Snap, Crackle, Pop

Recently there has been a significant increase in the cracking of joints in class. I've noticed the same thing in previous years as Autumn takes hold and other teachers that I have spoken to have also heard the same thing! So I thought a little investigation would be in order. Here is more information about three causes of noisy joints which I think of as snap, crackle and pop.

Snap

The kneecap (patella) is a lens-shaped bone embedded in the tendon of the quadriceps femoris. On it's underside is a ridge which articulates with the thigh bone (femur). As the knee bends and straightens, the patella slides within a slot on the femur called the trochlear groove. The patella moves in many directions within this groove to provide efficient, frictionless movement up and down, side-to-side, rotational, and tilting.

Structural alignment and muscular weakness or imbalance may cause the patella (kneecap) to track improperly on the femur (thigh bone) during movement, leading to pain around the kneecap. Bending and straightening the knee can realign the kneecap. This may be accompanied by a snapping sound as the kneecap slides back into its groove. For more information about the patellofemoral joint and the structure of the knee visit http://www.steadman-hawkins.com/pate/overview.asp (This website also has information on the joints of the hip, foot, ankle, hand, shoulder and spine.) You can find strengthening and stretching muscles for the knee at http://www.bigkneepain.com/knee-exercises.html

Crackle

The crackly noise many of us hear when we move our head is called crepitus. It can occur in any of the synovial joints and is caused by bone rubbing against bone or roughened cartilage when an arthritic joint is moved.  Perhaps it should be called decrepitus!

Pop

The is the sound that set me off on my quest to find out why joints seem to be noisier in the autumn. I have spent some considerable time trawling the web without finding the answer. There's a lot out there about cracking your finger joints (not a good idea) and also about why joint pain increases with a drop in air pressure and increase in humidity (there is general agreement that the later really does happen; no 'scientific explanation' as to the cause and differences of opinion as to why it happens. It seems that a change in atmospheric pressure affects the synovial fluid in a joint causing it to expand and press outwards. Where through wear and tear or arthritis there is less or no cartilage to provide cushioning the fluid presses on pressure sensors in the joint which registers as pain) but not about non-deliberate popping.

Based on the little snippets of information I gleaned here and there, putting two and two together and hopefully making four, this is my explanation of what is happening when we hear a popping noise in a joint. When atmospheric pressure drops the pressure within the synovial fluid drops and gases that were in solution in the fluid come out of solution and form a gas bubble. Any sudden increase in pressure e.g. from bending a joint, causes caviation, the collapse of the gas bubble, which is accompanied by the familiar popping sound. The same process happens when someone deliberately cracks their finger joint only there it is the pulling apart of the bones that causes the decrease in pressure and bubble to form. In the same way that you cannot immediately crack your fingers again so it is with your knees and other joints. After caviation has occurred it cannot happen again until another bubble has formed.

How yoga may help

According to ayurveda autumn and early winter is the season of Vata, the quality of air and ether (think of windy autumn days). Dry skin, cracking joints and poor circulation are a result of vata dominance. Just what we experience at this time of year. Yoga has many exercises for the maintenance of healthy joints.

There are the pawanmuktasana series of exercises from the Bihar School of Yoga.

"The word pawan means 'wind' or 'prana'; mukta means 'release' and asana means 'pose'" Swami Satyananda 

So literally these are the wind releasing poses. The first past of the pawanmuktasana series are the anti-rheumatic group and are "simple, gentle and comfortable" movements for the joints. The pawanmuktasana series are described in Asana, Pranayama, Mudra and Bandha by Swami Satyananda.

From the Himalayan Institute come the Joints and Glands exercises of Swami Rama. These exercises, outlined in Swami Rama's book Exercises for Joints and Glands: Gentle Movements to Enhance Your Wellbeing,  systematically go through the body from top to toe exercising and massaging almost all of the joints and glands.

Regular performance of such exercises may help delay the onset or slow the progression of degenerative conditions such as arthritis, rheumatism or stiffness and help counter muscular imbalances which lead to improper patella tracking (the snap and the crackle) but I can't see that they will override the laws of physics so I guess we will still experience the 'popping' in the joints when the barometer falls.

... and Clunk

For some of us certain movements always cause a clunking sound. This is caused by tendon friction rub. The sound is caused by a tendon or other fascia rubbing against bone. The sound has been described as two pieces of leather being rubbed together. Lying on your back on the floor and making a circle with one leg results in a clunking sound in most people. It happens when the iliotibial band, tensor fascia lata, or gluteus medius tendon slides over the greater trochanter or less commonly when the iliopsoas tendon catches on the anterior inferior iliac spine, the lesser trochanter, or the iliopectineal ridge during hip extension. Causes include leg length difference (usually the long side is symptomatic), tightness in the iliotibial band on the involved side, weakness in hip abductors and external rotators, poor lumbopelvic stability and abnormal foot mechanics (Overpronation). Yoga poses which stretch the tight muscles will help.