U.S. patent application number 10/154923 was filed with the patent office on 2002-11-14 for cannulated internally threaded bone screw.
Invention is credited to Berger, J. Lee.
Application Number | 20020169453 10/154923 |
Document ID | / |
Family ID | 22444400 |
Filed Date | 2002-11-14 |
United States Patent
Application |
20020169453 |
Kind Code |
A1 |
Berger, J. Lee |
November 14, 2002 |
Cannulated internally threaded bone screw
Abstract
A combination bone screw and driver assembly for driving a
cannulated internally threaded bonescrew, comprising: a bone screw
with shank having a head integrally formed at the proximal end and
defining a cannula extending through the head and shank. An
external thread is formed on the shank outer surface and an
internal thread formed on a surface defining the inner cannula. An
engagement structure is formed in the head to receive and rotatably
engage a driver having a shape complimentary to the shape of the
engagement structure. The driver comprises a cylindrical shaft
member defining an internal throughgoing cannula and an engagement
structure formed at the distal end of the shaft member to engage
the shaft member to a complimentary engagement structure formed on
the cannulated internally threaded screw, a handle member mounted
to the proximal end of the shaft member and a rod member movably
disposed within the cannula of the shaft member defining a thread
portion formed at one end which can be threaded along the internal
thread of said bone screw. A cap member removably mounted on the
other end of the rod member retains the rod member within the shaft
member when a the bone screw is threadedly engaged on the one end
of the rod member and applies torque to the rod member. In
operation a plurality of bores are drilled in different sections of
fractured bone site and at least two bone screws are driven into
respective bores of said different sections of a fractured bone
with a driver. The drivers are secured respectively, to the bone
screws to form a first and a second bone fixation and reduction
assembly; and the first and second bone fixation and reduction
assemblies are transported toward each other to reduce the
fracture. The first and second bone fixation and reduction
assemblies are then clamped together to effect fixation of the
fractured bone.
Inventors: |
Berger, J. Lee; (Franklin
Lakes, NJ) |
Correspondence
Address: |
John S. Hale
c/o Gipple & Hale
6665-A Old Dominion Drive
McLean
VA
22101
US
|
Family ID: |
22444400 |
Appl. No.: |
10/154923 |
Filed: |
May 28, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10154923 |
May 28, 2002 |
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09130374 |
Aug 7, 1998 |
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6436100 |
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Current U.S.
Class: |
606/295 ;
606/104; 606/302; 606/304; 606/311; 606/312; 606/59; 606/916 |
Current CPC
Class: |
A61B 17/60 20130101;
A61B 17/8875 20130101; A61B 2017/0046 20130101; A61B 17/80
20130101; A61B 17/8635 20130101; A61B 17/864 20130101 |
Class at
Publication: |
606/73 ;
606/104 |
International
Class: |
A61B 017/58 |
Claims
I claim:
1. A cannulated torque receiving bone screw comprising: an
elongated cylindrical shank defining a throughgoing cylindrical
bore and having a proximal end, a head integrally formed at the
proximal end, a distal end, and an outer surface, an engagement
structure defined by said head is shaped to receive and rotatably
engage a driver having a shape complimentary to the shape of the
engagement structure; an external thread is formed on said shank
outer surface and an internal thread is formed on a surface
defining said inner cylindrical bore.
2. A cannulated torque receiving bone screw as claimed in claim 1
wherein said head defines a geometrically shaped recess which is
axially aligned with said throughgoing bore.
3. A cannulated torque receiving bone screw as claimed in claim 2
wherein said head has a planar surface.
4. A cannulated torque receiving bone screw as claimed in claim 1
wherein said distal end defines a plurality of flutes.
5. A cannulated torque receiving bone screw as claimed in claim 1
wherein an outer periphery of said head defines an engagement
structure.
6. A cannulated torque receiving bone screw as claimed in claim 1
wherein said external thread formed on the outer surface of said
shank extends the length of said shank.
7. A cannulated torque receiving bone screw as claimed in claim 1
wherein said external thread formed on the outer surface of said
shank extends along a section of said shank and the rest of the
outer surface is unthreaded.
8. A cannulated torque receiving bone screw as claimed in claim 1
wherein said internal thread formed on a surface defining the bore
of said shank extends the length of said bore.
9. A cannulated torque receiving bone screw as claimed in claim 1
wherein a plurality of flutes extend distally from said tip portion
at least partially into said outer surface of said body portion and
said external thread structure.
10. A combination bone screw and driver assembly for driving a
cannulated internally threaded bonescrew, comprising: a bonescrew
with an elongated cylindrical shank having a proximal end, a distal
end, an outer surface; a head integrally formed at the proximal end
and a tip portion formed at the distal end; a cannula extending
through said head and shank defining an inner throughgoing
cylindrical bore; an engagement structure formed in said head
shaped to receive and rotatably engage a driver having a shape
complimentary to the shape of the engagement structure; an external
thread formed on said shank outer surface and an internal thread
formed on a surface defining said inner cylindrical bore; said
driver comprising a shaft member defining an internal throughgoing
cannula and an engagement structure formed at the distal end of
said shaft member to engage the shaft member to a complimentary
engagement structure formed in said head of the cannulated
internally threaded screw; a handle member mounted to the proximal
end of said shaft member; a rod removably mounted within said shaft
member cannula, said rod having a length which is greater than the
length of the shaft member, and an outer diameter which is less
than the inner diameter of said shaft member cannula, said rod
defining a thread portion formed at one end which can be threaded
along the internal thread of said bone screw; and a cap member
removably mounted on the other end of said rod to apply torque to
said rod and retain said rod within said shaft member when a said
bone screw is threadedly engaged on the one end of said rod.
