I agree completely with Darkeyes and Sky.

When my kids were growing up, I was much rougher with them that your description of your reaction to your son's defiance. I know that there were times I yanked on one of my kid's arm and never once dislocated anything.

The one big thing I learned, though, was to make sure that whatever discipline I enforced did not stem from MY anger or lack of patience. There were also plenty of times I had to count to 10, sometimes in another room, before I ACTED ON what had happened... not ACTED OUT. STOP, THINK, ACT has always worked great for me.