THE REGION OF THE KNEE 465 



calcaneo-navicular (" spring ") ligament (p. 484), and the 

 condition of flat-foot is brought about. In some cases flat-foot 

 is not the result but the cause of genu valgum. In the attitude 

 of rest adopted by young adolescents who are the subjects of 

 flat-foot, the feet are turned laterally and separated widely 

 from one another, while the knees are slightly flexed and the 

 thighs are adducted. When the limbs are in this position, the 

 medial condyle of the femur is tilted up off the tibia, stretch- 

 ing the tibial collateral ligament. The body-weight is now 

 transmitted through the lateral condyle of the femur, and 

 owing to the diminished pressure on the medial part of the 

 epiphyseal cartilage, the medial part of the distal extremity of 

 the diaphysis undergoes abnormal growth. Thus the apparent 

 genu valgum of the attitude of rest becomes transformed into 

 a real genu valgum. 



Certain anatomical changes are found in adults in whom 

 the rhachitic knock-knee of childhood has been permitted to 

 remain uncorrected. The patella may become displaced 

 laterally so that, on flexion of the knees, it slips backwards over 

 the lateral aspect of the joint. The biceps tendon sometimes 

 becomes shortened and causes an appreciable amount of lateral 

 rotation of the tibia. The disability caused by these changes 

 may be relieved by medial cuneiform osteotomy of the femur 

 (p. 438), combined with transplantation of the tibial tuberosity 

 with the attached ligamentum patellae to the medial aspect of 

 the tibia, in exaggerated cases. 



Genu Varum. Overgrowth of the lateral part of the 

 distal extremity of the femoral diaphysis or of the opposing 

 part of the tibial diaphysis may occur in rickets, giving rise to 

 the condition of " bow-knee " or genu varum. In this case 

 the plumb-line dropped from the centre of the femoral head 

 passes medial to the centre of the knee-joint, but lateral to the 

 centre of the ankle-joint. As a result, the body- weight is 

 distributed mainly over the lateral part of the foot, which is 

 so well adapted to bear the increased strain (p. 492) that but 

 little disability is experienced. Further, since the knees are 

 widely separated, they do not have to avoid each other in 

 walking, as is the case in genu valgum. 



If the child is kept off its feet, the bones tend to recover 

 their normal shape. This tendency is only apparent so long 

 as the bones remain soft. After the age of six or seven the 

 rhachitic softening disappears and the bones become more 



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