U.S. patent application number 11/331512 was filed with the patent office on 2006-06-15 for systems and methods for producing osteotomies.
Invention is credited to David A. McGuire.
Application Number | 20060129163 11/331512 |
Document ID | / |
Family ID | 27364002 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060129163 |
Kind Code |
A1 |
McGuire; David A. |
June 15, 2006 |
Systems and methods for producing osteotomies
Abstract
Systems and methods for producing minimally invasive osteotomies
to correct angular deformities of bones in and about the knee are
disclosed. A method includes locating a plane in which the angle
exhibited by the deformity is situated. An oblique cut is then made
along a surface of the bone, such that the cut is transverse to the
plane in which the angle is situated. Thereafter, the bone pieces
are rotated about the cut relative to one another until a desired
alignment between the bone pieces is achieved. To maintain the bone
pieces in alignment, a device having an elongated body for
extending into a tunnel between the bone pieces is provided. The
system also includes a rigid member fixedly positioned at one end
of the body. The rigid member is transverse to the body to engage
one bone piece. The system further includes a locking mechanism at
an opposite end of the body to engage the other bone piece. The
system permits the bone pieces to be pulled against one another
between the rigid member and the locking mechanism.
Inventors: |
McGuire; David A.;
(Anchorage, AK) |
Correspondence
Address: |
BROMBERG & SUNSTEIN LLP
125 SUMMER STREET
BOSTON
MA
02110-1618
US
|
Family ID: |
27364002 |
Appl. No.: |
11/331512 |
Filed: |
January 13, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10402826 |
Mar 28, 2003 |
7018383 |
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11331512 |
Jan 13, 2006 |
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09506714 |
Feb 18, 2000 |
6547793 |
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10402826 |
Mar 28, 2003 |
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|
08985568 |
Dec 5, 1997 |
6027504 |
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09506714 |
Feb 18, 2000 |
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60031989 |
Dec 6, 1996 |
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60063195 |
Oct 21, 1997 |
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Current U.S.
Class: |
606/102 |
Current CPC
Class: |
A61B 17/15 20130101;
Y10S 606/907 20130101; A61B 17/8891 20130101; A61B 17/683 20130101;
Y10S 606/916 20130101; A61B 17/66 20130101; A61B 17/0206 20130101;
A61B 17/171 20130101; A61B 17/151 20130101 |
Class at
Publication: |
606/102 |
International
Class: |
A61B 17/60 20060101
A61B017/60 |
Claims
1. A device for angle adjustment during an osteotomy of a bone, the
device comprising: a plurality of pins for engaging the bone a
support structure having a first portion and a second portion
wherein the first portion and the second portion are pivotally
attached such that pivoting may occur in only one plane wherein the
first portion is attached by a pin to the bone and the second
portion is attached by a pin to the bone; and an angle measurer
positioned between the first and the second portions to provide a
relative angle between the first and second portions.
2. A device according to claim 1, wherein the angle measurer is a
goniometer.
3. A device according to claim 1, further comprising: a locking
mechanism for restraining the first and second portions from
pivoting.
4. A device according to claim 3 wherein the locking mechanism
includes a protrusion from the angle measurer and a pin that passes
through the protrusion.
5. A device according to claim 1, wherein the first portion is
attached at a point above a point where the bone is to be separated
and wherein the second portion is attached at a point below where
the bone is to be separated.
6. A support for aligning bone pieces comprising: a first end to
which one bone piece is coupled, a second end to which another bone
piece is coupled, a point of pivot between the first and second
ends to move the bone pieces into alignment, and a device
positioned at the point of pivot to determine the angle of
alignment.
7. A support according to 6, wherein the support includes a frame
having two opposing members connected to one another at each of the
first and second ends.
8. A support according to claim 6, wherein the device is a
goniometer.
Description
RELATED U.S. APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 10/402,826 filed on Mar. 28, 2003, which is a
continuation of U.S. patent application Ser. No. 09/506,714 filed
on Feb. 18, 2000 which is a divisional application of U.S. Pat. No.
6,027,504 filed Dec. 5, 1997 which claims priority from U.S.
Provisional Application No. 60/031,989, filed Dec. 6, 1996 and from
U.S. Provisional Application No. 60/063,195, filed Oct. 21, 1997
which are all hereby incorporated herein by reference.
TECHNICAL FIELD
[0002] This invention relates to a device and method for producing
osteotomies in bones experiencing angular deformities, and in
particular osteotomies associated with angular deformities of the
femur and tibia.
BACKGROUND ART
[0003] Prior art methods for producing osteotomies to correct
angular deformity in a bone mass, such as a femur or tibia,
generally require making a large open incision around the deformed
site and cutting a wedge, at such site, completely across the
deformed bone mass, to initially form two bone pieces. Once the cut
has been made in the bone mass and the wedge removed, the bone
pieces may be realigned and the angle between the two bone pieces
adjusted for corrective purposes. However, because of the
invasiveness of the surgery, osteotomy procedures often result in
undesirable pain and extended period of immobility for the
patient.
