Why Do My Joints Make Popping, Cracking, Snapping (And Other) Noises?

One question that I get most often in clinic is about joint sounds. I’ll be performing manual (hands-on) treatment on a patient and they’ll say:

“Every time I bend my knee back it makes a cracking sound…is that normal?”

“I crack my back everyday when I move in a certain direction. It feels great but am I going to damage anything if I keep doing this?”

And of course, “I love cracking my knuckles, will I get arthritis from it?”

The short answer is that in most instances, joint cracking and other sounds that are produced during movement such as “cracking your knuckles” are fairly innocuous (especially when painless). However, we really need to dive into the weeds here because some joint sounds aren’t always “joint-friendly”.

There are a few different types of sounds that we need to differentiate.

First let’s talk about “popping”. All joints are surrounded and bathed in synovial fluid. When there is a change in pressure, gas bubbles form within the fluid. The subsequent implosion of those bubbles creates the popping sound you often hear when someone cracks their knuckles or they receive an adjustment from their physical therapist or chiropractor.

In medical lingo, this popping sound is known as a “cavitation”. Cavitations are painless, don’t cause any type of damage, and may even relieve symptoms if they are the end result of therapeutic technique. The gas can take up to 20 minutes to reabsorb, thus a cavitation can not be performed over and over again on the same joint in a short time-span.

If the popping sound is accompanied by pain, then we have something to worry about. A painful popping sound in the lower leg, for instance, while performing jump shot during basketball practice or when launching into a sprint, may be indicative that the patient suffered from an achilles tendon rupture and should be evaluated immediately by a physician. Likewise, a painful popping sound in the knee after planting the foot and cutting during a soccer game may indicate an ACL tear (this is the ligament that connects your thigh bone to your shin bone).

There are other sounds that aren’t as serious but could either lead to an injury overtime or may be indicative of a problematic tissue. Snapping along the knee could be indicative of IT band friction syndrome where the end of iliotibial band  (a band of connective tissue) actually snaps over the thigh bone repeatedly. This could lead to inflammatory issues over time. Likewise, snapping in the hip can occur due to thickening of tendons or tight muscles rubbing over the bone.

Clicking sounds can also be problematic if accompanied with pain. Clicking sounds may suggest a connective tissue abnormality, such as a torn meniscus in the knee, a torn labrum or cartilage around a joint. Nerves can also come out of their anatomical grooves and cause problems during movement.

A sensation of a shift especially when accompanied with clunking can be quite problematic as it may indicate a joint instability or laxity at best, and a subluxation or dislocation at worst. Patients who have a history of shoulder instability have joints that are “too loose.” This incongruency between the joint surfaces may cause them to rub against each other and interface in such a way that produces a clicking or clunking noise.

Patients who have been diagnosed with osteoarthritis, especially end-stage arthritis, will have a degeneration of cartilage around the joint. This creates a bone-on-bone interface which may produce a repetitive gear-like grinding sound. One may notice that the frequency of clicking and grinding may increase over time as the joint surfaces change as we age. This is especially true if someone has a long history of repetitive and/or overuse activities and sports in their lifetime.

Sometimes patients also experience a painful pop during exercise or even during manual treatment. This could also result from a breakdown of scar tissue surrounding an injury and may even be beneficial in the long run if it leads to improved mobility.

In conclusion, there can be a variety of explanations and reasons for joint sounds. Some (such as cracking the knuckles, receiving an adjustment, breaking down scar tissue) can be harmless and even beneficial. Others are painful and may indicate problems involving muscle, connective tissue, bone surfaces, and/or unstable joints.

Don’t worry about cracking your knuckles or other joints, but also don’t make it a point to attempt to do this repeatedly in a short-time span as it may cause issues in the joint capsule over time.

If you are uncertain whether what you’re experiencing is a normal joint sound or something problematic, don’t leave it to chance. Get in touch with the folks over at All Sports Physical Therapy where an experienced clinician can assess the tissue and determine if intervention is needed.

by Paul Mostoff, DPT

Head of Physical Therapy

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