A few years back I was undergoing physical therapy for my hip at the VA hospital. (This was before last year's replacement surgery.) It wasn't responding to therapy, so the therapist went into a back room, came out with a book she leafed through, and then she said "I think you have a torn labrum. Physical therapy can't help that, so I'm referring you to Orthopedics.
So I went to Orthopedics, he asked me a few questions and looked through my records (I'm pretty certain there were X-rays in there), and pronounced that I didn't have a torn labrum. I explained that the therapist had looked it up, and my symptoms were a perfect match. His response was classic: "I'm a doctor -- she's only a physical therapist. You don't have a torn labrum."
I mentioned that to her at my next appointment. And she laughed. "Actually, I have a doctorate in physical therapy so I am a doctor. So are most of the people here, but we generally prefer to just go by our first names." So now I call he Dr. Carly.
And I went outside of the VA for a second opinion to the guy other doctors send their hip patients to. His diagnosis? Torn labrum. And he said that at my age repair wasn't a good option, so I had it replaced.