Fastener with serrated thread for attachment to a bone plate at a selectable angle

• US 8,518,090 B2
• Filed: 09/27/2011
• Issued: 08/27/2013
• Est. Priority Date: 10/05/2010
• Status: Active Grant

• Current Assignee: Acumed Llc (Berkshire Hathaway Incorporated)
• Original Assignee: Acumed Llc (Berkshire Hathaway Incorporated)
• Inventors: Huebner, Randall J., Van Vleet, David W., Ventura, Rudolph A., Zuba, Jennifer R.
• Primary Examiner(s): Yang, Andrew
• Application Number:
  US13/246,687
• Publication Number:
  US 20120083847A1
• Time in Patent Office: 700 Days
• Field of Search: 606/289, 606/291
• US Class Current: 606/291
• 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 17/863 with thread interrupted or changing its form along shank, other than constant taper

Abstract

Bone plate system, including methods and apparatus, for attaching a fastener to a bone plate at a selectable angle. In an exemplary method, a bone plate and a fastener may be selected. The bone plate may define an aperture having an internal thread. The fastener may include a proximal region and a distal region. The proximal region may be tapered conically toward the distal region. The fastener may be disposed in the aperture and in bone, such that the serrated thread is cross-threaded with the internal thread to create an interference fit and locked engagement of the proximal region with the aperture.

Claims

1. A method of attaching a fastener to a bone plate, comprising:

selecting (i) a bone plate defining an aperture having an internal thread and (ii) a fastener defining a long axis and including a proximal region and a distal region, the proximal region having a conical portion with an angle of taper toward the distal region of about one to five degrees with respect to the long axis, the conical portion including a thread having a serrated portion; and

disposing the fastener in the aperture and in bone, such that the thread of the conical portion is cross-threaded with the internal thread to attach the proximal region to the aperture.

2. The method of claim 1, wherein the thread of the conical portion is configured to provide threaded engagement with the internal thread without cross-threading, if the fastener is arranged coaxially with the aperture.

3. The method of claim 1, wherein the serrated portion forms a plurality of teeth, wherein each tooth has a top where a height of the tooth is at a maximum for such tooth, and wherein the tops of all of the teeth of the serrated portion collectively represent less than one-half of a total length of the serrated portion as measured along a path followed by the serrated portion around the long axis.

4. The method of claim 1, wherein the serrated portion forms a plurality of teeth, wherein each tooth has a top where a height of the tooth is at a maximum for such tooth, and wherein the serrated portion includes a plurality of notches with each notch disposed between an adjacent pair of tops of the teeth.

5. The method of claim 4, wherein each notch has an arcuate profile.

6. The method of claim 1, wherein a height of the serrated portion progressively decreases and increases multiple times in alternation along each complete winding of the serrated portion around the long axis.

7. The method of claim 1, wherein the distal region includes a thread, and wherein the step of disposing includes a step of disposing the thread of the distal region in threaded engagement with the bone.

8. The method of claim 7, wherein the thread of the distal region and the thread of the conical portion follow different parts of a same helical path.

9. The method of claim 7, wherein the thread of the distal region and the thread of the conical portion have a same pitch.

10. The method of claim 7, wherein the thread of the distal region is not serrated substantially.

11. The method of claim 1, wherein a region of the aperture that includes the internal thread has a smaller angle of taper, if any, than the conical portion of the fastener, and wherein the step of disposing includes a step of wedging the conical portion into the region of the aperture as the fastener is turned.

12. The method of claim 1, wherein a height of the serrated portion varies continuously along at least a majority of a total length of the serrated portion as measured along a path followed by the serrated portion around the long axis.

13. A method of attaching a fastener to a bone plate, comprising:

selecting a bone plate defining an aperture having a region that includes an internal thread;

selecting a fastener including a proximal region and a distal region, the proximal region having a conical portion, the conical portion being tapered toward the distal region with a larger angle of taper than the region of the aperture and including a first thread having a serrated portion, the first thread of the conical portion being configured to be disposed in threaded engagement with the internal thread of the aperture without cross-threading, if the fastener and the aperture are coaxial to each other, the distal region being cylindrical and including a second thread; and

disposing the fastener in the aperture and in bone, such that the proximal region is wedged into the region of the aperture and the first thread is cross-threaded with the internal thread, to attach the proximal region to the aperture.

