It is sometimes necessary to apply continuous extension to the lower fragment to prevent overriding. For this purpose a Thomas' arm splint is employed, the extension tapes being attached to its lower end, but care must be taken that the traction is not sufficient to separate the fragments and leave a gap between them. The elbow should not be retained in the extended position for more than three weeks. In rare cases it is necessary to have recourse to operative treatment. When there is evidence that the radial nerve has been injured, and no sign of improvement appears within three or four days of the accident, operative interference is indicated. An incision is made on the lateral side of the arm, and the nerve exposed and freed from pressure, or stitched, as may be necessary; the opportunity should also be taken of dealing with the fracture. The limb is put up in a "cock-up" splint, with the hand in the attitude of marked dorsiflexion (Fig. 31). Satisfactory results have been obtained without the use of splints, by relying upon massage to overcome the spasm of muscles, and allowing the weight of the arm to act as an extending force (J. W. Dowden and A. Pirie Watson). In cases of _un-united fracture_, a vertical or semilunar incision is made over the lateral aspect of the bone, and the muscles separated from one another till the fracture is exposed, care being taken to avoid injuring the radial nerve. The fibrous tissue is removed from the ends of the bone, and the rawed surfaces fixed in apposition; the wound is then closed, and appropriate retentive apparatus applied. As soon as the wound has healed, massage and movement are employed. CHAPTER IV INJURIES IN THE REGION OF THE ELBOW AND FOREARM Surgical Anatomy--Examination of injured elbow--FRACTURE OF LOWER END OF HUMERUS: _Supra-condylar_; _Inter-condylar_; _Separation of epiphysis_; _Fracture of either condyle alone_; _Fracture of either epicondyle alone_--FRACTURE OF UPPER END OF ULNA: _Olecranon_; _Coronoid_--FRACTURE OF UPPER END OF RADIUS: _Head_; _Neck_; _Separation of epiphysis_--DISLOCATION OF ELBOW: _Both bones_; _Ulna alone_; _Radius alone_--FRACTURE OF FOREARM: _Both bones_; _Radius alone_; _Ulna alone_. The injuries met with in the region of the elbow-joint include the various fractures of the lower end of the humerus, and upper ends of the bones of the forearm, including the olecranon; and dislocations and sprains of the elbow-joint. The differential diagnosis is often exceedingly difficult on account of the swelling and tension which rapidly supervene on most of these injuries, the pain caused by manipulating the parts, and the difficulty of determining whether movement is taking place _at_ the joint or _near_ it.