They are rope-like structures made of strong, smooth, shiny fibers. Strong forces or sudden impacts, however, can eventually tear their fibers apart in much the same way a rope becomes frayed. This type of injury is called a strain, and usually results in formation of scar tissue. Over time, strained tendons become thickened, bumpy, and irregular. Without rest and time for the tissue to heal, strained tendons can become permanently weakened.
Damaged tendons can occur on either side of the elbow.
When it happens on the outside of the elbow, which is most common, it is called tennis elbow. No one knows exactly what causes the pain of tennis elbow. Most experts believe it is due to the small tears that develop in the tendons. Other possible causes include the development of scar-like tissue under the tendon, wear and tear of the elbow joint, or irritation and inflammation of nerves that pass near the elbow region. The development of tennis elbow often relates to the way that workers carry out activities such as gripping, twisting, reaching, and moving.