Rheumatoid arthritis is an autoimmune and inflammatory disease, which means that your immune system attacks healthy cells in your body by mistake, causing inflammation in the affected parts of the body.

Tennis elbow (lateral epicondylitis) is a painful condition that occurs when tendons in your elbow are overloaded, usually by repetitive motions of the wrist and arm.

It's usually caused when a herniated disc or bone spur in the spine presses on the nerve. Pain originates in the spine and radiates down the back of the leg. Sciatica typically affects only one side of the body.

CP is the most common motor disability in childhood. Cerebral means having to do with the brain. CP is caused by abnormal brain development or damage to the developing brain that affects a person’s ability to control his or her muscles.

Orthopedic surgery is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat spine diseases, sports injuries, and congenital disorders.

Knee pain can have causes that aren't due to underlying disease. Examples include heavy physical activity, lack of use, injuries such as sprains or strains, sitting in a constrained area or sitting on knees for a prolonged period.