Crepitus
One of the reasons I’ve reduced physical adjustments during shavasana (that wonderful final relaxation in a yoga class) is because my knees are like a creaking door from a Hammer House of Horror film. They startle students with their cracking and creaking as I squat low; not exactly the best way to relax nor the best advert for yoga.
This sound is called crepitus. It can come from different things, including movement between the surfaces and tissues of the joint or tiny gas bubbles in the synovial fluid. (I think of it as little joint farts). Crepitus can occur in perfectly healthy joints and is often harmless, although if it's accompanied by pain, swelling or other symptoms, that's a different story.
The term "crepitus" is derived from the Latin word "crepitare," which means "to rattle" or "to crackle”, which to my ears is far too similar to the word ‘decrepit’. But it turns out they have distinct meanings. "Decrepit" comes from the Latin word "decrepitus," which means "broken down" or "worn out." So no, my farting knees do not mean I am about to kick the bucket. Phew.
Anatomy of the knee
Our knees are remarkable joints, like bridges connecting two mighty structures - the thigh bone (femur) bone and the shin bone (tibia). Unlike the skull or pelvis, there are no big bony walls in the knees, instead, they rely on ligaments, tendons, muscles, and fascia.
Ligaments are like the ropes on a suspension bridge, ensuring your knee's stability. The anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) crisscross within your knee to control its forward and backward movements. Think of them as your knee's traffic cops, ensuring everything stays in its lane. On the sides, the medial collateral ligament (MCL) and the lateral collateral ligament (LCL) provide stability, preventing side-to-side wobbling.
Tendons on the other hand, are like sturdy, yet flexible elastic bands that connect your muscles to your bones, allowing your knee to bend and straighten smoothly.
And then there are the menisci, two C-shaped pads of cartilage which act like shock absorbers and help distribute load across the knee and contribute to the stability of the joint. I’m sure you’ve heard of someone tearing their meniscus while playing sports, it's like a cushion in your couch wearing out. All these parts work in harmony, and create the knobbliness of the knee, allowing it to perform its incredible feats.
Although we say it is a hinge joint, the knee is more complex than a simple door hinge. Instead of a straight back-and-forth movement, the knee is designed with two rounded ends, (condyles), like the rounded tip of a light bulb. These condyles enable your knee to bend (flexion) and straighten (extension) and to experience internal and external rotation, as well as pivot when needed. This unique combination of movements allows you to do everything from sitting cross-legged to standing tall.
When we walk, our knees withstand forces several times our body weight, and these forces increase further when we run. The menisci play an important role in distributing this load across the knee joint, transmitting around 40 - 70% of it, depending on factors such as which meniscus we're talking about and the position of the knee. As the knee bends, the proportion of load transmitted through the menisci can increase even further.
Random Knee Facts
Emus, the flightless Australian birds, have knees so powerful they can kick down fences and reach speeds of up to 30 miles per hour.
The World's Oldest Knee are fossilized remains from an extinct horse discovered in Idaho, dating back over 3.5 million years.
The Guinness World Record for the most knee bends in one hour is 2,295, achieved by Silvio Sabba in Italy in 2012.
Kangaroos have extremely powerful leg muscles and unique knee joints adapted for hopping. Their knees are so powerful that they can cover up to 44 feet in a single leap.
Ducks knees are often hidden beneath feathers. The joint that appears to bend backwards is actually nearer the ankle, not the knee.
Knee Idioms
knees knocking: meaning someone is scared and their legs are shaking. It’s from the Bible, used to describe the fear of the enemies of God’s people (Isaiah 35:3).
bend the knee: meaning to submit or show respect to someone more powerful from the Latin word genuflectionem, which means "bend the knee" ("knee", genu, and "bend", flectere). The Old English word cneowian, which means "to bend the knee, kneel", is also related to the phrase. It comes from the medieval practice of kneeling before a king or lord as a sign of loyalty or homage.
weak in the knees: The phrase originated from the Bible, where it was a Hebrew expression that referred to Old Testament figures who were terrified or not steady in their faith. It can be found in ancient Hebrew and Greek versions of the Bible and in later Latin translations.
the bee’s knees: this phrase means something very good or excellent. It came into use during the 1920s when flappers compared almost anything they considered excellent to a part of an animal, such as “the cat’s pyjamas”, “the snake’s hips”, or “the elephant’s adenoids”. The phrase originally referred to something that didn't exist, and was used as a spoof item apprentices would be sent to the stores to fetch.