11. A combination bone screw and driver assembly as claimed in
claim 10 wherein said handle member has two sections, each of which
defines a longitudinal groove which when aligned form a bore to
receive the proximal end of said shaft member.
12. A combination bone screw and driver assembly as claimed in
claim 10 wherein said handle member has a unitary body which
defines a longitudinal bore allowing the the proximal end of said
shaft member to be mounted therein.
13. A combination bone screw and driver assembly as claimed in
claim 10 wherein said rod thread portion has a greater diameter
than the shaft member cannula.
14. A combination bone screw and driver assembly as claimed in
claim 10 wherein said shaft member defines at least one annular
groove along its length.
15. A combination bone screw and driver assembly as claimed in
claim 10 further comprising a release member mounted in said cap
member, said release member being movable between a released
position and a locked position so that the cap member is
selectively rigidly secured to said rod member when the release
member is in the locked position and removable from said rod member
when the release member is in the released position.
16. A combination bone screw and driver assembly as claimed in
claim 10 wherein said release member is a set screw with a Allen
head.
17. A combination bone screw and driver assembly as claimed in
claim 10 wherein said cap member is cylindrical and knurled on the
outside surface.
18. A combination bone screw and driver assembly as claimed in
claim 15 wherein said rod includes a well formed at the proximal
end thereof which well cooperates with said release member to
releaseably lock the cap member to the rod.
19. A combination bone screw and driver assembly for driving a
cannulated internally threaded bonescrew, comprising: a bonescrew
with an elongated cylindrical shank having a proximal end, a distal
end, an outer surface; a head integrally formed at the proximal end
and a tip portion formed at the distal end; a cannula extending
through said head and shank defining an inner throughgoing
cylindrical bore; an engagement structure formed in said head
shaped to receive and rotatably engage a driver having an
engagement structure with a shape complimentary to the shape of the
engagement structure; an external thread formed on said shank outer
surface and an internal thread formed on a surface defining said
inner cylindrical bore running the length of said cylindrical bore;
said driver comprising a shaft member defining an internal
throughgoing cannula and an engagement structure formed at the
distal end of said shaft member to engage the shaft member to a
complimentary engagement structure formed on the cannulated
internally threaded screw; said shaft member additionally defining
at least one annular groove along its outer surface; a removable
handle member mounted to the proximal end of said shaft member; a
rod movably disposed within said shaft member cannula, said rod
having a length which is greater than the length of the shaft
member, and a section with an outer diameter which is less than the
diameter of said shaft member cannula, said rod defining a thread
portion formed at one end having a thread outer diameter which is
greater than the diameter of said shaft member cannula and which
can be threaded along the internal thread of said bone screw; and a
cap member removably mounted on the other end of said rod to retain
said rod member within said shaft member when a bone screw is
threadedly engaged with the thread portion of said rod.
20. A method for the reduction and fixation of a fractured bone,
comprising the steps of: a) drilling a plurality of bores in
different bone sections of a fractured bone site; b) driving bone
screws into respective bores of said different sections of a
fractured bone with a driver device; each of said driving devices
comprising; a shaft member having a throughgoing cannula and an
first engagement structure formed at a distal end; a handle member
mounted at the proximal end of said shaft member, a rod member
having a length greater than the length of the shaft member
slidably disposed within and removable from the cannula of the
shaft member; and a cap member secured to said proximal end of said
rod member; each of said bone screws comprising; a shank with a
throughgoing cannular, a head portion integrally formed at the
proximal end of said shank defining an engagement structure for
said shaft member engagement structure; an exterior thread formed
on the exterior surface of said shank; an interior thread formed on
an interior surface of said shank defining said cannula; c)
securing the driving devices to respective bone screws to form a
first and a second bone fixation and reduction assembly; d) moving
the first and second bone fixation and reduction assemblies toward
each other transporting the sections of fractured bone to reduce
the fracture; and e) clamping the first and second bone fixation
and reduction assemblies together to effect fixation of the
fractured bone.
21. A method for the reduction and fixation of a fractured bone as
claimed in claim 20 including the steps of: guiding a bone screw
and an associated driving device with the rod member removed into a
first guide hole in a bone portion of the fractured bone with a
guide wire; removing the guide wire from the first bone screw and
from the first driving device; and placing a rod of the first
driving device into the cannula thereof and rotating the cap member
to secure the first driving device to the bone screw.
22. A method for the reduction and fixation of a fractured bone as
claimed in claim 20 wherein the distal threaded end of each rod
member threadably engages the interior thread of the associated
bone screw; and the cap member is rotated to tighten the shaft
member to the bone screw.
