Colles's Fracture 283 



shock is received by the scaphoid and the rest of the first row of the 

 carpus, and by the front edge of the lower end of the radius. The 

 result is that the carpal surface of the bone is cracked off, not straight, 

 as happens when the carpal epiphysis is detached, but obliquely, 

 the line of fracture being very near to the wrist-joint in front, but 

 reaching fin., or more, above it posteriorly. The continuance of 

 the shock which cracked off the end of the bone thrusts it, and the 

 carpus with it, upwards on to the back of the radius. As the inner 

 part of the carpus, and the ulna (which does not actually enter into the 

 formation of the joint), receive little shock, there is, as a rule, no 

 fracture or displacement on the ulnar side, further than that the head 

 of the ulna may be left prominent and conspicuous when the outer 

 part of the carpus is thrust upwards. Thus, the hand is found abducted 



after the fracture and there is a considerable dorsal projection on the 

 lower end of the radius, and its styloid process is raised. (The figure 

 is after Erichsen.) 



There is another explanation of the way in which the fracture occurs, 

 that is by the sudden and powerful dragging upon the front of the 

 the lower end of radius by the over-stretched anterior ligament of the 

 joint and the flexor tendons when, in the fall, the hand is thrown back. 

 The displacement of the carpal fragment is probably not in the least 

 influenced by muscular action, but is all mechanical. 



As regards treatment of Colles's fracture, the hand must be dragged 

 forcibly downwards and adducted so as to replace the carpal fragment, 

 a pistol-shaped splint being then applied to keep it in the adducted posi- 

 tion, or some other form of splint which will keep the fragment in place. 



Fracture of the radius between the insertions of the biceps and 

 pronator teres is a rare injury. The fact of the bone being broken is 

 detected by pressing with the thumb or the tip of the index-finger just 

 below the external condyle, and finding that the head of the bone does 

 not move in pronation and supination. 



If the muscles exercised that important influence over the position 

 of fractured bones which is so often ascribed to them (but which I am 

 not prepared to admit), it is evident that the upper piece of the bone 

 would be flexed by the biceps and supinated by that muscle and the 

 supinator brevis, whilst the shaft of the bone would be rolled round by 

 the pronators teres and quadratus, and at the same time drawn towards 

 the ulna ; but this arrangement does not necessarily obtain. 



