I've been through the routines with knees, ranging from torn tendons and cartilage in my 30s to total knee replacement surgery in both knees in my 70s. They both now work extremely well and pain free, whereas I was pretty crippled with osteoarthritis before the surgery.
But it is as well to defer it as long as possible, since the prosthetic replacements don't last for ever - 25 years say - and the way to go is, as has been said, physiotherapy to start with. PTs really know how the body is put together. The first one that I had allowed me to defer any surgery for 20 odd years but then the successor PT finally said that surgery was the only option and got me referred to an orthopaedic surgeon, eventually having both knees replaced. After the surgery, the PT was critical in the healing and recovery process.
In many areas you can now self-refer for physiotherapy on the NHS, or it should be straightforward to get referred by your GP. The private hospitals also have good people if you think you are getting better treatment if you pay. However, places do vary in the provision of PT, and my area (South Warwickshire NHS Trust) is particularly good.
I wouldn't trust any woo-woo stuff read on the internet, though turmeric is a very acceptable spice in cooking.