Knee clicking describes the sounds and sensations that occur when you move your knee, such as popping, cracking, grinding, or snapping. However, while sometimes alarming, it is often a normal physiological phenomenon and typically does not indicate a serious problem.
Common Harmless Causes
A common cause of knee clicking is the release of gas bubbles within the joint. The knee contains synovial fluid, which can form tiny gas bubbles. When the joint moves, pressure changes can cause these bubbles to collapse or burst, producing a popping or cracking sound. This process is similar to cracking knuckles and is not associated with pain or joint damage.
Another reason for knee sounds involves the movement of tendons or ligaments. These tissues can sometimes snap or shift over bony prominences as the knee flexes and extends. For instance, the iliotibial (IT) band might snap over the side of the knee. Normal joint movement can also produce sounds due to friction between joint surfaces or the catching of soft tissues.
Underlying Medical Conditions
Knee clicking can sometimes signal an underlying medical condition, especially when accompanied by other symptoms. A meniscal tear, an injury to the C-shaped cartilage that cushions the knee, can cause clicking or a crunching sensation. Symptoms include pain, swelling, stiffness, or a feeling of the knee catching or locking. Tears can result from twisting the knee during sports or age-related wear and tear.
Cartilage damage, such as in osteoarthritis (OA), is another cause. In OA, cartilage covering bone ends wears away, leading to increased friction and a grinding or cracking noise. It presents with pain, swelling, and stiffness, particularly after inactivity. Chondromalacia patellae, or “runner’s knee,” involves softening and breakdown of cartilage beneath the kneecap. It can result in a grinding or clicking sensation, often with pain around the kneecap, especially when bending the knee, climbing stairs, or prolonged sitting.
Patellofemoral pain syndrome (PFPS), also known as runner’s knee, is a common condition causing pain around the kneecap that can involve clicking or grinding sounds. It often occurs due to issues with kneecap tracking, affected by factors like muscle weakness or overuse. Symptoms include dull, aching pain that worsens with activities like squatting, climbing stairs, or prolonged sitting with bent knees.
When to Consult a Doctor
While isolated knee clicking is often harmless, medical evaluation is appropriate if accompanied by other symptoms. Consult a healthcare professional if clicking is consistently accompanied by:
Pain, especially if severe or persistent.
Swelling around the knee.
Warmth in the knee.
Stiffness that limits movement or lasts for an extended period.
A sensation of the knee locking, catching, or giving way (instability).
Any significant change in the sound or frequency of the clicking, especially if it develops after an injury.
What to Expect at the Doctor’s Office
The diagnostic process typically begins with a physical examination. The doctor assesses the knee’s range of motion, stability, and identifies any areas of tenderness or swelling. They may also manipulate the knee to reproduce the clicking sound and determine if it is associated with pain.
Imaging tests may be ordered to investigate the knee’s internal structures. X-rays can help rule out bone abnormalities or signs of arthritis, while an MRI scan provides detailed images of soft tissues like cartilage, ligaments, and tendons, which can reveal meniscal tears or other damage.
Treatment depends on the underlying cause and symptom severity. Recommendations often include rest, ice to reduce swelling, and over-the-counter anti-inflammatory medications. Physical therapy focuses on strengthening knee muscles, improving flexibility, and correcting movement patterns. In some cases, for significant structural damage not improving with conservative measures, surgical options may be discussed.