Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DEVICE FOR RELEASABLY SECURING OBJECTS TO BONES
FIELD OF THE INVENTION
This invention relates to devices for securing objects to
bones. More particularly, this invention relates to devices
which releasably secure objects to bones such that the object
is temporarily axially and rotationally secured to the bone.
BACKGROUND OF THE INVENTION
Various types of surgical procedures now require objects,
such as tools or tracking devices, to be temporarily secured
to a bone during a procedure. For example, during image
guided surgery, it is sometimes necessary to attach active or
passive trackers to bones in order to determine the location
of a bone with respect to the image. This is required, for
instance, for alignment procedures, such as fracture
reductions. It is also often necessary to attach active or
passive dynamic reference objects to bones. In addition, it
is sometimes necessary to temporarily attach objects to bones,
such as drill guides or templates to perform a subsequent
drilling or sawing operation.
Furthermore, it is sometimes necessary to secure objects
to the bone which must remain temporarily secured after the
initial surgical procedure. For example, external fixation
devices are sometimes secured to bones or bone fragments to
hold the bone and bone fragments in place during healing.
Also, spinal rods must sometimes be secured to vertebrae,
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thereby temporarily mechanically immobilizing areas of the
spine, to treat certain types of spinal column disorders.
Also, to analyze and treat certain joint pathologies, it is
sometimes necessary to attach trackers to bones to measure the
discrete joint movements, such as, for example, to measure the
motion patterns of the human knee.
It has been known in the past to use bone screws to
secure objects to bones. Bone screws generally have a coarse
thread at one end for engaging the bone and a means at the
other end to easily attach clamps or instruments thereto.
While bone screws have worked well in the past, they are
susceptible to rotational displacement which can either loosen
or tighten the bone screw. This rotational displacement can
be caused in different ways, such as by the normal cyclical
force applied to the bone screw or through inadvertent contact
with the object attached to the bone screw by an external
source.
It is clear that rotational displacement of the bone
screw will affect the object secured to the bone screw. For
example, any rotational displacement of the bone screw may
cause a rotational displacement of the object with respect to
the bone. Furthermore, any rotational displacement of the
bone screw may cause an axial displacement of the bone screw
along the axis of rotation of the bone screw with respect to
the bone. It is clear that any axial and/or rotational
displacement of the bone screw with respect to the bone will
also cause an axial and/or rotational displacement of the
object with respect to the bone.
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In some cases, any rotational or axial displacement of
the screw can have a significant effect on the procedure. For
example, during image guided surgery, the objects, such as
tracking devices or instruments, secured to the bone screw
will be registered in six degrees of freedom, namely three
displacement degrees of freedom and three rotational degrees
of freedom. Accordingly, any axial or rotational displacement
of the bone screw will cause an axial or rotational
displacement of the object and require re-registration of the
object secured to the bone screw.
In the past, in order to avoid rotational displacement of
the bone screw, and therefore rotational or axial displacement
of objects attached to bone screws, more than one bone screw
has been used to attach an object to a bone. For example, two
or more bone screws, displaced along the bone, have been used
to prevent detrimental effects caused by rotational
displacement of one bone screw. However, using additional
bone screws weakens the bones being treated and increases the
length of time of the procedure. In addition, in some cases,
it is not practical to use several bone screws because the
bones or bone fragments are simply not large enough. Also,
use of several bone screws restricts access to the operative
site, which can be the case with the vertebrae of the spine.
Accordingly, there is a need in the art for a device
which prevents rotational displacement of bone screws. In
addition, there is a need in the art for a device which better
axially and rotationally secures objects to bones.
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SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to at
least partially overcome the disadvantages of the prior art.
Also, it is an object of this invention to provide an improved
type of device which can better axially and rotationally
secure objects to bones.
