I would like to wish your son the best of luck on his surgery!!
I have been OK'ed for the procedure, but now my Ford plant is closing up and in the process of looking for a job which I may have found. So I will probably have to suck it up for a year and maybe have the procedure OK'ed again and deal with my new employer.
Things were much simpler when you did not have to worry about the knee everyday and just enjoy life.