If you hear a popping sound from your knees while walking, running or even just straightening your leg, this could be due to any number of things. In general, the medical term for this type of pops, cracking or snapping is crepitus in the knees.
The good news is that in most cases, a popping sound from the knee is not an indicator of trouble.
However, there are many possible reasons why this may happen, and some of them represent medical conditions that demand attention. This is particularly true when the knee popping sound is accompanied by knee pain or swelling or pain in the adjacent areas.
In this text, we will provide a quick overview of the medical conditions that can cause popping sounds from the knees, together with the other commonly observed symptoms for each condition. We will also provide some advice as to the treatment steps to be taken for each condition, if any are needed.
Possible Causes Of A Knee Popping Sound & What To Do About It
Gas Bubbles In The Knees
It is quite normal for gas bubbles to accumulate from time to time in the synovial fluid present in the knee joint. The purpose of this fluid is to lubricate the joint and allow it to flex and extend without friction or other interference.
However, as you flex the knee, some of the gas bubbles may burst, making a popping sound. There will be no accompanying pain besides the popping.
What To Do
As mentioned, this is perfectly normal and you don’t need to do anything about it.
Movement Of Ligaments In The Knee
The ligaments and tendons in the knee are elastic and from time to time may have to stretch slightly as they pass over a small bony protrusion (epicondyle) in the joint.
Once over the protrusion, they then snap back to their normal lengths, making a clicking or snapping noise, much as a rubber band may do. The process is painless and quite normal.
What To Do
This is a normal event and you don’t need to be worried about it.
Knee osteoarthritis is a wear and tear condition caused by breakdown of the cartilage that covers the bone ends in the knee joint (and other joints also).
As the cartilage breaks down, the bone ends start to make direct contact with each other as the knee is flexed or extended. This may produce a scraping, popping or clicking noise from the joint. It will also produce increasing pain (as the condition worsens) as well as knee stiffness.
The pain and stiffness may be at its worst upon awakening in the morning or after a period of rest. Over time, inflammation and knee swelling may also develop, further decreasing the ability to walk or run in comfort.
The result will be a steady decrease in knee range of motion and function over time.
What To Do
Osteoarthritis is an increasingly common problem for people in their 60s and beyond. A doctor can propose a combination of activity modifications, pain relief medication , physical therapy and possibly using an unloading knee brace to help control the pain and preserve knee function and range of motion.
Sometimes, knee popping sounds can be the result of an injury suffered in a fall or collision. In other cases, it can be a repetitive stress injury caused by excessive running or jumping during sports activities.
Below are some of the injury related conditions that can cause your knee to make popping, clicking or scraping sounds:
Meniscus tears. The menisci are 2 C shaped pieces of cartilage that sit between the femur (thigh bone) and tibia (shin bone) and help to prevent the two bones touching each other directly.
Meniscal tears can cause knee popping or clicking as the joint is flexed or extended. However, this will normally be accompanied by knee pain and joint instability.
In some cases, pieces of cartilage come loose and float around inside the knee. These pieces of loose cartilage can get caught in the knee and make clicking or popping noises as you try to move the joint.
Chondromalacia patella is an injury due to damage to the cartilage covering the underside of the kneecap. It too can cause crepitus in the knee, but you will also experience pain that increases with activity.
Patellofemoral pain syndrome is a similar condition and is also known as runners knee. The precise causes are uncertain but it can sometimes produce popping sounds in the knee as well as pain that increases during periods of activity. Activity that involves deep knee bends, such as climbing stairs or cycling, will produce especially severe pain.
What To Do
In most cases, the treatment for these conditions requires rest and refraining from activity that will stress the knee. Icing, compressing and elevating the knee will also be integral parts of the treatment.
Doctors may suggest physical therapy to strengthen the ligaments and tendons in and around the knee. This is a vital step towards preventing recurrence of the injury and should not be neglected.
However, if a knee ligament or meniscus is completely severed, doctors will suggest surgery to repair the damage. Floating cartilage pieces inside the knee will also need to be removed by surgical intervention.
In advanced cases of knee osteoarthritis, surgeons may replace the original knee with an artificial one made from metal or plastic. After surgery, the patient may start hearing unusual noises from the knee such as clicks or pops.
However, this is not that unusual, nor is it a problem. Indeed, a 2018 study by Pazzinatto, Silva, et al concluded that there is no evidence that knee crepitus among osteoarthritis patients is predictive of knee replacement surgery in the next 3 years. The authors also concluded that there is no evidence that crepitus is predictive of declines in knee physical function or in overall quality of life.
DISCLAIMER: * Please note that, although Dunbar Medical distributes many premier brands in Sports Medicine and Home Health Care, we do not provide medical advice. As a result, we caution all users of this site not to regard its contents as medical, legal or other professional advice. Please do not attempt to use the information on this site to understand or treat any health or fitness problem or disease you may be experiencing. Instead, please seek the advice and assistance of a healthcare professional in order to understand the treatments or therapies that are appropriate for your particular condition.