LAWS OF BONE ARCHITECTURE 179 



Significance of the inner architecture of the distal portion of the femur. 



1. Relation between structure and function. 2. Conclusions 270 



Summary. Laws of bone structure 273 



Part VI 



Miscellaneous and conclusions 274 



The factor of safety in the human femur 274 



Confirmatory data. 1. Agreement of analysis with breaking tests. 2. 

 Distribution of fractures of the femur. Calculated probable distribu- 

 tion. Statistics. 3. Summary 281 



General comments 284 



Summary 285 



General conclusions 288 



Special conclusions 288 



Applications. 289 



Bibliography 291 



PART I 



Introduction 



The frequency with which injuries and deformities of the fe- 

 mur are encountered renders the establishment of the laws gov- 

 erning the inner architecture of this bone of great practical and 

 theoretical value. The development of modern views of the 

 significance of the inner architecture of the femur and of bone 

 in general will be briefly considered in a separate section. 



The femur has been more carefully and more extensively 

 studied than any other bone. This is easily accounted for by 

 the great complexity of the inner structure, the large size, the 

 unusual shape and the great importance of this bone from a 

 practical point of view. In spite of the large literature and the 

 immense amount of work that has been done upon this subject, 

 there is still much difference of opinion as to the proper inter- 

 pretation of the inner structure of the femur. 



If the mechanical structure of the normal femur is shown to con- 

 form closely to the mathematical proportions of a structure of 

 similar shape and physical properties, economically designed to 

 resist the action of loads similar in amount and manner of ap- 

 plication, it is conclusive that the structure of the femur is based 

 upon exact mathematical laws : and further, that this is the gen- 

 eral law of bone architecture: the form of bone is adapted to its 

 functions. 



