Is Joint Clicking Normal? What the Evidence Actually Shows

Key Takeaways: Is Joint Clicking Normal?

Joint sounds are common, and noise alone does not mean a joint is damaged. Knee crepitus occurs in roughly 4 in 10 knees overall and in more than a third of pain-free knees.
Knuckle cracking has not been shown to increase the risk of hand osteoarthritis. The familiar “crack” appears to come from rapid cavity formation inside the joint rather than a bubble simply bursting.
Context matters more than the sound itself. Pain, instability, locking, marked swelling, or a new sound after injury make a joint noise more clinically relevant.
Catching or locking does not automatically mean a torn meniscus. In one arthroscopy cohort, these symptoms were reported even more often in patients without a confirmed tear than in those with one.
Different joint noises can represent different phenomena. Knee crepitus, TMJ clicking, snapping scapula, and snapping hip should not all be treated as the same clinical finding.

Introduction: Is Joint Clicking Normal?

Joint cracking has always attracted more myths than most harmless bodily noises. Many people grew up hearing that cracking your knuckles would “wear out” the joints or gradually stretch the ligaments. Then Donald Unger’s unusual self-experiment became widely discussed: after cracking the knuckles of one hand for decades while largely leaving the other alone, he reported no obvious difference in arthritis between the two. It is a memorable story, but clinically I would treat it as an anecdotal self-experiment rather than serious evidence.

The same question still comes up surprisingly often in practice. Patients ask whether habitual knuckle cracking is harmful, some mention the popping they experience during chiropractic manipulation, and many are concerned because their knees click or crack when they walk, squat, or use the stairs. When there is no pain or other change in how the joint functions, I can often reassure them that the sound itself is not necessarily a sign that the joint is being damaged.

That is also where the research becomes useful. A large 2025 systematic review found that knee crepitus — audible crackling or grinding — occurs in roughly 4 in 10 knees in the general population [1]. More than a third of pain-free knees also had crepitus. So a noisy joint, by itself, is not a diagnosis. At the same time, “often harmless” is not the same as “always meaningless.” The clinically useful question is usually not simply whether a joint makes noise, but what kind of noise it is and whether anything else is happening alongside it.

What’s Actually Making That Clicking Sound

For decades, the standard explanation for a knuckle crack was that a gas bubble forms inside the joint and then collapses, producing the sound the same way a popping bubble does. Real-time MRI research overturned that idea. When researchers pulled on finger joints while imaging them at more than three frames per second, the crack coincided with the sudden appearance of a gas-filled cavity inside the joint — not the collapse of one. The cavity formed in under a third of a second and then simply persisted, visible on the scan, rather than bursting [2]. The joint surfaces separated abruptly once enough traction force overcame the resistance holding them together — a phenomenon called tribonucleation — and that rapid separation is what produces the sound. This also explains the well-known “refractory period”: you can’t crack the same knuckle again for roughly 20 minutes afterward, though this imaging study didn’t resolve exactly what happens to the gas during that window [2].

That’s the mechanism behind a true “crack” or “pop.” Other joint sounds have entirely different origins: a tendon or ligament snapping over a bony prominence produces a click that can repeat immediately (unlike a true crack, which can’t), while a grinding or grating sound — the kind most people mean when they say “crepitus” in a clinical sense — usually reflects roughened cartilage or synovial surfaces moving against each other.

Is knuckle cracking normal, then, in terms of long-term safety? The evidence gives a fairly direct answer. A case-control study of 215 people compared habitual knuckle-crackers with people who never cracked their knuckles and found no meaningful difference in the rate of hand osteoarthritis between the two groups, even after controlling for age, sex, and a history of heavy manual labor [3]. That result matches earlier studies on the same question, which is why the authors of the MRI cavitation study themselves noted that habitual knuckle cracking has not been shown to increase joint degeneration, even though the forces involved during the crack are large enough, in theory, to matter [2].

In my clinical experience, concern about knuckle cracking itself comes up more often with children and younger patients. They may have heard that cracking the fingers “wears out” the joints or stretches the ligaments and genuinely wonder whether they are harming themselves. Adults are often less concerned about the sound itself; many are already familiar with joint popping through experiences such as chiropractic manipulation. The questions I hear from adults are more often about whether a repeatedly clicking knee or another noisy joint is a sign that something is wrong.

That makes the same cavitation research relevant to a different clinical discussion. In facet joint lock and chiropractic for athletes, the interesting question is not simply why a joint makes a sound, but whether the audible pop during spinal manipulation actually means that a joint has been mechanically “unlocked.”

How Common Is Joint Clicking, Really

The clearest picture comes from the knee, simply because it’s been studied the most. A 2025 systematic review and meta-analysis pooling 103 studies and more than 42,000 knees found a general-population crepitus prevalence of 41%, and — this is the number that surprises most people — 36% even among people with no knee pain at all [1]. Among people who already have diagnosed knee osteoarthritis, the figure climbs to 81% [1]. Put those together and the picture is consistent: joint clicking is normal enough, at a population level, that hearing it in isolation tells you very little about any one person’s knee — though it does track upward with joint pathology on average.

