Certain yoga postures practiced by yogic gurus like "vajrasana" can bring stress to the knees and may damage them. This kind of exercise may put pressure on knees and can even dislodge them. Few patients have opted for the surgery and still some of them are finding difficulty walking even after surgery.
Dr Ashok Rajgopal claims that he has done this kind of surgery on many yoga gurus putting their knees and other joints under stress for longer period of times. Dr Rajgopal even believes that putting unnecessary stress on joints for longer period of time may even lead to arthritis.
Baba Ramdev through Television have made yoga popular in India and he belives that many deceases could be cured by just practicing yoga and breathing exercises regularly. Yoga is now part of the popular culture world over and in united states only equipments worth millions of dollars are sold every year.
This news is certainly not very good for many yoga practitioners as well as yoga gurus who teach yoga exercises on television and on through regular camps all around the world. Still this claim is large open for debates as things like this can not be generalized and much research and larger sample data is needed to come to any conclusions.