The alignment of the knees in Taiji is very important to protect the knees so they get stronger and healthier and for the structural integrity of the stance and your balance. Done correctly, with diligent training, it becomes immovable. Done incorrectly it can put unnecessary pressure on the knees and cause problems. So if your knees are misaligned or sore doing Taiji correctly will heal them. Here is guide for the correct way to do it. The Taiji master pictured in the video is Yang Cheng Fu, known as one of the greatest exponents of the art.
Interview with Angela Hsu Cantafio, tai chi instructor from Sydney Australia, and an international tai chi competition medallist. Angela explains in simple terms the history and benefits of tai chi. This clip is extracted from Angela's nea release DVD production: Tai Chi: The Combined 48.