Similar patterns hold outside the knee. In hip and groin research, labral tears — a structural finding many people assume must be symptomatic — turn up on imaging in roughly half of pain-free athletes, with pooled estimates around 54% of asymptomatic athletes at the person level and 33% per hip [4]. Symptomatic athletes, by contrast, showed a lower pooled labral tear rate of about 20% per hip in that same review [4] — a reminder that a structural label doesn’t map cleanly onto pain the way intuition suggests.

Is Joint Clicking Normal When It Tracks With Something Real?

None of this means crepitus is meaningless — it means it needs context. Two well-designed studies illustrate where that context comes from, and where the answer to “is joint clicking normal” starts to shift.

The first looked specifically at the kneecap. In a study of 888 women (1,776 knees), researchers found that crepitus was significantly associated with every MRI feature of patellofemoral joint damage they measured, while it showed no significant relationship with tibiofemoral (the main knee joint, between the thighbone and shinbone) damage at all [5]. In other words, in this cohort crepitus wasn’t a generic “something’s wrong in the knee” signal — it was associated with the kneecap joint specifically, and not with the main weight-bearing compartment. The researchers themselves note that confirming any real diagnostic value would need follow-up data.

The second is a longitudinal study that followed nearly 3,500 people without symptomatic knee osteoarthritis at the start, using data from the Osteoarthritis Initiative — some already had radiographic OA but not yet frequent knee symptoms. Researchers tracked how often participants reported crepitus and, in repeated annual analyses, looked at who went on to develop symptomatic OA by the following year. The relationship was dose-dependent: compared with people who never noticed crepitus, the odds of developing symptomatic osteoarthritis the following year rose steadily with how often crepitus was reported — about 1.5 times higher for those who noticed it rarely, up to roughly 3 times higher for those who noticed it constantly [6]. More than three-quarters of those later cases came from people who already had radiographic OA but not yet frequent knee symptoms at the start [6].

These are two separate findings, not one combined rule: in the Rotterdam cohort, crepitus mapped specifically to the kneecap joint rather than the main tibiofemoral compartment [5]; in the OAI cohort, crepitus predicted later symptomatic OA mostly among people who already had tibiofemoral radiographic changes [6]. Only the OAI data speak to frequency — and there, more frequent crepitus carried more weight than occasional crepitus.

In practice, I occasionally see patients who are concerned because their knees click or crack when they squat down. More broadly, patients can become surprisingly worried about the different sounds their joints make, especially when the noise is repetitive or seems unusually loud. Some may even start avoiding certain movements or limiting exercise because they are afraid the sound means they are damaging the joint.

When the clicking is painless and there are no other concerning changes in how the knee feels or functions, I often find that reassurance is one of the most useful parts of the consultation. The sound by itself is generally not a sign of something serious. From a clinical perspective, the context matters much more than the noise alone — particularly whether pain or other symptoms are present. In these situations, part of the value of the consultation is sometimes simply helping the patient separate an alarming sound from a genuinely concerning symptom.

Joint by Joint: Is Clicking Normal in the Knee, Hip, Shoulder, and Jaw?

Is shoulder clicking normal?

Painful, gritty crepitus of the scapula against the ribcage — snapping scapula syndrome — is a recognized clinical entity. A scoping review pulling together 40 studies found the diagnosis rests almost entirely on history and physical exam, with medial scapular border tenderness, crepitus, and audible snapping as the most consistently reported signs [7]. Importantly, the same review found that non-operative management was successful in most symptomatic patients and is generally recommended before surgery is considered; the largest pain-score improvements reported in the review came from injection and shockwave-therapy studies specifically, while separate exercise-based rehabilitation studies also reported improvement [7].

Is jaw clicking normal?

TMJ disc displacement, a common structural cause of jaw clicking, has a reported general-population prevalence of 18–35% [8] — and the same review concluded that a clicking jaw with the disc still reducing normally is typically a stable, pain-free, lifelong condition rather than a progressive one [8]. Degenerative joint changes are more strongly linked to the subgroup where the disc no longer reduces at all: a pooled analysis of TMD patients who already had disc displacement found degenerative disease in about 35% of joints with reducing disc displacement, versus 66% where the disc stopped reducing [9]. It’s a pattern worth remembering elsewhere, too: it’s often not the click itself but what else is going on around it that separates a benign case from a concerning one.

In my clinical experience, I do see patients with this kind of jaw clicking from time to time. Most of the cases I encounter are not particularly painful, but the clicking itself can still be bothersome. Some patients describe it as distracting, unpleasant, or simply irritating because they notice it repeatedly when chewing or opening the mouth.

Kneecap and quadriceps strength.

One cross-sectional study in people with patellofemoral pain found that how severe the crepitus was correlated with thinner quadriceps muscle, but simply having crepitus — or how often it occurred — showed no relationship with muscle thickness or strength [10]. The authors were careful to note this as an association, not proof that stronger quadriceps would quiet the kneecap down — this cross-sectional design can’t establish that causal question either way [10].

Is hip clicking normal?

