I think a stabilizer knee brace that reduces how much the knee can bend is the best option for those with painful osteoarthritis. In osteoarthritis, the cartilage and the materials between them wear out causing the bones to grind on one another during movement. This is where a lot of the inflammation and pain comes from.
Of course, the underlying condition needs to be treated. But wearing the right knee brace for some time can provide some relief from symptoms. At least, it will prevent it from worsening rapidly.