Lots and lots of people have knees which make crunch, grate or make crackle noises when they bend them.   Doctors call this noise ‘crepitus’ and it often sound like rice crispies.   This does not necessarily mean you have arthritis in your knees.  The way doctors work out whether the crepitus is something to worry about or not is by finding out if there are any additional problems like pain, stiffness and of course joint function (the way the joint works).

When you don’t need to worry

• If you only hear or feel occasional crunches, grating, crackles and pops – then you do not need to worry.
• Even if you hear or feel crunches frequently in your knees – providing you don’t have any pain or stiffness or swelling and you can walk, run and go up and down steps just fine, then you don’t need to worry.

When you do need to worry

If you have crunches/crackles/grating that is persistent (i.e. there all the time) AND you have any of the following, then you must go and see your doctor.

• Pain in the joint
• Stiffness in the joint
• Swelling in the joint (see picture, the knee with the arrow is swollen)
• Difficulty walking, running, going up and down steps or if your knee ‘gives way’/feels unstable.

But even then, your may not be because of arthritis.   It might be other conditions like Patellofemoral Pain Syndrome (often called Chondromalacia patella) – which is a less serious and worrying condition.  Go to the doctor to get a better and more expert opinion about what is going on.

Why do they crunch or crackle?

There are lots and lots of reasons why knees crunch or crackle when you grate them.  For example, with repetitive activities like running, rough spots develop on the cartilage at the back of the knee cap and this can produce a crunching or grinding sound without pain when the knee is bent.

How to prevent knee pain/arthritis

Regular exercise is the key to ensuring your knee has strength. Without it, your muscles weaken, leaving your joints without much support and leaving your muscles, bones, tendons, ligaments, and joints vulnerable to misalignment, injury and ultimately the wear type of arthritis called osteoarthritis.  A knee injury can double the risk of developing osteoarthritis.

Your best bet is to choose exercise with a low risk of knee injury. Daily moderate exercise is much better for your joints than occasional strenuous exercise. Focus on low-impact activities that build stamina, strength, and flexibility, such as yoga, walking, biking, swimming, and weight lifting. These types of exercise can help enhance circulation, improve your range of motion, and build the muscles that surround the knee joints.

One study revealed that a relatively small increase in quadriceps strength (20%–25%) can lead to a 20%–30% decrease in the chance of developing knee osteoarthritis. Aim for a minimum of 30 minutes of exercise on most days of the week.