A strain is a form of sprain. It is benign because it does not cause muscle tears or fractures. However, it is painful and inflammatory.
Knee strain is relatively currentespecially during the practice of a sport (skiing in particular). However, it must be taken seriously in order to avoid certain complications (recurrence, cartilage wear, etc.). The joint must therefore be put to rest, and it must be apply ice wrapped in a cloth to protect the skin.