366 ' HUMAN ANATOMY. 



epiphysis, a number of cases of arrest of growth have been reported. The disjunc- 

 tion has been mistaken for a dislocation of the knee or a supracondylar fracture 

 of the femur, but the undisturbed relations of the condyles and the head of the 

 tibia and the freedom of motion in the knee-joint serve to distinguish it from the 

 luxation, while the fracture is rare in children, and presents differential signs that 

 will be mentioned later (page 644). 



Fractures between the condyles (intercondylar), when T-shaped, as they often 

 are, are thought to be secondary to the main or supracondylar fracture, — i.e., the 

 shaft breaks above the condyles and the force continuing splits them apart. The 

 line of the latter fracture is nearly vertical and follows the intercondylar notch, 

 already weakened by numerous foramina for vessels. The proximity of the popliteal 

 vessels has resulted in grave complications from pressure or from rupture. Either 

 condyle may be split of? separately. The joint is necessarily involved in all these 

 fractures, and rapid distention may make the diagnosis difficult. The X-rays should, 

 of course, be employed in such cases, and indeed in all doubtful fractures of the 

 femur. 



Osteotomy for genu valgum may be done through an incision on the outer 

 side of the thigh — the region of safety — about two inches above the external condyle. 

 The ilio-tibial band of fascia is cut ; the incision passes in front of the biceps ; when 

 about two-thirds of the shaft has been divided by the osteotome, the remainder will 

 fracture easily, as the outer part of the bone is here thicker than. the inner. The 

 operation has the advantages of remoteness from the epiphyseal line, from important 

 blood-vessels, and from the synovial membrane of the knee. The bone is divided 

 at a narrow part. 



Disease. — Infective disease of the upper end of the femur usually involves the 

 hip-joint, even when it begins in the diaphysis, the epiphyseal line being intra- 

 articular. 



In spite of the protective covering of muscles surrounding the shaft, it is not 

 infrequently the subject of inflammation, probably as a result o.^ the great strains and 

 numerous traumatisms to which it is subjected, and of the physiological activity 

 necessitated by its rapid growth, which between birth and maturity is proportionately 

 nearly twice as much as that of the leg and more than twice as much as that of the 

 whole body. Thus, post-typhoidal osteitis attacks the femur in about twenty-five 

 per cent, of the cases in which the lower extremity is involved, and more frequently 

 than any other bone except the tibia and ribs, although the superficial bones of the 

 skeleton are involved by this disease three and a half times more frequently than the 

 deep bones. 



At the lower end of the femur, disease resulting in necrosis, especially of the 

 posterior aspect, often requires amputation, as, owing to the thinness of the perios- 

 teum in that region, there is scarcely any attempt at the formation of an involucrum 

 (Rose). 



Exostoses of the femur are not uncommon, especially in horsemen, in the neigh- 

 borhood of the tendon of the adductor longus — i.e., at the upper end of the femur 

 — and occasionally in that of the adductor magnus at the lower end,^ — -"rider's 

 bones." 



The great comparative frequency with which sarcomata attack the femur is in 

 accord with the general rule that they are more frequently found on long bones 

 than on short ones, on the lower limb than on the upper, and on bones near the 

 trunk than on those remote from it. As they are also more malignant the nearer 

 they approach the trunk, these tumors, like those of the humerus, are clinically more 

 serious than those of the distal portions of the extremity. Both central and sub- 

 periosteal sarcomata, but especially the former, have a predilection for the ends 

 of the bones ; but whereas they affect chiefly the upper end of the humerus and the 

 lower ends of the radius and ulna, in the inferior extremity they ar^ most often 

 found at the lower end of the femur and the upper ends of the tibia and fibula, — that 

 is, at the ends towards which the nutrient arteries are not directed, and at which 

 epiphyso-diaphvseal union takes place latest (page 272). 



Landmarks. — In very thin persons the head of the femur can sometimes be 

 felt immediately below Poupart's ligament and just external to its middle. 



