The sounds of a popping, cracking, clunking or grinding joint can be a powerful force. For some, it may signal potential doom, fearing they just broke something or that they put a joint “out of alignment”. For others, it is a welcome sign of relief, signaling that they “put their joint back in place”. Most of us simply want to know ‘what the heck was that, and is it bad?
This is important because the fear and uncertainty these sounds evoke will often keep people from exercising. Others will seek dangerous or ineffective methods to provoke the “crack” in search of a false hope for solving what ails them.
Hopefully what follows will clear up any confusion and give you the confidence to know if you should just move on or be concerned. At the very least, I think you will be entertained, and feel special that you have fodder for a know-it-all moment next time someone cracks their knuckles at a cocktail party.
Will You Get Arthritis If You Crack Your Knuckles?
Most of us are familiar with the wives tale that cracking your knuckles will lead to arthritis. A very cool study helped determine if this is true.
Decades ago an 8 year old boy was always told by his grandmother that his frequent habit of cracking his knuckles would give him arthritis. So the boy set out to investigate the validity of this advice (like any normal 8 year would do, right?). From that day on, each day he would crack every knuckle on this right hand only for the next 52 years. The boy eventually became a rheumatologist (of course) and on his 60th birthday he decided to x-ray his right and left hand to investigate the differences between the chronically cracked joints on the one hand compared to the other which had been left alone (this guy knows how to party). The result? There was absolutely no difference between hands. Makes me wonder what lengths the boy went to determine the validity of the Easter Bunny.
So it appears grandma was wrong. Popping your knuckles won’t cause arthritis. But that doesn’t completely answer what is going on when we hear that pop and crackle from our joints. Let’s take a deeper look.
Getting Out Of Line?
A common trick that many Chiros and some PTs use to instill fear and dependence in their patients is telling them that they are out of alignment, and the magic manipulation or activator (done several times a week for the rest of their life of course) will solve all problems and put them back in line.
Before I go further and unintentionally evoke the sentiment that I think joint manipulation (often resulting in an audible pop) is a sham or dangerous, I want to be clear: joint manipulation can be very therapeutic and has good evidence to back it up. I spent 2 years of my life in an intensive post doctorate fellowship program to learn the nuances of spinal manipulation and use it with my patients and family members.
But I get very critical when people justify its use based on the fantasy of realigning structures to evoke a sense of dependence while dodging the real cause and solutions for their problems. Doing so in the absence of any evidence that supports such a phenomenon is even more problematic.
This needs to be etched in the doorway of any manual therapist, chiro, or osteopath: manipulation will not realign your joints. Never. Ever.
Now, I don’t blame you if you thought it would. It seems plausible on the surface. Plus, this has been passed on as if it were common knowledge. Even as a trained clinician, in my early years I thought it might be possible to realign joints by manipulation. But the more time I spent learning about manipulation and working with people who had various joint problems, especially spine issues, I realized how simplistic and ridiculous this notion was. Let’s consider some common occurrence to see if realigning joints seems possible.
The force required to induce a manipulation is far less than many forces sustained in daily life. Consider a cough or sneeze. If the realignment theory holds true, than the reverse must be true as well. Surely the forces of a good sneeze, if they exceed those produced at the hands of a therapist, could put us out of alignment. If we get a cold or suffer from allergies, are we doomed to be malformed like Quasimodo? And God forbid if we fall or, gasp, play sports and make contact with another player, kick a ball, or swing a bat. This would certainly cripple us!
Clearly, it just doesn’t make sense that we can so easily be put back into alignment as much greater forces don’t put us out of alignment.
Chiropractors say they are realigning your spine by reducing a subluxation. Essentially, as the fairy tale goes, your spine has been temporarily dislocated, and they are relocating it. The fact is that forces that would be required to actually sublux our spines would cause fractures of the spine and consequent nerve damage. So it’s darn good that we can’t have such subluxations (without serious trauma). These are the figments of an overactive chiropractic imagination, not phenomenon that take place in reality and validated by science.
But wait, the x-rays show it? Yes, only when read by someone unskilled in radiology or biased with subluxation fantasy. Sure there will be alterations in spine position (scoliosis, etc) but these alterations could be habitually selected postural anomalies by the brain, or permanently altered shapes of the bone. For example, imagine someone taking a whole body x-ray of you while standing with a sharp pebble in your shoe. Naturally, you would sift your weight away from the painful side. On x-ray, you would be in “misalignment” but this is clearly due to your brain telling you to redistribute your weight away from the pain rather than some joint alignment problem. What happens when you remove the rock from you your shoe? Viola, your alignment improves. If a manipulation was done, that would be the smoke screen masking the true solution (remove the pain provoking stimulus), and the x-ray serves as an attempt to legitimize the rouse.
