US 7,325,470 B2Granted

Self-centering screw and retaining screw driver for use in surgery

AssigneeOrthohelix Surgical Designs, Inc.

InventorsDavid B. Kay, Lee A. Stmad, Dustin Ducharme

Life of this patent

Estimating the term…

Loading patent…

Abstract

The present invention relates to an orthopedic screw and a corresponding screw driver wherein the screw has a torque driving head with a rounded side a spherical wall for multiaxial use, a self starting, self tapping insertion tip and a threaded portion including a cancellous thread. The threaded portion has a major diameter defined by a spiraling thread and a minor diameter. The head is joined to the threaded portion by an area of from about 2 to about 6 turns of the thread along the longitudinal axis in which the minor diameter tapers by an angle of from about 4° to about 12° and the major diameter of the screw remaining substantially the same. The screw includes a multilobe torque driving recess joined to a cylindrical recess that corresponds to a cylindrical post on the torque driver so as to form a press fit which acts to self-center the screw, to help avoid stripping of the screw/driver interface and to hold the screw in place on the torque driver prior to implantation.

Claims7

Dependent claims

A surgical screw and screw driver, comprising:

a screw having a head and a insertion tip and a threaded portion with a longitudinal axis and having a major diameter defined by a spiraling thread and a minor diameter, the head having a terminal surface joined by a radiused area to a side wall further joined to the threaded portion, the terminal surface including a torque driving recess having a bottom wall with an opening along the longitudinal axis, the torque driving recess having a first cross sectional shape in the direction transverse to the longitudinal axis and the opening having a second cross sectional shape in the direction transverse to the longitudinal direction of the axis, the screw being made from surgical stainless steel or titanium;
and
a screw driver having a handle, a shaft and a torque driving head having a shape corresponding to the shape of the torque driving recess in the screw and terminating in a unitary pilot which has a frictional fit in the opening;
wherein the cross-sectional shape of the opening and of the pilot is circular in a direction transverse to the longitudinal axis and the cross-sectional shape of one of the opening and the pilot defines a dimension which is constant along the longitudinal axis and the other defines a dimension which continuously decreases along the longitudinal axis toward the bottom of the opening or the pilot.

1 more element

A surgical screw and screw driver, comprising:

a screw having a head and a insertion tip and a threaded portion with a longitudinal axis and having a major diameter defined by a spiraling thread and a minor diameter, the head having a torque driving recess having a bottom wall with an opening along the longitudinal axis, the torque driving recess having a multilobe or hexagonal cross sectional shape in the direction transverse to the longitudinal axis and the opening having a circular cross sectional shape in the direction transverse to the longitudinal direction of the axis, the screw being made from surgical stainless steel or titanium;
and
a screw driver having a handle, a shaft and a torque driving head having a first section which has a shape corresponding to the shape of the torque driving recess in the screw, a first filet forming a transition between the shaft and the first section, a second section having a pilot which has a circular cross-sectional shape and a second fillet which forms a transition between the first and second section, the pilot forming a frictional fit in the opening so as to hold the screw on the screw driver and the screw driver is self-centering in the screw so as to avoid stripping the torque driving recess in the screw.

Dependencies are inferred from the claim text.

Facts

Application: 11/340,372Filed 26 Jan 2006 · us provisional application
Priority: 16 Jun 2005
Published: US 2007/0005070 A14 Jan 2007
Granted: 5 Feb 2008
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

A61B 17/8615
Specially shaped for gripping driver: at the central region of the screw head
A61B 17/888
Characterised by the cross-section of the driver bit: the driver bit acting on the central region of the screw head
B25B 15/005
Characterised by cross-section: with cross- or star-shaped cross-section
B25B 23/108
The gripping device being an integral part of the driving bit: the driving bit being a Philips type bit, an Allen type bit or a socket