23. A method for the reduction and fixation of a fractured bone as
claimed in claim 20 including a step after step a) of: placing a
planar bone plate with a plurality of elongated slots over the
fracture site so that the slots overlie the bores in adjacent bone
sections; and replacement of step (e) with the step of securing the
first and second bone fixation assemblies in the bone plate.
24. A method for the reduction and fixation of a fractured bone
with a bone plate comprising the steps of: assembling a plurality
of driving devices, a bone plate, a plurality of bone screws, a
plurality of secondary screw members and a guide wire, each driving
device comprising; a shaft member defining a cannula from the
proximal end to the distal end and an engagement structure at the
distal end; a handle member removably mounted at the proximal end
of said shaft member; a rod member mounted within the cannula of
said shaft member, said rod being provided with a threaded portion
at the distal end; and a rotatable cap member releaseably secured
to said proximal end; each bone screw comprising; a shaft body with
an integral head and a cannula formed in said body leading from the
head to the distal end; an external thread formed-on an exterior
surface of said body and an interior thread formed on an interior
surface defining said cannula; and an engagement structure formed
on said head; said bone plate comprising; an essentially planar
base member with a plurality of elongated slots formed therein;
placing the bone plate adjacent the fracture site with the slots
positioned over bores drilled in bone sections of said fracture
site; guiding a bone screw through a first slot on the bone plate
into a bore and driving the first bone screw into a first section
of a fractured bone; guiding a second bone screw through a second
slot on the bone plate into another bore and driving the second
bone screw into a second section of a fractured bone; securing a
first and a second bone screw-driving device assembly to the first
and second bone screws, respectively; applying force to the first
and second bone screw-driving device assemblies to reduce the
fracture; and tightening the first and second bone screws to effect
the fixation of the fracture site.
25. The method of claim 24 for the repair of a fractured bone
further comprising the step of clamping said first bone screw
driving assembly to said second bone screw driving assembly to
effect fixation of the fracture site.
26. The method of claim 24 for the repair of a fractured bone
wherein each bone reduction and fixation assembly is provided with
a removable handle and wherein the method further comprises the
step of: connecting a plurality of rods to said first bone screw
driving assembly and said second bone screw driving assembly to
effect fixation of the fracture site.
Description
FIELD OF THE INVENTION
[0001] The invention generally relates to bone fracture reduction
and fixation and more particularly to a cannulated, internally
threaded bone screw and a reduction driving device and a method of
using the same to effect the reduction and fixation of bone
fractures.
BACKGROUND OF THE INVENTION
[0002] It is known to use screw-type devices and associated drivers
for bone fracture repair. These screw-type devices may be used in
combination with clamps to achieve bone fracture fixation. As one
example of same, U.S. Pat. No. 5,498,265 issued Mar. 12, 1996
discloses a bone screw and a driver for driving the screw into a
fracture site. The bone screw has a threaded shank having proximal
and distal externally threaded shank portions and an internally
threaded head sleeve portion which receives the threaded rod of the
driver. The driver has a handle and an inner rod connected to the
handle. The rod fits within the head sleeve and mates with a cutout
in the proximal end of the threaded shank portion. After the screw
is placed in a fractured bone, the length of the screw can be
adjusted longitudinally to compress the fracture.
[0003] U.S. Pat. No. 2,243,717, issued May 27, 1941, for a surgical
device shows a cannulated bone screw having a threaded end, a
square shaft portion, a round shaft portion and a screw portion. A
clamp formed with a head and skirt has a bore allowing it to be
mounted on the threaded end. A nut is threadedly mounted on the
threaded end of the bone screw. When the bone screw is used in
fracture repair, the fracture site is drilled to form a bore and
the screw portion of the bone screw is screwed into the bone bore
using wrench members specially adapted to drive the bone screw.
When the bone screw is firmly anchored in the bone, the guide wire
previously inserted is withdrawn, the clamp is applied to the
threaded end of the bone screw, and the nut is caused to engage the
threaded end. Tightening the nut moves the clamp towards the screw
portion to fix the fracture.
[0004] An example of a similar screw type device, the length of
which can be adjusted to compress a fracture site can be found in
U.S. Pat. No. 2,121,193, issued Dec. 21, 1932. U.S. Pat. No.
4,858,601, issued Aug. 22, 1989, is also directed toward a
adjustable length screw in the form of a sectioned bone screw which
is cannulated and threaded on its outer surface. The bone sections
are held together by a spindle received in the cannula and soldered
to a section.
[0005] Screw-type devices which are used in combination with
external clamping means to achieve bone fracture reduction and
fixation are also known. U.S. Pat. No. 5,690,633, issued Nov. 25,
1997, shows a fracture fixation device which combines the functions
of external fixation pins and external fixation or "lag-type"
screws in a single unit. The fracture fixation device includes
cannulated screw means for screwing into a first bone fragment over
a guide pin and engagement means in the form of a collar mounted on
a rod for engaging a second bone fragment. The screw means and
engagement means coact to compress first and second bone fragments.
Attachment means preferably integral with the screw means has an
outer end for attachment to an external fixator system which
includes an elongated external fixator rod and at least a pair of
external fixator connectors attached to the rod at spaced
locations.
