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US 5,871,486 AGranted
Variable pitch bone screw
AssigneeAcumed LLC
InventorsRandall J. Huebner, Gene L. Conrad, David G. Jensen
Life of this patent
Estimating the term…
Abstract
A bone screw having a continuously varying pitch includes a tapered root portion having a relatively small diameter on a leading end of the screw and a larger trailing diameter. The pitch of the screw decreases between the leading and trailing ends thus causing the bone fragments in a fracture to be drawn together when the screw is installed across the fragments. The radially outer diameter of the threads increases between the leading and trailing ends thus causing each successive thread portion to cut into bone radially outwardly from the preceding thread portion thereby providing uncut bone in which the succeeding threads can gain purchase.
Claims83
A screw comprising:
- an elongate root portion having a leading end, a trailing end and a longitudinal axis extending between the leading and trailing ends;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end, and where the screw thread is the only portion of the screw having a radius larger than the maximum radius of the root portion;
- and
- a crest formed on said screw tread, the crest having a radius measured from the longitudinal axis of the root portion which is smaller near the leading end of the root portion and larger near the trailing end of the root portion, where the radial distance between the root portion and the crest is larger near the leading end, where the radius of the crest is smaller, than it is near the trailing end, where the crest radius is larger, and where the pitch of the screw thread measured between corresponding points on consecutive thread crests is larger near the leading end and smaller near the trailing end, wherein the screw is formed of a biocompatible material.
1 more element
A screw comprising:
- an elongate root portion having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end, where the radius of the root portion tapers from a larger diameter near the trailing end to a smaller diameter near the leading end, where the length of the root portion is at least several times the diameter of the root portion;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion which is smaller near the leading end of the root portion and larger near the trailing end of the root portion, where the pitch of the screw thread measured between corresponding points on consecutive thread crests is larger near the leading end and smaller near the trailing end and the pitch changes continuously over the majority of the screw thread and the maximum radius of the crest is at least equal to the largest radius of any portion of the screw, wherein the screw is formed of a biocompatible material.
1 more element
A screw comprising:
- an elongate root portion having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end;
- a screw tread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion which is smaller near the leading end of the root portion and larger near the trailing end of the root portion, where the radial distance between the root portion and the crest increases from the trailing end to the leading end, and where the pitch of the screw thread measured between corresponding points on consecutive thread crests is larger near the leading end and smaller near the trailing end and, at least along part of the length of the root portion, the pitch gradually increases as the crest radius gradually decreases, and the crest radius decreases continuously over the majority of the screw thread, wherein the screw is formed of a biocompatible material.
1 more element
A screw comprising:
- a drive end including a drive socket;
- a stabilizing hole extending axially forward from the drive socket at least part way through the screw toward a tip end of the screw disposed opposite the drive end;
- an elongate root portion disposed between the drive end and the tip end and having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion which is smaller near the leading end of the root portion and larger near the trailing end of the root portion, where the radial distance between the root portion and the crest is at least as large near the leading end, where the radius of the crest is smaller, as it is near the trailing end, where the crest radius is larger, and where the pitch of the screw thread measured between corresponding points on consecutive thread crests is larger near the leading end and smaller near the trailing end, the screw being sized for orthopedic use.
3 more elements
A screw comprising:
- an elongate root portion having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion which is smaller near the leading end of the root portion and larger near the trailing end of the root portion, where the maximum radius of the crest is at least as large as the maximum radius of any portion of the screw, and the screw thread having a thread depth measured as the radial distance between the thread crest and the root portion with the thread depth near the leading end being larger than the change in crest radius from near the leading end to near the trailing end, and where the pitch of the screw thread measured between corresponding points on consecutive thread crests is larger near the leading end and smaller near the trailing end and changes substantially continuously over at least a region of the root portion including the central portion of the root portion, the crest further having a diameter equal to twice the radius, with the length of the root portion being substantially greater than the diameter of the crest, wherein the screw is formed of a biocompatible material.
1 more element
A screw comprising:
- an elongate root portion having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end, where the root portion tapers from a larger diameter near the trailing end to a smaller diameter near the leading end, where the length of the root portion is at least several times the diameter of the root portion;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion with the crest radius gradually tapering over the majority of the root portion from a larger value near the trailing end to a smaller value near the leading end and where the pitch of the screw thread measured between corresponding points on consecutive thread crests is larger near the leading end and smaller near the trailing end, the screw being sized for orthopedic use.
1 more element
A screw comprising:
- an elongate root portion having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion and the screw thread having a pitch measured between corresponding points on consecutive thread crests and a thread depth measured as the radial distance between the thread crest and the root portion, where the radius of the crest tapers gradually from a smaller radius near the leading end to a larger radius near the trailing end, the pitch changes gradually from a greater pitch near the leading end to a lesser pitch near the trailing end, the gradual change in radius of the crest being balanced with the gradual change in pitch between the leading end and trailing end so that, as the screw is screwed into a hole and succeeding screw threads cross-thread with tracks in the hole cut by preceding screw threads, the crest radius increases sufficiently so that the succeeding screw threads engage the hole radially outwardly from the tracks cut by the preceding screw threads with the thread depth near the leading end being sufficient to maintain a grip on the surrounding hole comparable to the grip of the threads near the trailing end, the crest further having a diameter equal to twice the radius, with the length of the root portion being substantially greater than the diameter of the crest, wherein the screw is formed of a biocompatible material.
