By Dr Ryan Burkhart
Patients often ask, “Is it bad to crack your knuckles?” or “I notice a pop coming from my hip. Was that a bad thing?”
This is a reasonable question to ask a chiropractor. Many of the techniques we utilize in patient care involve a release, or cavitation, of a joint that is not functioning as it should. This causes a sound best described as ‘crack’ or ‘pop.’
The best answer is that there are no adverse effects to cracking any joint in the body in the short term, including the knuckles. The joint capsule, or covering around the joint, is stretched to the point that Nitrogen gas is released from the synovial fluid (the lubrication for the joints of the knuckles and back). Within 20 minutes, the fluid and gas re-absorb back into the joint fluid.
Cavitation of a joint will increase range of motion and decrease pain (feels good). This is a good thing, especially when dealing with the spine. The mechanism for these changes are thought to be due to changes in the joint physiology and neurology at the brain and spinal cord.
Unfortunately, there are some long-term consequences to repetitive joint cavitation. There is research that suggests this can lead to swelling, due to changes or microtrauma to the joint capsule. This is probably related to joint laxity, which is similar to repetitive stretching of a rubber band. Over time, it just wears out.
For knuckles specifically, there has been documented loss of grip strength from daily or hourly joint cavitation.
One common misconception is that cracking your knuckles leads to arthritis. There is currently no known link or research supporting this notion. Conversely, joint immobility or dysfunctional motion is more commonly associated with arthritis.
Popping or cracking can also occur when a tendon rubs against bone. This commonly occurs at the knees and elbows. It is more likely when making a sudden movement or after being stationary for a long time. This may be associated with tendonitis or bursitis, but there is no research to support this causes a problem.
Savva, C. et al. (2014). The role of the descending inhibitory pain mechanism in musculoskeletal pain following high-velocity, low amplitude thrust manipulation. A review of the literature. Journal of Back and Musculoskeletal Rehabilitation, 00, 1-6. https://static1.squarespace.com/static/574f4044ab48decaf96b9095/t/594066c837c581d8604396fa/1497392840790/Descending+Pain+inhib+HVLAT.pdf.
Brodeur, R. (1995). The audible release associated with joint manipulation. J Manipulative Physiol Ther, 18(3), 155-164. https://www.ncbi.nlm.nih.gov/pubmed/7790795.