THE REGION OF THE KNEE 459 



of the medial femoral condyle. It is relaxed in extension, but 

 becomes tightened during flexion of the joint. 



Severe strains of the knee may cause rupture of one or both 

 cruciate ligaments without leading to actual dislocation of the 

 joint. In addition to preventing hyperextension of the knee, 

 the anterior cruciate ligament prevents the tibia from being 

 moved bodily forwards on the femur when the joint is passively 

 extended. If, following injury, this passive movement is 

 obtained, the diagnosis of rupture of the anterior cruciate 

 ligament can be made with some degree of certainty. Similarly 

 the posterior cruciate ligament prevents the same passive 

 movement of the tibia on the femur when the knee is flexed, 

 and this movement can only be obtained when the ligament 

 is ruptured. 



The articular surfaces of the tibial condyles are separated from one 

 another by a roughened non-articular area, which corresponds to the inter- 

 condylar fossa of the femur. This area, which is narrowest centrally, where 

 it is raised up to form the inter condylar eminence (tibial spine), gives attach- 

 ment to the inter-articular menisci and ligaments. Near its anterior margin 

 it gives attachment to the anterior extremity of the medial meniscus and 

 to the anterior cruciate ligament. The anterior extremity of the lateral 

 meniscus is attached immediately in front of the intercondylar eminence, 

 while its posterior extremity is attached to the eminence itself. The posterior 

 extremity of the medial meniscus receives attachment immediately behind 

 the eminence, and behind that lie the posterior cruciate ligament and the 

 posterior part of the capsule (Fig. 133). 



Fracture of the Intercondylar Eminence (Spine) of the Tibia is a 

 somewhat rare injury, which has been brought to light by the use of radio- 

 graphy. Forcible extension of the femur upon the fixed and medially 

 rotated tibia causes the lateral margin of the medial femoral condyle to 

 impinge on the medial tubercle of the eminence, and so fracture it. Similarly, 

 when the tibia is fixed in lateral rotation, forcible extension may cause the 

 lateral condyle to fracture the lateral tubercle of the eminence (Jones). 



It would appear that the injury only occurs in cases where one or other 

 tubercle is unusually well developed. The condition causes limitation of 

 movement, especially of extension, and if absolute rest in the extended 

 position fails to produce a good result, or if the case is one of long standing, 

 operative interference is advisable. The best exposure is obtained by splitting 

 the patella vertically, the knee being kept flexed. When the two fragments 

 are separated, the patellar sy no vial fold (ligamentum mucosum, p. 452) is 

 exposed and divided, and the region of the intercondylar eminence can then 

 be investigated. There is no necessity to wire the patella subsequently. 



Spread of Tuberculous Disease in the Region of 

 the Knee-Joint. Tuberculous disease at the distal end of the 

 femur usually commences in the distal part of the diaphysis, 

 and nearer to its posterior than to its anterior surface. It may 

 spread upwards along the diaphysis, or it may pass horizontally 

 towards the surface. In the latter case it usually spreads 