1 more element
A screw comprising:
- a drive end including a drive socket;
- a stabilizing hole extending axially forward from the drive socket at least part way through the screw toward a tip end of the screw disposed opposite the drive end;
- an elongate root portion disposed between the drive end and the tip end and having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion which is smaller near the leading end of the root portion and larger near the trailing end of the root portion, with the radial distance between the root portion and the crest near the leading end being larger than the change in crest radius from near the leading end to near the trailing end, and where the pitch of the screw thread measured between corresponding points on consecutive thread crests is larger near the leading end and smaller near the trailing end, wherein the screw is formed of a biocompatible material.
3 more elements
A screw comprising:
- a single threaded region with a leading end, a trailing end and a longitudinal axis extending therebetween, the threaded region including a root portion extending between the leading end and trailing end;
- a screw thread formed on the root portion within the threaded region, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the threaded region, the crest radius gradually tapering over the majority of the threaded region from a larger value near the trailing end to a smaller value near the leading end, and the screw thread having a pitch measured between corresponding points on consecutive thread crests which is larger near the leading end and smaller near the trailing end and a thread depth measured as the distance between the thread crest and the root portion in a direction radial to the longitudinal axis of the threaded region, the thread depth near the leading end being larger than the change in crest radius from near the leading end to near the trailing end, the crest further having a diameter equal to twice the radius, with the length of the root portion being substantially greater than the diameter of the crests the screw being sized for orthopedic use.
1 more element
A screw comprising:
- a single threaded region with a leading end, a trailing end and a longitudinal axis extending therebetween, the threaded region including a root portion extending between the leading end and trailing end;
- a screw thread formed on the root portion within the threaded region, the screw thread extending from the leading end to the trailing end, and where the screw thread is the only portion of the screw having a radius larger than the maximum radius of the root portion;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the threaded region, the crest radius being larger near the trailing end and smaller near the leading end, and the screw thread having a pitch measured between corresponding points on consecutive thread crests, where the pitch decreases substantially continuously over the majority of the threaded region from a larger value near the leading end to a smaller value near the trailing end, the crest further having a diameter equal to twice the radius, with the length of the root portion being substantially greater than the diameter of the crest wherein the screw is formed of a biocompatible material.
1 more element
A screw comprising:
- a single threaded region with a leading end, a trailing end and a longitudinal axis extending therebetween, the threaded region including a root portion extending between the leading end and trailing end;
- a screw thread formed on the root portion within the threaded region, the screw thread extending from the leading end to the trailing end, and where the screw thread is the only portion of the screw having a radius larger than the maximum radius of the root portion;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the threaded region, the crest radius tapering gradually over the majority of the threaded region between a larger value near the trailing end and smaller value near the leading end, and the screw read having a pitch measured between corresponding points on consecutive thread crests which is larger near the leading end and smaller near the trailing end, the crest further having a diameter equal to twice the radius, with the length of the root portion being substantially greater than the diameter of the crest, the screw being sized for orthopedic use.
1 more element
A screw comprising:
- a single threaded region with a leading end, a trailing end and a longitudinal axis extending therebetween, the threaded region including a root portion extending between the leading end and trailing end;
- a screw thread formed on the root portion within the threaded region, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the threaded region, the crest radius having a larger value near the trailing end and smaller value near the leading end, and the screw thread having a pitch measured between corresponding points on consecutive thread crests which is larger near the leading end and smaller near the trailing end and, at least along part of the length of the threaded region, the pitch gradually increases as the crest radius gradually decreases, the screw thread further having a thread depth measured as the radial distance between the thread crest and the root portion, the thread depth near the leading end being at least substantially as large as the radius of the root portion near the leading end, wherein the screw is formed of a biocompatible material.
1 more element
A screw comprising:
- a single threaded region with a leading end, a trailing end and a longitudinal axis extending therebetween, the threaded region including a root portion extending between the leading end and trailing end;
- a screw thread formed on the root portion within the threaded region, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the threaded region, the crest radius having a larger value near the trailing end and smaller value near the leading end and the maximum radius of the crest being at least equal to the largest radius of any portion of the screw, and the screw thread having a pitch measured between corresponding points on consecutive thread crests which is larger near the leading end and smaller near the trailing end, the screw thread further having a thread depth measured as the radial distance between the thread crest and the root portion, the thread depth near the leading end being at least substantially as large as the radius of the root portion near the leading end, the screw being sized for orthopedic use.
