elbow fracture elbow fracture elbow fractures are any broken bone in or near the elbow joint and include olecranon fractures, supracondylar humerus fractures and radial head fractures. the elbow joint is formed by three different bones: the ulna, radius, and humerus that permit the joint to move like a hinge and allow a person to straighten and bend their arm and these bones are connected by tendons, ligaments, and muscle to form the joint. the terrible triad of the elbow (not to be confused with the terrible triad of the knee) is a combination of: a fracture of the head of radius a fracture of the coronoid process of the ulna humeroulnar dislocation (generally posterior or posterolateral) the terrible triad of the elbow is confers joint instability and a major risk of developing osteoarthritis.