While the humeral and ulnar bones flex and extend similarly to a door hinge, the humeral and radial articulations are much more complex. Shaped like a contoured knob with a cup at the end, the elbow’s radial head smoothly rotates around the ulnar bone, causing the radiohumeral and radioulnar joints to efficiently turn the palm up (supination) or down (pronation) (Image 2. ). Sports and occupations that involve repetitive lifting, forceful forearm maneuvers, and recurrent vibration may, in time, damage the elbow’s extensor tendons and degrade the joint’s articular cartilage. In the presence of altered joint mechanics, the brain may decide to layer the area with a protective spasm, resulting in radial nerve symptoms that resemble lateral epicondylalgia, or tennis elbow. Famed hand surgeon Emanuel Kaplan, MD, was the first to suspect radial nerve denervation as a possible cause for some epicondylalgia cases. In dissection studies, he noted constriction of the radial nerve by adhesions to the capsule of the radiohumeral joint and the short extensor muscle of the wrist¹. A study published in the Manual Therapy Journal found that a significant percentage of double-blind subjects presenting with tennis elbow demonstrated a favorable response to articular stretching techniques to restore optimal extension, pronation, and supination.² A similar study on computer users found an immediate reduction in lateral elbow pain after radial nerve mobilization.³ The researchers concluded that mobilization with movement appears to be a promising alternative treatment for clients with tennis elbow. But why?