14. The method of claim 13, wherein the conical portion forms an angle of taper of about one to five degrees with respect to a long axis defined by the fastener.

15. The method of claim 14, wherein the conical portion forms an angle of taper of about two to four degrees with respect to the long axis.

16. The method of claim 13, wherein the serrated portion defines a plurality of arcuate notches that form teeth among the notches.

17. The method of claim 13, wherein the region of the aperture is not tapered.

18. The method of claim 13, wherein the first thread is continuous with the second thread.

19. The method of claim 13, wherein the serrated portion includes a plurality of teeth, and wherein the step of disposing deforms one or more of the teeth.

20. A system for bone fixation, comprising:

a bone plate defining an aperture having an internal thread; and

a fastener defining a long axis and including a proximal region and a distal region, the proximal region having a conical portion with an angle of taper toward the distal region of about one to five degrees with respect to the long axis, the conical portion including a thread having a serrated portion, the fastener being insertable into the aperture in a coaxial arrangement with the aperture to achieve threaded engagement of the thread of the conical portion with the internal thread without cross-threading and being insertable in a skewed arrangement to attach the proximal region to the aperture by cross-threading the thread of the conical portion and the internal thread.

21. A method of attaching a fastener to a bone plate, comprising:

selecting (i) a bone plate defining an aperture having an internal thread and (ii) a fastener defining a long axis and including a proximal region and a distal region, the proximal region being conical with an angle of taper toward the distal region of about one to five degrees with respect to the long axis and including a serrated thread; and

disposing the fastener in the aperture and in bone, such that the serrated thread is cross-threaded with the internal thread to create an interference fit and locked engagement of the proximal region with the aperture,

wherein the serrated thread of the fastener selected forms a plurality of teeth, wherein each tooth has a top where a height of the tooth is at a maximum for such tooth, and wherein the tops of all of the teeth of the serrated thread collectively represent less than one-half of a total length of the serrated thread as measured along a path followed by the serrated thread around the long axis.

22. A method of attaching a fastener to a bone plate, comprising:

selecting (i) a bone plate defining an aperture having an internal thread and (ii) a fastener defining a long axis and including a proximal region and a distal region, the proximal region being conical with an angle of taper toward the distal region of about one to five degrees with respect to the long axis and including a serrated thread; and

disposing the fastener in the aperture and in bone, such that the serrated thread is cross-threaded with the internal thread to create an interference fit and locked engagement of the proximal region with the aperture,

wherein the serrated thread of the fastener selected forms a plurality of teeth, wherein each tooth has a top where a height of the tooth is at a maximum for such tooth, and wherein the serrated thread includes a plurality of notches with each notch disposed between an adjacent pair of tops of the teeth.

23. A method of attaching a fastener to a bone plate, comprising:

selecting (i) a bone plate defining an aperture having an internal thread and (ii) a fastener defining a long axis and including a proximal region and a distal region, the proximal region being conical with an angle of taper toward the distal region of about one to five degrees with respect to the long axis and including a serrated thread; and

disposing the fastener in the aperture and in bone, such that the serrated thread is cross-threaded with the internal thread to create an interference fit and locked engagement of the proximal region with the aperture,

wherein a height of the serrated thread of the fastener selected progressively decreases and increases multiple times in alternation along each complete winding of the serrated thread around the long axis.

24. A method of attaching a fastener to a bone plate, comprising:

selecting (i) a bone plate defining an aperture having an internal thread and (ii) a fastener defining a long axis and including a proximal region and a distal region, the proximal region being conical with an angle of taper toward the distal region of about one to five degrees with respect to the long axis and including a serrated thread; and

disposing the fastener in the aperture and in bone, such that the serrated thread is cross-threaded with the internal thread to create an interference fit and locked engagement of the proximal region with the aperture,

wherein a height of the serrated thread of the fastener selected varies continuously along at least a majority of a total length of the serrated thread as measured along a path followed by the serrated thread around the long axis.