360 Anatomy Applied to Medicine and Surge* y. 



patellar aponeurotic structures falling in between the frag- 

 ments, and thus preventing their proper approximation, 

 and partly because of the separation that results. This 

 separation of the fragments depends on the degree of 

 laceration of the aponeuroses on either side of the bone. 

 As a rule the lesion is confined to the bone, and to its 

 periosteal coverings along with the thin and scattered 

 fibres of the tendon of the quadriceps, that pass in front of 

 the patella to become continuous with the ligamentum 

 patellae below, and when thus confined to the bone and the 

 fascia over it, the separation is rarely more than half an 

 inch, but, when, in addition, the lateral aponeuroses are 

 extensively torn, the separation may be two inches or 

 more" (MacEwen). Occasionally, in fracture, the 

 prepatellar bursa, the posterior wall of which is in 

 direct contact with the fibrous investment of the patella, 

 communicates with the joint cavity, since this wall is torn 

 by the separation of the bony fragments. In the 

 operative treatment of fractured patella, it is always ne- 

 cessary to cut away these aponeurotic structures that 

 overlie the fragments, and to suture the lateral aponeu- 

 roses, if torn. 



Dislocation at the knee joint is very rare, 

 partly because of the breadth of the ends of the bones 

 that enter into the formation of the joint, but, chiefly, on 

 account of the great strength of the ligaments that bind 

 the bones together. When dislocation occurs, the head 

 of the tibia may be displaced backwards, forwards, in- 

 wards or outwards. In backward displacement, the head 

 of the tibia is felt in the popliteal space, and a depression, 

 immediately below the patella, exists in front of the joint, 

 while the leg is, generally, in a state of extreme extension. 

 Condition of the soft parts. The posterior ligament is 

 torn, the hamstring muscles and the popliteal vessels and 



