Cracking joints - wikipedia Cracking joints Cracking finger joints ( knuckles ) -- cracking joints is the act of pulling bones apart to release air bubbles in the joints. The sound of a knuckle being cracked ( pictured : common knuckle joints ) happens when joint manipulation in humans produce a sharp cracking or popping sound. This occurs during deliberate knuckle - cracking, and it is possible to crack many other joints, such as those in the back and neck vertebrae, hips, wrists, elbows, shoulders, toes, ankles, knees, jaws, feet, sternum, and the Achilles tendon area. The mechanism that produces the cracking sound was until recently unknown. The act of cracking joints means bending a person 's joints to produce a distinct cracking or popping sound, often followed by a feeling of satisfaction or relaxation to the person. It is sometimes done as part of a joint adjustment / mobilization routinely performed by a chiropractor, osteopath or physical therapist. According to traditional belief, the popping of joints, especially knuckles, can lead to arthritis and other joint problems. However, medical research has so far failed to conclusively demonstrate a connection between knuckle cracking and long - term joint problems. The cracking mechanism and the resulting sound is caused by carbon dioxide cavitation bubbles suddenly partially collapsing inside the joints. Contents 1 Causes 2 Effects 3 See also 4 References Causes Play media MRI of a cracking finger joint, visualizing cavitation. For many decades, the physical mechanism that causes the cracking sound as a result of bending, twisting, or compressing joints was uncertain. Suggested causes included : Formation of bubbles of joint air as the joint is expanded. Cavitation within the joint -- small cavities of partial vacuum form in the synovial fluid and then rapidly collapse, producing a sharp sound. Rapid stretching of ligaments. Intra-articular ( within - joint ) adhesions being broken. There were several theories to explain the cracking of joints. Synovial fluid cavitation had some evidence to support it. When a spinal manipulation is performed, the applied force separates the articular surfaces of a fully encapsulated synovial joint, which in turn creates a reduction in pressure within the joint cavity. In this low - pressure environment, some of the gases that are dissolved in the synovial fluid ( which are naturally found in all bodily fluids ) leave the solution, making a bubble, or cavity, which rapidly collapses upon itself, resulting in a `` clicking '' sound. The contents of the resultant gas bubble are thought to be mainly carbon dioxide. The effects of this process will remain for a period of time known as the `` refractory period, '' during which the joint can not be `` re-cracked, '' which lasts about twenty minutes, while the gases are slowly reabsorbed into the synovial fluid. There is some evidence that ligament laxity may be associated with an increased tendency to cavitate. In 2015, research showed that bubbles remained in the fluid after cracking, suggesting that the cracking sound was produced when the bubble within the joint was formed, not when it collapsed. But in 2018, an improved mathematical model and further experimentation and simulation demonstrated that the cavitation bubbles only partially collapse during cracking, and explained that the 2015 experiments were observing the smaller remaining bubbles. The snapping of tendons or scar tissue over a prominence ( as in snapping hip syndrome ) can also generate a loud snapping or popping sound. Effects Cracking of the joints in the foot is sometimes used for massage The common claim that cracking one 's knuckles causes arthritis is not supported by evidence. A study published in 2011 examined the hand radiographs of 215 people ( aged 50 to 89 ) and compared the joints of those who regularly cracked their knuckles to those who did not. The study concluded that knuckle - cracking did not cause hand osteoarthritis, no matter how many years or how often a person cracked their knuckles. An earlier study also concluded that there was no increased preponderance of arthritis of the hand of chronic knuckle - crackers ; however, habitual knuckle - crackers were more likely to have hand swelling and lowered grip strength. Habitual knuckle - cracking was associated with manual labour, biting of the nails, smoking, and drinking alcohol and was