Clearly, if this simplistic alignment theory were true, wouldn’t you think scoliosis and kyphosis would be a thing of the past? You can’t just put the spine back in place with your hands.
What Is That Pop?
So let’s get back to the issue of what’s cracking. The audible pop associated with joint mobilization/manipulation is usually due to cavitation in which two joint surfaces are temporarily (and minimally) separated, causing gas to be released from the joint space. This can often result in mechanical, neurological, and psychological events often resulting in pain relief.
Mechanically, the release of pressure from the joint may reduce sensitization to hyperirritable joint tissue. But the effect is not because we have magically placed the joint right back into the right position.
More convincing is the neurophysiologic effect, in which afferent stimuli triggers the release of neurotransmitters in the brain which help modulate pain. A recent study revealed a few such mechanisms that manipulation can trigger. (Gustavo Plaza-Manzano, et ak J Orthop Sports Phys Ther 2014;44(4):231–239) Again…nothing is being realigned, but the chemicals in our brain that influence joint pain perception may be altered.
And finally, the well known placebo effect may be at play. This is a very strong and real response, in which if someone firmly believes something good (or bad) will happen when they experience this manipulation, validated by the pop and the surface logic of “realigning” them, then they will actually feel better (Ernst E. Family Practice 2000; 17: 554–556.) If they believe it will work, often times it will.
Addicted to Crack?
“Yeah but, it really works for me!” I know…I believe you.
That’s why I use it, and have it done to me. But it has limitations, it’s not magic. Sometimes it works, many times it doesn’t. The debate is really why, how, when, and for whom. Studying the research and treating patients will answer the above to the extent that we can use it wisely.
So what’s the harm of getting cracked if you find it works for you? Complications, sometimes severe, have been reported mostly in regards to cervical manipulation. But these issues are very rare, and are greatly reduced by proper screening and technique. More common, but less severe, are the extreme positions many people put themselves in trying to desperately get that pop. I have witnessed many folks who are Gumby hypermobile contorting themselves to positions that are putting extreme stress on known vulnerable tissues in their spine which are often the source of pain in efforts to get the desired “pop”. This is like ripping open a wound in attempts to scratch an itch.
A very significant and common harm is that it could force you to bark up the wrong tree. Let’s say you woke up with an achy back. You seek out your favorite “bone cracker” and “crack”…ahh, you feel relief! Very Cool, right?
Yes, immediate relief is possible (not very common though if you see multiple types of spine clients). But just as important, and perhaps more so, is figuring out what caused the pain in the first place? Without finding the cause, how can we assure it won’t come back? Usually poor ergonomic and faulty motor patterns are contributing factors. I often tell patients that doing treatments (manipulation, mobilization, exercise) without addressing ergonomics and habits contributing to the problem is like taking Tylenol for a head ache while repeatedly banging your head against the wall. Related to this, instability is often involved. What will manipulation do to address these issues? Absolutely nothing.
Focusing on manipulation at the center of treatment often marginalizes the importance of these other well supported contributing factors in the minds of the patient. It also places the locus of control away from the patient. This creates a “you fix me” psyche resulting in dependence, not empowerment. The result is a cycle of pain, visit, crack, pain, visit, crack…and a crack addict is created!
Us clinicians should be a bit more humble about our treatment methods and provide the facts about what is and what is not happening. Doing so creates not only trust, but an environment that empowers the patient to look to factors that they can control and have a positive influence upon their pain. This approach is strongly supported by research and real world results. (Gustafsson M, Gaston-Johansson F. Pain intensity and health locus of control: a comparison of patients with fibromyalgia and rheumatoid arthritis. Patient Educ Couns 1996;29:179–88. Crisson JE, Keefe FJ. The relationship of locus of control to pain coping strategies and psychological distress in chronic pain patients. Pain 1988;35:147–54)
Demystifying the crack at the hands of a clinician is one step in helping us focus on the other less sexy but more supported mechanisms of addressing joint problems.
Snap, Crackle, Pop…
The sounds of a pop at your spine and knuckles are familiar to most of us, but we hear these noises and others in our other joints, especially our knees, shoulders, ankles, hips, and even our shoulder blade. Here’s what is up some of these common noises.
Knee popping. A loud pop is common when movement occurs in a stiff joint (especially after periods of prolonged immobilization). This is rarely painful. In fact, it might feel good. Regardless, there is no evidence of any correlation to joint damage or pain when this occurs. As one of my professors taught us in summarizing the research on this “if you hear a lot of cracking, turn up the radio”. For those of you who are quite literal like me, this mean don’t worry about it.
