What is happening when a chiropractor cracks your joints?

The sound of joint “cracking” occurs for nearly the same reason that a champagne cork pops.

Champagne is a liquid that has a lot of gas dissolved in it. The gas stays dissolved in the liquid only because it’s bottled under pressure. Once the pressure is relieved by pulling the cork, a popping noise occurs as the dissolved gases precipitate out of solution.

A joint also has fluid in it – synovial fluid – bottled up tightly by the ligaments and capsule of the joint. Like all body tissues, the synovial fluid has gases dissolved in it. These gases are derived from the air you breathe – mostly oxygen and nitrogen.

One of the effects of a chiropractic adjustment can be to open up the joint space. The adjustment relieves the pressure in the joint and, just like a bottle of champagne, gases precipitate out of solution and cause a popping noise.

An Xray taken immediately after an adjustment will show a tiny hollow pocket in the joint that is now filled with these gases.

The technical term for the popping noise that occurs with an adjustment is crepitus.

What happens to the oxygen and nitrogen once they form a pocket inside the joint space?

The gases are gradually re-dissolved in the surrounding fluids over the next twenty minutes or so.

The gases continue to make space in the joint until they’re fully re-absorbed. This phenomenon extends the therapeutic action of the adjustment for many minutes beyond the moment of your adjustment

Is joint cracking (crepitus) a good thing?

Yes.

When skillfully performed by a doctor of chiropractic, the audible release that occurs with an adjustment is considered to indicate a beneficial response to treatment.

Does an adjustment have to create a pop in order to be effective?

No. Crepitus occurs when the adjustment suddenly creates more joint space. There are many other ways an adjustment can improve joint function. Among the possible beneficial effects, adjustments can:

• increase joint space gradually rather than suddenly
• release joint play restriction without increasing overall joint space
• create novel feedback from nerve receptors in the joint

What are the specific aspects of chiropractic methods that tend to create crepitus?

Providing a chiropractic adjustment requires a high level of technical skill and experience.

The two main features of an adjustment technique that make it more likely to create crepitus are paraphysiological motion and quickness.

Paraphysiological motion refers to movement of the joint in a direction for which the joint is designed but which can’t be achieved by your body’s own muscular control system.

For example, you can pull the end of your finger (and maybe create crepitus.) By pulling the end of your finger, you’ve slightly separated the small finger bones from each other. Your finger joints are physiologically designed to accommodate to this motion. But it never occurs through activation of the muscles of your hands.

The quickness of an adjustment is also significant. In fact, some doctors of chiropractic believe that speed is the most important feature of an adjustment.   There are two main reasons why quickness is thought to be significant:

• it overrides the body’s reflex muscle response that might otherwise counteract the adjustment
• it allows the force of the maneuver to be transmitted directly to the joint rather than being dissipated by the fluids in which the joint (like all body components) is floating

Is it harmful to crack your own joints?

Probably not.

Can you get too many adjustments?

Probably not. There’s no evidence that repeated chiropractic adjustments cause any harm. In fact, regular chiropractic treatment may be beneficial in minimizing the potential for arthritis. Also, our most recent knowledge shows that patients receiving more chiropractic adjustments do better than those receiving fewer.

Dr. Lavine has been an innovator in the use of movement and touch to promote health since 1981. He practices in New York City and Princeton, NJ.