease, injury, or another condition. But when pain accompanies a crunchy knee, treatment will depend on the underlying cause.
For instance, OA has a variety of treatments. Your doctor may prescribe nonsteroidal anti-inflammatory drugs (NSAIDs) and suggest applying ice packs to reduce inflammation. A brace can help support and rest the knee. Physical therapy will strengthen the muscles that support the knee and promote an increased range of motion.
In some cases, surgery or joint replacement may be necessary.
Natural medicines and treatments for joint pain are available at most drugstores and health food stores. Just keep in mind that few have been proven clinically effective.
Glucosamine, especially in combination with chondroitin, is a common treatment for arthritis. Fish oil, which is rich in omega-3 fatty acids and other nutrients, may be useful as well. Both are available in tablet or capsule form.