Mechanism of angulation of middle phalangeal shaft fractures

The reduction of middle/proximal fractures is achieved by axial traction and reversing the effects of the deforming forces acting on the fracture. The deforming forces that act on the middle phalanx are the flexor digitorum superficialis (FDS) and the intrinsic tendons. Fractures proximal to the FDS insertion will have an apex dorsal angulation (A), whereas fractures distal to the FDS insertion will have an apex volar angulation (B).