62 THE SUPERIOR EXTREMITY 



As soon as the coronoid process is drawn past the distal surface 

 of the trochlea, the forearm is flexed, as the displacement will 

 not recur with the elbow in this position. If the coronoid 

 process hitches in the olecranon fossa, the forearm may be 

 hyper-extended,, and, by using the tip of the olecranon as a 

 fulcrum against the distal end of the humerus, the coronoid is 

 lifted out of the olecranon fossa. It can then be drawn distally 

 by traction. 



In children, reduction is easily obtained (p. 58) if the surgeon 

 grasps the arm just proximal to the epicondyles in such a way 

 that he can exert the pressure of both thumbs to push the 

 olecranon downwards. 



The spasm of the brachialis assists in the replacement, as 

 soon as the tension of the triceps is overcome. 



Complications. The Ulnar Nerve may be stretched or 

 bruised at the time of dislocation, especially if the medial 

 epicondyle is broken off (p. 63). 



Fracture of the Coronoid Process may complicate the 

 posterior dislocation. Reduction is easy, but the displacement 

 readily recurs. The injury may be mistaken for a supracondylar 

 fracture of the humerus, unless the relations of the bony points 

 are' carefully studied. 



Fracture of the Epicondyles (p. 63). 



Myositis ossificans in the tendon of the brachialis is a 

 complication which not uncommonly follows dislocation of the 

 elbow. The osseous deposit interferes with complete flexion 

 and may or may not remain permanently. 



Subluxation of the Radius (p. 58) is produced by sudden 

 traction on the hand or wrist. It is probable that only a part 

 of the head of the radius slips out of the annular (orbicular) 

 ligament ; otherwise reduction would be difficult to obtain. 

 When the accident occurs, the forearm is in the position of 

 pronation and the greatest strain is thrown, through the radius, 

 on to the lateral part of the annular ligament. This oblique 

 strain drags the postero-lateral part of the head of the radius 

 through the ligament, leaving the medial half of the head within 

 the joint. Complete downward subluxation is prevented by 

 the interosseous membrane and the ligaments of the distal 

 radio-ulnar joint, and can occur only when these ligaments are 

 injured. The forcible supination, carried out by the surgeon, 

 screws the half-dislocated head back into place again. 



Fractures around the Elbow-Joint. The distal end 



