Hearing a click, pop, or grind when moving the shoulder is medically known as crepitus. This sound can range from an audible click to a deeper grinding sensation that is felt more than heard. While the noise can be alarming, the majority of shoulder clicking is harmless and does not signal a serious underlying problem. Understanding the source of the noise helps determine if it is a normal mechanical occurrence or a symptom requiring medical attention.
What Causes Popping and Clicking Sounds
Joint noises are caused by two primary physical mechanisms: a sudden change in pressure within the joint or the friction of soft tissues moving over bone. The first mechanism, called cavitation, occurs within the synovial fluid that lubricates the shoulder’s ball-and-socket joint. This fluid contains dissolved gases that form tiny bubbles when the joint is moved quickly. The rapid collapse of these gas bubbles creates a sharp popping sound, similar to cracking knuckles, and is generally painless.
The second mechanism involves the friction or snapping of anatomical structures like tendons or ligaments. The shoulder is a highly mobile joint where strong tendons pass over bony ridges or prominences. When a tendon or ligament momentarily catches on one of these structures before snapping back into position, it generates a clicking or snapping sound. This noise may be painless if the tissue is healthy, but it indicates a mechanical irregularity in the joint’s movement pattern.
Benign Causes of Shoulder Clicking
Most instances of painless shoulder clicking stem from minor mechanical irregularities not associated with structural joint damage. Muscle tightness or an imbalance in the muscle groups surrounding the shoulder can alter the precise rhythm of movement. For example, weak muscles in the back combined with tight chest muscles can cause the upper arm bone to sit slightly forward in the socket, leading to abnormal friction.
Another common source of benign clicking is Snapping Scapula Syndrome, which involves the shoulder blade (scapula) moving over the rib cage. The noise occurs when the bursa, a small fluid-filled sac, or other soft tissues catch between the scapula and the ribs during arm movement. This condition often results from poor posture or repetitive motions that disrupt the smooth gliding action of the shoulder blade.
Minor instability or joint laxity can also cause a slight, painless shift in the joint that results in a click. In individuals with hypermobility, the ligaments that stabilize the joint may be looser, allowing the head of the arm bone to move slightly before settling back into place. These mechanical variations are not dangerous, but they suggest that surrounding muscles may benefit from targeted strengthening to improve joint control.
Structural Damage Leading to Painful Clicking
When shoulder clicking is consistently accompanied by pain, weakness, or a catching sensation, it suggests damage to the joint’s internal structures. A frequent cause is a labral tear, involving the labrum, a ring of cartilage that deepens the shoulder socket and helps keep the joint stable. A tear in this cartilage, such as a SLAP tear, can result in painful clicking, catching, or a locking sensation as the torn fragment gets pinched during motion.
Rotator cuff issues are a significant source of painful clicking, often presenting as a grinding or deep popping noise during overhead activities. If the rotator cuff tendons are inflamed (tendinopathy) or partially torn, they can catch or rub against the surrounding bone. This often occurs within the narrow space beneath the acromion, a condition known as impingement. The resulting noise indicates that the damaged or irritated tendon is struggling to glide smoothly.
Instability of the long head of the biceps tendon can also cause painful clicking. This tendon runs through a groove in the upper arm bone. If the supporting tissue is torn, the tendon can sublux (partially dislocate) out of its groove, creating a distinct, painful snap. This biceps instability is often felt in the front of the shoulder, especially during rotation.
A persistent, grating sound, often described as crunching or grinding, may signal osteoarthritis in the shoulder joint. This condition involves the progressive breakdown of the smooth articular cartilage covering the ends of the bones. When this protective layer wears away, the rougher bone surfaces rub directly against each other. This leads to constant crepitus, typically accompanied by stiffness and deep joint pain.
When to Seek Medical Attention
While occasional, painless shoulder clicking can usually be managed with simple modifications and strengthening exercises, certain symptoms warrant a medical evaluation. Consult a healthcare professional if the clicking is consistently associated with acute or persistent pain that does not resolve with rest. The combination of noise and discomfort suggests that the soft tissues or cartilage are being irritated or damaged.
Seek professional help if the clicking is accompanied by a noticeable loss of strength, a feeling of instability, or the sensation that your shoulder is going to “give out.” Any clicking that causes the joint to lock up or catch during movement should be examined, as this often indicates a mechanical obstruction, such as a labral tear or a loose fragment of cartilage. If the clicking began immediately following a specific injury or traumatic event, a thorough diagnostic workup, including imaging like an X-ray or MRI, is necessary to rule out significant structural damage.