Q: My joints pop when I do certain yoga poses like twisting. Why does this happen? Should I be concerned about this?
A: Joint noises are a fairly common occurrence during yoga as well as other activities. There are a few different reasons they might occur and typically they are nothing to be worried about. However, there are some joint sounds that are reasons to be concerned.
When we move our body in certain ways sometimes a joint ‘pops’. There is a lot of speculation about what actually occurs during that pop, but the explanation I like the best is the following. Our joints are made to move unimpeded through their range of motion and then come back to their neutral position. Sometimes though the joint gets trapped in a non-neutral position. Within most of our joints we have a substance known as synovial fluid. Its job is to lubricate the cartilage surfaces of the joint to allow for ease of movement. Synovial fluid is made up of several things, one of which is nitrogen gas. When the joint moves normally the pressure remains constant within the joint. However, if the joint is slightly trapped outside of its neutral position and we make a movement, the pressure within the joint can increase. The increase of joint pressure as we try to move the joint can cause the nitrogen gas to come out of solution which makes the characteristic ‘pop’. Once the joint has moved and the restriction resolved, the nitrogen gas will go back into solution – until the joint gets trapped and we move it again.
I have no idea if they have disproved this theory, but it is the one that seems most rational. It accounts for the resistance of movement often felt in the joint before the pop as well as the popping sound and why you can’t just make the joint pop immediately again. This kind of noise is the one we experience when we pop our knuckles and is very likely the kind of pop going on when you twist your back.
There are other noises however that are not this nitrogen joint pop phenomenon. Some of our movements make clicking or snapping sounds or sensations that are outside of the joint itself. These types of clicks are typically very repeatable and occur each time we make a particular movement. These sounds are most likely the tendons of our muscles twanging across bony areas of our body. They often occur in shoulder or hip areas. This kind of twanging sound indicates that the joint in question that controls the movement is somewhat out of balance. Our body is set up so that when all the muscles that control the joint are the right length and the joint is in it correct posture then no tendons will pop across any bony projections. Even though this kind of crackling means we are somewhat out of balance, it usually is not harmful as long as we don’t constantly repeat the action. If however the noise happens and it feels uncomfortable or painful, this can mean there is an inflammation problem for that tendon area and the movement should be ceased or modified so the noise is not heard. Yoga is great for helping us to resolve this kind of joint noise.
A third type of noise that is infrequently heard is associated with problems within a joint. Unlike the light popping or crunching noises of the above issues, this noise can be described as a more grinding and deep. This noise is being made because a bony surface is grinding across another bony surface. I have on several occasions heard this joint grinding noise from my students who have advanced arthritis and no cartilage cushioning their joint surfaces. The sound is very distinctive and troubling and is definitely something that needs medical intervention.
There is one more type of joint sound that occurs almost exclusively in knees. The knee cap (patella) is imbedded in the tendon that attaches our quadriceps muscles to the lower leg bone (tibia). The back of our knee cap has a cartilage surface that is designed to slide across the front of the knee joint. This cartilage surface can become very rough – especially if a person has a genetic tendency towards this or if they have had repeated impact injuries where they fell on their knees. The sound this condition creates is a crackling and popping that will occur each time the knee is bent or straightened and sometimes can be very audible when doing things like climbing stairs. Once the condition occurs it is likely to be lifelong. The only good news is that the noise is typically without discomfort, although inflammation can sometimes occur. I always tell people with this condition that the only thing it will keep them from doing is being a ninja. No stealthy creeping around with crunchy knees.
So, that is about it for the joint sound run down. As a general rule of thumb, noise without pain is just internal percussion. Noise accompanied by pain is a reason for concern.