[0004] In addition to a period of immobility, prior art methods for
producing osteotomies have allowed only minimal control of the bone
pieces once the bone mass has been divided. For example, as it may
be difficult to control the alignment between the two bone pieces
of the deformed bone, the correction of the angular deformity may
provide clinical results that are unpredictable. Also contributing
to the unpredictability of the clinical results is the difficulty
in maintaining the bone pieces in approximation after they have
been aligned. Moreover, current osteotomy procedures typically
involve application of a uniform corrective angle to the bone
pieces, regardless of the individual. As individuals vary in
height, weight and age, a slight difference in the angle of a
deformed bone mass can cause a measurable difference in contact
pressure between the articular surfaces of a deformed bone mass and
another bone mass (e.g., between a deformed tibia and a femur). A
uniform change in the angle of the deformed bone mass for different
individuals, therefore, may not result in a sufficient change in
the contact pressure between the articular surfaces of the bones,
so as to avoid future degenerative problems.
[0005] Accordingly, there is a need for a method that produces
osteotomies in a minimally invasive, predictable, and measurable
manner, in addition to being individualized and reliable, so that
the procedure may be performed at an early stage in the course of
the disease. Such a method would permit avoidance of severe
degenerative changes that frequently accompany current methods for
producing osteotomies.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to systems and methods for
producing minimally invasive osteotomies to correct angular
deformities of bones in and about the knee. The method of the
present invention is accurate, reliable, predictable, measurable,
controllable and reproducible. As hereinafter provided, the method
is discussed in association with femoral and/or tibial osteotomies.
However, it should be appreciated that the method has applications
for other bones beyond those bones about the knee.
[0007] In accordance with one embodiment of the present invention,
the method for producing osteotomy in a first bone having an angle
of deformity includes drilling a tunnel through a surface of a
first bone at an area about the angular deformity, such that the
tunnel drilled is transverse to a plane in which the angle is
situated. Next, an oblique cut is made partially across the bone on
a surface that is parallel to the tunnel, so as to provide a cut
that is at an angle to the tunnel. In an embodiment of the
invention, the angle of the cut is such that when the bone is
realigned, the contact pressure between an articular surface of the
first bone and an articular surface of a second bone approaches a
desirable ratio within a physiologic tolerance. Once the cut is
partially made across the first bone, the first bone is secured
about the cut, for instance, by placing through the tunnel a device
which permits bone pieces of the first bone, once the first bone is
completely cut, to be maintained in approximation. The amount of
angular correction is then determined so that the contact pressure
between the first and second bone may be brought to within
physiological tolerance. In accordance with an embodiment of the
invention, the angular correction is determined by measuring
intra-articular pressure between the contact surfaces of the first
and second bones. After the amount of angular correction has been
determined, the cut is completed across the first bone to form two
bone pieces. The bone pieces are then rotated relative to one
another about the tunnel, so as to be brought into an alignment
which brings about the desirable contact pressure between the first
and second bones. The bone pieces are subsequently secured against
one another to maintain alignment and close approximation.
[0008] In an embodiment of the present invention, the bone pieces
are maintained in approximation by the use of a bone anchor
assembly having an elongated body for extending across a juncture
between the bone pieces. The elongated body includes a distal end
and a proximal end. A rigid member is fixedly positioned at the
distal end transverse to the body for engaging one bone piece. A
locking mechanism is also provided at the proximal end of the body
for engaging the other bone piece. To this end, the bone pieces may
be pulled against one another between the rigid member at the
distal end and the locking mechanism at the proximal end of the
device.
[0009] Prior to drilling the tunnel through the deformed bone, a
support structure of the present invention is preferably affixed
along a surface of the deformed bone adjacent the angular
deformity. The support structure is designed so that one end
attaches to a first end portion of the bone, and an opposite end
attaches to a second end portion of the bone. The support structure
is also pivotally movable at an area between its ends. In this
manner, once the bone pieces are formed, the support structure may
maintain the bone pieces close to one another, so that they may
subsequently be pivoted into alignment. To secure and maintain the
bone pieces in approximation after alignment, a bone anchor
assembly of the present invention is positioned through the tunnel
and tightened against the bone pieces.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIGS. 1A-D illustrate an angularly deformed femur having a
plurality of holes formed in accordance with embodiments of the
present invention, and having subcutaneously insertable pins
situated within the holes.
[0011] FIGS. 2A-D illustrate a separating device for use in the
formation of the holes illustrated in FIGS. 1A-D.
[0012] FIGS. 3A-D correspond to FIGS. 1A-D respectively and further
showing a support structure positioned along the anterior surface
of the femur.
[0013] FIGS. 4A-D correspond to FIGS. 3A-D respectively and further
showing a saw guide attached to the lateral surface of the
femur.
[0014] FIG. 5 illustrates one embodiment of a saw guide for use
with the present invention.
[0015] FIG. 6A is a top view of the saw guide of FIG. 5 positioned
against the femur in the manner shown in FIGS. 4A-D.