[0006] Further examples of external fixation devices and clamps can
be found in U.S. Pat. No. 1,789,060, issued Jan. 13, 1931, and U.S.
Pat. No. 4,360,012, issued Nov. 23, 1982.
[0007] A screw and driver for securing a bone block is disclosed in
U.S. Pat. No. 5,423,819, issued Jun. 13, 1995. The screw and driver
are both rotationally and axially releaseably coupled so the screw
can be inserted in a downwardly facing hole. The screw is
preferably threaded along its entire exterior surface length and
has a blind bore which opens on the proximal end of the screw. A
driver with an elongated shaft is inserted into a counterbore
portion of the axial blind bore of the screw so that the front
portion will compress radially. When the front portion is fully
inserted, it snugly engages the wall of the bore with a minor
spring biased interference so that the driver is releasably coupled
to the screw. The driver also includes an elongate intermediate
portion having a hexagonal cross-section and the counterbore of the
screw is provided with a complimentary hexagonal cross-sectional
configuration so that rotation of the intermediate portion causes
rotation of the screw. In one embodiment of the screw and driver, a
throughgoing axially aligned bore is provided in both the screw and
the driver to accommodate a K-wire allowing the screw to slide
freely along the wire.
[0008] U.S. Pat. No. 5,431,651, issued Jul. 11, 1995, shows a cross
pin and set screw femoral and tibial fixation apparatus and method
for mounting a ligament graft. The patent is directed towards an
arthroscopic surgical procedure for replacement of a cruciate
ligament in a knee and requires fixation of the ends of a ligament
in a prepared tunnel. Transverse holes are drilled in the femoral
tunnel during the procedure preferably using a drill guide. The
apparatus includes a drill guide for drilling the transverse hole
or holes which is arranged to be releasable from a first twist
drill so that the first twist drill is left in place to be used for
guiding further drilling and for passage of a fastener device. A
K-wire or the first twist drill that has been left in place is then
used for guiding a second twist drill for enlarging the transverse
hole and for guiding a cannulated screw fastener device in the
femoral bone end of a ligament graft that has been fitted in to the
femoral tunnel section. A set screw is mounted on a forward end of
a turning tool and the turning tool and set screw are cannulated to
receive a K-wire. A coupling end of the turning tool is seated in a
rear end recess in the set screw to mount the screw on the turning
tool so that the turning tool and set screw are rotatably coupled
but not axially coupled.
[0009] A cannulated bone screw is shown in U.S. Pat. No. 4,950,270,
issued Aug. 21, 1990. The bone screw has an axial cannula suitable
for use with a guide pin for positioning the screw in a bore. The
screw is provided with an exterior screw thread having a normal
helical winding for screwing insertion of the screw into a bone
material. The external threading extends the length of the screw to
facilitate the complete insertion of the same in the bone.
[0010] A cannulated screw and driver used in bone marrow harvesting
and bone biopsy systems is shown in U.S. Pat. No. 5,456,267, issued
Oct. 10, 1995. The cannulated screw has a torque receiving head and
threaded shaft exterior with one embodiment including inner threads
which terminate a hexagonal shaped interior portion. The head is
provided with a hexagonal shaped interior portion to permit
engagement with a driving tool. The screw includes a structure on
one end permitting attachment of a fitting for applying negative
pressure to facilitate marrow harvesting. The embodiment includes
inner threads on a first end, or in the alternative, pressure
fittings or twist lock fittings may be provided. The threads or
other structures must provide sufficient seal to permit the
negative pressure required for harvesting.
[0011] An examination of the prior art indicates the need for a
fracture reduction bone screw that provides an attachment site for
a bone screw driving device so that the bone screw and driving
device cooperate to form an assembly which can be manually
manipulated to effect fracture reduction and provide structural
support for conventional clamping devices to effect bone fracture
fixation.
SUMMARY OF THE INVENTION
[0012] The present invention discloses and describes a cannulated,
externally and internally threaded bone screw and a driving device
for same for use in the reduction and fixation of bone fractures.
The head of the screw is shaped to conform to the end portion of
the driving device and may be of various shapes and sizes.
[0013] The internal threading allows the bone screw to be used in a
wide range of orthopedic applications. For example, the internal
threading can serve as an attachment site for the driving device or
may be used for fixation of orthopedic equipment such as bone
plates, rods or other types of screws.
[0014] In the driving device, a distally threaded rod member and a
releasable lockable cap member are used to secure an internally
threaded bone screw to the distal end of the cannulated bone screw
driving device. After the bone screw is driven into a bone, a bone
fixation and reduction unit can be constructed by securing the bone
screw to the driver device by threading an end of the rod member
with the internal threading of the bone screw and rotating the cap
member mounted on the proximal end of the rod member to tighten the
engagement.
[0015] Because the screw is secured to the driver device by a
threaded rod and because the bone screw is constructed of high
grade surgical steel with machined external and internal threading,
considerable force can be applied to the unit to align the bone,
reduce the bone fracture and apply traction to the fracture site.
The driver can be quickly detached from the screw by manually
rotating the cap member to disengage the rod from the internal
screw threading. This allows the bone screw and driving device to
be used in a wide range of orthopedic applications. The bone screw
and driving device can also be used in various ways with
conventional bone plates.
