Dynamic tension bone screw
AssigneeBoehringer Mannheim GmbH
InventorJohn A. Engelhardt
Life of this patent
Estimating the term…
Abstract
A dynamic bone fixation screw for rejoining fracture fragments of a bone to their approximate original mutual dispositions. It includes a threaded distal end member for threaded engagement with one of the bone fragments and a head member at a proximal end for engagement with another of the bone fragments. A spring member integral with and extending between the distal end member and the head member enables a predetermined torque to be initially imparted to the bone. When stress relaxation in the bone occurs, the spring member relaxes accordingly while continuing to draw the bone fragments together. The bone screw is fabricated in a unique manner.
Claims5
A dynamic fixation screw constructed wholly from an elongated screw having a longitudinal axis for rejoining fracture fragments of a bone in their approximate original mutual dispositions comprising:
- a threaded distal end member for threaded engagement with one of the bone fragments;
- a head member at a proximal end for engagement with another of the bone fragments;
- and
- a threaded shank member of reduced outer diameter intermediate said distal end member and said head member, said elongated screw having a bore therein coaxial with said longitudinal axis extending through said head member and said shank member and having a diameter that slightly exceeds the root diameter of the threads in said threaded shank member thereby resulting in a spring member integral with said distal end member and with said head member for drawing the bone fragments together in a manner which continuously adjusts the force being applied to the bone according to the stress relaxation manifested by the bone.
Dependencies are inferred from the claim text.