Abstract
1. Linear fractures of the shaft of the long bones are divided into four basic types: 1) transverse; 2) oblique transverse; 3) spiral; and 4) oblique.
2. The mode of production of these fractures is deduced on the grounds of simple mechanical theory: 1) transverse fractures are a result of angulation; 2) oblique transyerse are the result of angulation with axial loading; 3) spiral fractures are the result of axial twists with or without axial loading; 4) oblique fractures are the result of angulation and axial twisting in the presence of axial loading.