#Supra-condylar# fracture is usually the result of a fall on the feet or knees, or of direct violence, and is most common in adult males. The line of fracture is generally irregularly transverse, or it may be slightly oblique from above downwards and forwards, so that the proximal fragment passes forward towards the patella, while the distal is rotated backward on its transverse axis by the gastrocnemius muscle. _Clinical features._--Soon after the accident a copious effusion of blood and synovia takes place into the cavity of the knee-joint, adding to the swelling caused by the displaced bones, and rendering it difficult to recognise the precise nature of the lesion. As it is important to make an accurate diagnosis, the X-rays should be employed if possible, and a general anæsthetic should be given when necessary. The proximal end of the distal fragment is usually palpable in the popliteal space, while the proximal fragment is unduly prominent in front. By flexing the knee the fragments may be brought into apposition and crepitus elicited. In oblique fractures, the pointed lower end of the proximal fragment may transfix the quadriceps extensor muscle and may be felt under the skin, or it may perforate the skin and thus render the fracture compound. It should be disengaged by fully flexing and making traction on the knee. The thigh is shortened to the extent of from 1/2 to 1 inch. The popliteal vessels lie so close to the bone that they are liable to be torn by the displaced distal fragment, giving rise to the usual signs of ruptured artery. Sometimes, owing to the feeble state of the circulation from shock, the bleeding does not take place at the time of the accident, but ensues some hours later. The vessels may merely be pressed upon by the displaced bone, but the nutrition of the limb beyond is endangered and gangrene may ensue if early reduction be not effected. _Treatment._--The small size of the distal fragment, its depth from the surface, and the accompanying effusion into and around the joint, render its control difficult. In the majority of cases the two fragments can only be brought into apposition when the knee is flexed on the thigh and the thigh on the pelvis, and it is almost always necessary to carry out the reduction under anæsthesia. In the few cases in which the fragments can be accurately approximated in the extended position of the limb, retention may be effected by means of a box splint reaching well up the thigh (p. 180). In the majority, however, flexion is necessary, and a Thomas' knee splint with flexion attachment bent to an angle of 30° (Fig. 81) and extension by means of ice-tong callipers secures the best apposition. If this apparatus is not available the limb must be fixed on a double-inclined plane, so constructed that the angle of flexion can be adjusted to meet the requirements of the individual case (Fig. 70).