476 The Knee-joint 



equator ; C, the ligament firmly holding it below, and A, the quadriceps 

 acting on it from above. 



The quadriceps, continuing its action, then draws the upper 

 fragment of the bone from the lower ; the 

 lower does not move, being firmly fixed by the 

 ligament. The front of the capsule of the 

 joint is often much torn, and then, of course, 

 the separation of the fragments is wide. But 

 sometimes the force is only just sufficient to 

 break the bone, not to tear through the an- 

 terior expansion from the quadriceps, and 

 then it is very easy to overlook the lesion and 

 to diagnose merely a * sprain.' In every case 

 of obscure injury to the knee, the surgeon 

 should catch hold of the upper and lower 

 halves of the patella with his two hands, and 

 try if he can move one inwards and the other 

 outwards at the same time. 



When the separation of the fragments is wide, the skin may be 

 pushed in between them till the fingers make out clearly the articular 

 part of the condyles of the femur. As the synovial membrane, the 

 bone, and the periosteum are all torn, blood, serum, and synovia are 

 quickly effused, and the knee is greatly swollen. This fluid has to be 

 aspirated before the fragments can be brought into apposition. The 

 knee is to be kept straight on a splint, so as to relax the* quadriceps, 

 and the limb is raised to remove all possible strain from the rcctus 

 femoris, which, coming from the pelvis, may possibly be dragging on 

 the upper fragment. The upper fragment is then to be coaxed down 

 towards the lower, and there steadied. Probably the fracture will be 

 repaired by ligament only, not by bone, for the reasons given on 

 page 464. 



Suturing the approximated fragments with wire is a method of 

 treatment introduced by Sir Joseph Lister, as suitable for old-standing 

 and recent cases of transverse fracture. But though that eminent 

 surgeon showed several patients who had been thus successfully 

 treated, the operation, with its attendant risks, has not been generally 

 adopted in the case of recent fracture. In old cases, however, with 

 widely separated fragments, and a comparatively useless limb, the 

 joint may be opened and the edges of the bone freshened and approxi- 

 mated with a good chance of obtaining bony union, and, due care 

 being taken, the risks of the operation may well be run. 



Even when the joint is opened, it may be necessary to divide the 

 tendon of the rectus femoris before the upper fragment can be brought 

 to the level of the lower fragment, which is immovably fixed by the 

 ligamentum patellae. 



Dislocation of the patella is generally outwards, and the accident 



