U.S. patent application number 09/290433 was filed with the patent office on 2001-06-21 for apparatus for rigidly fixing craniomaxillofacial tissue grafts and bone plates.
Invention is credited to BALFOUR, ALAN R., CARCHIDI, JOSEPH EDWARD.
Application Number | 20010004694 09/290433 |
Document ID | / |
Family ID | 26765742 |
Filed Date | 2001-06-21 |
United States Patent
Application |
20010004694 |
Kind Code |
A1 |
CARCHIDI, JOSEPH EDWARD ; et
al. |
June 21, 2001 |
APPARATUS FOR RIGIDLY FIXING CRANIOMAXILLOFACIAL TISSUE GRAFTS AND
BONE PLATES
Abstract
A self-drilling and tapping multi-drive bone screw (10) for
rigid fixation of craniomaxillofacial tissue grafts and bone plates
has a tip (12a) which incorporates a defined twist drill shaft with
a sharp cutting point tip (12b) to easily pierce and drill a pilot
hole and prepare for the insertion of self-tapping screw threads
(12c). A cylindrical dome shaped head (14) for rigid fixation of
craniomaxillofacial tissue grafts and geometrically sized bone
plates is formed on the screw distal to the drilling and tapping
features. A spline feature (14e) is incorporated into the
cylindrically dome shaped head for easy pickup, assembly and
insertion of the bone screw with a corresponding spline driver tool
(20). The spline driver feature also allows the bone screw (10) to
be driven with either a standard square or cross blade driver
tool.
Inventors: |
CARCHIDI, JOSEPH EDWARD;
(WEST BRIDGEWATER, MA) ; BALFOUR, ALAN R.;
(PETALUMA, CA) |
Correspondence
Address: |
JOHN A HAUG
P O BOX 386
WEST HARWICH
MA
02671
|
Family ID: |
26765742 |
Appl. No.: |
09/290433 |
Filed: |
April 13, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60081605 |
Apr 14, 1998 |
|
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Current U.S.
Class: |
606/312 ;
606/104 |
Current CPC
Class: |
A61B 17/888 20130101;
A61F 2/2846 20130101; A61B 17/8635 20130101; A61B 17/8615
20130101 |
Class at
Publication: |
606/73 ;
606/104 |
International
Class: |
A61B 017/58 |
Claims
What is claimed:
1. Apparatus for retention of tissue grafts and bone plates to a
bone site comprising an elongated body member having a generally
cylindrical shaft having a longitudinal axis and a selected
diameter and first and second opposite end portions, a relatively
sharp point formed at the first end portion aligned with the
longitudinal axis, helical drill flutes formed on the shaft along a
first axial length of the shaft having an outer diameter generally
equal to the selected diameter, self-tapping screw threads formed
on the shaft along a second axial length of the shaft, the
self-tapping screw threads having a second outer diameter greater
than the selected diameter, the helical drill flutes aligned with
and forming a continuation of the self-tapping threads along a
first portion of the second axial length forming cutting flutes and
a driving head formed at the second end of the shaft, the driving
head extending radially outwardly beyond the shaft forming an outer
periphery and being formed with a frusto-conical surface extending
from the outer periphery to the shaft and a female driving spline
formed at the second end of the member aligned with the
longitudinal axis of the body member.
2. Apparatus according to claim 1 in which the female driving
spline comprises a polygonal central recess and a radially
extending slot communicating with the central recess.
3. Apparatus according to claim 2 further comprising a circular
bore extending along the longitudinal axis in communication with
the central recess.
4. A driving tool for use with a threaded member having a female
driving spline formed at an end thereof having a central recess
having polygonal sides of a selected number and a radially
extending slot communicating with the central recess and
intersecting at least one of the sides comprising a polygonal
shaped portion having the selected number of sides and having a
size chosen to closely fit within the polygonal recess of the
central recess and a blade portion extending from the polygonal
shaped portion having a configuration chosen to be closely received
in the at least one radially extending slot.
5. A driving tool according to claim 4 in which the female spline
has a cylindrical bore extending along the longitudinal axis in
communication with the central recess and further comprising a
generally cylindrical male holding portion extending along the
longitudinal axis beyond the polygonal shaped portion, the
generally cylindrical male holding portion formed with a friction
holding taper configured to closely fit within the cylindrical bore
of the spline.
