The Connection Between Knee Popping And Pain
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Knee popping occurs in two forms: acute popping, which happens suddenly due to an injury like a ligament tear, and crepitus, a chronic clicking or cracking sound from joint friction.
With age, natural wear and tear can cause knee noises. If these sounds persist or come with pain or swelling, they may signal conditions like osteoarthritis. Relying solely on painkillers can mask the issue, potentially worsening it, and increasing the need for surgery.
The Regenexx approach provides a non-surgical path to recovery for those suffering from knee pain. Procedures using Regenexx proprietary methods help harness the body’s natural healing ability. Using interventional biologics, the Regenexx approach offers patients an alternative to surgery and reduces the need for prescription drugs.
The Anatomy Of The Knee
The knee connects the thigh bone (femur) to the shin bone (tibia). Cartilage, ligaments, tendons, and synovial fluid help stabilize the knee, absorb shock, and smooth movement.
With aging or injury, these structures can suffer damage or wear and tear, leading to sounds like popping or clicking.
Here are the key areas in the knee that can generate noise:
- Cartilage: This tissue cushions the joint, preventing friction between the bones. Damage or rough surfaces in the knee’s cartilage may cause clicking or grinding sounds, especially with movement.
- Synovial Fluid: A thick, lubricating substance that reduces friction in the joint. Small gas bubbles in the fluid can burst, creating a popping sound.
- Tendons and Ligaments: These structures can snap or shift over bones, leading to occasional popping or clicking.
- Meniscus: The fibrocartilage structure between the femur and tibia may cause a popping sound if torn or damaged.
Popping Joints, Painful Knees
Knee popping may be a pathological noise. Pathological noises are abnormal sounds that may indicate an underlying condition. These sounds often result from damage to knee structures, like worn cartilage or ligament tears.
These noises can vary in intensity and frequency, helping pinpoint the problem’s source. Two common types of knee noises are:
- Loud Pops: A sudden, loud pop often occurs during an injury, such as a torn ligament or tendon. This sound is typically accompanied by immediate pain, swelling, and instability. A 2023 research suggests that 70% of people with an anterior cruciate ligament (ACL) tear experience a loud “pop” accompanied by sharp pain at the time of injury.
- Crepitus: This is a softer, repetitive clicking or crackling sound that happens with movement. It is often caused by cartilage wear or joint friction, such as in osteoarthritis. While it may not always be painful, crepitus can be accompanied by stiffness and discomfort, especially during activities. A 2024 study suggests that crepitus is present in 41% of the general population and in 81% of patients with knee osteoarthritis.
Either symptom should be promptly addressed, even if not immediately accompanied by pain.
A new study aimed to find out if there was a connection between those pops and creaks coming from the knees and arthritis. The large-scale, national study included 3,495 subjects who had crepitus (knee sounds, such as creaking, grating, or popping) but did not have symptomatic knee arthritis at the start of the study.
For the purpose of the study, the researchers defined arthritis as bone spurs on X-ray with frequent knee pain. Subjects at baseline could have one or the other but not both. The subjects were examined, had X-rays, and completed questionnaires at the start of the study and then every 12 months thereafter, up to 48 months.
For most subjects, there was no significant change or worsening in the first year, which could be why so many continue to ignore their creaking and popping knees. However, over the four-year life of the study, around 18% of the subjects developed full-blown arthritis, with not just one indicator—frequent knee pain or bone spurs on X-ray—but both.
The results were most prominent in the knee popping group, with X-ray evidence of bone spurs at the baseline but no pain. This group was more likely to develop frequent pain later in the study and, therefore, knee arthritis. Another interesting finding was that the noisier the knees were, the greater the chance of knee arthritis.
So, researchers concluded that there is a connection between crepitus, knee popping, and the later development of knee arthritis. This may be because crepitus indicates knee instability. Unstable knees increase imbalance during movements and lead to excessive friction, which speeds up cartilage degeneration.
Identifying Associated Symptoms With Popping Knees
At first, knee popping may seem harmless, but it can signal an underlying condition or lead to cartilage degeneration. Over time, this may contribute to osteoarthritis, causing reduced mobility and potential disability. Symptoms associated with knee noises include:
Pain And Swelling
Knee noises don’t always come with pain. Pain and swelling may result from injuries like ligament tears, cartilage damage, or conditions like osteoarthritis. Swelling can result from inflammation or fluid buildup in the joint. This often happens after trauma or chronic conditions, causing stiffness and difficulty in moving.
Stiffness
Stiffness can occur alongside knee noises after an injury or from cartilage degeneration. Stiffness often results from swelling and pain, which limit movement. Cartilage damage can create bone friction, causing stiffness and popping sounds.
Restricted Range Of Motion
Restricted range of motion with knee popping may indicate a blockage within the joint, affecting normal movement. This could be due to:
- Structural damage such as a torn meniscus or ligament injury.
- Osteoarthritic joints with deformities like bone spurs, which interfere with movement.
- Loose bodies, such as small fragments of bone or cartilage within the joint.
Restricted motion can make it difficult to perform activities like kneeling, walking up stairs, or standing up from a seated position.
