Effect of stack pins on the stiffness of interlocking nails in an unstable osteotomy model.

Interlocking nails have been shown to be an effective means to stabilise long bone fractures. When used in non-load sharing fracture repairs with minimal medullary canal filling, the authors noted instability of the main fracture fragments. The addition of multiple intramedullary pins in stack pin fashion eliminated the instability. ILN and ILN/SP constructs were loaded in four-point bending using an unstable osteotomy model. The gap between the ILN and ILN/SP groups was compared. Significant changes were seen with the ILN/SP constructs in the cranial to caudal plane.