[0016] FIG. 6B shows a saw blade with a stop for use with the
present invention.
[0017] FIG. 6C shows the saw blade of FIG. 6B in use with the saw
guide of FIG. 6A.
[0018] FIGS. 7A-B illustrate a femur having a bone anchor extending
across a cut made by the saw and guide of FIGS. 5 and 6A-C.
[0019] FIGS. 8A-D show a bone anchor in accordance with one
embodiment of the present invention.
[0020] FIG. 8E is a bone anchor shown in FIGS. 8A-D extending
through a femur.
[0021] FIGS. 9A-B illustrate a femur having been corrected of its
angular deformity.
[0022] FIGS. 10A-B show the femur of FIGS. 9A-B with additional
bone anchors.
[0023] FIGS. 11A-B illustrate the end results of a corrected femur
of FIGS. 10A-B.
[0024] FIG. 12A illustrates a knee with a pressure transducer
portion therein.
[0025] FIG. 12B shows the pressure transducer shown in FIG.
12A.
[0026] FIGS. 12C-D illustrate a knee having a cannula and trocar
inserted through a lateral portal and a grasper inserted through a
medial portal.
[0027] FIG. 13A shows an embodiment of a tunnel for use with a bone
anchor in accordance with one embodiment of the present
invention.
[0028] FIG. 13B illustrates a method for forming a tunnel in FIG.
13A through a femur.
[0029] FIG. 13C shows a modified goniometer for forming tunnel
shown in FIG. 13A.
[0030] FIGS. 14A-B show alternate embodiments of a guide for
forming a bone anchor tunnel. FIG. 14A shows a longitudinal view,
as well as a series of cross-sectional views illustrating
progressively smaller inner diameters, in accordance with an
embodiment.
[0031] FIG. 14B is a cross-sectional view of another guide
embodiment illustrating parallel contiguous inner passageways.
[0032] FIGS. 14C-D illustrate other embodiments of a guide for
forming a bone anchor tunnel.
[0033] FIG. 15A shows a bone anchor in accordance with another
embodiment of the present invention.
[0034] FIG. 15B is a end view of the tunnel formed in FIG. 13A
having the device in FIG. 15 extending therethrough.
[0035] FIGS. 16A-C show a bone anchor in accordance with a further
embodiment of the present invention
[0036] FIG. 17 shows a driver for use with the device shown in
FIGS. 16A-C.
[0037] FIG. 18 illustrates a guide for forming multiple bone anchor
tunnels in accordance with an embodiment of the present
invention.
[0038] FIGS. 19A-D illustrate a tibial osteotomy in accordance with
an embodiment of the present invention.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0039] A preferred embodiment of the invention herein provides a
device and method for producing minimally invasive osteotomies in
and about the knee. In accordance with this embodiment, an
osteotomy permits accurate, precise and controllable correction of
angular deformities in bones about the knee, such that the amount
of trauma typically associated with osteotomy is lessened. In order
to provide an overall understanding of the present invention, the
embodiments of the method of the invention will be discussed with
reference to the embodiments of the devices of the invention.
However, it will be understood by persons of ordinary skill in the
art that embodiments of the invention are applicable to the
production of osteotomies of other bones within the body.
[0040] There are two common types of angular deformities usually
associated with the femur and tibia, valgus deformity and varus
deformity. In either of these conditions, the angular deformity
causes a deviation in the amount of contact pressure produced
within the intra-articular space between the femur and the tibia,
leading to degeneration of the knee joint. In general, valgus
deformity, otherwise known as knock-kneed deformity, can be
corrected by performing a femoral osteotomy to reduce the
relatively high contact pressure between the lateral femoral
condyle and the lateral tibial plateau, and increasing the
relatively low contact pressure between the femoral medial condyle
and the medial tibial plateau. Varus deformity, otherwise known as
bow-legged deformity, on the other hand, can be corrected by
performing a tibial osteotomy to reduce the relatively high contact
pressure between the medial tibial plateau and the medial femoral
condyle, and increasing the relatively low contact pressure between
the lateral tibial plateau and the lateral femoral condyle.
[0041] With reference now to femoral osteotomy, FIGS. 1A-D
illustrate a femur 10 having an angular deformity 111 near its
patellar surface 16. In FIG. 1A, sets of holes 12 and 14 are shown
formed on the anterior surface of the femur 10 relative to the
angular deformity 11. Holes 12 are formed near an end adjacent the
patellar surface 16 and substantially parallel to the medial and
lateral border of the patella 18. Holes 14, on the other hand, are
formed toward an opposite end of the femur 10 relative to the
deformity 11 and away from holes 12. Holes 12 and 14 establish
sites at which subcutaneously insertable pins 19 may be placed for
subsequent attachment of a femur support structure necessary for
producing an osteotomy in accordance with an embodiment of the
present invention. In a preferred embodiment, FIG. 1C shows one
hole 12 and one hole 14 formed on the lateral surface of the femur
10. Hole 12 is formed toward the patellar surface 16 and is
positioned substantially in the middle of femoral
anterior-posterior diameter A-P. Hole 14, on the other hand, is
positioned distal to hole 12 and sufficiently clear of an osteotomy
site to be formed, so as not to interfere therewith. The use of a
single hole, rather than a set of holes, may be desirable as there
is less stripping and thus less damage to the soft tissue
surrounding the femur 10.
