Tennis elbow is an inflammation, soreness, or pain on the outside (lateral) side of the upper arm near the elbow. There may be a partial tear of the tendon fibers, which connect muscle to bone, at or near their point of origin on the outside of the elbow.
This injury is due to repeated motions of the wrist or forearm. The injury is typically associated with tennis playing, hence the name "tennis elbow." However, any activity that involves repetitive twisting of the wrist (like using a screwdriver) can lead to this condition.