so I can get VA disability ?
You may be able to get disability benefits if you have had surgery or received other treatment at a VA hospital, approved hospital, or outpatient center for a disability related to your military service
can you tell me more about the 100 % rating, why does it happen?
Let's say your disability rating begins at 30%, and you need a surgery for complications.  Since the doctor wouldn't know if the surgery was successful until a certain time has passed you would be given a temporary 100% disability rating for 3 months