Cracking joints

Cracking joints is the action of moving joints to produce a sharp cracking or popping sound. The most common form of this occurs during deliberate knuckle-cracking. It is possible to crack many other joints, such as those between the back and neck vertebrae, hips, wrists, elbows, shoulders, toes, ankles, knees, jaws, and the Achilles tendon area.



To deliberately produce the clicking sounds, many people bend their fingers into unusual positions. These positions are usually ones that their own muscles are unable to achieve. However, cracking a joint that has been exercised recently is generally recognised to be palliative. For example, bending a finger backwards away from the palm (into extension), pulling them away from the hand (abduction), compressing a finger knuckle toward the palm (into flexion), or twisting a finger about (torsion).

The snapping of tendons or scar tissue over a prominence (as in snapping hip syndrome) can also generate a loud snapping or popping sound.[1]


The physical mechanism is uncertain, and cracking may possibly arise from several different causes. Suggested causes include:

  • Cavitation within the joint—small cavities of partial vacuum form in the fluid and then rapidly collapse, producing a sharp sound. This explains the popping that can occur in any joint, such as during spinal manipulation. Synovial fluid cavitation is the most likely theory and substantial evidence exists in support of it. Cracking knuckles releases gases from the joints.[2]
  • Rapid stretching of ligaments.[1]
  • Intra-articular (within-joint) adhesions being broken.[1]

Of these hypotheses, perhaps the most popular is cavitation. When a 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. This process is known as cavitation. The contents of the resultant gas bubble are thought to be mainly carbon dioxide.[3] The effects of this process will remain for a period of time known as the "refractory period", which can range from a few seconds to some hours while it is slowly reabsorbed back into the synovial fluid. There is some evidence that ligament laxity may be associated with an increased tendency to cavitate.[4]


The common advice that "cracking your knuckles gives you arthritis" is not supported by any evidence. A recent study 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.[5] The study concluded that knuckle-cracking did not cause hand osteoarthritis, no matter how many years or how often a person cracked their knuckles.[5] 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 lower grip strength.[6] 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.[6] This early study has been criticizied for not taking into consideration the possibility of confounding factors, such as if the ability to crack one's knuckles is associated with impaired hand functioning.[7] As such, it remains unclear if knuckle cracking is in itself associated with any impaired hand function.

Medical doctor Donald Unger regularly cracked the knuckles of his left hand for fifty years while not manipulating those of his right. No arthritis or other ailments formed in either hand, and he was awarded 2009's Ig Nobel Prize in Medicine.[8]

See also


  1. ^ a b c 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. 
  2. ^ Brodeur R. (1995). "The audible release associated with joint manipulation.". J Manipulative Physiol Ther 18 (3): 155–64. PMID 7790795. 
  3. ^ 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. 
  4. ^ Fryer, Gary and Jacob, Mudge and McLaughlin, Patrick (2002). "The Effect of Talocrural Joint Manipulation on Range of Motion at the Ankle". Journal of Manipulative and Physiological Therapeutics 25 (25): 384–390. doi:10.1067/mmt.2002.126129. PMID 12183696. 
  5. ^ a b 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. 
  6. ^ a b 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. 
  7. ^ Simkin, Peter (November 1990). "Habitual knuckle cracking and hand function.". Annals of Rheumatic Disease 49 (11): 957. 
  8. ^ Mirsky, Steve (December 2009). "Crack Research: Good news about knuckle cracking.". Scientific American. Retrieved 16 December 2009. 

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Cracking — may refer to: Cracking, the formation of a fracture or partial fracture in a solid material Fluid catalytic cracking, a catalytic process widely used in oil refineries for cracking large hydrocarbon molecules into smaller molecules Cracking… …   Wikipedia

  • Welding joints — are formed by welding two or more workpieces, made of metals or plastics, according to a particular geometry. The most common types are butt and lap joints; there are various lesser used welding joints including flange and corner joints. Contents …   Wikipedia

  • Joint manipulation — For extended detail of manipulation of spinal joints, see Spinal manipulation. Joint manipulation is a type of passive movement of a skeletal joint. It is usually aimed at one or more target synovial joints with the aim of achieving a therapeutic …   Wikipedia

  • Spinal manipulation — is a therapeutic intervention performed on synovial joints in the spinal column. The most commonly cited of these are the zygapophysial joints. However, the occipitoatlantal, atlantoaxial, lumbosacral, sacroiliac, costotransverse and… …   Wikipedia

  • Fingerknacken — menschlicher Finger Fingerknacken beschreibt das Überdehnen der Fingergelenke durch Ziehen an den Fingern oder durch Durchdrücken der Fingergelenke in Begleitung von knackenden Geräuschen. Im Gelenk werden die glatten Knorpelflächen durch einen… …   Deutsch Wikipedia

  • Crepitus — This article is about the medical term. For the Roman god, see Crepitus (mythology). Crepitus Classification and external resources ICD 9 719.60, 756.0 Crepitus is a medical term to descr …   Wikipedia

  • Spinal adjustment — { For the generic approach to manipulation of spinal joints, see Spinal manipulation. A chiropractor performs an adjustment on a patient. Spinal adjustment and chiropractic adjustment are terms used by chiropractors to describe their approaches… …   Wikipedia

  • Craquement des articulations — Le craquement des articulations est le fait d actionner celles ci afin de produire un bruit de craquement ou un claquement. La forme la plus commune de ceci est le craquage délibéré des phalanges des doigts de la main. Il est possible de faire… …   Wikipédia en Français

  • Sesame oil — (also known as gingelly oil or til oil ) is an edible vegetable oil derived from sesame seeds. Besides being used as a cooking oil in South India, it is often used as a flavor enhancer in Taiwanese, Korean, and Southeast Asian cuisine.… …   Wikipedia

  • Welding — is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material (the weld puddle ) that cools to… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”