Accordingly, in one of its aspects, the present invention
resides in a device for releasably securing an object to a
bone, said device comprising: a rotation restricting member
having an engaging element which engages the bone to restrict
rotation of the member; a fastening mechanism for fastening
the rotation restricting member to a bone screw engaging the
bone; a clamp for releasably securing the object to the
rotation restricting member or the bone screw; wherein after
the fastening mechanism has fastened the rotation restricting
member to the bone screw, the rotation restricting element is
biased towards the bone such that the engaging element engages
the bone to restrict rotation of the member; and wherein
releasably securing the object to the clamp axially and
rotationally secures the object to the bone.
In a further aspect, the present invention resides in a
device for releasably securing an object to a bone, said
device comprising: a clamp releasably securable to the object;
an axial supporting member for axially securing the device to
the bone; a rotation restricting member which, while engaging
the bone, restricts rotation of the device; a fastening
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mechanism for fastening the axial supporting member with
respect to the rotation restricting member; wherein the
fastening mechanism fastens the axial supporting member to the
rotation restricting member while the axial supporting member
and the rotation restricting member are engaging the bone; and
wherein objects can be releasably secured to the clamp, after
the fastening mechanism has fastened the axial supporting
member with respect to the rotational supporting member, to
axially and rotationally secure the objects to the bone.
In a still further aspect, the present invention resides
in a device to restrict rotational displacement of a bone
screw, said device comprising: a rotation restricting member
having an engaging element which engages the bone to restrict
rotation of the rotation restricting member; a fastening
mechanism for fastening the rotation restricting member to the
bone screw; wherein the fastening mechanism fastens the
rotation restricting member to the bone screw while the
engaging element is engaging the bone, thereby preventing
rotational displacement of the bone screw.
In a still further aspect, the present invention resides
in a device for releasably securing an object to a bone, said
device comprising: a rotation restricting member having an
engaging element which engages the bone to restrict rotation
of the member; a bone screw for engaging the bone; a biasing
member for axially biasing the rotation restricting element
with respect to the bone screw; wherein after the bone screw
has engaged the bone, the biasing member axially biases the
rotation restricting member with respect the bone screw such
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that the engaging element engages the bone to restrict
rotation of the member; and wherein releasably securing the
object to the rotation restricting member axially and
rotationally secures the object to the bone.
In a further aspect, the present invention provides a
method of releasably securing an object to a bone, said method
comprising the steps of: fixing a biasing member to a
longitudinal position on a bone screw, said bone screw having
a bone engaging end; axially inserting a rotation restricting
member onto the bone engaging end of the bone screw, said
rotation restricting member having an engaging element which
engages the bone to restrict rotation of the rotation
restricting member; driving the bone engaging element of the
bone screw into the bone until the biasing member biases the
engaging element of the rotation restricting member into the
bone; clamping the object to the rotation restricting element
or the bone screw.
In one aspect, the present invention provides a device
for releasably securing an object to a bone, said device
comprising: a rotation restricting member having an engaging
element which is adapted to engage the bone to restrict
rotation of the member; a fastening mechanism for fastening
the rotation restricting member to a bone screw; a clamp for
releasably securing the object to the rotation restricting
member or the bone screw; wherein after the fastening
mechanism has fastened the rotation restricting member to the
bone screw, the rotation restricting element is adapted to be
biased towards the bone such that the engaging element
engages the bone to restrict rotation of the member; and
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wherein releasably securing the object to the clamp permits
the object to be axially and rotationally secured to the
bone.
In a still further aspect, the present invention
provides a device for releasably securing an object to a
bone, said device comprising: a clamp releasably securable
to the object; an axial supporting member adapted to axially
secure the device to the bone; a rotation restricting member
which, while engaging the bone, restricts rotation of the
device; a fastening mechanism for fastening the axial
supporting member with respect to the rotation restricting
member; wherein the fastening mechanism fastens the axial
supporting member to the rotation restricting member while
the axial supporting member and the rotation restricting
member are engaging the bone; and wherein objects can be
releasably secured to the clamp, after the fastening
mechanism has fastened the axial supporting member with
respect to the rotational supporting member permitting
objects to be axially and rotationally secured to the bone.
