Many individuals experience knee popping sounds at some point in their lives. Although it can be a disturbing event, the majority of these cases are harmless and consistent with normal knee function.
Knee popping, clicking, grinding or other noises are so common that there is a term for the phenomenon among the medical community – knee crepidus.
As we will see below, knee popping sounds can be ignored in most cases when there are no accompanying symptoms. However, popping that occurs with knee pain or swelling is usually an indicator of a knee problem that requires medical attention and should not be ignored.
In this article, we will set out the most common reasons for knee popping or other sounds. For each cause, we will also summarize some of the accompanying symptoms that are commonly experienced. We will also suggest the most advisable reaction to each possible cause, whether this is to ignore the noise, to seek medical advice or to take some other action.
Knee Popping Sounds – Possible Causes
The knee joint contains a lubricating fluid (known as synovial fluid) that helps keep the joint lubricated with its bones and soft tissues moving smoothly over each other.
However, bubbles of gas can occasionally form in the fluid due to the normal operation of the knee. As you move the knee around,these bubbles rise to the surface and burst, making a popping sound. There will be no accompanying symptoms when this happens.
This cause of knee popping sounds is quite normal and should cause no concern. No action is needed.
Ligament Movement In The Knee
The ligaments & tendons in the knee are somewhat elastic and sometimes have to stretch as they navigate bony prominences inside the joint. When they have passed over the prominence, they will then snap back into position, making a popping sound just as a rubber band would. You will feel no pain or any other symptoms as this happens.
This too is part of the normal functioning of the knee joint and should not cause any concern. There is no need to seek medical attention or take any other action.
Knee Sprains & Other Soft Tissue Injuries
These are injuries caused by damage to a knee ligament or meniscus.
Knee sprains are caused by the overstretching or tearing of knee ligaments. Most knee sprains involve damage to the anterior cruciate, medial collateral or posterior cruciate ligaments. With many knee sprains, you may hear a “pop” at the time the injury happens.
Unlike the situation with the other causes of knee popping sounds we discuss in this article, this is usually just a single pop. You will then start to experience persistent knee pain and, in some cases, swelling of the joint. The joint range of motion will be reduced and you may experience difficulty placing weight on the injured leg.
There are 2 menisci in the knee. They are located between the femur (thigh bone) and tibia (shin bone) and help to cushion the 2 bones and prevent direct contact with each other.
Occasionally, you may suffer a tearing of one or both menisci. When this happens, knee movements may be accompanied by clicks or pops. In this case, however, the clicking and popping will be repeated – it will not be a one time event as with knee sprains.
Together with the repeated knee popping sounds, you will most likely experience knee pain and swelling, together with loss of range of motion.
Sometimes, a meniscus tear may be a complete severing, leaving a loose piece of cartilage floating around in the knee.As it gets caught in various places in the joint, you will experience clicking, popping or grinding noises as you try to move the knee
Patellofemoral Pain Syndrome
This condition is also known as Runner’s Knee. The main cause is damage to the underside of the patella (kneecap) due to excessive running, jumping or other activity that stresses the knee.
You may experience knee clicking or popping noises as you try to move your knee. There will also be knee pain but you will experience relief during periods of rest.
The pain from patellofemoral pain syndrome may be especially severe when performing activities that require deep knee bends, such as cycling or stair climbing.
A knee sprain, meniscus tear or other soft tissue injury will usually get better after a few weeks of resting the knee and avoiding placing any weight on it or playing sports.
A knee brace with lateral ligament support (e.g. a hinged knee brace) will help to protect your knee and promote recovery from sprains or meniscus tears. For Runners Knee, a knee strap can be helpful..
A doctor can recommend a course of physical therapy to strengthen the muscles and tissues of the knee and reduce the risk of another knee sprain in the future.
If the ligament or meniscus has been completely severed, however, you will likely require surgery to correct the problem. Afterward, you will need to undergo physical therapy to prepare for a return to normal activities.
This is another common cause of knee crepidus. It is the result of degeneration (usually due to wear and tear) of the cartilage covering bone ends in the knee joint. As this happens,you may start to hear knee pops, clicks and other sounds as you try to flex or extend the joint.
You will also experience increasing knee pain as well as joint stiffness and reduced joint range of motion.
However, unlike the pain due to soft tissue injuries, pain from knee osteoarthritis will tend to be at its worst upon awakening in the morning. It will also tend to be more severe after a period of inactivity such as a daytime nap.
In addition to knee pain and stiffness, you will also notice knee swelling as the condition progresses. Inflammation will also be an increasing problem.
If the doctor confirms that you have osteoarthritis, he will likely recommend a combination of activity modification, physical therapy and pain medication to manage the problem. Unfortunately, there is no underlying cure for this condition.
Unloader knee braces can be effective in reducing mild to moderate osteoarthritic knee pain and slowing the rate of progression of the condition. Alternatively, if the condition is mild, a knee sleeve can provide the warmth needed to counter the knee stiffness.
If you are overweight, weight loss can reduce the pressure on the knee and reduce the pain.
In its advanced stages, these measures will not be adequate. Doctors will then suggest a range of surgical solutions up to and including knee replacement.