Given that you were dealing with a bad knee for 20+ years, you probably need more time for it to get to 0. I would also think that having your hip replaced can only help.
Walking heel to toe, and taking a longer stride, if you can, can help gently stretch the back of the leg and improve extension over time.
In the early months I would be sitting on my couch with my legs up on an ottoman in front of me, and I would pushed the back of my knee down towards the couch. I didn’t use a rolled towel anywhere, just my leg, the couch and the ottoman, which was actually a couple of inches lower than the couch.
But I hadn’t really had any issues with extension before surgery, other than being in my 60s and not the least athletic. It wasn’t perfect, but it didn’t bother me and I didn’t even know what extension was until after my surgery when my surgeon kept checking it. I was never worried about my extension, it was my bend I was very concerned about.
Walking heel to toe, and taking a longer stride, if you can, can help gently stretch the back of the leg and improve extension over time.
In the early months I would be sitting on my couch with my legs up on an ottoman in front of me, and I would pushed the back of my knee down towards the couch. I didn’t use a rolled towel anywhere, just my leg, the couch and the ottoman, which was actually a couple of inches lower than the couch.
But I hadn’t really had any issues with extension before surgery, other than being in my 60s and not the least athletic. It wasn’t perfect, but it didn’t bother me and I didn’t even know what extension was until after my surgery when my surgeon kept checking it. I was never worried about my extension, it was my bend I was very concerned about.
United States
The hip seems to be doing well. off narcotics and other than some weakness in my quads keeping me using the walker everything looks good. The almost 11 month old knee however is a different story. It's swollen, tender, doesn't want to bend and is causing much more pain than my hip. I'm using much more ice on my knee than I am on my hip. 
For the first time in over 18 months I'm able to take the dog for a walk
and live a normal life. For those of you in the early days hang in there, it's not an easy journey but the destination is well worth getting to.
I have a hard time coming up with the words to describe the difference my joint replacements have made in my life. I hadn't realized how small my world had become, pain was a constant companion, and that pain affected my decisions about everything I did. Two years into recovery the world is my oyster. My ROM continued to improve over the last year, I'm now at 135 degrees of flexion and -1 of extension. The best part of all, I'm PAIN FREE! I'm now retired and can hike, bike, swim, fish, scuba dive, all things that had become very limited or had been eliminated from my life due to joint pain. A big thanks to all of the BoneSmart staff and fellow BoneSmarties for all of the advice and support I received here, it made my recovery much better than it would have been without all of you! 





This is so encouraging to hear! I’m beyond thrilled to hear how amazing things are for you.