Knee pain

I am awaiting a knee replacement due to osteoarthritis. I had a partial replacement in my other knee 18 months ago. I am really struggling with pain. I am taking dihydracodine, naproxen, pregablin and amitripline. my knee keeps locking and is really painful to move back from bent to straight and vice versa. I currently use a crutch. I am wondering if a brace would be appropriate and whether I should explore this with my GP. I am working at present but it is getting harder and harder.