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. Tennis elbow is associated with jobs that require repeated or forceful movements of the fingers, wrist, and forearm. It can develop because of too much force at once or small amounts of force for too long a period.
Tennis elbow can cause extreme tenderness on the outer side of the elbow.
This tenderness becomes painful when the wrist and elbow are moved in certain ways. In a medical examination, pain experienced in any three of these movements can indicate the possibility of tennis elbow. Usually there is no outward sign of redness or swelling. Most often tennis elbow affects only one arm, usually the one that does most at work. Tennis elbow can appear in many different ways.