The elbow joint is formed where the humerus (the upper arm bone) meets the radius and ulna (the two long bones of the forearm).  Tendons are strong, fibrous structures in the body that hold muscles to bones.  As the muscle contracts, it pulls on the bone and the body moves.  Too much strain on a tendon can result in damage.  If the tendon is strained and damaged more quickly than it can heal, it may become painful and inflamed.  This is known as tendinitis. The muscles on the back of the forearm are known as the extensors.  As they contract, they pull back on the wrist and fingers.  The common extensor tendon is formed where the extensor muscles come together to attach to the humerus.  The bony prominence where the common extensor tendon attaches is called the lateral epicondyle. Overuse of the extensor muscles of the forearm can result in chronic pain at the lateral epicondyle.  This is known as lateral epicondylitis, or tennis elbow.  The offending activity is usually a strenuous, repetitive extending motion of the wrist.  Examples include using a hammer and performing a backhand in tennis. Tennis elbow is usually diagnosed based on symptoms and a physical exam.  Pain is located on the side of the elbow and is worse with resisted extension of the wrist.  The lateral epicondyle and common extensor tendon are tender.  X-rays are typically normal.  An MRI may demonstrate swelling or tendon injury at the lateral epicondyle. Tennis elbow is usually treated non-surgically.  Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can help to relieve pain and swelling.  A steroid injection at the lateral epicondyle may also be helpful.  A tennis elbow strap or brace may help to rest the common extensor tendon.  Avoiding activities that require wrist extension helps to put the tendon at rest and allow inflammation to calm down.  Physical therapy may help as well.  Even with good, appropriate treatment, tennis elbow often takes several months to resolve. If tennis elbow does not improve after a few months of treatment, surgical options may be considered.  Surgery involves debridement of the damaged tendon.