A strain occurs when a muscle is stretched or torn. A sprain occurs when a ligament is stretched or torn.

Strains are often the result of overuse or improper use of a muscle, while sprains typically occur when a joint is subjected to excessive force or unnatural movements (e.g., sudden twists, turns, or stops). Sprains can be categorized by degree of severity:

• A first-degree sprain stretches the ligament but does not tear it. Symptoms include mild pain with normal movement.
• A second-degree sprain is characterized by a partially torn ligament, significant pain and swelling, restricted movement, and mild to moderate joint instability.
• In a third-degree sprain, the ligament is completely torn with mild to severe pain, swelling, and significant joint instability.