[0042] Referring now to FIGS. 2A-D, a device 20 is shown for
exposing the underlying femur 10 of FIGS. 1A-D from the periosteum
(i.e., soft tissue) that overlies the femur prior to producing
holes 12 and 14. In accordance with an embodiment of the present
invention, the device 20 includes an elongated body 21 having a
first end 22 and a second end 23. The device also includes a
spreading mechanism 24 located at the first end 22 of the body 21.
The spreading mechanism 24, from the bottom view in FIG. 2B, is
substantially cylindrical in cross-section, and includes four
similarly shaped members 25. Each of the members 25 terminates in a
sharp end 26, so as to allow the mechanism 24 to penetrate the soft
tissue without the need for an incision or dissection of the soft
tissue. A sheath 27, disposed about the spreading mechanism 24, is
preferably bivalved so that it may conform to the spreading
movement of the mechanism 24. The separating device 20 further
includes actuating handles 28 located at the second end 23 of the
body 21. After the mechanism 24 has penetrated the soft tissue, the
handles 28, as shown in FIG. 2C, may be moved in the direction L of
the arrow toward one another to spread the members 25 apart.
Spreading the members 25, in the manner shown in FIG. 2D, causes
spreading of the overlying soft tissue so as to expose the
underlying femur 10. If necessary, a trocar (not shown) may be
introduced into the newly created spread area so that subsequently
a larger bivalve sheath may be inserted therein. The larger bivalve
sheath in turn will allow progressive dilation of the soft tissue
without the need for an incision into the soft tissue. Once the
underlying femur 10 is exposed, a conventional surgical drill can
be used to produce holes 12 and 14.
[0043] Referring again to FIGS. 1A-D, while FIG. 1A illustrates a
set of two holes 12 and a set of two holes 14, a single hole can be
provided in lieu of the set of holes 12 substantially between and
slightly below the holes 12 in FIG. 1A. Alternatively, or in
addition, a single hole may be utilized in lieu of the set of holes
14, positioned in the vicinity of such holes. Subcutaneously
insertable pins 19 may be inserted into holes 12 and 14, as shown
in FIGS. 1B and 1D. Pins 19 may be threaded so that they can be
securely positioned within holes 12 and 14. Likewise, holes 12 and
14 may be complementarity threaded to receive threaded pins 19.
[0044] With the subcutaneously insertable pins 19 in place, looking
now at FIGS. 3A-D, a support structure 30 may be affixed to the
femur 10 via each of the pins 19. The support structure 30 is
affixed in such a manner so that subsequent to the formation of two
bone pieces during the osteotomy (discussed below), the bone pieces
may be maintained in a desired alignment in close proximity to one
another. Otherwise, it may be difficult to correct the angular
deformity and to secure the bone pieces to one another. The support
structure 30 includes a first portion 301 positioned away from the
patellar surface 16 and a second portion 302 positioned adjacent
the patellar surface 16. The first portion 301 and second portion
302 are mounted so as to pivot in the plane X-X in FIGS. 3B and 3D,
but to preclude any substantial movement outside of the plane
X-X.
[0045] With particular reference now to FIGS. 3C-D, when the pins
are situated on the lateral surface of the femur 10, the support
structure 30, in accordance with a preferred embodiment of the
invention, includes bars 35. Bars 35 are designed to extend at a
substantially right angle from the upper and lower portions of the
support structure 30 along the lateral surface of the femur 10, so
that the bars 35 may be coupled to the pins 19. The support
structure 30 shown in FIGS. 3C-D may also include a releasable
locking mechanism (not shown) at the intersection between the bars
35 and the first and second portions 301 and 302 to provide
rigidity to the support structure 30. If additional rigidity is
desired, pins 19 may also be placed on the medial surface of the
femur 10 opposite the pins 19 on the lateral surface, and the
support structure 30 provided with additional bars 35 along the
medial side for attachment to those pins 19.
[0046] To accurately control the alignment of bone pieces during
the osteotomy, a goniometer 34 is positioned between the first
portion 301 and the second portion 302 of support structure 30 to
provide an accurate read out of the relative angle between the
upper and lower portions. The preferred goniometer 34 is configured
in such a manner that precise corrections to tenths of a degree or
less may be achieved.