A study following football players over two years found that hip crepitus was five times more common in players with hip or groin pain than in pain-free controls, and among the symptomatic group, crepitus was linked to the number of cartilage regions showing damage but not to the other imaged features in that analysis, including bony morphology [11]. As with the knee, it’s the pattern of association — not the sound by itself — that carries the information.

It is also worth separating ordinary hip crepitus from snapping hip, or coxa saltans, which is a distinct clinical entity. I do come across it from time to time in practice. It is not something I would describe as especially common, but it is established enough as a diagnosis that it is usually taught separately in medical training rather than treated as just another form of harmless joint noise.

From a clinical perspective, that distinction matters. A patient describing a reproducible snap around the hip is not necessarily describing the same phenomenon as the crepitus measured in imaging studies. Snapping hip has its own mechanical explanations and clinical context, so I would not automatically group it together with more nonspecific clicking or crackling around the joint.

Knee Clicking and Catching: Symptoms That Are Often Over-Read

Catching and locking in the knee are commonly assumed to mean a torn meniscus, and that assumption still plays into decisions about knee arthroscopy. The evidence doesn’t support it as cleanly as the assumption implies. In a large study of 817 patients heading into knee arthroscopy for a suspected meniscus tear, 55% reported catching or locking symptoms before surgery — 53% of those who turned out to have a confirmed tear, and 64% of those whose meniscus was intact, a difference that wasn’t statistically significant [12]. A separate review analyzing 38 studies on the same question found that mechanical symptoms have only modest sensitivity and specificity for detecting an actual meniscus tear, and found little evidence that people with these symptoms do better after arthroscopic surgery than people without them [13].

This doesn’t mean catching or locking never matters — a true mechanical lock, where the knee physically cannot straighten, is a clinically different finding from an intermittent catching sensation and generally warrants assessment. But it does mean that a click or catch alone, without a locked knee, swelling, or a clear mechanism of injury, is weaker evidence of a structural tear than most people — patients and clinicians both — tend to assume.

In practice, I make a clear distinction between intermittent catching and a genuinely locked knee. When a patient cannot fully extend the knee because of a mechanical block, a meniscal injury becomes one of the structural causes I take more seriously. In that situation, I tend to have a relatively low threshold for orthopedic assessment rather than treating the symptom as just another harmless joint noise.

MRI can also become relevant when a structural meniscal injury is suspected and the diagnosis needs to be clarified. In my experience, this is quite different from the much more common situation in which a patient simply notices an occasional click or catch without a true loss of motion. The latter, by itself, is far less convincing evidence of a meniscal tear.

Red Flags: When Joint Clicking Isn’t Normal

Given everything above, the sound itself is rarely the useful signal. A knee-specific review of physiological versus pathological noise found that painless, sporadic sound with no history of injury is typical of the harmless kind, while pain, swelling or effusion, and a clear connection to an injury are what tend to mark the noise worth investigating [14]. What tends to separate normal joint clicking from something worth having examined:

Pain that accompanies the sound, rather than a painless click or pop [14]
Swelling or effusion, especially if it develops within hours of an activity or injury [14]
A joint that locks and will not fully straighten — a true mechanical block, not just a catching sensation
A sound that is new following a specific injury, rather than a longstanding habit [14]
Instability — a sense the joint might give way under load
Progressive worsening in frequency, loudness, or associated discomfort over weeks to months

A painless pop during a squat, a knuckle that’s cracked the same way for twenty years, or an occasional click when standing up from a chair generally don’t meet this bar.

In practice, the two features that make me pay the most attention are pain and instability. Swelling matters as well, but I would not interpret swelling by itself as evidence of something serious. Knee swelling can occur for different reasons and varies in clinical significance, so I still look at the whole picture — how the swelling started, whether there was an injury, whether the knee is painful, and whether it feels stable.

A red or noticeably warm knee is different. That kind of presentation often warrants an in-person assessment rather than being treated as just another harmless noisy joint, particularly if the redness or warmth is new or accompanied by pain or swelling.

Interestingly, I have noticed something similar in my own knee: when it becomes swollen, it also tends to click more easily. I would not present that as scientific evidence, of course, but it is a useful reminder that the amount of noise a joint makes can change without the sound itself necessarily being the main problem. Clinically, I am much more interested in what accompanies the clicking than in the clicking alone.

Conclusion: Is Joint Clicking Normal?

So, is joint clicking normal? In many cases, yes. Joint sounds are common, and the sound itself often tells us much less than people assume. Knuckle cracking has not been shown to increase the risk of hand osteoarthritis, and knee crepitus is common even in people without pain. What matters clinically is the context around the sound.

This is also how I tend to approach it in practice. If a joint clicks or crackles but is otherwise painless, stable, and functioning normally, reassurance is often more useful than trying to eliminate the sound itself. I become much more interested when the noise is accompanied by pain, instability, locking, significant swelling, or a clear change after an injury. A red or unusually warm joint is also a different situation and may warrant an in-person assessment.

Perhaps the most useful takeaway is that a noisy joint and a damaged joint are not the same thing. The mistake is not in noticing the sound, but in assuming that the sound alone tells you what is happening inside the joint. In practice, the symptoms and function around that noise usually matter far more than the noise itself.