98 CLINICAL APPLIED ANATOMY. 



which, being brittle rather than extensile, snaps. This peculi- 

 arity is seen not only in the case of the patella and the olecranon, 

 but also in Pott's fracture. 



In the transverse fracture, the upper fragment as a rule is larger 

 than the lower. Frequently the line of laceration of the tendinous 

 expansion over the front of the bone does not correspond to the 

 line of fracture in the bone itself, but is at a different level. 

 Further, this aponeurosis is stretched before it is torn, so that its 

 lacerated edge may be very ragged, and the ribbon-like portions 

 may easily find their way between the fragments of bone, and 

 possibly bring about a want of bony union. 



A transverse fracture may also occur by direct violence, but 

 stellate or comminuted, and vertical fractures are more commonly 

 ithe outcome of this form of violence. 



The amount of separation in a transverse fracture of the patella 

 varies greatly, and is dependent upon several factors. The first 

 of these is the action of the quadriceps muscle, which by its inser- 

 tion into the upper fragment tends to draw this away from the 

 lower ; but the distance that it can be dragged upwards is regulated 

 by the amount of tearing of the lateral aponeurosis associated with 

 the insertions of the vasti. Secondly, two other minor factors 

 come into play, firstly whether or not the joint is passively or 

 actively flexed after the injury has occurred, and secondly the 

 amount of effusion of blood and synovial fluid which occurs into 

 the joint. 



Hence it is obvious that it will not be politic to attempt to bring 

 the fragments into apposition until the almost spasmodic contrac- 

 tion of the quadriceps has passed off and some of the effusion into 

 the joint has been absorbed. Thus it is incorrect to endeavour by 

 mechanical, or operative means, to approximate the fragments 

 until three or four days at least have elapsed since the lesion 

 occurred. There are two other reasons for delay in the operative 

 treatment of fractured patella, namely, to allow time for the torn 

 vessels to become closed," and to give ample opportunity for 

 obtaining asepsis of the operation area. 



Fractures of the Bones of the Leg. Fractures of the bones of 



