Flow yoga for seniors to help knee and leg problems

I teach yoga classes with older adults and I have noticed that they do not receive enough leg exercises in their lifestyle. Some of them have knee replacements and other knee issues. What is a good sequence of leg exercises that could help them? I know little about flow (Vinyasa) yoga but from what I understand about flow yoga, it could help. What is have in mind is giving them this sequence as follows: Tadasana; to help with posture and balance, a downward dog over a chair, warrior 1, warrior 2, crescent. Then back to a mountain pose,and repeat the sequence. My question is; does repetition of the sequence add further benefits to the standing postures? Does the blood flow with nutrients increase even more with repetition of postures? Is there a good book on flow yoga that one could recommend? The seniors I am teaching are young old, and quite active. We do only sitting and standing yoga in the class. Hanuman