Physio will recommend rehab exercise...

usually involve bending and straightening your legs depend on your mobility

example
-poor mobility can be sitting down , bend and stretch out your legs
-good mobility can be doing squat exercise, with hand supporting your body weight.
-free squat if very good mobility, with lot of stretching involve
-walking up stairs is good, walking down not so good, but if you are strong enough, ok to do so
-weighted squats, dead lifts, etc

all low impact exercise, slow and steady instead of running
change to different cardio exercise... cycling instead of running