by julee snyder
The knee is a meeting of the femur and the tibia covered and protected by the patella. The tibia is the straightest bone of the body and transfers the body’s weight into the foot. The top of the tibia is called the tibial plateau and has two shallow cups covered by the menisci. The menisci are two C-shaped pieces of cartilage that face each other to form a figure-eight shape. The menisci are only pinned down at their ends and are thus free to move in response to the needs of the knees.
The distal end of the femur has two doming condyles at its end that sit into the cups of the menisci along the tibia. When the knee bends, the femoral surface rolls changing the articular shape. The menisci, because they are free to move, shift to accommodate the changing articular surface of the femur.
Between the menisci is the tibial fossa where the two cruciate ligaments attach. Ligaments are designed to limit range of motion to protect the joint. Cruciate means cross as these two ligaments cross over each other. The anterior cruciate ligament (ACL) attaches to front of the tibial plateau and then to the inside of the lateral condyle of the femur. It resists the tibia sliding forward out from under the femur. The posterior cruciate ligament (PCL) attaches to the back side of the tibial plateau and then to the inside of the medial condyle of the femur. It resists the tibia sliding out from under the femur in the backwards direction. There are two more important ligaments of the knee: the medial collateral ligament on the inside of the knee and the posterior collateral ligament on the outside of the knee. These ligaments resist any side-to side deviation.
The primary joint actions of the knee are flexion and extension. Hyperextension of the knee should be avoided as it negates the flow of gravity and levity through the full line of the leg while hanging in the ligaments of the knee – never a good thing. Something else to know about the knee is that while in flexion it has the ability to rotate medially and laterally. This means that the knee is more vulnerable in a bent position. Dancers are notorious for finding their turnout in a bent knee position, because it gives them more range, and then straightening their legs. This is also something to be avoided.
What you need to know for practice is that the knee is a transition joint. It transfers forces from the upper body to the foot and back up again. I advise my students to become aware of the relationship between the foot and the pelvis. The foot and pelvis always go together, otherwise you are applying torque to the knee.
In a bent knee position, you will want to track the alignment of the knee so that it is always in line with the second and third toes. For symmetrical poses like tadasana, forward bend, bridge and chair, you can practice with a block or ball between your thighs. This will help to balance the strength on the inside and outside of the legs. In asymmetrical poses like warrior two, the placement of the back foot has an enormous effect on one’s ease in finding a healthy placement of the front foot. I recommend turning the back foot in about 30-degrees and allowing a slight turn of the pelvis toward the front leg.
Some people have pain in the lateral knee during pigeon or even cross-legged sitting. This is usually do to a limitation in the hip rotators. It is helpful to support the knee in these poses. In sitting, a blanket under the sitting bones and a block under the knee is usually enough. I recommend doing pigeon over a bolster. Place the bolster perpendicular to the mat so that it supports the front of the back hip and the bottom of the front one. Slip the front foot under the bolster to reduce the angle of pull on the knee. If there is pain in deep flexion, like child’s pose or virasana, try rolling a wash cloth or hand towel behind the knee. If that is not enough, try a blanket or a bolster. Make your poses work for you!
Lastly, work to balance strength and flexibility on all sides of the joint. I’ll go more into that in a post called “the four gates.”