[0016] The reduction and fixation assembly can be used alone or
with other assemblies to align and reduce fractures. The assemblies
may, for example, be secured to fractured bone sections in pairs
with one assembly on each side of the fracture site, and manually
manipulated to reduce the fracture. Following fracture reduction,
the driving devices can be easily removed by manually manipulating
the cap member, leaving the bone screw in place or the assemblies
themselves may be used as external fracture fixation devices. For
example, once the fracture is reduced, a handle portion of the
driving device may be removed and conventional cross bars or other
clamping devices may be attached between shaft portions of the
assemblies to convert the assemblies into an external fixator
device to effect fracture fixation.
[0017] In a first example of the use of a bone plate with the bone
screw and driving device, a plurality of bone screws are driven
with a first driving device into a fractured bone through the
apertures in a bone plate. A plurality of driving devices are
secured to bone screws on opposite sides of the fracture with
respective threaded rods to provide reduction and fixation
assemblies on each side of the fracture site to effect fracture
alignment and reduction. Following fracture alignment and
reduction, the bone screws can be tightened to hold the plate in
place for fracture fixation and the driving devices are removed
leaving the bone screws in the bone.
[0018] In a second example using a bone plate with the bone screw
and driving device, a plurality of bone screws can be driven with a
driving device into a fractured bone in alignment to receive the
apertures in a bone plate and support the same. After fracture
reduction with a pair of reduction and fixation assemblies, a
conventional bone plate can be applied to the fracture site by
mounting the plate on the aligned internally threaded bone screws
with a second set of conventional screws which extend through the
apertures in the bone plate and threadedly engage the internal
threading of the bone screws. The head portions of the bone screws
can thus be used to support a conventional bone plate or other
conventional orthopedic equipment and the internally threaded
cannula of each screw can receive and threadedly engage a
conventional second screw to secure the bone plate or other
structure to the fracture site.
[0019] Yet another object of the invention is to provide a bone
screw-driver assembly of simple construction which can be used to
apply traction to the fracture site.
[0020] It is an object of the invention to provide a self-drilling,
self-tapping cannulated bone screw that is both externally and
internally threaded. The internal threading can advantageously
provide an attachment site for a reduction screw driving device
that can be used to drive the internally threaded bone screws into
bony tissue including cortical or cancellous bone during orthopedic
surgical procedures.
[0021] It is a further object of the present invention to provide
an internally threaded bone screw that can be used for bone
reduction and fixation of fractured bones, for the fixation of
orthopedic equipment such as plates, rods to bone, particularly
fractured bone, or for the fixation of other types of screws in
orthopedic procedures.
[0022] It is a further object of the invention to provide a rod
member that is threaded at a distal end and cap member that is
releaseably locked to a proximal end of the rod member to provide
torque to the rod member.
[0023] It is also an object of the invention use the rod member and
cap member to adapt a cannulated screwdriver, and a cannulated,
internally threaded bone screw to construct a bone fixation and
reduction assembly.
[0024] Another object of this invention is to use the bone screw
driver assembly to align and reduce fractures.
[0025] Yet another object of this invention is to describe a
plurality of methods for using the bone screw-driver assembly
during surgical procedures following fracture alignment and
reduction to effect bone fracture fixation.
[0026] It is a further object of this invention to show how a
plurality of the assemblies can be used for fixation of fractures
using external support structures; and to show how a driving device
can be easily removed from an assembly once the bone screw is in
place and the screw can be used for the application of a surgical
plate to the fracture site.
[0027] These and other objects, advantages, and novel features of
the present invention will become apparent when considered with the
teaching contained in the detailed disclosure along with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a partially exploded view of the bone reduction
and fixation invention showing a driver and cannulated, internally
and externally threaded bone screw;
[0029] FIG. 2 is a side elevational view of the bone reduction and
fixation assembly of FIG. 1;
[0030] FIG. 3 is a cross-sectional view of the bone reduction and
fixation assembly of FIG. 2;
[0031] FIG. 4 is a side elevational view of a fully externally
threaded cannulated and internally threaded bone screw used in the
invention;
[0032] FIG. 5 is an enlarged front elevational view of the head of
the bone screw of FIG. 4;
[0033] FIG. 6 is a side elevational view of a partially externally
threaded, cannulated and internally threaded bone screw used in the
invention;
[0034] FIG. 7 is an enlarged front elevational view of the head of
the bone screw of FIG. 6;
[0035] FIG. 8 is a schematic fragmentary side elevational view of a
fracture site showing a plurality of bone reduction and fixation
assemblies secured to portions of the fractured bone to reduce the
bone fracture;
[0036] FIG. 9 is a schematic side elevational view similar to FIG.
8 showing a conventional bone plate mounted on the bone fracture
sections by a plurality of reduction and fixation assemblies to
effect fracture fixation;
[0037] FIG. 10 is a schematic side elevational view similar to FIG.