1 more element
A screw comprising:
- a drive end including a drive socket;
- a stabilizing hole extending axially forward from the drive socket at least part way through the screw toward a tip end of the screw disposed opposite the drive end;
- a single threaded region disposed between the drive end and the tip end and having a leading end, a trailing end and a longitudinal axis extending therebetween, the threaded region including a root portion extending between the leading end and trailing end of the threaded region;
- a screw thread formed on the root portion within the threaded region, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the threaded region, the crest radius having a larger value near the trailing end and smaller value near the leading end, and the screw thread having a pitch measured between corresponding points on consecutive thread crests which is larger near the leading end and smaller near the trailing end, the screw thread further having a thread depth measured as the radial distance between the thread crest and the root portion, the thread depth near the leading end being at least substantially as large as the radius of the root portion near the leading end, the screw being sized for orthopedic use.
3 more elements
A screw comprising:
- a drive end including a drive socket;
- a stabilizing hole extending axially forward from the drive socket at least part way through the screw toward a tip end of the screw disposed opposite the drive end;
- an elongate root portion disposed between the drive end and the tip end and having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion, the crest radius gradually tapering over the majority of the threaded region from a larger value near the trailing end to a smaller value near the leading end, and where the pitch of the screw thread measured between corresponding points on consecutive thread crests is larger near the leading end and smaller near the trailing end the screw being sized for orthopedic use.
3 more elements
A screw comprising:
- a drive end including a drive socket;
- a stabilizing hole extending axially forward from the drive socket at least part way through the screw toward a tip end of the screw disposed opposite the drive end;
- an elongate root portion disposed between the drive end and the tip end and having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion which is smaller near the leading end of the root portion and larger near the trailing end of the root portion, and where the pitch of the screw thread measured between corresponding points on consecutive thread crests decreases substantially continuously over the majority of the threaded region from a larger value near the leading end to a smaller value near the trailing end the screw being sized for orthopedic use.
3 more elements
A screw comprising:
- an elongate root portion having a leading end, a trailing end and a longitudinal axis extending between the leading and trailing ends, where the root portion tapers from a larger diameter near the trailing end to a smaller diameter near the leading end, where the length of the root portion is at least several times the diameter of the root portion;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion which is smaller near the leading end of the root portion and larger near the trailing end of the root portion, and where the pitch of the screw thread measured between corresponding points on consecutive thread crests decreases substantially continuously over the majority of the threaded region from a larger value near the leading end to a smaller value near the trailing end, where, at least along part of the length of the threaded region, the pitch gradually increases as the crest radius gradually decreases, wherein the screw is formed of a biocompatible material.
1 more element
A screw comprising:
- an elongate root portion having a leading end, a trailing end and a longitudinal axis extending between the leading end and trailing end, where the root portion tapers from a larger radius near the trailing end to a smaller radius near the leading end;
- a screw thread formed on the root portion, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the root portion, the crest radius gradually tapering over the majority of the threaded region from a larger value near the trailing end to a smaller value near the leading end, and where the pitch of the screw thread measured between corresponding points on consecutive thread crests decreases substantially continuously over the majority of the threaded region from a larger value near the leading end to a smaller value near the trailing end, the crest further having a diameter equal to twice the radius, with the length of the root portion being substantially greater than the diameter of the crest, wherein the screw is formed of a biocompatible material.
1 more element
A screw comprising:
- a single threaded region with a leading end, a trailing end and a longitudinal axis extending therebetween, the threaded region including a root portion extending between the leading end and trailing end;
- a screw thread formed on the root portion within the threaded region, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the threaded region, the crest radius having a larger value near the trailing end and smaller value near the leading end, and the screw thread having a pitch measured between corresponding points on consecutive thread crests which is larger near the leading end and smaller near the trailing end and, at least along part of the length of the threaded region, the pitch gradually increases as the crest radius gradually decreases, the screw thread further having a thread depth measured as the radial distance between the thread crest and the root portion, the thread depth near the leading end being larger than the change in crest radius from near the leading end to near the trailing end and larger than the thread depth near the trailing end, the screw being sized for orthopedic use.
1 more element
A bare screw comprising:
- a single threaded region with a leading end, a trailing end and a longitudinal axis extending therebetween, the threaded region including a root portion extending between the leading end and trailing end;
- a screw thread formed on the root portion within the threaded region, the screw thread extending from the leading end to the trailing end;
- and
- a crest formed on said screw thread, the crest having a radius measured from the longitudinal axis of the threaded region, the crest radius having a larger value near the tailing end and smaller value near the leading end, and the screw thread having a pitch measured between corresponding points on consecutive thread crests which is larger near the leading end and smaller near the trailing end and, at least along part of the length of the threaded region, the pitch gradually increases as the crest radius gradually decreases, the screw thread further having a thread depth measured as the radial distance between the thread crest and the root portion, where the thread depth is larger near the leading end, where the radius of the crest is smaller, than it is near the trailing end, where the crest radius is larger, the screw being sized for orthopedic use.
1 more element
Dependencies are inferred from the claim text.