LAWS OF BONE ARCHITECTURE 283 



3. The tendency to break at any point varies directly as the 

 distance from the nearer support to the given point, the femur 

 being assumed to be supported at both ends. 



Upon these assumed conditions, calculations of the distribu- 

 tion of the breaks occurring from blows on the femur, reduced to 

 percentages are as follows: 



PER CENT 



Neck of femur 4.2 



Upper third (exclusive of neck) 19.0 



Middle third 60.2 



Lower third 16.6 



100.0 



A large number of breaks occurs in the neck from causes other 

 than blows at an angle to the axis of the femur. For this reason 

 consideration of the fractures in the neck will be omitted in this 

 study. Then there results the following calculated distribution 

 of fractures of the femur exclusive of those of the neck: 



PER CENT 



Upper third 19.9 



Middle third 62.9 



Lower third 17.2 



100.0 



The statistics of the location of fractures of the femur as given 

 by Hyde (75) for Bellevue Hospital are as follows: 



PER CENT 



(Neck 61) 



Upper third (exclusive of neck) 34 14.0 



Middle third 168 69.8 



Lower third (including 7 condyles) 39 16.2 



241 100.0 



Similar statistics given by Hamilton, quoted by Stimson ('12), 

 are as follows: 



PER CENT 



(Neck 84) 



Upper third 30 19.6 



Middle third 86 56.7 



Lower third 36 23.7 



152 100.0 



