Something else that I have found helps is what they call parafin treatments. Messy, but it works for hours and sometimes longer.

Get large plastic tablecloth, and about a 3 inch decent paintbrush. Melt parafin on lowest possible heat and **Carefully** paint on knee, using thin layers. Much better thin layers than one or two thick ones, less chance of a burn.

Cod liver oil has helped me a good bit. Thankfully it comes in a pill form with no taste.