I know in Iowa that a PA is considered the equivalent of an MD when it comes to the statement for allowing casts, etc. Matter of fact, the IHSAA actually had a list of who are authorized signatures. They are:

a. Medical Doctor (MD)
b. Doctor of Osteopathic Medicine (DO)
c. Doctor of Chiropractic Medicine (DC)
d. Advanced Registered Nurse Practioner (ARNP)
e. Physician's Asssistant (PA)

In Nebraska, they never said anything about any more than an MD or a DO. So, I would suggest contacting your state association regarding an interpretation on this. I think Iowa developed theirs based on state law regarding who can write prescriptions.