First, we would always recommend that you reach out to your physician to ensure that everything is in working order for you. We do also have some great go-to modifications for knee pain and below are some additional tips:
Stay above the pain. When you bend your knees, make sure to work in a range of motion that is above any pain or discomfort.
Watch knee placement. A good rule of thumb: Keep the knees within the range of your foot. In other words, don't let your knees go past your toes, and don't let them track inside of your big toe or outside of your pinkie toe.
Keep feet flat. Any posture that is on the toes can be modified to a flat-foot option.
If rotation in the hips (like Horse Pose), puts pressure on the knees, find a parallel modification, like Incline Chair or Standing Tall.
Here are our favorite postures for knee issues:
Sumo Squat. Feet slightly wider than the knees, knees track in line with the middle toe, and draw your seat down and back.
Reverse Seated Chair. if you don't have a barre, you can easily do this along the wall. It's like a wall sit. Back against the wall and stack your knees over the ankle. Hold or maybe move 1-3 inches up and down.
Standing Seat work or All Fours.