Pop Goes the Knuckle….
By Dyan Quesada MPT, ATC

Are you one of those people that frequently pops their knuckles, back, neck, toes, or any other part of your body? If so, how often do those around you tell you to stop because “it is bad for you.” What exactly happens when you “pop” a joint?

When force is placed on a joint such as your knuckle, the “pop” is a sound resulting from the release of nitrogen gas into the joint cavity. This occurs because a negative pressure is created. The nitrogen is normally dissolved in fluid that is present in the joint (synovial fluid,) but explodes out of the solution when the pressure is significantly reduced. When this happens, the joint becomes swollen, since gas occupies more space than fluid. The joint remains swollen anywhere from 10 minutes to several hours until the gas is reabsorbed back into the synovial fluid. A second “pop” is not possible until this occurs.

The beneficial effects of a “pop” include more movement and less pain. The harmful effects are less obvious and include:

● Muscles become more relaxed and do not protect the joint as well (in this state the joint
   is very vulnerable to injury)

● Partial dislocation of the joint (subluxation) due to increases in range of motion

● If in the spine, trauma is inflicted on the disc

● Long term, this leads to instability and too much movement (hypermobility)
   in the joint. At this point, not much can be done to treat or correct this condition.

It is important to be educated on this if we are receiving care from practitioners that perform joint manipulation (physical therapists, chiropractors, osteopathic physicians.) If a joint is hypermobile already, joint manipulation is not indicated as a means to treat pain, because this will cause further instability and injury to the joint. Typically in the spine, parts of the spine are hypermobile, and other parts have very little movement (hypomobile). Thus, joint manipulation is only indicated at the hypomobile areas, and not for the entire spine.