The body emits many types of cracking noises, including knee cracking, back cracking, and cracking knuckles, and these all mean different things.
Knee Cracking Causes
There are many reasons behind knees cracking or a knee popping. Knees crack, and the cracking knees may happen often, but those popping sounds are not necessarily a sign of something being wrong. Joints crack in general, and the knees may do so when squatting or going through their full range-of-motion. It becomes a concern if swelling or pain is involved. Aging causes the cartilage to become uneven, leading to rougher surfaces that glide over each other. In addition, ligaments tighten upon movement. If there is pain, though, it could be symptomatic of some more serious conditions. Meniscus tears involve the meniscus, which “is a rubbery C-shaped disc that cushions your knee and acts as a shock-absorber” and spreads the weight evenly so that bones are not rubbing together. It can tear from “sudden twisting or…sports”. Over time, arthritis may result from the cartilage wearing down, leading to the knees “grinding”. Osteoarthritis is a common arthritic condition that typically impacts “middle-aged and older people”. There are many ways to keep the knees healthy. Regular exercise, including squats and lunges (with resistance bands or weights), walking up some stairs, and riding a stationary bike can build muscle, and that supports the knees. It is important to warm up before exercising to prevent injury. Flexibility is key. Dynamic stretches, with a full range-of-motion before exercising, and static stretches (holding the stretch) after exercise, also can prevent injuries. It is necessary to also have proper shoes that fit and to maintain a healthy weight.1 An unrelated, but more serious condition, is a cracked knee cap. Falling onto a knee can cause this, and these patellar fractions “often require surgery to heal” and “may cause arthritis in the knee”.2
Is it Bad to Crack Your Knuckles?
Patients often ask doctors, “Does cracking your knuckles cause arthritis?” To fully understand the answer to that question, it is important to know the facts about what knuckle cracking is and the mechanisms behind it. All joints in the body have a synovial membrane surrounding them, and this membrane “forms a capsule around the ends of your bones”. The membrane contains synovial fluid, a shock absorber and lubricant to prevent the bones from grinding. Cracking any joint, including the knuckles, “expands the space between your bones”, leading to negative pressure, and synovial fluid is drawn into the gap. When the fluid enters, it leads to a “popping sound”. Persistently cracking the knuckles leads to the ligaments and synovial membrane loosening, “making it…easier for your joints to crack”. Related to this are people who crack their own necks, and this could lead to “lax ligaments”. With regard to osteoarthritis, this is a situation in which the joint cartilage is being damaged, reducing synovial fluid, and “research has not shown a correlation between knuckle cracking and osteoarthritis in your hands”. To reduce the risk of osteoarthritis, there needs to be changes in diet and lifestyle, but aging itself is also a factor. Repetitive movements can contribute to that arthritis, but knuckle cracking has no link to that condition at this time. However, habitually cracking the knuckles was found, in a study, to lead to a likelihood of “hand swelling and lower grip strength” as a result of loosening ligaments and repeated stretching. Knuckle pads may also result, and these are “firm nodules that sometimes form over certain joints in your fingers”. While they don’t produce symptoms, these pads do have cosmetic and psychological effects”. People feel relief after cracking knuckles, and this positive perception tends to reinforce the habit due to the “stress relief”.3 To recap, cracking the knuckles bursts the synovial fluid bubbles (gasses like oxygen, nitrogen, and carbon dioxide). When the joint expands, the fluid fills the empty space, the joint settles, and the fluid returns to the proper location, leading the bubbles to pop and make that cracking sound. It takes about 15-30 minutes for the gasses to dissolve back into the synovial fluid, and that is why it takes time to be able to crack the knuckles again.4
The back may crack on its own. For example, a person may feel back tension, twist, and then “crack” the back, leading to a reduction in tension. While this might be an occasional relief, it should not be done on a regular basis on one’s own. It can lead to spinal damage and needing to crack the back often to get relief. Self-adjustment of the back could cause “hypermobility”, or a situation in with the spine and surrounding muscles are repeatedly stretched. This leads to a reduction in “natural elasticity”. A healthcare professional can recommend back exercises to strengthen the back. They may allow for the occasional self-adjustment in a chair or on the floor, and these adjustments should be done slowly and carefully, per the healthcare professional’s instructions.5 There are many online instructions for back cracking methods, but some could lead to a dangerous situation, including “broken ribs and lung injuries”. That is why seeking help from a chiropractor is a safer approach.6
Chiropractic Care is Different
Chiropractic care is not the same as self-adjustment and knuckle cracking. The adjustment performed by a chiropractor “is a specific force at a specific place that improves the motion in the spine…only done on a joint that isn’t functioning well”. Chiropractors can reduce stiffness and improve range of motion. Just randomly cracking the neck, back, or knuckles on one’s own can lead to harm. Chiropractic is safe and going to a chiropractor once does not mean a patient has to go “forever”. It is true, however, that untreated problems can lead the joints to wear down, causing nerve irritation and tissue sensitivity; therefore, it may take several treatments over time to have optimal relief. Some patients also choose to see a chiropractor proactively to prevent dysfunction. Chiropractors are well-educated and are experts in musculoskeletal care. Not all patients have to “get cracked”. There are many types of gentle adjustments that do not include the popping noise.7 Calling what a chiropractor does “neck popping” and “back cracking” is not accurate. The spinal manipulation, or chiropractic adjustment leads to an “audible release”, but that does not make it the same thing as the cracking sounds made when twisting a particular way or self-adjusting. The term that chiropractors use for the noise is “cavitation”. The chiropractor may or may not cause the cavitation, but they are “applying a corrective force” to reduce misalignment while “the joint is being moved from the abnormal position”. This is done with minimal force and with precision. Self-adjustment leads to laxity and looseness if it is done aggressively and too often. Every time this is done, the supporting tissues weaken. Making “a lot of noise” when overstretching the joints is not the same thing as what a chiropractor does. Seeking chiropractic care can help with all kinds of joint pain, from the knees and neck to the back, including the lower back. The treatments are safe and tailored to the individual patient. Patients can also have a say in choosing how long they need chiropractic care.8