Weakness
Weakness with popping sounds may suggest issues with the tendons or ligaments supporting the knee joint. Weakness can occur after an injury or degenerative condition, leading to instability and a higher risk of damage.
Instability Of Knees
Knee instability refers to looseness or unsteadiness in the joint or a feeling that the knee might buckle or “give out”. This can happen due to ligament injuries, such as tears in the anterior cruciate ligament (ACL) or medial collateral ligament (MCL). These injuries weaken the structures that stabilize the knee, causing instability and joint dysfunction.
Why Is My Knee Popping?
Knee popping can result from various causes, from harmless symptoms to signs of injury or degenerative conditions. Knowing the causes of knee popping can help determine if medical attention is needed.
Air Bubbles
Knee popping occurs when small air bubbles form and burst in the synovial fluid that lubricates the joint. Movements like bending or stretching change the pressure inside the joint capsule, causing gasses normally dissolved in the liquid to form bubbles.
When these bubbles burst, they create a popping sound, much like cracking knuckles. This popping type is painless and usually doesn’t indicate any underlying knee problem.
Signs of popping sounds deriving from air bubbles include:
- It is an intermittent occurrence and is not associated with pain or swelling.
- The sound happens during normal joint movement, such as bending or straightening the knee.
- Often noticed during periods of inactivity, followed by sudden movement.
Cartilage Injury
Cartilage injuries, especially to the meniscus, can also cause knee popping. Cartilage cushions the knee, provides stability, smooths movement, and prevents bone friction.
Cartilage injuries often occur due to sudden twisting or overuse. These injuries can cause popping or clicking sounds, often with pain, swelling, and difficulty moving the knee fully.
Ligament Injuries
A loud ‘pop’ may occur after a direct blow or a non-contact knee injury. This often indicates knee ligament damage and may be associated with sharp pain, swelling, and instability.
Conditions That May Cause Knee Pain And Popping
When a loud “pop” or crepitus are pathological symptoms, they can indicate several conditions, including:
Patellar Tendon Tear
A patellar tendon tear happens when the tendon connecting the kneecap (patella) to the shinbone ruptures, often due to excessive strain during jumping or lifting. This injury prevents the knee from straightening, often with a sudden popping sound, pain, swelling, and inability to bear weight.
Knee Arthritis
Arthritis refers to inflammatory joint conditions. Rheumatoid arthritis is an autoimmune disease where the immune system attacks healthy tissues. Osteoarthritis, a degenerative joint disease, wears down the protective cartilage over time, causing increased friction between bones and producing a grinding or crackling sound called crepitus. Arthritis typically causes chronic pain and stiffness, with popping or cracking sounds, especially after rest periods.
When It’s More Than Just Popping, Clicking, And Snapping
Knee popping, clicking, or snapping is often harmless, but when accompanied by pain, swelling, or instability, it may signal an underlying condition that requires medical attention. Persistent or painful popping isn’t normal and may indicate ligament tears, cartilage damage, or degenerative conditions like arthritis. A professional evaluation is essential to determine the cause.
To improve diagnostic accuracy and guide informed treatment decisions, physicians in the licensed Regenexx network may use SANS evaluation to provide an analysis of joint health.
During evaluation, the physician will review existing MRIs and scans and examine your body in motion. This specialized evaluation method may also use advanced diagnostic tools such as ultrasound to determine the causes of pain.
The Regenexx Approach To Healthy Knee Function
Overlooking pathological noises and knee pain can let underlying conditions go unaddressed. Over time, worsening joint degeneration can increase the risk of reliance on medications and surgery.
Physicians in the licensed Regenexx network provide an alternative by using interventional orthobiologics. Customized treatment plans may include one or more of the orthobiologics below.
Regenexx-SD Injectate
Procedures using Regenexx-SD injectate include a patented protocol that utilizes Bone Marrow Concentrate (BMC), which contains the patient’s mesenchymal stem cells. The cell processing for a Regenexx-SD injectate routinely achieves 20x concentration— far above what non-Regenexx cell processing can achieve.
Regenexx-SCP Injectate
Procedures using Regenexx-SCP injectate represent a supercharged version of platelet-rich plasma (PRP). In this process, blood is drawn then processed to isolate the platelets and growth factors. The growth factors are then purified, concentrated, and injected into the knee area using imaging guidance for precision. Regenexx-SCP injectate provides a higher concentration of growth factors than typical PRP procedures.
Regenexx-PL Injectate
Procedures using Regenexx-PL injectate are a highly specialized derivative of platelet-rich plasma (PRP) with a faster and more concentrated release of growth factors compared to typical PRP. The PL injectate is often combined with other orthobiologics such as PRP and bone marrow concentrate.
Addressing Knee Pain And Popping
Knee popping and pain can disrupt daily activities. Since these symptoms can be chronic, medications may only address the symptoms, potentially leaving underlying conditions untreated and increasing the need for surgery.
Physicians within the licensed Regenexx network offer an alternative through interventional orthobiologics, which help support the body’s healing process. To learn if procedures using Regenexx injectates are right for your knee condition, contact a physician in the licensed Regenexx network.
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