In a further aspect, the present invention provides a
device to restrict rotational displacement of a bone screw,
said device comprising: a rotation restricting member having
an engaging element which is adapted to engage the bone to
restrict rotation of the rotation restricting member; a
fastening mechanism for fastening the rotation restricting
member to the bone screw; wherein the fastening mechanism
fastens the rotation restricting member to the bone screw
while the engaging element is engaging the bone, thereby
preventing rotational displacement of the bone screw.
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In a still further aspect, the present invention
provides a device for releasably securing an object to a
bone, said device comprising: a rotation restricting member
having an engaging element which is adapted to engage the
bone to restrict rotation of the member; a bone screw adapted
to engage the bone; a biasing member for axially biasing the
rotation restricting element with respect to the bone screw;
wherein after the bone screw has engaged the bone, the
biasing member axially biases the rotation restricting member
with respect the bone screw such that the engaging element
engages the bone to restrict rotation of the member; and
wherein releasably securing the object to the rotation
restricting member permits the object to be axially and
rotationally secured to the bone.
Accordingly, one advantage of the present invention is
that an object, such as a tracker or surgical tool, can be
better secured, both rotationally and axially, to bones. A
further advantage of the present invention is that rotation of
the bone screw is restricted, thereby avoiding rotational
displacement of the bone screw. A further advantage of the
device to restrict rotation of the bone screw is that the
device is located near the bone screw and fastened to the bone
screw such that the device has a small "footprint" and does
not require a large space on the bone. This allows the device
according to the present invention to be more easily used in a
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surgical setting, and, prevents the need for several bone
screws to be inserted into a single bone.
A further advantage of the present invention is that,
because the device requires a small footprint, the present
invention can be used in relatively small bones, such as the
vertebrae which form the spinal column and on fragments of
bones. The present invention also does not overly obstruct
the operative site. Furthermore, even in larger bones where
two or more bone screws can be inserted to better rotationally
secure an object to the bone, it is often not desirable to use
more bone screws because additional bone screws require more
time to insert and remove, and, further weaken the bone.
A further advantage of the present invention is that the
rotation restricting member will generally engage only the
surface of the bone, and will not threadably engage a bone,
such as in a manner that a bone screw does. Accordingly, a
further advantage of the present invention is that the device
according to the present invention rotationally and axially
secures an object to the bone in a relatively non-intrusive
manner, especially as compared with using two or more bone
screws.
A still further advantage of the present invention is
that the rotation restrictive member can take several
different forms in different embodiments. This permits
different fastening mechanisms to be used. Also, this
provides a further advantage in that specific types of
fastening mechanisms can be used in different situations to
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best axially and rotationally secure an object to a bone for
each type of situation.
A still further advantage of the present invention is
that the biasing member can be fixed to a specific
longitudinal position on the bone screw. In this way, the
bone screw can be inserted a predetermined distance into the
bone before the biasing member biases the engaging element of
the rotation restricting member into the bone. This ensures
that the bone screw will not be inserted into the bone beyond
a predetermined depth.
