PRACTICAL CONSIDERATIONS : THE FEMUR. 



363 



Fig. 380. 



and gemelli. Disjunction from indirect violence — through the action of these 

 muscles — is rare, on account of : (i) The prolongation downward and outward of 

 the fibres of the capsular ligament which extend below the epiphyseal line. (2) The 

 attachment above that line of some of the aponeurotic fibres of origin of the vastus 

 externus. (3) The toughness of the periosteum. 



For these same reasons, when disjunction does occur, there is usually but little 

 displacement. If it exists, and is marked, the epiphysis is drawn into approxi- 

 mately the same position as that occupied by the head of the bone in a dislocation 

 onto the dorsum of the ilium. The age of the patient (epiphyseal separation being 

 impossible after nineteen and dislocation rare before that age) and the failure of the 

 displaced epiphysis to move with rotation of the femur are aids to 

 diagnosis. The absence of rotation and of shortening of the limb 

 distinguishes this lesion from ' ' extracapsular' ' fracture of the 

 neck. 



About fifty per cent, of the recorded cases have died of py- 

 aemia. This is probably because : ( i ) The greater trochanter is 

 an apophysis rather than an epiphysis, and is in contact at its 

 base with cancellous tissue of a lighter and more spongy character 

 than that adjoining the true terminal epiphyses of the long bones. 

 (2) The violence causing the injury is direct and thus associated 

 with much bruising and crushing of that tissue. (3) The disjunction 

 is attended by extensive detachment of the periosteum from the 

 vascular upper end of the bone, as the periosteum over the tro- 

 chanter is very thin and the dense tendinous fibres are almost di- 

 rectly attached to the osseous tissue itself (Poland). 



The epiphysis for the lesser trochanter can be separated usu- 

 ally only between the thirteenth year and the nineteenth, when it 

 joins the shaft. But one case has been recorded. It was then 

 torn oflf in a boy of fourteen, as the result of the strain on the ilio- 

 psoas in a fall backward on the feet. Death from pyaemia followed. 



Fracture of the 7ieck of the fetmir is common (especially in 

 old age), in spite of its depth and its thick covering of soft parts, 

 because : ( i) In falls upon the feet or hip it receives and transmits 

 much of the weight of the body, which, in the former case at 

 least, reaches it in a direction which causes a cross-strain favorable 

 to fracture. (2) It is a comparatively fixed portion of a very 

 long lever into the upper end of which many powerful muscles are 

 inserted. (3) It is of itself lengthened and thus made more vul- 

 nerable, — as compared, for example, with the neck of the hu- 

 merus, — so as to increase the leverage of these muscles, the degree 

 of mobility of the hip-joint, and the basis of support for the trunk. 

 (4) Its mechanical" weakness increases in old age (a) from the 

 absorption of cancellous tissue which occurs everywhere in the 

 skeleton, but begins and proceeds most quickly (according to 

 Humphry) in the femoral neck ; (<5) from a corresponding thin- 

 'ning of the compact tissue, including that part of the cortex which unites the lesser 

 trochanter and the under and anterior part of the head, the line of greatest press- 

 ure in the erect position. (5) The angle between the neck and the shaft is 

 believed by many surgeons gradually to decrease, though this change is not in- 

 variable and is denied by some excellent authorities. It is true, however, that the 

 angle is smaller the less the stature ; that it is thus smaller in women, and that 

 in them, after the age of fifty, these fractures are two and a half times more common 

 than in men. 



When the age of the patient is advanced, and the violence is slight and indirect, 

 the femoral neck breaks more frequently near its junction with the head, because 

 there it is thinnest and weakest. Such fractures are entirely intracapsular. 



In younger persons, and especially if the violence is severe and is received 

 directly upon the hip, the fracture is more apt to involve the base or wider portion 

 of the neck, and is likely to be partly intra- and partly extracapsular. If it is 



Lines of fracture of 

 femur. 



