In so far as using his anatomical knowledge to more effectively fight people, absolutely. I headcanon that John's hand-to-hand combat skills are effective mainly because he's strategic about his hits rather than because he's the most powerful man in the room.

To elaborate now that I'm coming back to this, there's a scene in canon where we see a druggie threatening John with a knife. John just moves in closer and disarms the druggie in about three seconds flat by spraining his arm. His comment when the guy whines that his arm has been broken is "It's sprained. I'm a doctor. I know how to sprain people."