Bone screw
First Claim
1. A bone screw having a central axis and including a head, a front portion having a thread and tapering toward a tip, and a central portion, wherein at least a section of the central portion comprises:
- a contiguous thread with a substantially constant throughout said at least a section of the central portion outside diameter; and
M segments having a body widening toward the head and N segments having a circular-cylindrical cross-section, wherein M≧
1 and N≧
2, with M and N integral numbers larger than 0 and differing at most by a magnitude of 1, and the M and N segments mutually alternate.
2 Assignments
0 Petitions
Accused Products
Abstract
The central portion of the screw according to the invention has a series of segments varying in diameter, typically having a segment located near the screw head with a large diameter, a segment located near the front portion with a small diameter, and intermediate segments tapering in the direction of the segment with the small diameter. A continuous thread extends along the central portion from the screw head to the screw tip where the thread has a substantially uniform outside diameter along the entire length of the central portion. The screw, which is particularly well-suited as a pedicle screw, has improved resistance to tearing, cutting and bending, and, largely independent of bone quality, good hold in bone.
637 Citations
34 Claims
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1. A bone screw having a central axis and including a head, a front portion having a thread and tapering toward a tip, and a central portion, wherein at least a section of the central portion comprises:
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a contiguous thread with a substantially constant throughout said at least a section of the central portion outside diameter; and
M segments having a body widening toward the head and N segments having a circular-cylindrical cross-section, wherein M≧
1 and N≧
2, with M and N integral numbers larger than 0 and differing at most by a magnitude of 1, and the M and N segments mutually alternate.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A bone screw comprising:
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a screw head;
a front portion tapering towards a tip; and
a central portion disposed between the head and the front portion, at least a section of the central portion including a substantially contiguous thread defining a thread inner diameter and a thread outer diameter;
wherein the thread outer diameter is substantially constant, and the thread inner diameter varies along the at least a section the central portion. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A bone screw comprising:
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a screw head having a substantially frusto-spherical shape;
a front portion tapering toward a tip; and
a central portion disposed between the head and the front portion, wherein at least a section of the central portion includes a substantially contiguous thread defining a thread inner diameter and a thread outer diameter, and the thread inner diameter varies along the at least a section, and wherein the thread outer diameter is substantially constant along the at least a section of the central portion. - View Dependent Claims (32, 33, 34)
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Specification