Tennis elbow is inflammation or, in some cases, microtearing of the tendons that join the forearm muscles on the outside of the elbow. The forearm muscles and tendons become damaged from overuse — repeating the same motions again and again. This leads to pain and tenderness on the outside of the elbow.

Causes

Tennis elbow is mostly caused by overusing your forearm due to a repetitive or strenuous activity. It can also sometimes occur after banging or knocking your elbow. If the muscles in your forearm are strained, tiny tears and inflammation can develop near the bony lump (lateral epicondyle) on the outside of your elbow.