Your tai chi moves are only as good as you can direct your internal energy (qi) and vector the energy of gravity.  The secret to healing and protecting your knees (which also empowers the martial applications of tai chi) requires that you learn to move from your kua. “Kua” refers to the inside hip crease where your legs attach to your torso.  It’s called the “inguinal crease” in western anatomy.  Kua turning is not just used in tai chi, but also in the internal kung fu styles of baguazhang and xingyiquan.  Watch the short video, below, to help you understand this.  Then, take action and practice it.