suggested to result in functional hand impairment. This early study has been criticized for not taking into consideration the possibility of confounding factors, such as whether the ability to crack one 's knuckles is associated with impaired hand functioning rather than being a cause of it. Medical doctor Donald Unger cracked the knuckles of his left hand every day for more than sixty years, but did not crack the knuckles of his right hand. No arthritis or other ailments formed in either hand, earning him the 2009 Ig Nobel Prize in Medicine, a parody of the Nobel Prize. See also Crepitus -- sounds made by joints References ^ Jump up to : Dvorsky, George. `` Simulation May Finally Explain Why Knuckle Cracking Makes That Awful Sound ''. Gizmodo. Retrieved 2018 - 03 - 30. ^ Jump up to : Gregory N. Kawchuk ; Jerome Fryer ; Jacob L. Jaremko ; Hongbo Zeng ; Lindsay Rowe ; Richard Thompson ( 2015 ). `` Real - Time Visualization of Joint Cavitation ''. PLoS ONE. 10 ( 6 ) : 384 -- 390. doi : 10.1371 / journal. pone. 0119470. PMC 4398549. PMID 25875374. Jump up ^ Knapton, Sarah ( 15 April 2015 ). `` Why knuckle cracking makes a popping sound, and why it might be beneficial ''. The Daily Telegraph. London. Retrieved 17 December 2016. Jump up ^ Sample, Ian ; editor, science ( 15 April 2015 ). `` Cracked it ! Scientists solve puzzle of why knuckles pop when pulled ''. The Guardian. London. Retrieved 20 September 2016. ^ Jump up to : Protopapas M, Cymet T, Protapapas M ( 1 May 2002 ). `` Joint cracking and popping : understanding noises that accompany articular release ''. J Am Osteopath Assoc. 102 ( 5 ) : 283 -- 7. PMID 12033758. Jump up ^ Brodeur R. ( 1995 ). `` The audible release associated with joint manipulation ''. J Manipulative Physiol Ther. 18 ( 3 ) : 155 -- 64. PMID 7790795. Jump up ^ Maigne, Jean - Yves ; Vautravers, Philippe ( September 2003 ). `` Mechanism of action of spinal manipulative therapy ''. Joint Bone Spine. 70 ( 5 ) : 336 -- 341. doi : 10.1016 / S1297 - 319X ( 03 ) 00074 - 5. Jump up ^ Unsworth A, Dowson D, Wright V ( 1971 ). `` ' Cracking joints '. A bioengineering study of cavitation in the metacarpophalangeal joint ''. Ann Rheum Dis. 30 ( 4 ) : 348 -- 58. doi : 10.1136 / ard. 30.4. 348. PMC 1005793. PMID 5557778. ( 1 ) Jump up ^ Fryer, Gary ; Jacob Mudge & McLaughlin, Patrick ( 2002 ). `` The Effect of Talocrural Joint Manipulation on Range of Motion at the Ankle ''. Journal of Manipulative and Physiological Therapeutics. 25 ( 6 ) : 384 -- 390. doi : 10.1067 / mmt. 2002.126129. PMID 12183696. Jump up ^ `` Why Does Cracking Your Knuckles Make So Much Noise ? Science Finally Has an Answer ''. Time. Retrieved 2018 - 03 - 30. Jump up ^ Chandran Suja, V. ; Barakat, A.I. ( 2018 - 03 - 29 ). `` A Mathematical Model for the Sounds Produced by Knuckle Cracking ''. Scientific Reports. 8 ( 1 ). doi : 10.1038 / s41598 - 018 - 22664 - 4. ISSN 2045 - 2322. ^ Jump up to : Deweber K, Olszewski M, Ortolano R ( 2011 ). `` Knuckle cracking and hand osteoarthritis ''. J Am Board Fam Med. 24 ( 2 ) : 169 -- 174. doi : 10.3122 / jabfm. 2011.02. 100156. PMID 21383216. ^ Jump up to : Castellanos J. ; Axelrod D. ( 1990 ). `` Effect of habitual knuckle cracking on hand function ''. Annals of the Rheumatic Diseases. 49 ( 5 ) : 49 ( 5 ) : 308 -- 9. doi : 10.1136 / ard. 49.5. 308. PMC 1004074. PMID 2344210. Jump up ^ Simkin, Peter ( November 1990 ). `` Habitual knuckle cracking and hand function ''. Annals of Rheumatic Disease. 49 ( 11 ) : 957. doi : 10.1136 / ard. 49.11. 957 - b. Jump up ^ `` 2009 Winners of the Ig ® Nobel Prize ''. Improbable Research. Retrieved 27 November 2011. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Cracking_joints&oldid=838499624 '' Categories : Habits Joints Hidden categories : Use dmy dates from July 2012 Articles containing video clips Talk Contents About Wikipedia Deutsch فارسی Français Հայերեն Italiano עברית 日本 語 Simple English Suomi 3 more Edit links This page was last edited on 27 April 2018, at 12 : 19. About Wikipedia

Question: where does the sound come from when you crack your knuckles
Answer: caused by carbon dioxide cavitation bubbles suddenly partially collapsing inside the joints; carbon dioxide cavitation bubbles suddenly partially collapsing inside the joints; carbon dioxide cavitation bubbles suddenly partially collapsing inside the joints; carbon dioxide cavitation bubbles suddenly partially collapsing inside the joints