While cracking and grinding sounds during neck movements are fairly common in the general population, the exact causes of these sounds are not always well understood. Some of the more common causes of neck cracking and grinding sounds, also called neck crepitus, include:
- Pressure changes within the cervical facet joints
- Ligament or tendon movements around bone or near their bony attachments
- Adjacent bones grinding together
These causes of neck crepitus are explored in more detail below.
Articular Pressure Changes
Synovial joints, such as the cervical facet joints in the neck, have a joint capsule filled with synovial fluid that lubricates and protects the smooth cartilage of adjacent bones. As a synovial joint moves and adjacent bones rub and articulate with each other, the pressure within the joint changes and may cause tiny gas bubbles to form and eventually collapse again within the synovial fluid. These pressure changes likely play a role in some neck-cracking sounds.
Various studies have been performed by purposely cracking knuckles (the synovial joints of the fingers), but the conclusions in the medical literature as to what actually makes the noises have been mixed. Based on a study published in 1971, for several decades the medical community widely accepted that joint-cracking sounds could be made by the bubble collapsing or popping within the synovial fluid.1 However, some doubts in this theory were raised by a 2015 study that examined MRI video of knuckle cracking and concluded that the sounds came from the bubble forming.2 More recently, a 2018 study created and tested a new mathematical model that lends support to the 1971 theory that the sounds come from the collapse (or even partial collapse) of the bubble.3
When a joint cracks due to articular pressure changes, it is thought that the joint’s internal pressure resets after about 20 minutes and can then be cracked again.
Ligament or Tendon Moving Around Bone
Another possible factor in neck crepitus could be the snapping sound of ligaments and/or tendons as they move over bones or other tissues located in the neck region. Ligaments and tendons are soft tissues that attach to bones, yet they also can have strong elasticity similar to a rubber band.
One theory as to why crepitus tends to become more frequent as a person ages is that the joints and surrounding tissues, including the tendons and ligaments, weaken over time. Other factors that can influence how tendons and ligaments function, and in some cases might also contribute to crepitus, include:
- Swelling or stiffness
- Injury or overstretching
- Spinal degeneration
- Unusual or sudden movement
- Changes following surgery
These factors may or may not contribute to crepitus as the evidence thus far is anecdotal. It is also possible for healthy tendons and ligaments to still make cracking or snapping noises.
It is possible for bone to grind against bone if the facet joint cartilage has worn down due to osteoarthritis. This condition can occur gradually with the normal aging process, or it can be accelerated if there has been a traumatic injury such as whiplash or a sports-related injury.
Neck crepitus caused by bone grinding against bone is typically accompanied by pain and limited neck motion. Also, these bone-on-bone cracking and grinding sounds can usually be repeated with each movement.
Cause of Neck Crepitus May Not Be Found
When a person experiences neck crepitus, it is unlikely that the cause of the sounds will ever be determined, especially if they are not accompanied by pain. Even in cases where neck crepitus is accompanied by pain, the focus tends to be on finding the cause of pain and treating it, rather than determining the exact mechanism of the sounds.
See Neck Pain Causes