[0047] Once the support structure 30 has been affixed to the femur
10, the osteotomy may be performed in a number of ways. In one
embodiment, a central tunnel 36, as shown in FIGS. 3B and 3D, is
first drilled through the femur 10 near an approximate vertex of
the angle exhibited by the deformity 11 and in a direction that is
transverse to the plane in which such angle is situated. The tunnel
36 may be formed through opening 70 in the goniometer 40 by using a
cannulated coring reamer (not shown) similar to that disclosed in
U.S. patent application Ser. No. 08/475,015, entitled "Coring
Reamer", filed Jun. 7, 1995, now U.S. Pat. No. 5,865,834, issued
Feb. 2, 1999, in the name of the present inventor, and which is
hereby incorporated herein by reference. When using the cannulated
coring reamer, a guidewire may be placed in the femur 10 to
facilitate the drilling of the tunnel 36. Additionally, the
goniometer 34 may be placed at a sufficient distance from the femur
10 so that when the coring reamer moves through opening 70 and into
the femur 10, the goniometer 34 may act as a guide to allow a
substantially straight tunnel 36 to be drilled. A conventional
drill (not shown) with a drill bit may also be used to form tunnel
36 through opening 70 in a similar manner. To guard against damage
to the soft tissue surrounding the posterior surface of the femur,
the coring reamer and the drill may be equipped with a stop (not
shown) to limit the distance beyond which they can extend from the
posterior surface of the femur. The tunnel 36 created in this
embodiment is preferably substantially cylindrical in shape, and is
intended for use with a suitable bone anchor (discussed below),
such as shown in FIGS. 8A-8E, FIGS. 15A-B and FIGS. 16A-C.
[0048] Referring now to FIGS. 14A-D, to facilitate drilling of a
substantially cylindrical tunnel 36, a rigid cylindrical guide 145,
shown in FIG. 14A may be provided. Guide 145, in one embodiment, is
provided with an outer diameter 1451 that is substantially similar
to that of opening 70 in goniometer 34, and an inner diameter 1452
that is substantially similar to the diameter of the coring reamer
or drill bit. If there arises a need to increase or decrease the
diameter of the tunnel 36, a set of cylindrical guides 145 may be
provided, whereby each guide would have the same outer diameter
1451, but a different inner diameter 1452 to match the diameter of
the tunnel 36 to be created.
[0049] In a related embodiment of the present invention, tunnel 36
may be modified, as shown in FIGS. 13A-B to include a pair of
parallel contiguous passageways 130 on opposite sides of the tunnel
to accommodate another style of bone anchor described below, such
as illustrated in FIGS. 15A-15B and 16A-16C. To form passageways
130, a second reamer 131 having a diameter substantially smaller
than the diameter of the cannulated coring reamer is used. The
second reamer 131, like the coring reamer, may be cannulated for
use with a guidewire. A first passageway 130 may be formed by
placing the second reamer against an edge on one side of tunnel 36
(FIG. 13B) and pushing the second reamer through the femur 10 along
the entire length of the tunnel. In order to place the second
reamer against an edge of the tunnel 36, it should be appreciated
that opening 70 in goniometer 34 may need to be modified so that
its profile matches that of tunnel 36 shown in FIG. 13A. The
opening 70, therefore, may be provided with widened areas 132,
shown in FIG. 13C, to accommodate the second reamer when it is
introduced along the sides of tunnel 36. After one passageway is
formed, a second passageway 130 may then be formed along an
opposite side of the tunnel 36 by placing the second reamer through
the other widened area 132. The passageways 130 are formed so that
each intersects or overlaps with an edge of the tunnel 36.
[0050] The passageways 130 along opposite sides of tunnel 36 may
also be formed by using a reamer or drill bit in combination with a
rigid cylindrical guide 146, illustrated in FIG. 14B. Cylindrical
guide 146, in accordance with a preferred embodiment of the
invention, includes an outer diameter 1461 that is substantially
similar to that of the opening 70 in the goniometer 34, and an
inner profile 1462 that includes widened areas 1463 on opposite
sides of a central opening 1464. To form passageways 130 using
guide 146, a cylindrical guide 145 with an inner diameter 1452
sufficiently sized to accommodate a bone anchor may initially be
used to form a cylindrical tunnel 36. Thereafter, the cylindrical
guide 145 is removed from the opening 70 and replaced with the
guide 146. Guide 146 preferably includes a profile wherein the
central opening 1464 is similar in diameter to the cylindrical
tunnel 36 just created, and wherein the widened areas 1463 extend
radially from the central opening. By way of example, if the
goniometer 34 is provided with an opening 70 having a diameter of
about 10 millimeters to about 12 millimeters (mm), the cylindrical
guide 145 preferably includes an inner diameter 1452 for forming a
tunnel that is about 6 mm to about 8 mm in diameter, and the guide
146 should have an inner profile 1462 with a central opening 1464
that is about 6 mm and widened areas 1463 that extend radially
about 1 mm to about 2 mm on each side of the central opening 1464.
