In the majority of cases the styloid process of the ulna is torn off by traction exerted through the medial ulno-carpal (internal lateral) ligament, and in a considerable proportion there is also a fracture of one of the carpal bones. The resulting _displacement_ is of a threefold character: (1) the distal fragment is displaced backwards; (2) its carpal surface is rotated backwards on a transverse diameter of the forearm; while (3) the whole fragment is rotated so that the radial styloid comes to lie at a higher level than normal. [Illustration: FIG. 45.--Radiogram showing the line of fracture and upward displacement of the radial styloid in Colles' Fracture.] _Clinical Features._--In a typical case there is a prominence on the dorsum of the wrist, caused by the displaced distal fragment, with a depression just above it (Fig. 43); and the wrist is broadened from side to side. The natural hollow on the palmar aspect of the radius is filled up by the projection of the proximal fragment. The carpus is carried to the radial side by the upward rotation of the distal fragment, and the radial styloid is as high, or even higher, than that of the ulna. The lower end of the ulna is rendered unduly prominent by the flexion of the hand to the radial side. The fingers are partly flexed and slightly deviated towards the ulnar side; and the patient supports the injured wrist in the palm of the opposite hand, and avoids movement of the part. Occasionally the median nerve is bruised or torn, causing motor and sensory disturbances in its area of distribution. The general outline of the wrist and hand has been compared not inaptly to that of "an inverted spoon." Pronation and stipulation are lost, the joint is swollen, and there is tenderness on pressure, especially over the line of fracture. Tenderness over the position of the ulnar styloid may indicate fracture of that process, although it is sometimes present without fracture. No attempt should be made to elicit crepitus in a suspected case of Colles' fracture as the manipulations are painful, and are liable to increase the displacement. _Treatment._--It cannot be too strongly insisted upon that success in the treatment of Colles' fracture with displacement and impaction depends chiefly upon complete and accurate reduction, and to enable this to be effected a general anæsthetic is almost essential. The surgeon grasps the patient's hand, as if shaking hands with him, and, resting the palmar surface of the wrist on his bent knee, makes traction through the hand, and counter-extension through the forearm, with lateral movements, if necessary, to undo impaction. When the fragments are freed from one another, the wrist is flexed, and the hand carried to the ulnar side, while the lower fragment is moulded into position by the thumb of the surgeon's disengaged hand. When reduction is complete, the deformity disappears, and the two styloid processes regain their normal positions relative to one another.