Patent ID: 9107678
Filing Date: 2015-08-18
Classification: A61B

Abstract:
1. A bone fixation system comprising a bone screw having a screw shaft and a head; wherein the screw shaft comprises a self-cutting thread having a constant first diameter, the self-cutting thread being adapted for self-cutting a corresponding thread in a bore of a bone; wherein the screw head is provided with a blocking thread having a constant second diameter; wherein the constant second diameter is larger than the constant first diameter; a bone plate having a bone facing surface and an opposite surface facing away from the bone, the bone plate having a through bore therein for receiving the bone screw, the bore having a first threaded bore portion with a constant first diameter thread adjacent the bone contacting surface for engaging the screw self-cutting thread first constant diameter and a second threaded bore portion with a constant second diameter adjacent the opposite surface for engaging the blocking thread second constant diameter, the first and second threaded bore portions being coaxial; the first constant diameter self-cutting thread of the screw shaft engaging both the constant diameter first threaded portion of the bore of the bone plate and the bone when the constant second diameter blocking thread of the screw head is fully seated in the second threaded bore portion of the plate having the constant second diameter; wherein a pitch (p) of the blocking thread and a pitch (p′) of the self-cutting thread are the same, and wherein the blocking thread and the self-cutting thread correspond with respect to inclination and phase to corresponding threads of the bone plate to be mounted by the bone screw; and wherein the through bore of the bone plate further comprises a non-threaded circumferentially extending gap portion which is coaxially aligned with the coaxial central axis of the guiding portion and the blocking portion, wherein the non-threaded circumferentially extending gap portion has a larger diameter than the blocking portion.