8 showing a plurality of conventional clamping devices mounted on
the bone reduction and fixation assemblies to effect fracture
fixation; and
[0038] FIG. 11 is a schematic side elevational view showing a
plurality of aligned internally threaded bone screws of the present
invention supporting a conventional bone plate with a plurality of
conventional surgical screws threadedly engaged with the threaded
bone screws to secure the bone plate to the fracture site.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE
INVENTION
[0039] The preferred mode and best embodiment of the present
invention is shown in FIGS. 1 to 7. Referring now to the drawings,
FIGS. 1-3 show a cannulated, internally and externally threaded
bone screw 20 and a cannulated driver device 22 constructed
according to the principles of the present invention.
[0040] The driver device 22 includes a shaft member 26 defining a
throughgoing bore 27, a handle 28 and includes a rod 30 and a cap
member 32. The rod 30 and cap member 32 are used to releasably
secure the bone screw 20 to the driver device 22 as will later be
described. The shaft member 26 is an elongated, generally
cylindrical structure which has a cylindrical throughgoing bore or
cannula 27 best seen in the cross-sectional view of FIG. 3 which
extends longitudinally from a proximal end 34 of the shaft member
26 to a distal end 36.
[0041] The shaft member 26 is an integral tubular structure
preferably constructed of surgical steel, although any suitable
material can be used, and includes a shaped engagement structure 38
integrally formed at the distal end 36 and one or more annular
grooves 37 spaced along its length. The engagement structure 38
which preferably has a hexagonal configuration facilitates the
mating and rotational engagement of the bone screw 20 with the
driver as will be described and the grooves 37 may be used as
attachment sites for conventional clamp members during a bone
fixation procedure. It will be appreciated that the engagement
structure 38 may take any angular configuration such as square,
octagonal or the like and can alternatively engage the outer
periphery of the screw head.
[0042] The handle 28 has a throughgoing bore 39 to receive the
proximal end 34 of the shaft member 26 and is preferably
constructed of wood or plastic. The handle 28 is secured to the
shaft member 26 by securing the handle sections together with
conventional rivets 39 or by other suitable means. The rivets do
not extend into or through the bore of the shaft member 26.
Alternatively, the handle member 28 may be removably mounted to the
shaft member 26.
[0043] The rod 30 is an integral, solid, generally cylindrical
structure preferably constructed of surgical or high grade steel
and is provided with a threaded section 42 at its distal end and a
machined recess or well 44 near its proximal end which receives set
screw 47. The cap member 32 is a generally cylindrical structure
that has a blind bore 43 to receive the proximal end of the rod 30
and a cylindrical, internally threaded passage 45 which extends
from a side surface of the cap member 32 into the blind bore 43 to
permit the passage of a conventional set screw 47 having an Allen
head. A conical end portion of the Allen set screw is received
within the well 44 in the rod 30 to lock the cap member 32 to the
rod 30. The outer surface of cap 32 is knurled at 33 to allow the
cap 32 and secured rod 30 to be rotated within bore 27 of the shaft
26 so that threaded end 42 can be screwed into the inner thread 58
of the cannulated bone screw 20.
[0044] The outer diameter of the cylindrical rod 30 is less than
the inner diameter of the cylindrical bore 27 in the shaft member
26 so that the rod 30 can be easily received therein and pass
therethrough. Conversely the threaded end section 42 has threads
with an outer diameter greater than the outer diameter of bore 27
so that rod 30 cannot be pulled through the bore 27 of the shaft
26. When the cap member 32 is releaseably locked to the proximal
end of the rod 30, cap member 32 prevents a portion of the proximal
end of the rod 30 from entering the cannula 27 of the shaft member
26. As best seen in FIG. 3, the rod 30 is longer than the shaft
member 26 so that when the cap member 32 is mounted on the rod 30
and the rod 30 is disposed within the cannula or bore 27 of the
shaft member 26, the threaded section 42 of the rod 30 extends a
predetermined length beyond the distal end 36 of the shaft member
26 to threadedly engage the internal threading 58 of the bone screw
20.
[0045] The cannulated, internally threaded bone screw 20 shown in
cross-section in FIG. 3 is mounted on the driver device 22 and is
also shown in FIGS. 4 and 6. The bone screw 20 is an integral
structure preferably made of surgical steel and includes a shank
46, a head 48 and a tip portion 50. The shank 46 of the bone screw
20 has an external thread 52 which is helically formed thereabout,
and extends from the head 48 to the tip portion 50. The head 48 has
a generally larger outer diameter than the shank 46 and defines a
hexagonal shaped recess 49 so that the bone screw can receive
torque from the engagement structure 38 and apply a compressive
force to a bone surface or to retain a bone plate against a bone
for fracture fixation. The exterior surface of the tip portion is
tapered and provided with a plurality of flutes 54 so that the bone
screw is self drilling. The plurality of flutes 54 extend
proximally longitudinally from the tip portion 50 and may extend
into the shank 46.
[0046] A throughgoing internal bore or cannula 56 extends from the
head 48 through the shank 46 to the tip portion 50 and is provided
with an internal thread 58, preferably throughout its length. As
best seen in FIG. 5, a recess 49 shaped to receive the shaft
engagement head 38 is formed in the head 48 of the bone screw 20.
