What is Crepitus?

Crepitus, which is more commonly known as cracking joints is a phenomenon where people experience a popping, grating or cracking sound under the skin. While sometimes the production of this sound is unintentional, most of us are actually used to producing a deliberate sound. The knuckles, neck, back, knees, elbows, wrists, hips, toes and Achilles tendon are the areas where crepitus can happen.

Activities and Conditions that can Cause Crepitus

Let us first look at the causes that produce an unintentional cracking sound.

  • The popping, grating or the snapping sounds are common in people who suffer from degenerative arthritis conditions like osteoarthritis and rheumatoid arthritis. The erosion of the cartilage between the joints causes the bones to grind against each other and produce the sound.
  • Another common incidence of joint sounds is in fractured bones. The rubbing together of the fractured surfaces also can cause a sound.
  • Apart from the joints, the presence of gas in soft tissues also produces a sound.
  • Crunching or popping sounds are also common with the knee, sometimes with pain and sometimes without.

Let us look at the intentional causes now.

  • Most of us are used to either bending fingers outwards (away from the palm) or the knuckles inwards which produces a sound. This technique is now used as a form of palliative medicine (health care that relieves patients of their sufferings).

Theories of Crepitus

The sounds made by joint cracking usually imply an underlying disease or a ligament/tendon tear. These sounds can either be with or without pain. If there is no pain accompanying the sound, then there is no need to worry about it.

  • When people intentionally crack their joints, it is not known exactly as to what causes the sound. There are three theories that have been proposed in order to understand this phenomenon, viz. joint capitation, rapid ligament stretch and breaking of the adhesions within the joint.
  • Among the three, the one that supports crepitus is the joint cavitaion theory. The synovial fluid in the joints produce a vacuum when cracked. This vacuum collapses almost immediately which results in the sound.

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