Once the guide 146 is in place, passageways 130 may be formed by
drilling through the widened areas 1463. In an embodiment of the
invention, the passageways 130 are formed so that they aligned
longitudinally along a central axis C of the femur 10, such as that
shown in FIGS. 13A and 15B. To ensure that the passageways 130 are
directly opposite one another, guide 146 must be prevented from
rotating from its original position after the formation of one
passageway 130. To this end, the guide 146 may be configured to
include at least one protrusion 1465 on its outer diameter 1461,
and the goniometer 34 may be configured to include at least one
slot 75, as shown in FIGS. 3A and 3D, abutting the opening 70 to
receive the protrusion 1465. Of course, the passageways 130 may be
formed so that they are through to the axis C. The slot 75, in this
embodiment, would then be moved to a position shown in FIG. 4C to
accommodate the protrusion 1465.
[0051] Substantially straight passageways 130 may also be formed
along opposite sides of tunnel 36 by employing a guide 140, shown
in FIGS. 14C and 14D. The guide 140 includes a distal portion 142
to be inserted into tunnel 36. The distal portion 142 preferably
has a width substantially similar to the diameter of tunnel 36. In
this manner, guide 140 can snugly fit within tunnel 36. The guide
140 further includes an optional sleeve 144 axially attached to the
distal portion 142. The optional sleeve 144 is provided with at
least two (2) opposing channels 141, so as to guide a reamer or
drill bit alongside the tunnel 36. If desired, additional opposing
channels may be provided circumferentially about the sleeve 144, so
as to decrease the amount of rotational alignment needed for
drilling the passageways. Extending posteriorly from the sleeve 144
is an elongated proximal portion 148, which terminates in a stop
149. The stop 149 may include holes 147 corresponding in number and
in alignment with channels 141. The proximal portion 148 and stop
149 provide a surgeon with a place to hold and maneuver the guide
140 into the tunnel 36. If desired, the elongated proximal portion
148 may be removably attachable to the sleeve 144. Alternatively,
the elongated proximal portion 148 may be made integral with sleeve
144. Once the guide 140 is in place, a reamer or drill bit may be
introduced through a hole 147 in the stop 149, through a channel
146 in sleeve 144, and along the proximal portion 148 to drill a
substantially straight passageway 130. The optional sleeve 144 with
channels 146 facilitate alignment of the drill parallel with that
of bone tunnel 36. Guide 140 may also include a protrusion, similar
to protrusion 1465 in guide 146, for mating with a slot 75 in the
goniometer 34 to insure that the passageways 130 are substantially
opposite to one another when being drilled.
[0052] Subsequent to the formation of the tunnel 36, a saw guide 40
may be positioned against a lateral surface of the femur 10 and
attached to the support structure 30 (FIGS. 4A-4D). The attachment
of the saw guide 40 to the support structure 30 may be accomplished
using a clamping mechanism 45 or other means known in the art. Once
secured, the saw guide 40 permits a fast and accurate cut to be
made across the width of the femur 10. The saw guide 40, shown in
FIG. 5, includes opposing concave surfaces 42 and 43. The concave
surfaces are designed so that surface 42 may engage the femur 10
(FIGS. 6A and 6C), while surface 43 may guide a cutting blade along
a path defined by its concave surface. A slot 44 extends from
concave surface 43 to concave surface 42 and is positioned
diagonally across the guide 40. As illustrated in FIG. 4B, when the
saw guide 40 is situated against the lateral surface of the femur
10 adjacent the angular deformity, the slot 44 extends from a
proximal portion 46 of the femur to a distal portion 48 and lies
diagonally from the anterior surface A to posterior surface P of
the femur 10. In this manner, a predictable, and relatively
ellipsoidal arc, similar to surface 43, can be produced on the
medial surface of the femur 10 when a cut is made obliquely along
the lateral surface. The saw guide 40 is intended for use with a
horizontally situated oscillating blade 60 (FIG. 6B). Blade 60 is
preferably designed with a rounded portion. The rounded portion on
blade 60 allows the femur 10 to be cut, as shown in FIG. 6C,
without the need to strip the periosteum (i.e., soft tissue) from
all sides of the femur 10 (FIG. 6A). The blade 60 is also provided
with a stop 62, which conforms to concave surface 43 of the saw
guide 40, to accurately control the distance the blade 60 extends
once it has penetrated through the femur 10. The ability to control
the extension distance prevents tissue on the other side of the
femur from being damaged by the blade 60. The stop 62, when used in
combination with the blade 60, allows for controllable extension of
the blade 60 to a distance of a millimeter or less from the
opposite side of the femur 10. In one embodiment, the blade 60 is
detachable and adjustable, for example, by means of a set screw, so
that the depth of the cut may be further controlled and precisely
varied. The ability to precisely control the cutting depth obviates
the possibility of injury to medial structures, even though the
periosteum (i.e., soft tissue) is not stripped. If desirable, prior
to cutting the femur 10, a depth gauge may be used as a tap so that
holes may subsequently be drilled through the femur 10 sequentially
from the proximal anterior position to the distal posterior
position along the slot 44 of the saw guide 40. This procedure will
allow for a very precise measurement of the ellipsoidal arc.