There are times when you get a loud pop at the knee when something really bad happens. This is often reported when a ligament ruptures like the ACL. The noise, however, is not from the ligament rupturing. Pulling apart a tissue like that wouldn’t usually make a noise. Rather, the pop or “thunk” is usually the joint subluxing or separating, like popping a knuckle, only louder. This happens with pretty extreme trauma, like while skiing or playing basketball, not exercising. Even when I ruptured my patella tendon right in half, there was no sound (other that of my back hitting the pavement).
Knee crackling, like grinding sand, is very common at the patellofemoral joints. This is very common when going up and down the stairs. The crackling of my wife’s knees going up the stairs is loud enough to hear throughout the house. Yet she works out intensely without issues. And that is not uncommon. Some have speculated that the grinding noise is due to softening or irregularity of the joint surface of the knee cap. When this irregular surface rubs over the surface of the tibia under load (like when squatting or ascending stairs), this makes a noise like a shoe with sand on the sole rubbing over the floor.
My knee following the several trauma of a patella tendon rupture is an interesting case study to investigate this theory. As a result of attempting to repair the patella tendon and restore functioning, the resultant length of the tendon, and accordingly the position of the knee cap, was permanently altered. This changes the surface area contact of the patella upon the adjacent tibia joint surface, and also the force mechanism of the muscles and tendons acting on the joint. Accordingly, when I was finally able to ascend stairs, the noises my knee made were quite disturbing even to a seasoned clinician. I moved forward with confidence, knowing that there was likely little damage going on, and the consequences of not gradually strengthening my knee were far worse that the consequences from the noises common from my knee.
A few years later, my knees rarely make any noise with stairs. My theory is that the articular surface of my knee cap softened due to the months of immobilization. Upon reloading it, coupled with the altered surface area being loaded as the consequence of my knee being structurally altered, the tissues were irregular. However, over time with graded loading, the joint surfaces adapted and smoothed out, thus resulting in minimal noises. We witness this in the clinic many times. Folks who have been immobile will hear some unsettling sounds when new movements are restored. They should be encouraged to continue moving and reassured that over time these noises may dissipate. Again, we have no proof that the noises are bad or good in these cases. However there seems to be a common pattern of joints getting less noisy with more movement after immobilization.
Clunky Hips
When hips make noises, we often hear a deep ‘thunk’ or a superficial snapping. The deep thunk is common in those moving after a period of immobility, just like with the knee example above, or in those who are hypermobile (dancers). These issues are rarely indicative of any problems. The superficial snapping can correlate with pain. This can occur from a tendon moving over an inflamed or thicken bursa, or a tendon gliding over a boney anomaly (such as a bump on a bone). Interestingly, I see this more often in women with a wider pelvis, and it often gets better with strengthening the glutes, stretching the hip flexors, and improving lumbopelvic stability. Several theories can explain why or how, but given that it is a low risk intervention that can help many other issues, proceeding with this approach without fully understanding the mechanism is something I feel very comfortable with.
Clicking Shoulders
Given the similarities between the shoulder and the hip, similar phenomenon are found there as well. The key difference is that shoulders have a much greater degree of mobility and far less stability. So joint irregularities, noises, and damage are all more common there. In the clinic I find those with greater amounts of mobility (swimmers and baseball players), those with significant arthritis, and those with poor scapula thoracic and scapula humeral function tend to have more noisy shoulders. Just like with the other joints mentioned, those who are immobile will experience more noises when they attempt more movement, but then over time this noise often diminishes.
Again, we can’t conclude that joint noises are always related to pain, as we commonly see painful silent shoulders, and vice versa.
Those with instability and poor shoulder mechanics need these issues addressed, which basically involves movement. So again, the noises should not discourage us from moving out of fear that joint damage will result.
Snapping Scapula
Finally, a less common site of “joint” noise is at the shoulder blade, sometimes referred to as snapping scapula. This snapping can occur with or without pain and has been suspected to be caused by a few possible issues. First, atrophy of the underlying subscapularis and serratus muscle alters the interface between the scapula and the bumpy rib cage over which it glides causing the superior angle of the scapula to catch upon the underlying bone. Also, the two bursae that lay between the scapula and the ribs may become thickened, altering the surface area between the bones of the scapula and rib cage. Finally, anomalies of the ribs (bumps on the bone) can affect the articulating surface causing snapping.
Should You Be Worried?
The most important issue when you get any symptom is to know if you should be concerned and worry. Hearing noises coming from your joints can be unsettling. As we reviewed above, it should be clear that rarely does joint noise tell us that something bad is happening. In fact, more often it will indicate that we should move. There can be many obstacles that clutter our road to improved health and fitness, so it’s important that we clear our path as much as possible. Hopefully we’ve cleared another obstacle from your path. So if you hear noises, be calm, and proceed to improving your movement quality. Just as important, don’t chase noises under false pretenses of realigning joints.
Most important, be sure to reach out if you need to know how to ensure you are doing the right things based on your unique needs to reach your goals.
