Your employer cannot require you to use your vacation or other PTO in order to allow you to be off of work when you have been injured at work and the authorized treating physician has deemed you totally unable to work.
However, there is a seven-day waiting period for wage replacement benefits to begin. Therefore, whatever days of work you miss in the first seven days of disability would not be paid time off unless you use your PTO to cover the missed hours of work.
You should also be aware that the doctor’s determination that you are unable to work does not protect you from losing your job or from losing the position you held when you were last working. An injured worker would need to use the benefits afforded under the Family Medical Leave Act, which is federal and not specific to a workplace injury case.