Further aspects of the invention will become apparent
upon reading the following detailed description and drawings
which illustrate the invention and preferred embodiments of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, which illustrate embodiments of the
invention:
Figure 1 is a schematic diagram of one embodiment of the
present invention utilizing a sleeve;
Figures 2A, 2B, 2C and 2D illustrate insertion of the
device shown in Figure 1 into a bone;
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Figure 3A shows a further embodiment of the present
invention utilizing a washer having serrated teeth;
Figure 3B shows a further embodiment of the present
invention utilizing a retainer as the fastening mechanism;
Figure 3C shows a front view and Figure 3D shows a side
view, respectively, of an embodiment of the present invention
utilizing a further type of fastening mechanism having an
eccentrically mounted disc;
Figure 3E shows a further embodiment of the present
invention utilizing a pin;
Figure 3F illustrates a further embodiment of the present
invention utilizing a thumb screw as the fastening mechanism;
and
Figure 3G illustrates a further embodiment of the present
invention utilizing an internally threaded bone screw.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in Figure 1, one embodiment of the present
invention provides a device, shown generally by reference
numeral 10, for temporarily axially and rotationally securing
objects 8 to a bone. As shown in Figure 1, the device 10
comprises a sleeve 14 having serrated teeth 16 for engaging
the bone 6. A fastening mechanism, shown generally in Figure
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1 by nut 18, is used to bias the sleeve 14 against the bone
such that the serrated teeth 16 engage the bone 6. While the
sleeve 14 is biased towards the bone 6, the serrated teeth 16
are biased into engagement with the bone 6, thereby fastening
the sleeve 14 to the bone 6. Thus the nut 18 acts as a
biasing member to bias the sleeve 14 towards the bone 6 and to
thereby fasten the sleeve 14 to the bone screw 12 and to also
fasten the sleeve 14 to the bone 6.
Bone screws, such as bone screw 12 shown in Figure 1, are
generally well known in the art. As shown in Figure 1, the
bone screw 12 includes a first threaded end 22 which generally
has a coarse thread for anchoring the bone screw 12 in the
bone. While the first threaded end 22 of the bone screw 12
can be inserted directly into and engage the bone 6, it is
sometimes useful to have a hole drilled or drilled and tapped
in the bone 6 to guide the bone screw 12. The bone screw 12
also may have a second end 24, opposite the first threaded end
22. The second end 24 may be threaded, as shown in Figure 1,
or have other means that can be used to fasten elements to the
bone screw 12.
The device 10 further comprises a clamp 20 for releasably
securing the object 8 to the sleeve 14 or bone screw 12. The
clamp 20 is shown generally in the figures, and, it is
understood that any type of clamp which can secure the object
8 to the sleeve 14 or the bone screw 12 can be used.
Preferably, the clamp 20 releasably secures the object 8
to the sleeve 14 because the sleeve 14 is less susceptible to
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rotational displacement by inadvertent contact with the object
8. However, once it is fastened to the bone screw 12, the
sleeve 14 restricts rotation of the bone screw 12 such that
the clamp 20 could releasably secure the object 8 to the bone
screw 12 also. In the case of the embodiment shown in Figure
1, the bone screw 12 will not move much because of friction
between the nut 18 and sleeve 14 and between the nut 18 and
bone screw 12. To increase this friction, it is further
preferred for the threads on the first threaded end 22 to
differ from the threads of the second threaded end 24 thereby
further restricting rotation of the sleeve 14 and bone screw
12 about the longitudinal axis LA.
The object 8 shown in Figure 1 is a representation of a
tracking device, such as the tracking device disclosed in U.S.
Patent 5,834,759. The tracking device could be used, for
instance, to track the location of the bone 6 during image
guided surgery. It is understood that even though a tracking
device is shown as being the object 8 which the clamp 20
releasably secures to the sleeve 14, any type of object 8
could be used. In addition, it is understood that in some
cases, the object 8 may comprise a clamp 20 such that the
object 8 could be directly clamped to the sleeve 14.
Figures 2A, 2B, 2C and 2D show the device 10 being
inserted into a bone 6. As shown in Figure 2A, the sleeve 14
axially receives the bone screw 12. As also shown in Figure
2A, the clamp 20 is secured to the sleeve 14 at this step, but
could also be secured at a later step. As shown in Figure 2B,
a screw driver shaft 4 is used to screw the bone screw 12 into
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the bone 6 by rotating the bone screw 12 in the direction RS
about the longitudinal axis LA. It is apparent that
rotationally displacing the bone screw 12 the direction Rs will
cause the bone screw 12 to become axially displaced along the
longitudinal axis LA. Depending on the situation, a pilot hole
(not shown) could be drilled or drilled and tapped to assist
in rotating the screw driver shaft 4 and driving the bone
screw 12 into the proper location.