This recess is axially aligned with the cannula 56. The walls of
the recess 49 have a hexagonal cross-section and define an
engagement recess portion of the bone screw 20. As shown in FIG. 1,
the engagement structure 38 of the driver device 22 is formed by a
hexagonal configuration on the distal end of the shaft 26 and is
dimensioned to be received within the recess 49 formed in the head
of the bone screw 20 to rotatably engage the bone screw and the
driver. It is understood that this structure is exemplary only and
that the engagement portion of the bone screw may also be formed on
the outer periphery of the head portion.
[0047] The method of bone fixation and reduction of the present
invention can be performed using a wide range of cannulated,
internally threaded bone screws. An alternative embodiment of an
internally threaded bone screw 220 is shown in FIGS. 6 and 7. This
embodiment is constructed for use in cancellous bone. The external
surface of body portion 246 of the bone screw 220 is partially
threaded at section 222 and smooth surfaced or unthreaded at
section 224 and the tip portion 250 is provided with a plurality of
flutes 254. The integral head 248 has a larger exterior diameter
than the body portion and defines a hexagonal recess 249 which
seats the shaft engagement end 38 and the internal threading
preferably extends the entire length of the bone screw cannula
256.
[0048] The internal and exterior threads of the bone screws 20 and
220 are preferably formed by machining and the internal thread
structures may partially or fully cover the wall of the respective
interior bores of the bone screws 20, 220. Each the bone screws 20
and 220 is self-drilling and self-tapping.
[0049] The bone screw 20 and driver device 22 can be assembled
using the rod 30 and cap member 32 as shown, for example, in FIGS.
1-3, to form a bone reduction and fixation assembly 60 which can be
used to effect bone fraction reduction and fixation.
[0050] The engagement structure 38 of the shaft member 26 and the
engagement seat 49 of the bone screw 20 are of complimentary size
and shape so that the engagement structure 38 can be snugly
received within the engagement seat 49 of the bone screw 20 to
rotationally lock the driver device 22 with the bone screw 20. When
the driver device 22 and bone screw 20 are so engaged, the
throughgoing bore 27 of the shaft member 26 is axially aligned with
the internally threaded bore 56 of the bone screw 20. The rod 30 is
used to releasably axially secure the bone screw 20 to the driver
device 22 by securing the cap member 32 on the rod 30 by tightening
the Allen set screw 47 into the recess 44 of the rod member. The
threaded section 42 of the rod 30 is threaded on the internal
thread 58 projecting from the internal bore 56 of the bone screw 20
and the rod 30 is rotated by manually manipulating the cap member
32 until the bone screw 20 is tightly axially releaseably
interlocked to the driver device 22. Reverse rotation will of
course unlock the driver device 22 and bone screw 20.
[0051] This configuration is best seen in FIGS. 2 and 3. When thus
rotationally and axially releasably interlocked, the driver device
22 and the bone screw 20 form a single assembly which is referred
to as the bone reduction and fixation assembly and is generally
designated by the reference numeral 60 as shown in FIG. 3. Because
the bone screw 20 and driver device 22 are tightly held together by
the steel rod 30, the assembly 60 does more than maintain the bone
screw in engagement with the driver to facilitate screw positioning
and the driving insertion thereof into cortical or cancellous bone.
This rigid engagement allows the surgeon to manually manipulate the
fractured bones to reduce the fracture after the screw (or screws)
has been inserted (See FIG. 8) and permits fracture fixation after
the fracture has been reduced through conventional bone clamps
mounted between adjacent assemblies 60.
[0052] FIG. 8 shows an example of how an internally threaded bone
screw can be used as a fracture reduction device at a fracture site
66 in a bone 68. In this example the fracture 66 has separated the
bone 68 into two portions 68a and 68b. Two identical bone fracture
reduction and fixation assemblies 60a and 60b are secured to the
bone portions 68a and 68b, respectively, adjacent the fracture site
66. The description for insertion of a bone screw 20a, 20b is given
with reference to assembly 60a; it being understood that bone screw
60b is inserted in the same way.
[0053] A guide hole (not shown) is formed in the cortical portion
of the bone fragment 68a proximate the fracture site 66. A smooth
surgical guide wire or K-wire is inserted in the guide hole. A
conventional cannulated surgical drill, optionally used in
conjunction with a conventional drill guide, may be used to form a
guide hole. The conventional surgical guide wire or K-wire may be
inserted in the guide hole through the cannula of the drill before
the same is removed therefrom, leaving the guide wire in place.
[0054] With the smooth guide wire in place within the guide hole,
the cannulated, internally threaded bone screw 20 is inserted over
the guide wire with the cannulated driver device 22 to engage two
cortices of bone. The threaded rod 30 and the cap member 32 have
not been mounted on the cannulated driving device when the guide
wire is used to guide the bone screw and driver to the guide hole.
After the bone screw 20 is driven into the bone using the driver
device 22 the smooth guide wire is removed leaving the bone screw
in the bone portion 68a. The engagement end 38 of the driver device
22 is interengaged with the recess or seat 49 of the bone screw 20
and the externally threaded rod 30 is rotated and tightened into
the internal thread of the cannulated screw by manually rotating
the cap member 32.
