Clearly, none of the extant studies could be done without the support and involvement of emergency medicine physicians and trauma surgeons.
The studies could not be done sans the aid of the physicians.
The studies would be better off without the help of physicians.
Two people are dancing.
The newcomer was asked to show his number.
The musicians are playing music.
I understand your point completely but I feel I need to take another angle on this topic for us to have a conversation.
The people are outside.
The women are  inside.