I have several students in my classes who are naturally hyperextended. It's such a beautiful aesthetic in ballet, but man is it bad on the knees! They are constantly dealing with knee pain and swelling, and one of them asked if I knew how to fix it. I told her I thought she wasn't supposed to straighten her knees all the way, which for a hyperextended person means locking your knees, but I wasn't 100% sure. So, I consulted the experts, a.k.a. Dance Magazine. This article thankfully confirms what I thought and told my student, and it describes what is exactly going on in a hyperextended knee.
I also learned that hyperextension is a kind of made up condition in dance. In the medical field, it's used to describe an injury, not a natural condition (see: Mayo Clinic). That isn't addressed in the Dance Magazine article, but it at leasts helps us dancers and teachers know how to fix it! Check it out: http://www.dance-teacher.com/content/hyperextension-and-bowleggedness.
