Locking plate and bone screw

• US 5,601,553 A
• Filed: 10/03/1994
• Issued: 02/11/1997
• Est. Priority Date: 10/03/1994
• Status: Expired due to Term

• Current Assignee: Synthes USA LLC (Johnson & Johnson)
• Original Assignee: Synthes USA LLC (Johnson & Johnson)
• Inventors: Thalgott, John, Trebing, Linda
• Primary Examiner(s): Buiz, Michael Powell
• Assistant Examiner(s): LEONARDO, MARK
• Application Number:
  US08/317,246
• Time in Patent Office: 862 Days
• Field of Search: 606/60, 606/61, 606/69, 606/70, 606/71, 606/72, 606/73, 411/412, 411/413, 411/414, 411/386, 411/399
• US Class Current: 606/86.00B
• CPC Class Codes: A61B 17/15 Guides therefor arrangements for guiding straight saw blades in general B23D51/025
• CPC Class Codes: A61B 17/1728 for holes for bone plates or plate screws
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 17/7059 Cortical plates A61B17/7007, A61B17/7058 take precedence
• CPC Class Codes: A61B 17/8004 with means for distracting or compressing the bone or bones
• CPC Class Codes: A61B 17/8057 the interlocking form comprising a thread
• CPC Class Codes: A61B 17/8061 specially adapted for particular bones A61B17/70 and A61B17/74 take precedence
• CPC Class Codes: A61B 17/8605 Heads, i.e. proximal ends projecting from bone
• CPC Class Codes: A61B 17/863 with thread interrupted or changing its form along shank, other than constant taper

Abstract

A bone plate for stabilizing the anterior column of the spine has a lower curved surface and an upper surface having two intersecting planes in each of which is a screw hole, the axes of the holes being skewed relative to one another. A bone screw used to secure the plate, has a single start buttress thread near the tip and a two start machine thread near the head, the threads being continuous and of constant pitch.

Claims

1. A bone plate comprising an upper surface and a lower surface for application to a bone, the lower surface being curved to conform to a cylindrical bone and the upper surface having two flat intersecting planes, a first screw hole having an axis normal to one of said intersecting planes and a second screw hole having an axis normal to the other intersecting plane, said planes providing directional guides for insertion of screws in said holes.

2. The bone plate claimed in claim 1 and having a third screw hole which is unthreaded and furnished with a camming surface.

6. The bone plate claimed in claim 1 wherein said screw holes are threaded to receive locking screws, said plate comprising at least one additional hole, unthreaded, to receive a temporary anchoring screw.

7. The bone plate claimed in claim 6, said plate having an anterior edge and a posterior edge, said anterior edge having a notch for receiving a manipulation instrument.

8. The bone plate claimed in claim 7 wherein said posterior edge is concave and extends in a continuous uninterrupted curve.

12. The screw claimed in claim 8 and having cutting plates adjacent said tip.

3. A bone plate for stabilizing the anterior column of the spine comprising an elongated body of physiologically acceptable metals having a longitudinal axis having a bottom surface curved about its longitudinal axis and having an anterior edge and a posterior edge extending generally parallel to the longitudinal axis, said anterior edge having a notch and screw holes at the ends of said notch, the posterior edge being concave and extending in a continuous uninterrupted curve in a plane containing the longitudinal axis, there being screw holes at the ends of said posterior edge.

4. The bone plate claimed in claim 3, said screw holes being threaded.

5. The bone plate claimed in claim 4 and comprising a plurality of unthreaded screw holes.

9. A bone plate comprising an upper surface and a lower surface, the lower surface being curved for application to a bone and the upper surface having two flat intersecting planes, in combination with at least one screw hole in each of the planes of said upper surface, said screw holes having axes which are skewed with respect to one another and in separate planes, each axis being normal to the plane of the surface on which it is situated, the planes providing a directional guide for insertion of screws into said screw holes.

10. The bone plate claimed in claim 9 and also including a plurality of elongated screw holes having camming surfaces.

11. A bone screw comprising a shaft, a head and an unthreaded pointed tip, said shaft having an upper section adjacent the head and a lower cylindrical section adjacent the tip, the lower section having a first unthreaded part next to the tip and a second part having a single start buttress thread, and the upper section having a two-start machine screw thread, the threads taken as a whole being of constant pitch and the lead being continuous over both threads, the minor diameter of said machine screw thread being greater than the minor diameter of said buttress thread.

13. An orthopaedic fixation system for use in spinal surgery comprising a bone plate having a plurality of threaded screw holes for receiving locking screws and a plurality of locking screws, each of said screws having a section of single start buttress threads and a section of two-start machine threads the lead being continuous over said two sections.

14. The orthopaedic fixation system claimed in claim 13 wherein the major diameter of the buttress thread is greater than the minor diameter of the thread in the threaded screw holes.

15. An orthopedic fixation system for use in spinal surgery comprising a bone plate having a lower surface for application to the spinal column, an upper surface having two flat intersecting planes and a threaded screw hole in each of said planes, each of said screw holes having an axis normal to the plane on which it is situated, in combination with a screw for each of said screw holes, each of said screws having a buttress thread for engagement with cancellous bone and a machine screw thread for engagement with said screw holes and cortical bone, the planes providing a directional guide for insertion of screws into said screw holes.

16. A method for applying a bone plate having a threaded screw hole and an unthreaded screw hole to a bone which comprises positioning said plate adjacent the bone surface, then inserting a bone screw through said unthreaded screw hole into the bone temporarily to fix said plate to the bone and then securing the plate to the bone by inserting a screw through the threaded screw hole in engagement with the threads in said hole and into engagement with said bone.