Bone screw

摘要

A bone screw comprises a threaded portion. The threaded portion has a first thread including a first front surface (11), a first back surface (12) and a crest. A second thread including a second front surface (16) and a second back surface (17) is formed on at least part of the crest of the first thread. Because of the presence of the second thread, a contact area between the screw and a bone and an axial pullout force-bearing area are both significantly increased, without significantly influencing the bending resistance, so that the mechanical property of the screw is entirely improved.

主权项

1. A bone screw, comprising a threaded portion, which has a first thread including a first front surface, a first back surface and a crest, characterized in that a second thread including a second front surface and a second back surface is formed on at least part of the crest of the first thread, wherein the second thread includes a plurality of thread segments, and wherein the plurality of thread segments have cross sections that are not completely the same in the cross section passing through an axis of the screw, the second thread is segmentedly distributed on central portions of top ends of parts of the first thread, wherein there is no second thread on the first thread between two adjacent thread segments of the second thread, and wherein the first thread is a single thread continuously extending on the threaded portion of the bone screw.