Patent US5417533A successfully refreshed from Google Patents.
US5417533A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bone screw with improved threads
Assignee: National Medical Specialty Inc
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Filing: 1990-07-13
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Granted: 1995-05-23
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Expires: 2010-07-13
Abstract
Abstract A bone screw having a helical thread that gradually increases in thickness from the tip to the head of the screw. The thin thread at the tip of the screw can be inserted into a bone with minimal tearing or cracking of the bone. The thicker treads ascending from the tip to the head of the screw displaces bone against the superior (top) thread surfaces. This displacement of bone increases the screw's resistance to being pulled-out of the bone. The thicker core just below the screw head increases the screw's ability to withstand compressive and distractive loads. The core is thickest just below the head because it is at that point on the screw that the fulcrum loads are greatest.
Inventors
- 👤 Jeffrey Lasner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:52
CPC Classifications
A; A61; A61B; A61B17/00; A61B17/56; A61B17/58; A61B17/68; A61B17/84; A61B17/86; A61B17/8625; A61B17/863
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
75 words
A screw comprising: a conical core having a tip at one end and a head at the other end wherein the tip has a diameter narrower than the head, and a thread helix attached to said core and curling around an axis of said core, the thickness of said thread increasing in the direction from the tip to the head of said screw, the thread having a sharp apex and a substantially constant outside diameter.
Claim 2
Dependent Claim
75 words
A screw comprising: a conical core having a tip at one end and a head at the other end wherein the tip has a diameter narrower than the head, and a thread helix attached to said core and curling around an axis of said core, the thickness of said thread increasing in the direction from the tip to the head of said screw, the thread having a sharp apex and a substantially constant outside diameter.
Claim 3
Dependent Claim
21 words
A screw as in claim 1 wherein said thread has inferior and superior surfaces that intersect to form the sharp apex.
Claim 4
Dependent Claim
21 words
A screw as in claim 1 wherein the thickness of said thread is measured where the thread attaches to the core.
Claim 5
Dependent Claim
11 words
A screw as in claim 1 wherein the tip is tapered.
Claim 6
Dependent Claim
22 words
A screw as in claim 1 wherein the head includes an opening having an axis perpendicular to the axis of the core.
Claim 7
Dependent Claim
12 words
A screw as in claim 1 adapted to attach to a bone.
Claim 8
Dependent Claim
79 words
A bone screw comprising: a conical core having a narrow tip and head at an end opposite to said tip, wherein the core has a diameter that gradually and substantially uniformly increases from the tip to the head; a helical thread extending radially outward from said core, said thread having superior and inferior thread surfaces intersecting to form a helical thread apex, wherein the apex is sharp and the apex defines a substantially uniform outside diameter of the thread.
Claim 9
Dependent Claim
79 words
A bone screw comprising: a conical core having a narrow tip and head at an end opposite to said tip, wherein the core has a diameter that gradually and substantially uniformly increases from the tip to the head; a helical thread extending radially outward from said core, said thread having superior and inferior thread surfaces intersecting to form a helical thread apex, wherein the apex is sharp and the apex defines a substantially uniform outside diameter of the thread.
Claim 10
Dependent Claim
12 words
A bone screw as in claim 7 wherein said tip is tapered.
Claim 11
Dependent Claim
37 words
A bone screw as in claim 7 wherein the thread has a thickness at a location where the thread attaches to the core, and the thickness gradually increases from the tip to the head of the core.
Claim 12
Dependent Claim
20 words
A bone screw as in claim 7 wherein the head includes an opening having an axis perpendicular to said core.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-05-22 | 1998-11-21 | 1999-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-05-22 | 2002-11-21 | 2003-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-22 | 2006-11-21 | 2007-05-23 | $7700.00 | Window Closed / Lapsed |