[0055] The bone screw 20 and driver device 22 are thus locked
together to form the bone reduction and fixation assembly 60a. As
shown in FIG. 8, a second assembly 60b can be secured to the bone
portion 68b using a second internally threaded bone screw 20b by
repeating this procedure. The surgeon can then manipulate the bone
portions 68a, 68b by grasping the handle members 28a, 28b and
pulling each of the handles towards each other in direction "A" to
reduce the fracture 66 manually.
[0056] FIG. 9 shows that the internally threaded bone reduction
screw can be applied through a conventional bone fixation plate 76
which is shown in place over the fracture site 66. When the
cannulated, internally threaded bone screw 20 is used with a
conventional fixation plate 76, typically at least one of the bone
screws 20a or 20b is inserted through an elongated slot 77 in the
plate so that the bone portions 68a and 68b can be brought together
in direction "A" to reduce the fracture 66 before the plate 76 is
firmly fastened on the bone portions.
[0057] FIG. 10 shows that when the bone fracture 66 has been
appropriately aligned and reduced by the assemblies 60a, 60b,
conventional external fixator cross bars 70 can be mounted between
the shaft members 26a, 26b so that the assemblies 60a, 60b can be
used for bone fixation holding bone segments 68a, 68b in a fixed
position. Although the handles 28a, 28b are shown still in place on
the assemblies 60a, 60b and have previously been described as being
mounted to the shaft member 26 with conventional rivets, it is
within the scope of the invention to provide a removable handle 28
on each assembly 60 so that the handles can be removed after the
external fixator cross bars 70 have been mounted therebetween to
hold the fractured bone together.
[0058] The external fixator cross bars 70 are conventional and the
structure thereof and the method of mounting the same is well
known. Conventional devices such as the cross bars 70 typically are
comprised of a rigid central bar structure and a conventional
clamping device mounted on each end of the bar structure and are
well known in the art. Any conventionally known clamping device or
cross bar can be used with the assemblies 60 to form an external
fixator.
[0059] The firm fixation of the inventive bone screw 20 is superior
to Schantz screws or other types of external fixation pins and
should result in decreased incidence of pin loosening.
[0060] The external fixation device can be easily removed in one
step by loosening the bone screw 20 with the driver device 22.
[0061] FIG. 11 shows a plurality of internally threaded bone screws
20 cooperating to form a fixation site to receive and support a
conventional bone plate 78. The cortical bone screws 20 are
inserted in the bone portions 68a, 68b in appropriate vertical and
horizontal alignment to receive a second set of conventional
surgical screws 80 which extend through the slots or cylindrical
apertures 79 formed in the bone plate 78. The top surfaces of the
heads of the bone screws 20 form support surfaces to support the
bone plate 78.
[0062] The bone plate 78 may be affixed to the bone 68 by forming a
series appropriately aligned and appropriately directed guide holes
in the bone portions 68a and 68b. A conventional drill and drill
guide may be used for this purpose. As each guide hole is formed, a
bone screw 20 is placed therein using a K-wire as previously
described. Two or more reduction and fixation assemblies 60 may be
used in the manner described above to manually reduce the fracture
before the conventional plate is applied. When the desired number
of bone screws 20 are placed in the bone fragments 68a, 68b, the
bone plate 78 is placed on the heads of the bone screws which have
flat or other appropriately shaped surfaces thereon to support the
bone plate 78.
[0063] In the example illustrated in FIG. 11, the top surfaces 82
of the bone screws 20 are planar and the screws have been placed in
the bone such that the top surfaces 82 are essentially coplanar.
The bone screws 20 are aligned to coincide with the apertures in
the bone plate 78. The surgical screws 80 are screwed into the
internal threading of the bone screws 20 to secure the plate to the
fracture site 66.
[0064] It is clear from the forgoing that the machined internal
threading of the self-drilling, self-tapping cannulated screw
described herein, provides the orthopedic surgeon with many ways to
effect fracture reduction and fixation. The threaded rod 30 can be
used with a cannulated driving device, including many conventional
cannulated driving devices, to form a fracture fixation and
reduction assembly 60 of the invention.
[0065] When the bone screw 20 and driver device 22 are secured
together to form the assembly 60, this fixed assembly can be used
as a fracture reduction tool to assist in aligning fractures of
bone. The assembly 60 can also be used to apply traction to a
fracture site. The screw can be inserted directly into bone or
through a conventional fixation plate.
[0066] In addition to this use in internal fixation of fractures of
the bone, the assembly 60 can be used as an external fixation
device for bone fractures. Once the fracture is reduced, the handle
of the driver device 22 may be removed and cross bars 70 may be
attached to the shaft member 26 converting the assembly 60 to an
external fixator device.
[0067] The internally threaded screw can be used independently as a
bone fixation screw. The internal threads may be used to apply
optional devices such a screws, plates or rods for other fixation
purposes. It is understood that the bone screws shown herein are
exemplary only and not intended to be limiting. One skilled in art
will appreciate that the internally threaded cannulated screws can
be manufactured in various shapes and sizes and that the internal
threads may partially or fully encompass the length of the bone
screws.
[0068] In the foregoing description, the invention has been
described with reference to a particular preferred embodiment,
although it is to be understood that specific details shown are
merely illustrative, and the invention may be carried out in other
ways without departing from the true spirit and scope of the
following claims:
* * * * *