"The purpose of Yoga poses is to generate physical vitality so one can proceed through life with positive energy flow and with a holistic connection to what brings balance and harmony. Standing Yoga poses offer these benefits when mindfulness and proper intention is applied. Without mindfulness, some standing Yoga poses present a tendency towards knee locks and hyperextension, which can produce chronic problems in the function and health of the knee joint.
Some people have a greater tendency towards locking the knees as they have joint structures that promote a hyper extended position when the legs straightened. The legs splay backwards almost like a crescent shape. This hyper extended locked knee position tends to generate a passive stance and allows the body weight to transmit heavily into the ligaments, cartilage and posterior connective tissue of the knees. In addition, this hyperextension and internal rotation creates a line of poor body mechanics including the production unwanted anterior pelvic tilt (promoting excessive lordotic spinal positions) and excessive pronation of the foot." Read full article.