Knee Safety in Hip Openers
By Dr. Robin Armstrong • February 23rd, 2009 • 14591 Views
Remember the children's song: With the leg bone connected to the knee bone and the knee bone connected to the thigh bone. This could be a yoga anthem worth chanting before class. Our bodies function as a whole, and no one action goes without a counter action, reaction, or complementary action in another part of our anatomy. This is especially important to remember when it comes to hip openers, which can unfortunately lead to the non-existent ‘knee opener' which is yoga code for a painful and long recovery from an injury to our knee.
The knee joint is actually composed of two joints: The femur bone of the thigh as it meets the tibia bone of the shin, and the patella bone of the knee cap as it lies on top of the femur. The patella is held by the tendon of the quadriceps, the main muscle that acts to extend / straighten the knee. If we contract our quadriceps, our knee cap rises.
The femur and tibia are connected by four major ligaments: Two cruciate ligaments (anterior and posterior) and two collateral ligaments (medial and lateral). These ligaments help prevent excessive motion at the knee. There is another important structure at the knee that is unfortunately one of the more common sights of injury in a yoga class – the meniscus. There are two menisci, medial and lateral (inner and outer), which are thin pieces of cartilage that act as spacers in between the femur and tibia, evenly distributing weight at the joint. The meniscus becomes prone to tearing when the knee is in full flexion combined with twisting.
This brings us to the biomechanics of the knee. The main action of the knee is flexion to extension. It is known as a hinge joint, meaning it hinges open like a door. Try to twist open a door and it rips off its hinges, try to twist at the knee and you leave it vulnerable to injury. There is a slight amount of tibial rotation on the femur between 0 degrees and 20 degrees of flexion, known as the screw home mechanism. This action is so the bones glide on one another as we unlock the knee from extension....