SNAP, CRACKLE AND POP…, WHAT IS IT?
Various parts of the joint; ligaments, tendons, cartilage and synovial fluid, can snap, crackle and pop for different reasons.
Ligaments connect bone to bone to strengthen the joint. Tendons connect muscle to bone and move the bone by the force created by the muscle. When a joint moves, cracking noises are created by the loosening and tightening of ligaments as well as the change in position of the tendons and their snapping back in place. Such noises are normal and especially common in the knee and ankle joints.
On the other hand, grinding cartilage is a sign of an arthritic or injured joint. Smooth cartilage coats the ends of the bones that come together to form the joint. A joint capsule containing a lubricant surrounds the cartilage surface.
In a normal joint, the lubricated cartilage surfaces glide past each other with less friction than skate on ice. Unfortunately, cartilage has very little ability to repair itself. Worn cartilage can make noise as it grates together. Loose pieces of cartilage can even break off and get caught in the joint causing it to lock.
Some people can pop their knuckles by pulling on their fingers, which increases the space in the joint capsules. This reduces the pressure on the synovial fluid. This is the lubrication in the joints. Synovial fluid contains dissolved gasses (carbon dioxide, oxygen and nitrogen), and like the bubbles of gas that form when a bottle of sparkling water is opened, the reduced pressure on the synovial fluid can cause a bubble to pop into existence. The bubble can be seen on an X-ray and takes about 20 minutes to re-dissolve in the synovial fluid.
Microphones on a knuckle detect two separate sounds when the joint is cracked. One is the sound of the gas bubble forming. The other is probably the joint capsule, which would be pulled inward slightly as the pressure in the joint decreased, snapping back into place because the formation of the gas bubble increases the pressure within the capsule. Habitual knuckle crackers are not more likely to develop arthritis, but they are more likely to experience minor swelling and have poorer grip strength.
- Reprinted from San Diego Union Tribune.
Why did the Chiropractor go to rehab?
Because he was hooked on crack.