_Old-standing Dislocations._--No attempt should be made to reduce by manipulation a dislocation of the elbow which has remained displaced for five or six weeks, especially when it has been complicated by a fracture. The joint surfaces become welded together by adhesions, and separated fragments often form attachments which lock the joint. Attempts to break these down are attended with considerable risk of re-fracturing the bone or of tearing the soft parts. In such cases it is best to expose the joint, and if reduction is not easily effected a sufficient amount of the lower end of the humerus should be removed to provide a movable joint. #Dislocation of the ulna alone# is a rare injury, and is usually associated with fracture of one or other of its processes or of the inner condyle. #Dislocation of the radius alone#, on the other hand, is comparatively common, especially as a concomitant of fracture of the upper third of the shaft of the ulna (Fig. 40). The injury may result from a blow on the back of the upper end of the radius, a fall on the outstretched hand, or, in children, from forcible traction on the forearm while in the pronated position. The displaced head usually passes _forward_, and rests on the anterior edge of the capitellum, thus preventing complete flexion and supination of the limb. The limb is held partly flexed and pronated. The displaced head of the radius can be felt to rotate with the shaft in its abnormal position, and the articular facet on the head of the radius may also be felt; there is a depression posteriorly below the lateral epicondyle where the head should be. The radial side of the forearm is slightly shortened. The superficial and deep (posterior interosseous) branches of the radial nerve are liable to be pressed upon or torn by the displaced head of the radius, especially if the ulna is fractured, leading to disturbances in the area of their distribution. [Illustration: FIG. 40.--Radiogram of Forward Dislocation of Head of Radius, with Fracture of Shaft of Ulna.] In a few cases the displacement of the head has been _backwards_ or _laterally_. _Treatment._--To effect reduction, the forearm should be alternately flexed and extended, while traction is made upon it from the wrist, and the head of the radius is pressed backward with the thumb in the fold of the elbow. When reduction is prevented by the interposition of a portion of the torn ligaments between the bones, it is sometimes necessary to open the joint to ensure accurate adjustment. The joint is fixed in acute flexion to relax the biceps, to allow of union of the torn ligaments, and to prevent recurrence. In old-standing cases, to obtain a useful joint, or to remove pressure from the branches of the radial nerve, resection of the head of the radius may be necessary.