Osteosynthetic fastening device

• US 5,520,689 A
• Filed: 03/08/1995
• Issued: 05/28/1996
• Est. Priority Date: 06/04/1992
• Status: Expired due to Term

• Current Assignee: Synthes USA LLC (Johnson & Johnson)
• Original Assignee: Synthes USA LLC (Johnson & Johnson)
• Inventors: Fluckiger, Markus, Schlapfer, Johannes F.
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): Tucker, Guy V.
• Application Number:
  US08/400,482
• Time in Patent Office: 447 Days
• Field of Search: 606/61, 606/72, 606/73, 606/57, 606/59, 606/54, 606/60, 623/17
• US Class Current: 606/270
• CPC Class Codes: A61B 17/701 Longitudinal elements with a non-circular, e.g. rectangular, cross-section A61B17/7005, A61B17/7007 take precedence
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/704 the longitudinal element passing through a ball-joint in the screw head
• CPC Class Codes: A61B 2017/603 with three points of contact, e.g. tripod

Abstract

An osteosynthetic fastening device, preferably in the form of a pedicle screw or a spinal column hook, has a channel in its upper section for receiving a support rod and a retaining element which clamps the rod in the socket through a spherical contact element.

Claims

1. An osteosynthetic fastening element useful as a pedicle screw or spinal hook, said element comprising, a longitudinal axis, a lower portion for attachment to a bone and an upper portion adjoining the lower portion along the longitudinal axis, said upper portion having a channel transverse to said longitudinal axis for receiving a longitudinal support rod, a cylindrical socket with an axis coaxial with said longitudinal axis and a fixation element in said socket, said fixation element having a cavity and a spheroidal contact element in said cavity and having a portion protruding from the bottom of said cavity, a peripheral part of said portion being cut away to provide a flat or concave surface for contacting a support rod in said transverse channel.

2. The fastener according to claim 1 wherein the socket is provided with interior threading and the fixation element is provided with a matching exterior threading.

3. The fastener according to claim 1 wherein the spheroidal contact element is so situated in the cavity that it can turn.

4. The fastener according to claim 1 wherein the spheroidal contact element is the segment of a sphere.

5. The fastener according to claim 1 wherein the spheroidal contact element is a spherical layer.

6. The fastener according to claim 1 wherein the spherical contact element has a concave cylindrical countersink, perpendicular to a radius of the spherical contact element, forming said surface to provide an interlocking fit onto a longitudinal support rod.

7. The fastener according to claim 1 wherein the fixation element has a polygonal socket on its top side, running parallel to the longitudinal axis to accommodate a fitting tool.

8. The fastener according to claim 1 wherein the fixation element on its top side has a slot running transverse to the longitudinal axis, and a central borehole having interior threading to accommodate a fitting tool.

9. The fastener according to claim 1 wherein:

(A) the bottom of the transverse channel has a concave, cylindrical surface, whose axis is perpendicular to the longitudinal axis;

(B) a tipping part is provided for positioning between the bottom of the transverse channel and a longitudinal support rod in said channel, said tipping part having on one side a convex surface that matches the surface of the bottom of the channel, and on another side a concave, cylindrical surface to fit the surface of a longitudinal support rod;

(C) the center of rotation of said tipping part being identical to the center of rotation of the spheroidal contact element.

10. The fastener according to claim 9 wherein the floor of the transverse channel and the convex surface of the tipping part have toothed surfaces.

11. The fastener according to claim 9 wherein the floor of the transverse channel has a toothed and the tipping part a smooth surface.

12. The fastener according to claim 9 wherein the floor of the transverse channel has a smooth and the tipping part a toothed surface.

13. The fastener according to claim 9 wherein the floor of the transverse channel and the tipping part have smooth surfaces.

14. The fastener according to claim 9 wherein the floor of the transverse channel and the tipping part have irregularly structured surfaces.

15. The fastener according to claim 9 wherein the center of rotation of the tipping part and the spheroidal contact element are at the level of the longitudinal axis of a support rod in said channel.

16. The fastener according to claim 15 wherein the tipping part and the spheroidal contact element are a single element adapted to be slipped on a support rod.

17. The fastener according to claim 15 wherein the tipping part is spheroidal and the tipping part and the spheroidal contact collar-like element adapted to be slipped on the support rod.

18. The fastener according to claim 9 wherein the center of rotation of forms is located to be on top of a support rod positioned in said channel.

19. The fastener according to claim 9 wherein the floor of the socket and the tipping part are wedge-shaped.

20. The fastener according to claim 1 wherein the transverse channel is open at the top to form a U-shape having two sides for a longitudinal support rod.

21. The fastener according to claim 20 and comprising a stabilizer cap mountable over the two sides.

22. A fastening system for use in osteosynthesis comprising a support rod and a fastening element adapted for use as a pedicle screw or spinal hook, said fastening element having a longitudinal axis, a lower portion for attachment to a bone and an upper portion adjoining the upper portion along the longitudinal axis, said upper portion having a transverse channel for receiving said support rod, a cylindrical socket with an axis coaxial with said longitudinal axis and a fixation element in said socket, said fixation element having a cavity and a spheroidal contact element in said cavity, said contact element having a peripheral part cut away to provide a flat or concave surface for contacting the support rod in said channel.