414 



HUMAN ANATOMY. 



Fig. 427. 



the outer, or vice versa ; fluctuation cannot be obtained in every direction, — i.e., 

 from side to side under the patella or obliquely ; the patella will lie directly upon 

 the femur. 



The diagnosis from bursal enlargements will be considered in relation to those 

 structures. 



Syphilitic disease of the gummatous type is apt to begin in the subcutaneous 

 tissue without the joint, which it involves secondarily. In its earlier stages the 

 swelling would therefore be periarticular, and recognizable by the foregoing symp- 

 toms. Later, as it extends in both directions, there will usually be ulceration of 

 the skin. 



The knee is more often the seat of the so-called loose bodies than is any other 

 joint. They are sometimes the result of osteo-arthritis (which affects the knee by 



preference), causing thickening and fibrinous 

 or calcareous change in some of the syno- 

 vial fringes ; or they may be produced in 

 those fringes from embryonic remnants, and 

 are then composed of hyaline cartilage or 

 fibro-cartilage ; or they may result from the 

 organization of inflammatory lymph after an 

 acute arthritis ; or they may be portions of 

 an interarticular or articular cartilage de- 

 tached by violence, although this is rare. 



In a case of suppurative arthritis the 

 incisions for drainage should be made on 

 either side of the patella and a little below 

 its middle, and should be placed towards 

 the posterior aspect of the lateral pouches 

 of the synovial membrane. 



Ge7iu valgum — ' ' knock-knee' ' — in 

 young children may be directly due to 

 rickets, or may follow Charcot's disease, in- 

 fantile paralysis, or any sprain or dislocation 

 of the knee that leaves the internal lateral 

 ligament weak or defective. In children 

 and adolescents without these antecedents 

 its essential cause is still a matter of dispute. 

 There can be no doubt, however, that in 

 the great majority of cases the production 

 of the deformity is favored by static modi- 

 fications of certain anatomical conditions 

 which are probably the cause and not the 

 result of the diaphyseal overgrowth of 

 femur and tibia (Mikulicz), of the contrac- 

 tion of the biceps and tensor vaginae femoris 

 (Duchenne), of the elongation of the in- 

 ternal lateral ligament (Stromeyer), and of 

 the atrophy of the external condyle (Gllier) 

 which are found in most cases of this de- 

 formity, and each of which has been given etiological importance. 



The angle between the femoral and tibial axes (corresponding to that between 

 the arm and forearm) opens outward at the knee. It results not, as in the upper 

 extremity, from an outward obliquity of the lower segment of the limb, but from the 

 inward slant of the thighs from the pelvis to the knees, the tibiae (like the humerus) 

 being parallel to the longitudinal axis of the body and to each other. That the line 

 of the knee-joint may be horizontal, the internal condyle of the femur is longer than 

 the external. In a normal person standing erect in the military attitude of "atten- 

 tion" the weight of the trunk is transmitted downward from the head of the femur 

 in a vertical line which passes through the external condyle (Fig. 427). The erect 

 position must therefore be maintained, not merely through the approximation of the 



Line of pressure between hip and knee. 



