Do doctors that do hip arthroscopies also do open surgical dislocation, or do they need to be specially trained for that?

Open first: Most doctors I know learn to do the surgery open and then specialize when they learn to do the arthroscopic procedures. The anatomy needs to be seen many times directly before you can identify structures using a scope. After open suregery a doctor can then specialize in arthroscopic surgery.

Yes: Usually surgeons are trained in open and arthroscopic surgery of the joints. . But always ask how much experience they have with each procedure.

Yes , of course: These procedures are done by orthopedic surgeons who had four or more years of training after MD , some even had more additional training , and orthopedic board certification , and years of experience .

Depends: Most Orthopedic surgeons are trained in all types of surgeries in the joint areas, however some may "specialize" and become more adept at doing one procedure over the other. So ask the Dr. who they would have do the procedure if it was them, and then go to that Dr. Best wishes.