In Figure 2C, the bone screw 12 has engaged the bone 6
and has been screwed to the proper depth. At this time, the
nut 18 can be rotated about the threads 24. Rotation of the
nut 18 about the threads on the second threaded end 24 axially
biases the sleeve 14 towards the bone 6 and biases the
serrated teeth 16 into engagement with the bone 6. In this
way, the sleeve 14 is fastened to the bone screw 12 and the
serrated teeth 16 engage the surface of the bone 6 to restrict
rotation of the sleeve 14 about the longitudinal axis LA of the
device 10.
In Figure 2D, the device 10 is shown with the sleeve 14
and serrated teeth 16 biased towards the bone 6, and, the nut
18 having fastened the sleeve 14 to the bone screw 12. At
this time, the object 8 can be releasably secured to the
device 10 by means of the clamp 20. Releasably securing the
object 8 to the device 10 will axially and rotationally secure
the object 8 to the bone 6.
Figure 3A shows a further embodiment of the present
invention. As shown in Figure 3A, rather than having a sleeve
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14 as the rotation restricting member, a washer 25 is shown as
the rotation restricting member. The washer 25 has an opening
23 which axially receives the bone screw 12. As shown in
Figure 3A, the opening 23 receives the first threaded end of
the bone screw 12, which are generally the coarse threads 22
to engage the bone 6. The washer 25 also has serrated teeth
26 which act as the engaging element to engage the surface of
the bone 6. In this embodiment, a nut 28, which engages the
threads 22, acts as the fastening mechanism and biasing member
to axially bias the washer 25 towards the bone 6, thereby
biasing the serrated teeth 26 into engagement with the bone 6
and fastening the washer 25 to the bone screw 12 and fastening
the washer 25 to the bone 6. The clamp 20 could then be
attached to the washer 25.
Figure 3B shows a further embodiment of the present
invention where a retainer 38 is fixed to the bone screw 12.
The retainer 38 has a stop 36 which engages a portion 34 of
the sleeve 14. The sleeve 14 in the embodiment shown in
Figure 3B is similar to the sleeve 14 shown in Figure 1.
As the bone screw 12 is inserted into a bone 6, the stop
36 of the retainer 38 will engage the portion 34 of the sleeve
14, thereby axially biasing the sleeve 14 towards the bone 6
and bringing the serrated teeth 16 into engagement with the
surface of the bone 6. This embodiment shown in Figure 3B may
be used where the bone screw 12 must be inserted to a
particular depth before the sleeve 14 restricts further
rotation of the bone screw 12. This embodiment could be
advantageous where a surgeon does not desire the bone screw 12
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to be inserted past the predetermined depth in the bone 6 and
can control the predetermined depth by fixing the retainer 38
to a desired longitudinal position along the longitudinal axis
LA of the bone screw 12.
In a preferred embodiment, the retainer 38 is axially
adjustable so that the predetermined depth the bone screw 12
may be inserted is set by the surgeon before the procedure is
commenced. The retainer 38 could be axially adjusted, for
example, by having the retainer 38 threadably engage the bone
screw 12. In addition, if the retainer 38 is fixed to the
bone screw 12, washers or other elements can be placed between
the stop 36 and the portion 34 of the sleeve 14 to effectively
lower the longitudinal position at which the stop 36 will
engage the portion 34 of the sleeve 14.
If desired, the other embodiments of the invention may
also be adapted to be used to insert the bone screw 12 to a
particular depth before the sleeve 14 restricts further
rotation of the bone screw 12. For example, with respect to
the embodiment illustrated in Figure 1, the nut 18 could be
rotated to a longitudinal position on the bone screw 12 and
then the bone screw 12 could be inserted into the bone 6 a
predetermined distance until the sleeve engages the nut 18.
