446 SURGICAL APPLIED ANATOMY. [Chap. xxi. 



with a twisting of the former bone, is the common 

 cause of the lesion. It is probable that in all luxa- 

 tions of the knee, the crucial ligaments are torn. 

 The lateral ligaments also are usually ruptured, but in 

 the partial luxations they may be sometimes found to 

 be intact. The tendinous expansion of the vasti in 

 front of the knee seldom escapes some laceration, even 

 in the partial dislocations. The projection of the spine 

 of the tibia between the femoral condyles offers an 

 obstruction to lateral luxation. In the antero-posterior 

 displacements, the tibia is more often luxated forwards 

 than backwards. In these injuries, not only are the 

 crucial and lateral ligaments torn, together with the 

 anterior part of the capsule, but the posterior ligament, 

 the gastrocnemius, the biceps, and less often the semi- 

 membranosus, suffer more or less extensive laceration. 

 The popliteal vessels and nerves are much compressed, 

 and appear to be more severely injured by the femur 

 in the forward dislocation than by the tibia in the 

 backward displacement. 



The lower end of the femur. The condylar 

 part of the femur is composed almost wholly of can- 

 cellous bone, with but a slight layer of compact tissue. 

 It is so spongy that it may be pierced by a bullet, as 

 pointed out by Legouest, without any splintering of 

 the bone being produced, and without damage to the 

 articulation. The fractures that may be met with in 

 the lower end of the bone are the following: (1) A 

 fracture of the shaft above the condyles ; (2) a sepa- 

 ration of the lower epiphysis ; (3) a fracture separating 

 either the outer or inner condyle ; (4) a T-shaped 

 fracture, i.e., a transverse fracture above the condyles 

 with a vertical one between those processes. These 

 lesions are, as a rule, due to well localised direct vio- 

 lence. Fractures Nos. 1 and 4 may be produced by in- 

 direct violence, as by a fall upon the feet from a height. 

 Henry Morris states that lateral flexion, or force 



