THE PATELLA. 



bearing on practice to which allusion must be made. It has been stated above that the 

 lower end of the femur is the only epiphysis in which ossification has commenced at the time of 

 birth. The presence of this ossific centre is, therefore, a proof, in newly-born children found 

 dead, that the child has arrived at the full period of utero-gestation, and is always relied upon in 

 medico-legal investigations. The position of the epiphysial line should be carefully noted. It 

 is <>n a level with the adductor tubercle, and the epiphysis does not, therefore, form the whole 

 of the cartilage-clad portion of the lower end of the bone. It is essential to bear this point in 

 mind in performing excision of the knee, since growth in length of the femur takes place chiefly 

 from the lower epiphysis. and any interference with the epiphysial cartilage in a young child 

 would involve suc-h ultimate shortening of the limb, from want of growth, as to render it 

 almost useless. Separation of the lower epiphysis may take place up to the age of twenty, at 

 wlik-h time it becomes completely joined to the shaft of the bone ; but. as a matter of fact, few 

 occur after the age of sixteen or seventeen. The upper epiphysis of the femur is of 

 interest principally on account of its being the seat of origin of a large number of cases of 

 tubercular disease of the hip-joint. The disease commences in the majority of cases in the 

 highly vascular and growing tissue in the neighborhood of the epiphysis, and from here extends 

 into the joint. 



Fractures of the femur are divided, like those of the other long bones, into fractures of the 

 upper end ; of the shaft : and of the lower end. The fractures of the upper end may be 

 classified into 1 fracture of the neck ; (2) fracture at the junction of the neck with the great 

 trochanter; (3) fracture of the great trochanter; and (4) separation of the epiphysis, either 

 of the head or of the great trochanter. The first of these, fracture of the neck, is usually 

 termed intracapsular fracture, but this is scarcely a correct designation, as, owing to the attach- 

 ment of the capsular ligament, the fracture may be partly within and partly without the cap- 

 sule, when the fracture occurs at the lower part of the neck. It generally occurs in old people, 

 principally women, and usually from a very slight degree of indirect violence. Probably 

 the main cause of the fracture taking place in old people is in consequence of the degenerative 

 changes which the bone has undergone. Merkel believes that it is mainly due to the absorp- 

 tion of the calcar femorale. These fractures are occasionally impacted. As a rule they unite by 

 fibrous tissue, and frequently no union takes place, and the surfaces of the fracture become 



rh and eburnated. 



Fractures at the junction of the neck with the great trochanter are usually termed extra- 

 capsular. but this designation is also incorrect, as the fracture is partly within the capsule, 

 owing to its attachment in front to the anterior intertrochanteric line, which is situated below 

 the line of fracture. These fractures are produced by direct violence to the great trochanter. as 

 from a blow or fall laterally on the hip. From the manner in which the accident is caused, the 

 neck of the bone is driven into the trochanter, where it may remain impacted, or the trochanter 

 may be split up into two or more fragments, and thus no fixation takes place. 



Fractures of the great trochanter may be either "oblique fracture through the trochanter 

 major, without implicating the neck of the bone" (Astley Cooper), or separation of the great 

 troehanter. Most of the recorded cases of this latter injury occurred in young persons, and were 

 probably cases of separation of the epiphysis of the great trochanter. Separation of the epiphysis 

 of the head of the femur has been said to occur, but, as far as I know, has never been verified 

 by post-mortem examination. 



Fractures of the shaft may occur at any part, but the most usual situation is at or near the 

 centre of the bone. They may be caused by direct or indirect violence or by muscular action. 

 Fractures of the upper third of the shaft are almost always the result of indirect violence, 

 whilst thu<e of the lower third are the result, for the most part, of direct violence. In the 

 middle third fractures occur from both forms of injury in about equal proportions. Fractures 

 of the shaft are generally oblique, but thev may be transverse, longitudinal, or spiral. The 

 transverse fracture occurs most frequently in children. The fractures of the lower end of the 

 femur include transverse fracture above the condyles. the most common ; and this may be com- 

 plicated by a vertical fracture between the condyles. constituting the T-shaped fracture. In 

 these eases the popliteal artery is in danger of being wounded. Oblique fracture, separating 

 either the internal or external condyle. ancf a longitudinal incomplete fracture between the con- 

 dyle>. may also take place. 



The femur as well as the other bones of the leg are frequently the seat of acute necrosis in 

 young children. This is no doubt due to their greater exposure to injury, which is often the 

 exciting cause of this disease. Tumors not unfrequently are found growing from the femur : 

 the most common forms being sarcoma, which may grow either from the periosteum or from the 

 medullary tissue within the interior of the bone ; and exostosis. which is commonly found 

 originating in the neighborhood of the epiphysial cartilage of the lower end. 



THE LEG. 



The skeleton of the Leg consists of three bones : the Patella, a large sesamoid 

 bone, placed in front of the knee : the Tibia : and the Fibula. 



The Patella 'Figs. 218, 219.) 

 The Patella (patella, a small pan) is a flat, triangular bone, situated at the 



