Sprain

A sprain is an injury involving a stretched or torn ligament (the tissue that connects two or more bones at a joint is stretched or torn).

Signs and symptoms

 * pain
 * swelling
 * bruising
 * not being able to use the joint
 * you may feel a tear or pop in the joint as it happens
 * joints may then feel either stiff or unstable, more severe sprains may make it impossible to put weight on the joint because it is too unstable

Grade I
A ligament is stretched or has a very mild tear, little or no instability at the joint.

Grade II
An incomplete (partial) tear in the ligament, with some looseness in the joint.

Grade III
A completely torn or ruptured ligament. This may feel like a broken bone since it’s often impossible to put weight on the joint or use the affected limb because the joint too unstable.

Prevalence
Sprains commonly occur in the general population.

Symptom recognition
Sprains are not a diagnostic symptom of ME or CFS. 

Learn more

 * Sprains and Strains - National Institute of Arthritis and Musculoskeletal and Skin Diseases
 * Understanding Sprains and Strains - WebMD