Allograft bone fixation screw method and apparatus
First Claim
1. A bone screw comprising a shank with a threaded portion and an unthreaded portion which tapers outwardly adjacent an integrally formed drive head to form a tapered undercut for the drive head, said tapered undercut being funnel shaped and tapered at an angle ranging from 10°
- to 45°
from the center axis of the shank and has its greatest diameter adjacent said drive head, said drive head being substantially wedge shaped.
1 Assignment
0 Petitions
Accused Products
Abstract
A combination driver and bone screw assembly comprising a screw shank with a uniform diameter threaded portion, an unthreaded portion with a outwardly tapered end and a driving end portion of substantially wedge shaped configuration which can be engagably seated in a wedge shaped notch seat of a driver member. The driver member comprises a body, a drive head defining a wedge shaped notch seat secured to the body forming a shoulder and a drive collar mounted around the drive head and seated on the shoulder.
In operation a bore is drilled in the patients bone with the top portion of the bore having a tapered geometry which widens from the diameter of the bore. The bone screw driving end portion is placed in the wedge shaped notch seat of a driver member and a drive collar is mounted around the driver drive head and engages the shoulder. The driver member is rotated driving the bone screw into the previously cut bore in the patients bone until the tapered surface of the bore engages the tapered undercut surface of the screw.
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Citations
38 Claims
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1. A bone screw comprising a shank with a threaded portion and an unthreaded portion which tapers outwardly adjacent an integrally formed drive head to form a tapered undercut for the drive head, said tapered undercut being funnel shaped and tapered at an angle ranging from 10°
- to 45°
from the center axis of the shank and has its greatest diameter adjacent said drive head, said drive head being substantially wedge shaped. - View Dependent Claims (2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 32)
- to 45°
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3. A bone screw constructed of allograft bone comprising a shank with a threaded portion and an unthreaded portion which tapers outwardly adjacent an integrally formed drive head to form a tapered undercut for the drive head, said tapered undercut being funnel shaped and tapered at an angle ranging from 10°
- to 45°
from the center axis of the shank and has its greatest diameter adjacent said drive head, said drive head being provided with at least two flat surfaces adapted to engage a driving tool and receive torque from said driving tool. - View Dependent Claims (19, 20, 21, 22)
- to 45°
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23. A bone screw constructed of allograft bone comprising:
- a shank with a portion provided with a thread of a given pitch running along a portion of its length and terminating in a conical end;
an unthreaded portion of said shank is formed with an outwardly flaring section having a diameter which is greater than the diameter of said threaded portion, said outwardly flaring section being located adjacent to and integrally formed with a screw head having a wedge shape configuration with angular inclined planes. - View Dependent Claims (24, 25, 26, 27, 28)
- a shank with a portion provided with a thread of a given pitch running along a portion of its length and terminating in a conical end;
- 29. A bone screw constructed of allograft bone comprising a shank with a substantially uniform diameter threaded portion having a distal pointed end and an unthreaded portion adjacent said threaded portion, said unthreaded portion defining an outwardly tapered end with a male wedge shaped driving head defining inclined planes, said bone screw having a shear stress in relation to torque calculated by the formula Tmax =1.57 r3 tmax with said unthreaded outwardly tapered end forming a tapered undercut for said male wedge shaped driving head at an angle less than the angle formed by the inclined planes of said driving head.
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33. A bone screw comprising a shank with a threaded portion and an unthreaded portion which tapers outwardly adjacent an integrally formed drive head to form a tapered undercut for the drive head, said screw being threaded about 1/2 the length of its shank and ranging in length from 1 to 1.25 inches, said drive head being substantially wedge shaped.
- 34. A bone screw constructed of allograft bone comprising a shank with a threaded portion and an unthreaded portion which tapers outwardly adjacent an integrally formed drive head to form a tapered undercut for the drive head, said drive head being substantially wedge shaped, said wedge shaped drive head having a shear stress in relation to torque determined by the formula Tmax =1.57 r3 tmax.
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36. A bone screw constructed of allograft bone comprising a shank with a threaded portion and an unthreaded portion which tapers outwardly adjacent an integrally formed drive head to form a tapered undercut for the drive head, said tapered undercut having a cross sectional area taken transverse a central axis of said screw across its distal end which is greater than a cross sectional area taken transverse to a central axis of said screw across the unthreaded portion of the shank, said tapered undercut when extended to intersect a longitudinal center axis of said shank forming an angle ranging from about 20°
- to about 30°
, said drive head being provided with at least two flat surfaces adapted to receive torque from a driver. - View Dependent Claims (37, 38)
- to about 30°
Specification