Patent ID: 8915917

Claim:
An intramedullary nail comprising: a nail stem; an insert within the nail stem and having an insert bone screw aperture to receive a bone screw for engagement with a proximal bone fragment; the nail stem having a distal aperture to receive a bone screw for engagement with a distal bone fragment, and a proximal aperture arranged for alignment with said insert bone screw aperture; a motion assembly allowing limited and repeated relative axial relative movement of the insert and the nail stem; wherein the insert is adapted to guide insertion of a bone screw through the stem proximal aperture, and the insert is constrained by being keyed in the stem to move axially only within the stem without relative rotation of the insert and the stem; wherein said motion assembly is adapted to allow limited and repeated axial relative movement of the insert and the stem of less than 1.5 mm by a difference in cross-sectional size between the bone screw and the stem proximal aperture, said difference allowing movement, wherein the motion assembly is adapted to provide spring bias and/or damping between the nail stem and the insert, and wherein the motion assembly comprises a removable spring.