In the embodiment shown in Figure 1, however, the nut 18 may
rotate slightly as the bone screw 12 is rotated by the screw
driver shaft 4. To prevent this rotation, a thumb screw (not
shown) could be inserted into a perpendicularly threaded hole
(not shown) in the nut 18. The thumb screw (not shown) would
be preferably made from plastic and would engage the bone
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screw 12 to prevent rotation of the nut 18 and movement of the
nut 18 from the longitudinal position.
Figures 3C and 3D show a front view and side view,
respectively, of a further embodiment of the present
invention. The sleeve 14 shown in Figures 3C and 3D is
similar to the sleeve 14 shown in Figure 1. However, the
sleeve 14 shown in Figures 3C and 3D comprises a cam or
eccentrically mounted disc 42 connected to a locking lever 44.
The eccentrically mounted disc 42 and locking lever 44
together act as a locking mechanism, shown generally by
reference numeral 48.
The fastening mechanism 48 will also generally
rotationally and axially fasten the bone screw 12 to the
sleeve 14. This would better restrict rotation of the bone
screw 12.
As is apparent from Figures 3C and 3D, the fastening
mechanism 48 has a first or unlocked position shown in dashed
lines where the locking lever 44 is substantially parallel to
the longitudinal direction. In the first or unlocked
position, the sleeve 14 can move relative to the bone screw
12. Movement of the locking lever 44 from the first or
unlocked position towards the second or locked position, shown
in solid lines, will cause the cam or eccentrically mounted
disc 42 to engage the bone screw 12, thereby rotationally and
axially fastening the sleeve 14 to the bone screw 12. In
order to not obstruct the operative site, the locking lever 44
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is preferably removable so that it can be removed when the
locking mechanism 48 is in the locked or unlocked positions.
As the cam or eccentrically mounted disc 42 engages the
bone screw 12 when it is moved to the locking position, the
cam or disc 42 grips the bone screw 12 and will frictionally
forces the teeth 16 into the bone 6. Preferably, the sleeve
14 would be biased toward the bone 6 such that the teeth 16
engage the bone 6 when in the unlocked position. But the
motion of moving the lever 44 to the locked position
additionally biases the sleeve 14 towards the bone 6 by
gripping and pulling up on the bone screw 12. When the lever
44 is moved to the unlocked position, the biasing force would
be released.
Figure 3E shows an embodiment of the present invention
where a pin 54 is used as the rotation restricting member,
rather than the sleeve 14. As shown in Figure 3E, the pin has
a hole or opening 53 which can axially receive the bone screw
12.
Rather than having serrated teeth, such as serrated teeth
16 shown in Figure 1 to engage the surface of the bone 6, the
pin 54 has a tip 56, which is preferably somewhat sharp. The
tip 56 acts as the engaging element to engage the surface of
the bone 6 to restrict rotation of the pin 54.
As shown in Figure 3E, the fastening mechanism comprises
a nut 18, similar to the nut 18 shown in Figure 1. As shown
in Figure 3E, the nut 18 engages the second set of threads 24
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on the bone screw 12. It is also understood that a nut,
similar to the nut 25 shown in Figure 3A, could be used to
engage the first set of threads 22 in order to axially bias
the pin 54 towards the bone 6 so that the tip 56 engages the
bone surface.
Figure 3F shows a still further embodiment of the present
invention. In Figure 3F, the sleeve 14 is similar to that
shown in Figure 1. However, the fastening mechanism shown in
Figure 3F comprises a screw 58 which comprises threads 56
connected to the sleeve 14. The threads 56 are located upon
an axis Lp which is substantially perpendicular to the
longitudinal axis LA. As the screw 58 is rotated about the
substantially perpendicular axis LP, the screw 58 engages the
bone screw 12, thereby fastening the sleeve 14 to the bone
screw 12.