6. Apparatus for retention of tissue grafts and bone plates to a
bone site comprising an elongated body member having a generally
cylindrical shaft having a longitudinal axis and a selected
diameter and first and second opposite end portions, a relatively
sharp point formed at the first end portion aligned with the
longitudinal axis, helical drill flutes formed on the shaft along a
first axial length of the shaft having an outer diameter generally
equal to the selected diameter, self-tapping screw threads formed
on the shaft along a second axial length of the shaft, the
self-tapping screw threads having a second outer diameter greater
than the selected diameter, the helical drill flutes aligned with
and forming a continuation of the self-tapping threads along a
first portion of the second axial length forming cutting flutes and
a driving head formed at the second end of the shaft, the driving
head extending radially outwardly beyond the shaft forming an outer
periphery and being formed with a frusto-conical surface extending
from the outer periphery to the shaft and a female driving spline
formed at the second end of the member aligned with the
longitudinal axis of the body member, the female driving spline
having side surfaces forming a polygonally shaped recess, at least
one radially extending blade shaped slot communicating with the
recess, an elongated tool member having a polygonal shaped portion
having the selected number of sides and having a size chosen to
closely fit within the polygonal recess of the central recess and a
blade portion extending from the polygonal shaped portion having a
configuration chosen to be closely received in the at least one
radially extending slot.
7. Apparatus according to claim 6 in which the female spline has a
cylindrical bore extending along the longitudinal axis in
communication with the central recess and the elongated tool member
has a generally cylindrical male holding portion extending along
the longitudinal axis beyond the polygonal shaped portion, the
generally cylindrical male holding portion formed with a friction
holding taper configured to closely fit within the cylindrical bore
of the spline.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to surgical apparatus and
more particularly to bone screws for the retention of tissue grafts
and bone plates.
BACKGROUND OF THE INVENTION
[0002] Presently, a variety of bone screws and surgical procedures
are used for the retention of craniomaxillofacial tissue grafts and
bone plates with a primary objective being to minimize the surgical
steps and to maximize fixation. These procedures generally fall
into one of two categories: a self-threading screw that
incorporates a self-cutting flute to minimize the need to
surgically prepare a pilot hole or a self-threading screw without a
self-starting cutting flute which always requires a surgically
prepared pilot hole.
[0003] For the latter type, the physician must perform multiple
operations which involves first locating and drilling a pre-sized
hole. Once the pilot hole is prepared, the physician must relocate
the hole to insert the self-threading bone screw. Since most of the
craniomaxillofacial procedures require small diameter bone screws,
relocating the pilot hole prior to insertion of the bone screw can
be difficult. However, the advantage to this procedure, if
performed correctly, is that the pre-drilled pilot hole will act as
a guide to insert the self-threading bone screw and minimize the
risk of screw and/or bone fractures due to excessive applied
seating torque.
[0004] To overcome the surgical requirements of drilling a pilot
hole into a surgical site prior to inserting a bone screw, a
variety of bone screw systems have incorporated a self-starting
cutting flute into the apex of the screw. This self-starting
cutting flute is designed to initially penetrate and cut into the
bone site and then to lead the self-threading features of the screw
into place. Although, conceptually, these screws eliminate the
pitfalls of a pre-drilled hole and maximize the bone screw
fixation, locating and inserting these screws become difficult.
Since a pilot hole is not drilled, these screws are difficult to
locate and start in the denser cortical bone and effectively become
challenging to insert. In addition, these screws require
substantially higher seating torque which lead to greater risk of
screw or bone fracturing during insertion.
SUMMARY OF THE INVENTION
[0005] An object of the present invention is the provision of
apparatus to overcome the above noted prior art limitations.
Another object is the provision of apparatus for rigidly fixing
craniomaxillofacial tissue grafts and bone plates in a single
surgical procedure. These and other objects and features of the
invention will be apparent from the following description taken
with reference to the accompanying drawings.
