Cartilage is a soft, rubbery, gel-like coating on the ends of bones, where they articulate, that protects joints and facilitates movement.

A ligament is an elastic band of tissue that connects bone to bone and provides stability to the joint.

A tendon is a band of tissue that connects muscle to bone.

Bursitis is an inflammation or irritation of a bursa, which is a fluid-filled sac located around joints. Bursitis causes a reduction in or a loss of motion at the affected joint. Bursitis typically occurs in the heel, hip, knee, shoulder, and thumb.

Orthopedics (alternatively, orthopaedics) is a medical specialty focused on the diagnosis and treatment of conditions, disorders, and injuries of the muscles, bones, joints, tendons, ligaments, and nerves.

A doctor who specializes in this medical specialty is called an orthopedic (alternatively, orthopaedic) surgeon or orthopedist.

Tendonitis, medically spelled tendinitis, is an inflammation or irritation of a tendon. Chronic strain, overuse or misuse of a tendon leading to a repetitive stress injury, or a serious acute injury can lead to a weakness, tear, or swelling of the tendon tissue, resulting in pain and stiffness near the tendon. Tendonitis usually occurs in the elbow, hip, knee, shoulder, thumb and wrist, but can occur in any tendon.