Many of us never took formal PT or did exercises. I am one of them. I had 11 knee surgeries, 2 of them kneecap removals and 1 tkr. Even after those I never took PT. But, I didn't just sit around and do nothing. I took care of myself, my house and yard as my knee allowed me to do. As I healed, I did more. But, my knee was always in control. This was enough therapy for me and would be for any tkr patient. All the awful pain of PT is so unnecessary.
All you have to do is use it in your daily living. Your knee knows how to rehab itself and doesn't need anyone telling it how. Just use it by easily walking and it will come back like new. You have to be patient, though, it doesn't happen quickly. ADL,(activities of daily living), going to the bathroom, brushing your teeth and bathing, fixing a light meal, getting something to drink and or a snack, those kinds of things will be all the exercise your knee needs. If you just use it daily in your living, you can have a less painful recovery. We know what works, we've been there
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Having that tear is even more reason to be very, very gentle with your knee. Twice, I was in an immobilizer for 6-8 after knee surgeries. After removing the brace, within a few weeks my knee was where it was supposed to be ROM wise. They do snap back if treated like a newborn baby, with lots of TLC.