Device for fixing the sacral bone to adjacent vertebrae during osteosynthesis of the backbone

• US 6,290,703 B1
• Filed: 01/12/2000
• Issued: 09/18/2001
• Est. Priority Date: 05/13/1996
• Status: Expired due to Term

• Current Assignee: Stryker European Operations Holdings, LLC (Stryker Corporation)
• Original Assignee: Stryker France S.A. (Stryker Corporation)
• Inventors: Ganem, Franck
• Primary Examiner(s): Philogene, Pedro
• Application Number:
  US09/481,952
• Time in Patent Office: 615 Days
• Field of Search: 606/61, 606/60, 606/69, 606/70, 606/71, 606/73
• US Class Current: 606/250
• CPC Class Codes: A61B 17/7055 connected to sacrum, pelvis or skull
• CPC Class Codes: A61B 17/7059 Cortical plates A61B17/7007, A61B17/7058 take precedence
• CPC Class Codes: A61B 17/8042 the additional component being a cover over the screw head
• CPC Class Codes: A61B 17/8047 wherein the additional element surrounds the screw head in the plate hole A61B17/8052 takes precedence
• CPC Class Codes: A61B 2017/00858 high friction or non-slip

Abstract

A bone fixing device, in particular for fixing to the sacrum for osteosynthesis of the backbone. An elongate link receives at least one bone-fastening screw, which passes through an orifice formed in the link. In the bottom of the link there is a bearing surface of essentially circular cross-section. The head of the screw includes an essentially spherical surface for bearing against the bearing surface. The link includes a first thread in the vicinity of the orifice. The device further includes a plug having a second thread suitable for co-operating with the first thread. The plus is suitable for coming into clamping contact against said screw head to hold it in a desired angular position. The link is constituted by a single-piece plate-shaped element having the orifice and the first thread formed therein, with the bearing surface being essentially spherical.

Claims

1. A device for fixing the sacral bone to vertebrae adjacent to the sacral bone during posterior osteosynthesis of the backbone, the bone fixing device comprising:

a plurality of bone fastening screws, each bone fastening screw having a head;

a first elongated member and a second elongated member, each elongated member extending substantially parallel to the other elongated member and each elongated member having a first end portion, a second end portion and a third intermediate portion coupled between the first and second portions, each portion being in general alignment relative to one another, each elongated member further having

means for receiving at least a first bone fastening screw at an angle in the first portion,

means for receiving at least a second bone fastening screw in the second portion, and

means for securing each bone fastening screw to the associated elongated member at the angle,

wherein the third intermediate portion of each elongated member is rod-shaped and cooperates with a rod-type securing device for osteosynthesis.

2. The bone fixing device of claim 1, wherein the third intermediate portion has the shape of a cylindrical rod.

3. The bone fixing device of claim 2, further comprising:

at least one intermediate bone fixing member having a bone anchoring portion and having a receiving chamber for the rod-shaped intermediate portion of at least one of the first elongated member and second elongated member; and

means for locking the rod-shaped intermediate portion in the chamber.

4. The bone fixing device of claim 2, further comprising:

means for traverse linking of the rod-shaped intermediate portions of the first intermediate portion to the second intermediate portion.

5. The bone fixing device of claim 1, wherein at least one of the plurality of bone fastening screws is a top-loading screw,

wherein the third intermediate portion is a cylindrical rod having a cylindrical circumference, the cylindrical rod being in general alignment relative to the first end portion and the second end portion, and

wherein the top-loading screw is fixed about the cylindrical circumference of the cylindrical rod.

6. The bone fixing device of claim 5, the head of each screw having a bottom portion, the bottom portion having a spherical profile,

each means for receiving including an orifice through which a bone fastening screw may pass, the orifice further defined by a bottom region and a top region, the bottom region having a spherical profile complementary to the spherical profile of the screw head so as to act as a bearing surface, the top region having first threads,

the means for securing including a plug, the plug having second threads adapted to cooperate with the first threads of the top region of the orifice to clamp a bone fastening screw to the elongated member at an angle.

7. The bone fixing device of claim 6, the head of each screw having a top potion, the top portion having a spherical profile that extends from the bottom portion of the head, the plug further having a concave spherical profile complementary to the spherical profile of the top portion of the screw head.

8. The bone fixing device of claim 6, wherein each orifice of the first portion is connected by a single longitudinal slot that permits the movement of one bone fastening screw from one bearing surface to another bearing surface without extracting the bone fastening screw from the orifice.

9. The bone fixing device of claim 5, further comprising:

at least one transition region, wherein each of the bearing surfaces and its associated first threads are mutually truncated at one of the transition regions therebetween.

10. The device of claim 5, the elongated through orifice having an end and a major axis having a direction, the integral link member further having a linking portion, the linking portion adapted to extend from one end of the elongated through orifice in a direction corresponding to the major axis of the elongated through orifice.

11. The device of claim 5, the head of each screw further having a top portion of an essentially spherical shape, the plug further having a bottom surface, the bottom surface having a spherical cavity that is complementary in shape to the spherical shape of the top portion of each screw head.

12. The bone fixing device of claim 5 wherein the elongated through orifice has a length adapted to simultaneously receive at least two bone fastening screws and at least two corresponding plugs.

13. The bone fixing device of claim 5, further comprising:

a stiffness-attenuating material coupled to at least part of the screw head whereby stiffness of assembly between the link member and the bone fastening screw is reduced. wherein the stiffness-attenuating material comprises at least one piece of flexible material interposed and compressed between the screw head and the plug.

14. The bone fixing device of claim 13 wherein the stiffness-attenuating material is comprised of a plurality of flexible materials, each flexible material having different flexibilities so as to enable different degrees of stiffness attenuation between the link member and the bone fastening screw without varying the torque applied to the plug from one flexible material to another flexible material.