REGION OF THE KNEE. 



54i 



Flo. 552. Dislocation of patella outward. 



edge of the patella to rest against the outer surface of the condyle; for the inner edge 

 to be jammed into the upper portion of the intercondyloid notch with its outer edge 

 sticking up; for the patella to be reversed with its articular surface forward and its 

 anterior surface resting on the condyles. 



For treating the affection in slight cases an elastic knee-cap may be of service, 

 but a cure is probably best achieved by the operation of Goldthwait {Boston Med. 

 andSnrg. Journ., Feb. 13, 1904). In this the tendo patellae is split longitudinally 

 and its outer half detached from the 

 tibial tubercle, passed under the remain- 

 ing half, and sewed fast to the perios- 

 teum and expansion of the sartorius at 

 the inner side of the anterior surface of 

 the tibia. This shifts the pull of the 

 quadriceps more inward and the short- 

 ening of the tendon holds the outer 

 edges of the patella more firmly against 

 the edge of the external condyle. Simple 

 folding of the inner part of the capsule 

 has been unsuccessful. 



Dislocation of the Knee. The 

 knee is rarely luxated and then only by 

 such extreme trauma as sometimes to 

 rupture the popliteal vessels and require 

 amputation. It is frequently compound. 

 The tibia may be luxated anteriorly (the 

 most frequent), posteriorly, to either 

 side, or it may be rotated on the femur. 

 These displacements are usually due 

 to hyperextension and rotation. The laceration of the surrounding tissues is so ex- 

 tensive that replacement is usually easy by direct traction and manipulation. As a 

 result of weakening of the ligaments by disease the hamstring tendons frequently pull 

 the tibia backward, producing a subluxation often difficult to replace (Fig. 553). 



Dislocation of the Semilunar Cartilages. The semilunar cartilages do not 

 become displaced in their entirety, but a portion of one of them is torn partly or com- 

 pletely loose and in moving about gets caught between the bones and produces the 

 characteristic symptoms. The joint becomes useless at once and the patient may 



fall. The detachment of the cartilage, 

 which is usually the internal one, is 

 caused by either a direct blow on the 

 part or by a twisting of the partly flexed 

 limb. Use of the limb cannot be re- 

 sumed until the caught cartilage is re- 

 leased. This is most readily achieved 

 by extending the leg and then sharply 

 flexing it. Sometimes the loosened car- 

 tilage instead of remaining attached at 

 one end is free in the joint and may 

 make its appearance alongside of the 

 patella. In one of my cases one end of 

 the semilunar cartilage was attached to the crucial ligament while the other was 

 attached to the capsular ligament, thus allowing the part between to stretch across 

 the surface of the condyle and be compressed in walking. These floating cartilages 

 form the " gelenkmatis " of the Germans. These two conditions were first described 

 by Hey under the name of internal derangements of the knee-joint. Synovial disease 

 may also produce symptoms closely resembling those of detached cartilage. 



Epiphyseal Separations. The epiphyseal line marking the lower epiphysis 

 of the femur starts at the adductor tubercle, at the upper edge of the internal condyle, 

 and passes across transversely just above the edge of the articular surface. It joins 

 with the shaft between the twentieth and the twenty-second year, sometimes as late as 



FIG. 553 

 Sfna e i 



Subluxation of the knee from tuberculous 

 f the bones ' (Fr m an 