[0053] Referring now to FIGS. 7A and 7B, after the tunnel 36 has
been formed, an oblique cut may be made through the slot 44 of the
saw guide 40, shown in FIG. 7B. The oblique cut is preferably made
on a surface of the femur 10 which is parallel to the tunnel 36. In
the present illustration, the cut is made on the lateral surface of
the femur 10. The oblique cut is initially formed partially across
the femur 10, from the posterior surface P toward the anterior
surface A. In a preferred embodiment, the cut extends from
approximately 2/3 to approximately 3/4 of the way across the width
of the femur 10.
[0054] Once the initial partial cut has been made, a bone anchor
assembly for maintaining the bone pieces in approximation may be
placed through the tunnel 36 and loosely secured therein. In one
embodiment of the present invention, when a tunnel similar to
cylindrical tunnel 36 (FIGS. 3B and 3D) is formed in the femur 10,
a bone anchor assembly 72, as shown in FIGS. 8A and 8B, is
employed. The bone anchor 72 includes an elongated body 73 for
placement through the cylindrical tunnel 36. The bone anchor 72
further includes a pivoting member 74 situated at a first end 75 of
the body 73 and a threaded portion 76 located at the second end 77
of the body 73. In its non-deployed position in FIGS. 8A and 8B,
the pivoting member 74 extends from the first end 75 and is axially
aligned to the body 73. The pivoting member 74, after being
introduced through opening 70 in goniometer 34 and into the tunnel
36, is capable of being deployed into a position transverse to the
body 73 (FIGS. 8C-E) to act as an anchor against the posterior
surface P of the femur 10. Once the bone anchor 72 is deployed, the
threaded member 76 on the body 73 preferably remains extended from
the anterior surface A of the femur 10. In this manner, a
complementarity threaded member 78, for example, a washer, may
engage the threaded portion 76 to form a locking mechanism to
secure the bone anchor against the bone pieces. Of course other
locking mechanisms may be provided so long as they remain capable
of securing the bone anchor within the tunnel while maintaining the
bone pieces in close approximation. Prior to placing the bone
anchor 72 through the tunnel, a rigid sleeve 79 may be provided
extending along the length of the tunnel 36. The sleeve 79, in one
embodiment, includes a substantially smooth interior surface, so
that it may act as a lining along which the bone anchor 72 can
easily slide through the tunnel 36 without interference from loose
tissue which may be present in the tunnel. In addition, the sleeve
79 assures a close and precise fit within the tunnel 36 so that
translation of the bone pieces, often associated with other
osteotomy procedures, may be avoided. The sleeve 79 may also be
used to provide rigidity to the tunnel and a limit to the
compression experienced by the bone when the anchor assembly is
securely tightened in place.
[0055] In another embodiment of the invention, looking now at FIGS.
15A-B, when a tunnel is formed with opposing passageways 130, a
bone anchor 152 is employed. The bone anchor 152, in a preferred
embodiment, includes an elongated body 153 for placement through
the tunnel 36. The bone anchor 152 further includes a cross member
154 situated at a first end 155 of the body 153, and a threaded
portion 156 at a second end 157 of the body 153. This design is
similar to that of FIGS. 8A and 8B, except that the cross member
154 is configured in fixed relation to the body 153, whereas in
FIGS. 8A-B, the corresponding member 74 is pivoted. The cross
member 154 is transverse to the body 153 so as to act as an anchor
against the posterior surface P of the femur 10. This embodiment of
a bone anchor is used in connection with the tunnel configuration
discussed above in connection with FIGS. 13A-C and 14A-D, and is
inserted as illustrated in FIG. 15B. Prior to placing the bone
anchor through the tunnel 36, shown in FIG. 15B, a rigid sleeve
(not shown) having a cross-sectional profile similar to that of
tunnel 36 is placed within the tunnel. This rigid sleeve, similar
to rigid sleeve 79, acts as a lining along which the bone anchor
152 can easily slide through the tunnel 36 without interference
from loose tissue within the tunnel. The sleeve may also act to
provide rigidity to the tunnel and to limit the compression
experienced by the bone when the bone anchor 152 is securely
tightened in place. To place the bone anchor 152 through the tunnel
36, the distal end 155 of the bone anchor is initially positioned
so that the cross member 154 spans from one passageway 130 to the
opposing passageway 130. Thereafter, the cross member 154 may be
pushed through the tunnel, along the rigid sleeve, toward the
posterior surface P of the femur 10, as shown in FIGS. 8E and 15B.
Once the cross member 154 extends from the tunnel 36 and
passageways 130, the bone anchor 152 may be rotated in either a
clockwise or counterclockwise direction so that the cross member
154 becomes offset from the opposing passageways 130. In one
embodiment, the cross member 154 may be positioned at approximately
ninety degrees to the passageways 130, as illustrated in FIG. 15B.
The cross member 154 is then pulled against the posterior surface P
of the femur 10. To secure the cross member 154 in place, the
threaded portion 156 of the bone anchor 152 preferably remains
extended from the anterior surface of the femur 10 so that a mating
internally threaded member 158 may engage the threaded portion 156
to form a locking mechanism through the tunnel 36 to secure the
bone anchor 152 against the bone pieces. Spikes or protrusions 159
may be provided on cross member 154 so as to dig into the posterior
surface P of the femur 10. In this manner, the cross member 154 may
securely act as an anchor against the posterior surface P of the
femur 10.
