Hi Deb!
How are you doing? I am 5 months post op and I can leg press 360-400lbs, walking lunge w/ a 45lb plate held overhead and can deadlift 135-150lbs (light, but for 20+ reps). I have only been doing light squats 135lbs for high reps and not going too deep (90 degrees). I still do air squats (no weight--for really high reps). Start out light and go for perfect form. Seated leg extension and leg flexion are the easiest to perform when starting out.
I started weight training about 2 months ago very, very easy and very, very slow. Get your doc's approval first. The only thing I noticed is the lack of stability and strength of your operated side. It improves with every workout, just know when to rest and don't do legs more than 2x/wk.
take care,
spencer