By Elisabeth Murphy, PT, DPT
What is happening when you “pop” your knuckles or your back? The majority of joints in our bodies (for example, the hips, the knuckles or finger joints, and shoulders) are called “synovial” joints. On synovial joints, there is thin membrane surrounding the entire joint called the synovium. Inside this membrane and in-between the bones and cartilage there is a fluid that helps lubricate the joint. A synovial joint is very movable and flexible.
With movement, change in pressure or force at this joint, tiny air bubbles may form and release, leading to a “pop” sound at the joint. There is usually an element of force required to achieve this air movement—pulling on the fingers to crack the knuckles or aggressive, sudden movement of the neck or back. Some experts also think that a very forceful movement may cause a sudden change in the length of the ligaments (bands of tough, flexible, fibrous connective tissue that connect one bone to another), creating the “popping” sensation or sound.
Contrary to popular belief, there is no evidence to support the suggestion that popping your knuckles or other joints leads to arthritis or otherwise damages your joints. However, a few research studies suggest that repetitive cracking or aggressive pushing/pulling on joints to achieve that “pop” may weaken the ligaments over time.
Many dancers also have clicking or snapping in their hips, ankles or shoulders as they move or stretch. This type of sound is different from air movement within the joint, and instead comes from tendons (cords of strong fibrous collagen tissue attaching muscle to bone) pulling or snapping over the bone. This should not hurt, provided the tendon is healthy and not inflamed or irritated.
In general, if it hurts or feels uncomfortable when you have popping, clicking or snapping – stop doing it! Any type of swelling or loss of movement associated with painful popping, clicking, or snapping suggests inflammation or injury, and should be evaluated by a doctor or healthcare provider.
*Disclaimer: The information contained within this blog post is not intended as a substitute or replacement for evaluation from a doctor or healthcare provider. If you have concerns, please seek medical care from a certified practitioner.
1. Brodeur R. The audible release associated with joint manipulation. J Manipulative Physiol Ther 1995 Mar-Apr;18(3):155-64.
2. Roston JB, Haines RW. Cracking in the metacarpo-phalangeal joint. J Anat. 1947 Apr;81(Pt 2):165–173.