Clicking, cracking, and popping of the knee joint is a very common occurrence, in fact studies show that the vast majority of people will have knee ‘crepitus’ (the medical term for noisy knees from the latin meaning “to rattle”) at some point in their lifetime.
A study carried out in 1990 estimated 99% of knees make some sort of noise!
But, how do you know if it’s nothing to be worried about or a sign that something is wrong? The easiest way to distinguish this is to ask two simple questions:
- Does the clicking hurt?
- Does the clicking limit range of the knee?
What Is the Source of the Crepitus?
If the answer to both of these questions is no, then the crepitus is nothing to worry about. There are a few different physiological structures that can cause crepitus in the knee, including:
- Synovial fluid – this is the fluid that lubricates all the joints of the body. Gas bubbles can build up in this fluid and then ‘pop’ as the joint moves, causing an audible sound. This is the same effect that happens when you crack your knuckles
- Tendons/ligaments – tendons and ligaments are tight bands of tissue, and they can flick over each other or over bony prominences in the knee, giving a clicking sensation typically when bending the knee
- Patellofemoral joint – the kneecap slides up and down in a small groove to help facilitate movement in the knee. This movement can create a small grating sound due to the uneven surfaces of the kneecap and this groove
Crepitus associated with these structures is known as “physiological” crepitus. The important thing to note is that this is associated with normal knee function and is not something to be concerned about.
If the answer to one or both of those questions is yes, this can be a sign of injury or dysfunction. This type of crepitus is known as “pathological” crepitus. Causes of this include:
- Meniscus – the meniscus is a c-shaped pad that acts as cushioning for the knee joint. A tear in the meniscus can cause a painful click that may also be associated with catching and locking of the knee joint. Meniscal tears normally occur with a twisting-type injury, but as we age our meniscus becomes easier to tear
- Patellofemoral pain syndrome – painful clicking or popping of the kneecap is a sign that the kneecap is tracking poorly in its groove, typically occurring as we move into a squat position
- Cartilage wear/osteoarthritis – crepitus in the knee associated with arthritis will be accompanied by stiffness in the joint, as well as swelling and pain with movement.
What Is Crepitus Not a Sign Of?
Studies show that lots of people who have crepitus in their knees will modify their behaviours and develop poor health beliefs about their knees. Some crucial facts to remember are:
- Crepitus is not a predictor of pain and/or future knee function
- There is no evidence to suggest that crepitus gets worse as we age
- There is no evidence to suggest that crepitus “wears the knee out” or causes arthritis
- Crepitus is not a sign of “bone-on-bone” knees
What Do I Do if I Have Clicky Knees?
If you are still concerned about the crepitus in your knee, physiotherapists are trained to be able to assess and diagnose the cause the crepitus. Most crepitus does not require treatment to fix, as there is nothing wrong with the knee in the first place.
Things you can also be doing to help promote healthy knees include:
- Stay within a healthy weight range – studies show that being overweight is one of the highest predictors of knee pain
- Resistance exercises – build up the strength of the muscles of the legs by using weights, resistance bands or doing bodyweight exercises like squats and lunges
- Cardio exercises – there is no evidence to support that runners have more knee injuries than non-runners, or that running “wears out” the knee joints
- Warm up before exercising – doing exercise with cold muscles and joints leads to injury
This article was written by Physiotherapist – Sam Crossland, from our Precision Physio Concord clinic. If you would like more information, or feel you might benefit from a session with one of the Precision Physio team, you can either come into our clinics, or work with us online.
How Do I Book An Appointment?
We’re taking the health of our clients, members and staff very seriously and our preference would be for you to call to book an appointment so that we can make sure to explain our approach to keeping you safe. You can call any of these numbers to schedule a session:
Evolving with the current environment, we are also now offering online appointments, meaning that we can support anyone who is unable to leave their home. Sessions are done via our state of the art Telehealth system and as long as you have a laptop or tablet with an inbuilt camera, or a phone with camera, we can help!
To learn more about online consultations, please call us on any of the numbers listed above.