Take a medium-sized soft towel, fold it and tuck it under your knees. Once you do this and try doing poses like Camel pose, Child’s pose, you will feel a nice stretch in your lower back and shoulders without any added pressure on the knees. Experts advise that it’s best to use props to support the practice rather than forcing yourself in a pose.
You can even try keeping a folded mat under your knees. There are many poses that could benefit from using this technique. But poses like Cat-Cow, Chaturanga and Camel pose benefit greatly.