I have used a THC topical that helped with tendinitis. Efficacy was the same as a topical analgesic (think Voltaren). Can't comment on price or where to get, a friend I know let me try some out. Used topically, apparently THC won't enter the bloodstream so there was no risk of accidentally getting high by using it.
I have severe osteoarthritis in my hip and have tried a variety of cannabis topicals. They don't work for me. I think you'd probably have to be dipped in a vat of the stuff to get enough absorption, until the re-jig the chemistry to increase absorption, if that is even possible.
An update. I made a tincture with ethanol and mixed sativa flowers. Vitamixed it, then put it in a jar in the dark, swishing it every day for 6 weeks. Then I filtered it through a coffee filter. It makes a good lineament that helps with my knee arthritis a bit. You can also take it orally. Use Ethanol Not iso.