"More is not always better."
The knee is a hinge joint, which means it is capable of flexing and extending. It is a joint that is primarily held together by ligaments. Some people are born with tight ligaments, and some are born with loose ligaments that allow for an increased range of motion. Research has shown that most dancers have looser ligaments than the average person but has also concluded that dance does not result in loose ligaments. This laxity appears to be genetic, and researchers have concluded that those who dance choose to because they have this expanded range of motion.
A result of this increased range of motion is less control. Loose knee ligaments allow that joint to go beyond extension into a state of hyperextension that results in the legs curving backwards. This backward curve misaligns the leg and puts pressure on the anterior cruciate ligament (ACL) whose job it is to prevent the joint from overextending. Continual pressure stretches out the ACL further and contributes to instability of the knees, which must support the weight of the body on a daily basis. For these reasons, it is important that dancers be taught how to straighten their legs without hyperextending them.
When dancers with loose ligaments are told to straighten their legs, they tend to lock the knees in the hyperextended position that causes them to stand in a first position with space between their heels. Instead of asking them to straighten their legs, educators should ask them to lengthen their legs. Hyperextended dancers should bend their knees slightly and shift their weight forward while using the quadriceps muscles to lengthen the front of the thigh to lift the patella, or kneecap, up toward the pelvis. This action will eventually strengthen the muscles around the knee, limit the hyperextension, stabilize the joint and enable the heels to touch in first position.
The long line of a hyperextended leg looks beautiful in a non-weight bearing position of a tendu, degagé or arabesque, but rather than locking or hyperextending the knee, dancers should constantly be thinking about lengthening the back of the leg.
It is extremely important that dancers with hyperextended knees learn to avoid locking the knees and to work correctly before beginning pointe work. When dancing on pointe, correct alignment is the key to avoiding unnecessary strain on the body.
All dancers should avoid stretches which put unnecessary pressure on the ACL and place the knee in a hyperextended position such as a split stretch with the front ankle up on a chair while seated on the floor or sitting with the legs straight out in front while flexing the feet until the back of the knees touch the floor.
Dancers who learn to respect and work effectively with the bodies they have will be able to dance longer, stronger, happier and healthier.