#Sub-luxation of the head of the radius#, or "dislocation by elongation," is a comparatively common injury in children between the ages of two and six. It almost invariably results from the child being lifted or dragged by the hand or forearm. The traction and torsion thus put upon the radius causes the front part of its head to pass out of the annular ligament, the edge of which slips between the bones. The person holding the child may feel a click at the moment of displacement. The child complains of pain in the region of the elbow: the arm at once becomes useless, and is held flexed, midway between pronation and supination. All movements are painful, but especially movements in the direction of supination. The deformity is slight, but the head of the radius may be unduly prominent in front. From the way in which the injury is produced the wrist also is often swollen, and in some cases the patient is brought to the surgeon on account of the condition of the wrist, and attention is not directed to the elbow. _Treatment._--Reduction frequently takes place spontaneously or during examination, the function of the arm being at once completely restored. In other cases it is necessary, under anæsthesia, to manipulate the head of the bone into position. This is usually easily done by flexing the elbow, making slight traction on the forearm, and alternately pronating and supinating it. After reduction, a few days' massage is all that is necessary, the joint in the intervals being kept at rest in a sling. #Sprain# of the elbow is comparatively common as a result of a fall on the hand or a twist of the forearm. The point of maximum tenderness is usually over the radio-humeral joint, the radial collateral and annular ligaments being those most frequently damaged. Effusion takes place into the synovial cavity, and a soft, puffy swelling fills up the natural hollows about the joint. The bony points about the elbow retain their normal relationship to one another--a feature which aids in determining the diagnosis between a sprain and a dislocation or fracture. In children it is often difficult to distinguish between a sprain and the partial separation of an epiphysis. Sprains of the elbow are treated on the same lines as similar lesions elsewhere--by massage and movement. The condition known as _tennis elbow_ is characterised by severe pain over the attachment of one or other of the muscles about the elbow, particularly the insertion of the pronator teres during the act of pronation, and is due to stretching or tearing of the fibres of that muscle, and of the adjacent intermuscular septa. A similar injury--_sculler's sprain_--occurs in rowing-men from feathering the oar. The treatment consists in massage and movement, care being taken to avoid the movement which produced the sprain. FRACTURE OF THE FOREARM The _shafts_ of the bones of the forearm may be broken separately, but it is much more common to find both broken together.