Knee clicking, or crepitus, is a common sensation experienced when bending or straightening the knee. These sounds can include popping, clicking, grinding, or crackling. While often harmless, knee clicking can sometimes signal an underlying issue that requires attention.
Common, Harmless Reasons for Knee Clicking
One common, harmless cause of knee clicking is the release of gas bubbles within the joint’s synovial fluid. This process, called cavitation, occurs when pressure changes cause tiny nitrogen bubbles to form and burst. The sound is similar to cracking knuckles and is typically painless and not associated with joint damage.
Another benign reason involves the movement of tendons or ligaments. As the knee bends or straightens, these soft tissues can momentarily snap or glide over bony prominences. This creates a popping or clicking sensation as the tissue returns to its normal position. Such sounds are usually painless and do not suggest an injury.
Sometimes, clicking is simply part of the knee joint’s normal mechanics. These natural physiological noises do not indicate future issues like arthritis and often go unnoticed.
When Knee Clicking Might Indicate a Problem
Knee clicking can indicate underlying medical conditions or injuries, especially when accompanied by other symptoms.
Torn Meniscus
A torn meniscus, the C-shaped cartilage cushioning the knee joint, can cause clicking, popping, or a locking sensation. This clicking is often accompanied by pain, swelling, and difficulty bending or straightening the knee.
Cartilage Damage
Damage to the articular cartilage, which covers the ends of bones in the joint, can also lead to problematic sounds. Conditions like osteoarthritis or chondromalacia patellae involve the wearing down or softening of this smooth cartilage. A rough or uneven cartilage surface can cause a grinding or creaking sensation, often with pain and stiffness, particularly during activities like walking or climbing stairs.
Patellofemoral Pain Syndrome (PFPS)
Patellofemoral pain syndrome (PFPS), also known as “runner’s knee,” involves issues with how the kneecap tracks in its groove on the thigh bone. This misalignment or irritation can result in clicking or grinding sounds, especially during activities like squatting or climbing stairs. Pain around or behind the kneecap is a common symptom, often worsening with activity or prolonged sitting.
Loose Bodies
Small fragments of bone or cartilage, known as loose bodies, can also cause problematic knee clicking. These fragments can break off due to trauma or degenerative conditions and float freely within the joint. When a loose body gets caught between joint surfaces, it can cause clicking, popping, pain, a locking or catching sensation, and may also lead to swelling.
When to Consult a Healthcare Professional
While many instances of knee clicking are harmless, certain accompanying symptoms warrant a doctor’s visit. Seek medical attention if you experience:
Pain with the clicking sound.
Swelling around the knee joint.
A sensation of the knee locking, catching, or giving way.
Clicking that began after a specific injury or trauma.
Inability to bear weight on the affected leg.
These symptoms can indicate a mechanical issue within the joint, such as a torn meniscus or loose body, or suggest inflammation or injury.
Approaches to Managing Knee Clicking
For painless knee clicking without other concerning symptoms, continued activity and gentle stretching can help maintain joint mobility and muscle flexibility.
When knee clicking is associated with pain or other problematic symptoms, professional guidance is typically needed. Conservative treatments often include the RICE method (rest, ice, compression, elevation) and over-the-counter pain relievers like NSAIDs to manage pain and inflammation.
Physical therapy is important for addressing problematic knee clicking. Therapists can design personalized exercise regimens to strengthen knee muscles, improve flexibility, and correct movement patterns. Lifestyle adjustments, such as maintaining a healthy weight to reduce stress on the knee joints and engaging in low-impact exercises like swimming or cycling, can also be beneficial. In some instances, medical interventions like injections or surgical procedures may be considered after a thorough professional assessment to address the underlying cause.