226 



HEALTH AND DISEASE 



heard by applying the ear over the surface of the quarter while the leg is 



moved about by an assistant. 



The difficulty in question is particularly emphasized in fracture of the 



neck of the femur, owing to our inability to restrict the movement of the 



detached head and bring the body of the bone into contact with its broken 



surface. 



In fracture of the thigh or the pelvis or front ribs, where great masses 

 of muscle intervene between the ear and the fracture, 

 crepitus may not be recognized unless movement of 

 the broken parts one ujjon the other is of consider- 

 able extent. 



For various reasons this most important and re- 

 liable symptom cannot always be made to reveal it- 

 self. The broken pieces may be firmly held together 

 so as to preclude any movement one upon the other 

 such as would yield a rubbing sound. This is fre- 

 quently the case in fracture of the long pastern and 

 some other bones. 



In impacted fractures (fig. 328), where one piece 

 of bone is driven into the other, and in incomplete 

 fractures where there is no movement of the imper- 

 fectly-divided bone, and in those instances already 

 referred to where the broken pieces are firmly held 

 together by strong ligaments, no crepitus or rubbing 

 is likely to be heard, and considerable difficulty is 

 experienced in bringing it about where a piece of torn 

 muscle or fascia has insinuated itself between the 

 broken ends of the bone, or where one piece has been 

 drawn some distance away from the other by the force 

 of muscular contraction, as where the point of the 

 elbow is raised from the body of the bone by the 

 great extensor of the arm, or a piece of the patella 



is displaced upwards by the straight muscle of the thigh. 



A sound sinmlating crepitus is sometimes heard where the tissues about 



the seat of injury become infiltrated with air, or where inflamed tendons 



rub against their investing sheaths. 



This false crepitus, however, does not emit that harsh grating sound 



which is so characteristic of the rubbing together of the rough surfaces of 



a broken bone. 



Care must be taken not to mistake a dislocation for a fracture. Where 



the latter takes place in the middle of a long bone there is not much danger 



Fig. 328. 



ture of Femur 



-Impacted Frac- 



