FEACTUEES OF THE EADIUS. 89 



A fractured olecranon always involves the elbow joint. Im- 

 mediately after the fracture the triceps, acting upon the upper 

 fragment, draws it away from the lower, the extent of separation 

 depending first upon the activity of the muscles, and secondly 

 upon the amount of tearing of the tendino-aponeurotic fibres 

 investing the process laterally. The fragments may be further 

 separated by the dipping in of a fringe-like apron of the stretched 

 and lacerated surrounding aponeurosis. The result of this 

 separation is that in most cases where wiring is not undertaken 

 union occurs only by fibrous tissue. 



Fractures by direct violence are often associated with but 

 little separation, and some of these may possibly unite by bony 

 tissue. In the majority of cases of fracture of the olecranon 

 process with marked separation, exposure and wiring of the 

 fragments is indicated. 



Fractures of the Radius alone. This fracture is most com- 

 monly seen close above the distal extremity of the radius in the 

 form of the well-known Colles's fracture. It is usually produced 

 by indirect violence, as by a fall upon the outstretched palm of 

 the hand, by which there is induced extreme dorsi-flexion of the 

 wrist. This will bring about a nearly transverse fracture of the 

 radius within three-quarters of an inch of its lower articular 

 surface. Immediately upon the break of the bone, the weight 

 of the body continuing to act forces the lower fragment towards 

 the radial side of the forearm. It is further, for the same reason, 

 carried upwards and backwards, and also rotated so that the 

 lower articular surface, instead of looking directly downwards, 

 now looks downwards and somewhat backwards. Thus it 

 happens that the tip of the styloid process of the radius, which 

 normally is at a lower level than that of the ulna, now comes to 

 lie at the same level or even higher. Not infrequently the 

 triangular fibro-cartilage drags off the ulnar styloid process. 

 When impaction occurs, as it frequently does, the posterior 

 portion of the upper fragment is impacted into the anterior 

 portion of the lower fragment. 



The unsatisfactory results following upon Colles's fracture are 



