My knees are probably very shot - but it’s nearly 20 years since the hospital threw one last “probably won’t work “ option at me
it was a hospital run physio program. The people who benefitted did the exercises every day every week for a year or so
it focussed on the lower body - so think planks and Russian twists and bridges ( posterior chain ) down to ankle raises and pops , and every muscle in between - strength, flexibility, cardio and balance exercises
different levels / the initial squats are very shallow . You build to sitting and rising from a chair finally with single legs and weight.
lunges - a step forward with a bit of weight, step ups onto the stairs, step up on stairs with only one leg , drop down onto a cushion with your back knee
the sessions started with cycling around 100rpm and gradually build the resistance
you can do it - try searching nhs knee physio because the exercises are probably on line somewhere ( edit … well that took me a while to write / see PP for a link)
i was discharged with instructions “no marathons , don’t run through pain”