One difference between the locking mechanism 58 and other
locking mechanisms, such as the retainer 38 and the nut 18, is
that the locking mechanism 58 does not, in and of itself, act
to bias the sleeve 14 towards the surface of the bone 6.
Rather, the locking mechanism 58 shown in Figure 3F can fasten
the sleeve 14 to the bone screw 12 after the sleeve 14 and
serrated teeth 16 have been biased towards the bone 6, such as
by means of a separate tool or hammer, or, a surgeon pressing
the sleeve 14 towards the bone surface. After the sleeve 14 is
biased towards the bone 6 and the serrated teeth 16 have been
biased into engagement with the surface of the bone 6, the
screw 58 is rotated so that the sleeve 14 is fastened to the
bone screw 12. In either case, after the fastening mechanism
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58 has fastened the sleeve 14 to the bone screw 12, it is
understood that the serrated teeth 16 will be biased towards
the bone 6 and will engage the surface of the bone 6 so as to
fasten the sleeve 14 to the bone 6 and restrict rotation of
the sleeve 14 about the longitudinal axis LA.
Figure 3G shows a further embodiment of the present where
the bone screw 12 has internal threads 62 and the fastening
mechanism comprises a thumb-screw 68 having external threads
64. The external threads 64 engage the internal threads 62 to
axially bias the sleeve 14 towards the bone 6, thereby biasing
the serrated teeth 16 into engagement with the bone 6 and
fastening the sleeve 14 to the bone screw 12.
It is understood that while the invention describes the
object 8 being rotationally and axially secured to the bone 6,
this does not necessarily mean that a large force applied to
the object 8 or the bone screw 12 would not axially or
rotationally displace the object 8 with respect to the bone 6.
Rather, the device 10, and in particular the rotation
restricting member, such as the sleeve 14, washer 25 or pin
54, axially and rotationally secures the object 8 to the bone
6 better than a bone screw 12 used alone. Nevertheless, the
device according to the present invention would still be
susceptible to displacement by large external forces.
It is also understood that while the present invention
has been described in terms of a bone screw 12 to axially
secure the device 10 and object 8 to the bone 6, it is
understood that other types of axial supporting members could
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be used. For instance, a pin or nail (not shown), without
necessarily having threads 22, could be used as an axial
supporting member for axially securing the device 10 and the
object 8 to the bone 6. In addition, bone screws which do
not have coarse threads could also be used, such as for
insertion in a drilled and tapped hole. Accordingly, it is
understood that the present invention is not necessarily
restricted to use of a bone screw 12, but rather encompasses
other types of axial supporting members for axially securing
the device 10 and object 8 to the bone 6.
It is also understood that while the present invention
has been described in terms of a rotation restricting member,
such as a sleeve 14, a washer 25 or pin 54, the present
invention is not limited to these types of rotation
restricting members. Rather, the present invention
encompasses all types of rotation restricting elements that
can be biased towards the bone 6 after it is fastened to an
axial supporting member, such as a bone screw 12, such that an
engaging element, including serrated teeth 16, 26, can engage
the bone 6 to restrict rotation of the rotation restricting
member.
It is further understood that reference to a bone 6 is
not restricted to a particular bone. Rather, subject to
the discretion of a surgeon, the present invention couLd he
used in association with any bone or bone fragment within a
human being, an animal or a cadaver.
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It will be understood that, although various features of
the invention have been described with respect to one or
another of the embodiments of the invention, the various
features and embodiments of the invention may be combined or
used in conjunction with other features and embodiments of the
invention as described and illustrated herein.
Although this disclosure has described and illustrated
certain preferred embodiments of the invention, it is to be
understood that the invention is not restricted to these
particular embodiments. Rather, the invention includes all
embodiments which are functional or mechanical equivalents of
the specific embodiments and features that have been described
and illustrated herein.
