APPLIED ANATOMY. 



7. The primary luxation is a low anterior or posterior one. This may be 

 changed by subsequent rotation of the thigh. 



8. Luxations may occur either when the thigh is in abduction or adduction. 

 Luxation by Abduction. If the thigh is forcibly abducted the adductor muscles 



rupture and, the abduction increasing, the head is raised out of the socket by the 

 lever action of the femur as its neck strikes the rim of the acetabulum and its greater 



FIG. 514. Luxation of the hip by indirect or leverage action. The shaft of the femur, from the greater 

 trochanter out, is the long arm of the lever, the head and neck form the short arm and the upper edge of the ace- 

 tabulum and ilium immediately above is the fulcrum. When the femur is abducted the head is lifted out of its, 

 socket rupturing the capsular ligament. 



trochanter the ilium above. The head and neck are the short arm of the lever, the 

 rim of the acetabulum or ilium is the fulcrum, and the shaft and distal extremity of 

 the femur are the long arm. The head rises from the socket, ruptures a part at 

 least of the capsular ligament, and then a thrusting force is added which pushes the 

 head forward, producing a thyroid luxation (Fig. 514). 



If while the limb is hyperabducted the shaft of the femur is rotated out and the 



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FIG. 515. Posterior luxation of the hip produced by rotation and direct thrust. The femur is seen to be 

 flexed on the pelvis, adducted and rotated inward; a thrust in the direction of the arrow then sends the head out 

 of the acetabulum onto the posterior plane. 



limb brought straight down, parallel with that of the opposite side, then likewise the 

 head may pass forward into the thyroid or pubic position. If while the head is on 

 the anterior plane the thigh is flexed and the shaft rotated inward, then the head 

 follows around the outer edge of the acetabulum and passes from a thyroid to a 

 dorsal position, forming a posterior luxation. 



