The elbow is an essential joint for movement of the hand and forearm. The functionality of the upper extremity relies on elbow motion. If a person's elbow motion decreases by 50%, upper extremity impairment increases by as much as 80%.' The elbow controls pronation, supi-nation, flexion, and extension of the forearm. Pronation positions the forearm with the palm facing down and the arm extended. This position causes the paths of the radius and ulna to cross at the midpoint of the shafts. Supination of the forearm brings the palm of the hand face up with the forearm extended. This position brings the radius and ulna parallel with each other.2
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