A sprain is when one or more ligaments in a joint become torn or stretched beyond its normal limits.
A strain, more commonly called a pulled muscle, is an injury to muscle fibers or tendon due to excessive force and stretching.
Sprains and strains may be caused from falls, direct forces or blows, improper warm-up leading to over stretching tissues, and inadequate rest between sport practices and competitions.
You should call the doctor for a sprain or strain if your child has severe pain and cannot put any weight on the injured joint or move it, the injured area looks different compared to the uninjured side, or has numbness in any part of the injured area.