FACET INTERFERENCE SCREW

• US 20110004247A1
• Filed: 03/05/2009
• Published: 01/06/2011
• Est. Priority Date: 03/06/2008
• Status: Active Grant

• Current Assignee: DePuy Synthes Products LLC (Johnson & Johnson)
• Original Assignee: DePuy Synthes Products LLC (Johnson & Johnson)
• Inventors: Lechmann, Beat, Zurschmiede, Silas, Pavlov, Paul W.
• Granted Patent: US 8,696,708 B2
• Time in Patent Office: Days
• US Class Current: 606/247
• CPC Class Codes: A61B 17/7064 Devices acting on, attached to, or simulating the effect of, vertebral facets; Tools therefor
• CPC Class Codes: A61B 17/862 at the periphery of the screw head
• CPC Class Codes: A61B 17/866 Material or manufacture
• CPC Class Codes: A61B 17/8685 comprising multiple separate parts
• CPC Class Codes: A61B 17/8883 the driver bit acting on the periphery of the screw head
• CPC Class Codes: A61B 17/8891 at its periphery
• CPC Class Codes: A61F 2/4405 for apophyseal or facet joints, i.e. between adjacent spinous or transverse processes devices implanted between spinous or transverse processes A61B17/7062
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30617 Visible markings for adjusting, locating or measuring
• CPC Class Codes: A61F 2002/30672 temporary
• CPC Class Codes: A61F 2002/4677 using a guide wire
• CPC Class Codes: A61F 2250/0059 temporary
• CPC Class Codes: A61F 2250/0097 Visible markings, e.g. indicia
• CPC Class Codes: A61F 2310/00017 Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00407 Coating made of titanium or of Ti-based alloys
• CPC Class Codes: A61F 2310/00604 Coating made of aluminium oxide or hydroxides
• CPC Class Codes: A61F 2310/00634 Coating made of zirconium oxide or hydroxides
• CPC Class Codes: A61F 2310/0073 Coating or prosthesis-covering structure made of compounds based on metal carbides
• CPC Class Codes: A61F 2310/00748 : Coating made of titanium carbide
• CPC Class Codes: A61F 2310/00754 : Coating made of chromium carbide
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: A61F 2310/00856 : Coating or prosthesis-covering structure made of compounds based on metal nitrides
• CPC Class Codes: A61F 2310/0088 : Coating made of titanium nitride
• CPC Class Codes: A61F 2310/00886 : Coating made of chromium nitride

Abstract

A facet interference screw (10) for insertion between the facet joints of adjacent superior and inferior vertebrae includes an externally threaded shaft portion and a head. The facet interference screw is preferably split into first (20) and second (30) components, each including an outer, semicircular externally threaded surface (22, 32) so that when coupled together the semicircular externally threaded surfaces form the externally threaded shaft portion. The inner surfaces (24, 34) of the first and second components may include curved contacting surfaces so that when inserted, the first component is movable with respect to the second component. Alternatively, the screw may include a damping component (60a′) between the inner surfaces of the first and second components to facilitate damping of the first and second components with respect to one another. The damping component preferably also facilitates articulated motion of the first and second components.

Claims

1. A facet interference screw for insertion into a facet joint between an inferior facet of a superior vertebra and a superior facet of an inferior vertebra, the facet interference screw comprising:

a first component including a first outer semicircular, threaded surface and a first inner surface; and

a second component including a second outer semicircular, threaded surface and a second inner surface, the first and second components defining a head portion, a tip, a longitudinal axis extending between the head and the tip and an externally threaded shaft portion in an assembled configuration, the first and second inner surfaces extending from the head portion to the tip in the assembled configuration, the first and second surfaces being substantially in contact in the assembled configuration.

2. The screw of claim 1, wherein the first and second inner surfaces are generally parallel to an articulation plane of the facet interference screw.

3. The screw of claim 1, wherein the inner surfaces of the first and second components of the facet interference screw are curved.

4. The screw of claim 1, further comprising:

a damping component located between the inner surfaces of the first and second components.

5. The screw of claim 4, wherein the inner surface of at least one of the first and second components includes a guiding mechanism.

6. The screw of claim 4, wherein the damping component includes an upper damping component having an outer surface contacting the inner surface of the first component and an inner surface and a lower damping component having an outer surface for contacting the inner surface of the second component and an inner surface, the inner surfaces of the upper and lower damping components being curved and in contact with each other such that the upper damping component is articulable with respect to the lower damping component.

7. The screw of claim 6, wherein the curved contacting surfaces are spherical surfaces.

8. The screw of claim 4, wherein the damping component has a profile that matches the profile of the first and second components.

9. The screw of claim 1 further comprising:

an indicator on the head that is aligned with an articulation plane of the facet interference screw.

10. A facet interference screw for insertion into a facet joint between an inferior facet formed on a superior vertebra and a superior facet formed on an inferior vertebra, the facet interference screw comprising:

a first component having an externally threaded surface and a first inner surface;

a second component having an externally threaded surface and a second inner surface, wherein the first and second components define a head, a tip and a shaft portion in an assembled configuration; and

a damping component located between the first and second components and extending generally along the longitudinal axis, the damping component being in contact with the first and second inner surfaces.

11. The facet interference screw of claim 10 wherein the damping component is constructed of an elastomeric-thermoplastic polymer.

12. The facet interference screw of claim 10 wherein the damping component is adhesively bonded to the first and second inner surfaces.

13. The facet interference screw of claim 10 further comprising:

an indicator positioned on the head to identify an orientation of an articulation plane of the facet interference screw, the articulation plane extending through the damping component.

14. The facet interference screw of claim 10 wherein the damping component includes a cannulated opening extending from the head to the tip, generally co-axially with the longitudinal axis.

15. A method for inserting a first facet interference screw and a second facet interference screw, each including a first component having an externally threaded surface and a first inner surface and a second component having an externally threaded surface and a second inner surface, the method comprising the steps of:

a) inserting a temporary spacer between the first and second inner surfaces of the first and second components;

b) inserting a guide wire at least partially into facet joints between adjacent superior and inferior vertebra;

c) guiding the first and second interference screws down the guide wires such that tips of the first and second interference screws are positioned adjacent the facet joints;

d) driving the first and second facet interference screws simultaneously into each of the facets joints until the heads contact the bone of the facet joints; and

d) removing the guide wire, which causes the guide wire to contact and remove the temporary spacer from between the first and second inner surfaces of the first and second components.

16. The method of claim 15, comprising the further step of:

e) inserting a damping component between the first and second inner surfaces following step (d).

17. The method of claim 15 comprising the further step of:

e) aligning an indicator on the heads of the first and second interference screws with facet joint planes of the facet joints.