ABNORMAL CONDITIONS OF THE KNEE-JOINT. 

 Fig. 8. Fig. 9. 



67 



Femur displaced inwards. Patella anckyksed. 



elongated and was directed backwards. The 

 crucial ligaments were also elongated, and 

 instead of crossing each other were untwisted 

 as it were and lay side by side. The carti- 

 lages were altogether removed, and when the 

 femur was forcibly separated from the tibia, 

 there were corresponding elevations and de- 

 pressions which marked the several points of 

 contact between the bones, in which a species 

 of anchylosis had occurred. The body of the 

 tibia was greatly enlarged and hypertrophied, 

 and round perforations existed in its head, 

 from which sequestra had been discharged. 



II. ABNORMAL CONDITIONS OF THE KNEE- 

 JOINT RESULTING FROM ACCIDENT. FraC- 



tures and dislocations are the principal acci- 

 dents to which the bones of the knee-joint are 

 liable. The muscular and tendinous fibres 

 common to the rectus, cruixEus, and vasti are 

 occasionally torn from the patella, and the 

 ligament of this bone is also sometimes rup- 

 tured. Tho proper ligaments, too, and other 

 structures of the knee-joint, suffer from sudden 

 injuries, which we must here advert to as 

 briefly as we can. 



Fractures of the shaft of the femur near to 

 the knee-joint may be transverse or oblique, 

 or one or both of the condyles may be broken 

 off from this joint. 



1. When a transverse fracture is situate 

 immediately above the condyles of the femur, 



Disj)la.o&ient backwards of tfie superior extremity of 

 the lower fragment. 



it is the inferior fragment which is displaced, 

 its superior extremity being directed backwards 

 towards the popliteal space (see fig. 9) ; the an- 

 terior part of the condyles and trochlea have 

 their aspect directed upwards, and form a 

 swelling above the patella, giving to the joint 

 a singular appearance. This direction back- 

 wards of the superior extremity of the lower 

 fragment is the result of the action of the 

 gastrocnemii, the plantaris, and popliteus 

 muscles. 



2. Oblique fractures of the lower extremity of 

 the femur near the knee-joint are more serious 

 and embarrassing than transverse fractures, not 

 only on account of the immediate danger of 

 the penetration of the skin by the upper frag- 

 ment, and of the accident being thus rendered 

 compound, but also on account of the great 

 difficulty which is always experienced in main- 

 taining the bones in apposition during the 

 treatment of the case. 



Sir A. Cooper says the appearances presented 

 by the usual oblique fracture of the lower ex- 

 tremity of the femur are the following: " The 

 lower and broken extremity of the shaft of the 

 femur projects, and forms a sharp point, which 

 pierces the rectus muscle, just above the pa- 

 tella, threatens to tear the skin, and sometimes 



F 2 



