434 



SURGICAL ANATOMY. 



requisite in keeping the pointed extremity of the upper fragment in proper position ; other- 

 wise, after union of the fracture, the power of extension of the limb is partially destroyed, 

 from the Rectus muscle being held down by the fractured end of the bone, and from the patella, 

 when elevated, being drawn upwards against the projecting fragment. 



Fig. 268. Fracture of the Femur above the Coiidyles. Fig. 269. Fracture of the Patella. 



Fig. 270. Oblique Fracture of the Shaft 

 of the Tibia. 



Fracture of the patella (Fig. 269) may be produced by muscular action, or by direct 

 violence. When produced by muscular action, it occurs thus : a person in danger of falling 

 forwards, attempts to recover himself by throwing the body backwards, and the violent 



action of the Quadriceps Extensor upon the pa- 

 tella snaps that bone transversely across. The 

 upper fragment is drawn up the thigh by the 

 Quadriceps Extensor, the lower fragment being 

 retained in its position by the ligamentum 

 patellae ; the extent of separation of the two 

 fragments depending upon the degree of lacera- 

 tion of the ligamentous structures around the 

 bone. The patient is totally unable to straighten, 

 the limb ; the prominence of the patella is lost ; 

 and a marked but varying interval can be felt 

 between the fragments. The treatment consists 

 in relaxing the opposing muscles, which may be 

 effected by raising the trunk, and slightly ele- 

 vating the limb, which should be kept in a 

 straight position. Union is usually ligamentous. 

 In fracture from direct violence, the bone is 

 generally comminuted, or fractured obliquely or 

 perpendicularly. 



Oblique fracture of the shaft of tlie tibia 

 (Fig. 270) usually occurs at the lower fourth of 

 the bone, this being the narrowest and weakest 

 part, and is usually accompanied with fracture 

 of the fibula. If the fracture has taken place 

 obliquely from above, downwards, and forwards, 

 the fragments ride over one another, the lower 

 fragments being drawn backwards and upwards 

 by the powerful action of the muscles of the calf; 

 the pointed extremity of the upper fragment pro- 

 jects forwards immediately beneath the integu- 

 ment, often protruding through it, and rendering 

 the fracture a compound one. If the direction 

 of the fracture is the reverse of that shown in 

 the figure, the pointed extremity of the lower 

 fragment projects forwards, riding upon the lower 

 end of the upper one. By bending the knee, 

 which relaxes the opposing muscles, and making- 



