DISLOCATIONS OF THE PATELLA. 59 



part of the thigh ; extension is to be made at the knee, which is 

 gradually to be made to approximate its fellow. 



In dislocation ujywards and inwards^ the head of the bone rests 

 upon the horizontal portion of the pubes, under Poupart's ligament, 

 where it forms a tumour. The limb is shortened an inch, and the 

 foot is turned outward, and cannot be rotated. The reduction is 

 effected by extension in the axis of the body. 



Reduction of the thigh is indicated by an audible noise when the 

 head of the bone returns to its socket, by the natural length and 

 direction of the limb, by the cessation of pain, and the free motion 

 of the joint. 



After reduction there is sometimes a slight elongation of the limb, 

 which depends upon the swelling of the ligaments of the joint. The 

 patient should be kept at rest, and may require antiphlogistic treat- 

 ment ; walking should not be attempted for several weeks. 



DISLOCATIONS OF THE KNEE. 



Dislocation at this joint is rare on account of its great strength. 

 The displacement may be forwards, backwards, and laterally ; is 

 usually incomplete and readily reduced. 



The reduction is accomplished by extension of the leg and coap- 

 tating the extremities of the bones. Subsequent inflammation and 

 its results, anchylosis, suppuration, &c., are to be avoided by strict 

 antiphlogistic means ; sustaining the weakness of the joint by splints 

 or rollers, and removing the stiffness by lotions and frictions. 



The semilunar cartilages are sometimes displaced by twisting 

 the joint, especially if an unusual relaxation of the ligaments should 

 exist. The limb is immediately rendered stiff, and the pain is severe 

 parts to their position, although the pain and swelling remain for 

 and sickening. Extreme flexion usually is sufhcient to restore the 

 some time and require attention. 



DISLOCATIONS OF THE PATELLA. 



The patella may be dislocated anteriorly, posteriorly, and late- 

 rally. Outivards is the most frequent displacement, and is charac- 

 terized by the leg being stretched, a prominence externally formed 

 by the patella, and a projection internally of the internal condyle. 



Reduction is effected by raising the leg and resting the patient's heel 

 on the surgeon's shoulder, thus relaxing the muscles of the thigh ; at 

 the same time the patella is to be forced into its place with the hand. 

 This bone can only be displaced u'pward by a rupture of its tendon, 

 and downward by a laceration of the -rectus muscle. It may be 

 displaced by semi-rotation, one edge resting on the trochlea of the 

 femur, and the other forming a prominent ridge. Extreme flexion 

 and coaptation will reduce it. 