[0006] Briefly stated, a bone screw made in accordance with the
present invention incorporates a sharp piercing twist drill point
tip in series with a self-tapping threaded body. A cylindrical dome
shaped head is formed distal to the tip and body of the bone screw
that drives the screw in or out of the surgical site using a unique
spline driver tool. The invention solves the problems of locating
and self-starting a self-tapping bone screw into place while
minimizing the surgical steps and maximizing the fixation. This
invention allows the physician to take advantage of a pre-drilled
hole without compromising the surgical results common to the
standard multiple step procedure. Finally, the component provides
the physician with a cost effective, easy to use, functional
equivalent to rigidly fix craniomazillofacial tissue grafts and
bone plates in a desired surgical site.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a front elevational view, partly in cross section,
of a self-drilling and self-tapping bone screw made in accordance
with the invention,
[0008] FIG. 2 is left side elevational view of the FIG. 1
screw,
[0009] FIG. 3 is a right side elevational view of the FIG. 1
screw,
[0010] FIG. 4 is a front elevational view of a delivery and drive
tool for use with the FIG. 1 screw,
[0011] FIG. 5 is a view, similar to FIG. 4 but exploded to show the
separate components of the tool,
[0012] FIG. 6 is an enlarged view of an end portion of the FIGS. 4
and 5 tool, and
[0013] FIG. 7 is a left side elevational view of FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] With reference to FIGS. 1-3, self-drilling and self-tapping
bone screw 10 comprises a self-drilling and self-tapping bone screw
cylindrical body 12 and cylindrical dome shaped driving head 14.
The self-drilling and self-tapping bone screw cylindrical body 12
locates, drills and threads the screw body into the graft site with
minimal effort while achieving maximum fixation. To achieve this,
the self-drilling and self-tapping bone screw cylindrical body 12
incorporates a sharp twist drill point tip 12a with a highly
effective piercing and cutting tip 12b at one end of a longitudinal
axis 12f to easily pierce and drill a pilot hole in preparation for
the self-tapping thread 12c. The twist drill point tip 12a is
selected to exactly match the diameter size of the shaft having the
self-tapping thread 12c to further assist in the bone screw's
insertion. The helical flutes 20 of the twist drill point tip 12a
are extended along the drill shaft and into the first couple of
threads of the larger diameter self-tapping screw threads 12c
forming radially projecting flat surfaces to provide cutting flutes
12d for the bone screw's thread. These cutting flutes 12d aid in
driving the self-tapping screw thread 12c down until the beveled
seating neck 14a, to be discussed below, is completely seated.
[0015] The coronal end of the self-drilling and self-tapping bone
screw 10 incorporates a cylindrical dome shaped head 14 for
retention of the craniomaxillofacial tissue grafts and bone plates
to the surgical site. On the inner side of the bone screw head 14
is a bevelled, or frusto-conical seating neck 14a that matches the
standard mating bevel angle on bone screw plates (not shown).
Opposite the beveled seating neck 14a is a smooth cylindrical dome
shaped driving head 14b having an outer periphery which extends
radially outwardly of the shaft portion of body 12. In the center
of the driving head is a square recess 14c and a cross-slot recess
14d that, when combined, forms a unique female spline 14e along
with a circular bore 14f formed inwardly of the square recess.
[0016] To deliver self-drilling and self-tapping screw 10 to the
graft site, FIGS. 4-7 depict a press-fit, pick up and delivery
spline driver tool 20. The body of the press-fit, pick-up and
delivery spline driver tool 20 is made up of a detachable insert
driver 24 and an oversized handle 22. The detachable insert driver
24 is connected and driven by the oversized handle 22 utilizing a
coronal insert annular groove 24a and central milled polygonal
feature 24b, such as hexagonal, at one end. Bone screw spline
driver head 24c is formed at the opposite end from the connecting
and driving features 24a and 24b of detachable insert driver 24.
This male spline driver head is made up of a combined cylindrical
shaft tip 24f having a frictional locking taper that frictionally
locks into bore 14c having an appropriately sized diamter in bone
screw 10. The friction lock allows bone screw 10 to be easily
picked up and delivered by the physician to the surgical site to
prevent any risk of contamination.
[0017] Placing the twist drill tip in series with the self-tapping
threads allows the physician to insert the bone screw in a single
surgical procedure. As the bone screw is driven into the surgical
site, bone chips will fill the space left by the helical cutting
flutes that extend along the drill shaft and into the first couple
of threads of the self-tapping screw. Once inserted in the bore
formed by the drill shaft body, the self-tapping threads of the
bone screw are engaged to rigidly fix and drive the screw into
place.
[0018] It should be understood that this invention includes all
modifications and equivalents of the described embodiment falling
within the scope of the appended claims.
* * * * *