take a knee: this phrase means to kneel down as a gesture of respect, solidarity, or protest. Ancient civilizations in Mesopotamia, Egypt, Greece and India all adopted the gesture for different reasons from power and respect to political protest. In recent years as a form of social activism against racial injustice. It was originated by American football player Colin Kaepernick on September 1, 2016, in protest against the lack of attention given to the issues of racial inequality and police brutality in the United States
knee-high to a grasshopper: this phrase means very young or small. It comes from the comparison of a child’s height to that of a grasshopper. It originated in the United States in 1814 as the phrase "knee-high to a toad" The phrase was later modified to include other animals such as mosquito, duck, jackrabbit, bumble bee, splinter, and others. The grasshopper version of the phrase was introduced in a political opinion article describing the opposition in about 1850.
knees up: British slang for a party, especially with dancing, and dates back to the 1940s. It is connected with the popular song Knees up Mother Brown, which became a popular song in East End pubs and bars by the 1800s.
Yoga and Knees
I am not sure how useful a list of ‘yoga poses for knees’ is going to be. Any yoga pose can be used to focus on the knee…
E.g. Mountain pose, standing on 2 feet. Are the knees locked? Are they knocking in? Are the quads engaged? Does that lift the knee?
E.g. Warrior II. Is there excessive strain on the bent knee? Is the knee tracking in the direction of the toes? Does the knee veer inward? How does engaging the quadriceps affect the knee joint? What about the back leg, is the knee locked? Which direction does the knee point? Where is the direction coming from the foot? The hip? The knee?
But we like our lists, so far be it from me to buck convention. So here are a few yoga poses with a focus on the knee:
Child's Pose (Balasana): This often called a ‘resting’ pose places pressure and strain on the knees (which doesn’t mean it is a bad thing!). For knee issues, widen your knees and place a cushion under your hips for support, or place rolled mat or towel between thigh and calves.
Bridge Pose (Setu Bandha Sarvangasana): A useful way to strengthen the muscles around the hips and legs while the feet remain supported on the floor. Experiment with your foot position and notice how your knees respond.
Chair Pose (Utkatasana): Strengthens the quadriceps and other muscles of the legs that help support and control the knee. Experiment with the depth of the bend, or use a wall or chair for support. A block between the thighs can also be used to bring more awareness and engagement to the inner thighs.
Tree Pose (Vrksasana): Improves balance and stability, which is also beneficial for knee health. Use a wall or hold onto a chair for support if needed. Choose your height of the bent leg: ball of foot/toe can be on the floor, the foot can be on ankle, on the calf, on the knee, on the inner thigh or heel to groin.
Extended Triangle Pose (Utthita Trikonasana): Lengthens and strengthens the inner and outer thigh muscles, supporting knee stability. Notice if you’re dumping into the knee, consider pushing into the heels and toe mound into the floor. Use a block for support if you can't reach the floor.
Low Lunge (Anjaneyasana): Stretches and strengthens the quadriceps and hip flexors. If you have knee issues, place a cushion under your back knee or lessen the depth of the lunge.
Supine Hand-to-Big-Toe Pose (Supta Padangusthasana): Stretches the hamstrings while minimizing knee strain. Use a strap or towel to reach your foot without overextending your knee.
I was undecided whether to add this pose, because it is such an advanced pose that places a significant amount of strain on the knees. It certainly is not a pose for everyone.
Lotus Pose (Padmasana): Deeply stretches and opens the hips and places the knees in a position of extreme flexion. An option is to consider Half Lotus Pose instead (one foot on the opposite thigh while keeping the other foot on the floor.) or just not do lotus at all. (We need our knees more than we need lotus pose).
This list could be filled with so much more information, but what I think is more important to know is that there is a modification for every pose. If you’re struggling to find modifications that work for your body, come and see me for a private session and we can work them out together. If the front of the knees hurt when you kneel, how about a high blanket under the shins? If the backs of the knees hurt when you kneel, how about a rolled up towel there? If you struggle in chair pose, how about a block between the thighs? There are so many options. It’s about experimenting and playing with what works for you and your body. And always asking HOW DOES THIS FEEL IN MY BODY? Who cares that it doesn’t look like the photos. How does it FEEL? Once you start to work from within, then your yoga will take off.
And to conclude as always try to end on a light note, so I scoured the internet for some funny knee jokes, but kneedless to say they were too terrible to share.
Are you a yoga teacher?
Read The Dodgy Knee Cheat Sheet for practical ways to support students with knee osteoarthritis in a general yoga class.
