I had been on Anastrozole for about a year with gradually worsening knee issues - getting up and down stairs, in and out of chairs. I couldn't kneel, and getting down on the floor was just about impossible. Some days I could go for a walk, and other days I couldn't make it down the block. Last November was the worst. It was painful just dragging myself up the stairs, and I thought I'd have to put bars alongside the toilet as the pain was so extreme getting up and down. In December I switched from Anastrozole back to Letrozole and noticed a real improvement. Then I started collagen supplements (started with the gummies), and within a few months I was almost entirely pain free. I've been working on knee flexibility and am no longer reluctant to look for the lost cat toy under the sofa. I'm almost to the point that I can get up from the floor without holding onto something. (I'll be 68 next month). I've read several posts here about joint pain due to the covid shot and the prolia shot. Since my knees improved I've had both shots with no ill effects which is why the finger points to Anastrazole. Looking back I remember within a week of starting it, I had one day I got out of bed and couldn't put any weight on my left leg for an hour. Then off and on knee pain. I blamed the gabapentin I started at the same time, but I stopped that in a few weeks, but no improvement. I also had to take painkillers before bed or extreme knee pain would wake me up in the middle of the night. There's no way it was anything but the Anastrozole.