Although the terms sprain and strain are used loosely and have no precise clinical definition, a sprain generally refers to an injury to a ligament - one of the tough, fibrous cords within a joint that connects the bones together, and a strain refers to muscle injury.

Sprains and strains often occur together in or near a joint, since joints absorb the stress of movement and are vulnerable to be being twisted or wrenched. The ankle and the knee are the most common sites of such injuries.

In mild...