[0056] In a further embodiment of the invention, looking now at
FIGS. 16A-B, bone anchor 162 is modified from that shown in FIG.
15, so that its elongated body 163 does not extend beyond the
tunnel 36. To secure such a modified bone anchor within tunnel 36,
bone anchor 162, in an embodiment, is designed so that the
elongated body 163 is threaded to receive a complementary threaded
member 168. Threaded member 168, as shown in FIG. 16B, is capable
of extending into the tunnel 36 and over the body 163. The threaded
member 168, as shown in FIG. 16B, is preferably provided with a
flared end 169 to engage the anterior surface A of the femur 10. In
addition, the threaded member 168 preferably includes a diameter
which approaches that of the tunnel 36. In this manner, the
threaded member 168 allows the bone anchor 162 to securely engage
against the bone pieces. The threaded member 168 also preferably
includes a recess 167 for receiving a driver 170, such as an allen
wrench, designed to rotate the threaded member 168 onto the
elongated body 163. Recess 167 may be of any shape for sufficiently
receiving a complementary-shaped driver 170. In a preferred
embodiment of the invention, recess 167, as shown in FIG. 16C, and
driver 170 are hexagonal in shape. A sleeve 1601 may also be
provided extending along the entire length of the tunnel to provide
rigidity to the tunnel 36.
[0057] Referring now to FIG. 17, driver 170 includes retractable
teeth 172 at its distal end for engaging recess 167 of member 168.
The teeth allow the member 168 to be maintained on the driver 170
when the member is being maneuvered into the tunnel 36 and rotated
onto the elongated body 163. Once the member 168 is securely
tightened about elongated body 163, the teeth 172 may be retracted,
for example, by a switch (not shown) on the driver, and the driver
170 removed from the tunnel 36.
[0058] The bone anchor, in the illustrated embodiments, may be
cannulated to receive a guidewire so as to facilitate the placement
of the bone anchor through the tunnel 36. The driver for placing
the threaded member onto the elongated body of each bone anchor may
also be cannulated. In addition, because the bone anchor must come
in contact with biological tissue and must be sufficiently strong,
so as to maintain the bone pieces in approximation, it is
preferable that the bone anchor be made from a biocompatible
material, for instance, stainless steel or plastic. The bone anchor
may also made from a bioabsorbable material, for instance
polylactic acid (PLA).
[0059] The angle of the correction on the femur 10 may next be
determined. Looking now at FIGS. 12 A-D, in accordance with one
embodiment of the present invention, intra-articular pressure
between the femur 10 and the tibia may next be measured by using a
pressure transducer 120. In general, intra-articular pressure
between the femur and the tibia tends to vary from individual to
individual and is often dependent on the height, weight and age of
the individual. To this end, the employment of a pressure
transducer allows for variations in individual characteristics to
be taken into account, so that, for each particular individual, a
more precise cut angle can be made on the femur 10. Otherwise, the
cut may be inappropriate, and may result in a bone alignment that
is insufficient to reduce the intra-articular pressure between the
femur and the tibia. According to an embodiment of the invention,
the angle of the cut determined from intra-articular pressure
measurements preferably allows pressure applied by the femur on its
lateral femoral condyle and medial femoral condyle to substantially
approach a desired ratio within a physiologic tolerance, once the
correction has been made.
[0060] The pressure transducer 120, in a preferred embodiment of
the invention, is a TekScan pressure transducer, manufactured by
TekScan Inc. of Boston, Mass. Pressure transducer 120 includes a
sensing tip 1201 and a body 1202 along which measurement
information may be transmitted to a reading display (not shown).
Looking now at FIGS. 12C and 12D, to measure the contact pressure
within the intra-articular space of, for example, a right knee 122
of an individual, in one embodiment of the invention, a cannula 123
is first introduced through a lateral portal 124, such that its
proximal end 1230 remains on the exterior of the knee 122. The
cannula 123 is preferably hollow to receive a trocar 125. Once the
cannula 123 is in place, the pressure transducer 120 may be
introduced into the knee 122 by first maneuvering its sensing tip
1201 through the proximal end 1230 of the cannula 123, then pushing
the body 1202 medially along the cannula using the trocar 125. A
grasper 126 is next introduced through a medial portal 127 to pull
the pressure transducer 120 from the cannula 123 into the knee. The
sensing tip 1201 of pressure transducer 120, looking again at FIG.
12A, may subsequently be positioned about the lateral aspect of the
knee, for example, under the lateral femoral condyle 128. Once in
position, the lateral condyle 128 is made to press down onto the
sensing tip 1201, in order to measure the contact pressure thereat.
The sensing tip 1201 is then maneuvered to the medial aspect of the
knee, for example, under the medial femoral condyle 129, and the
contact pressure again measured. By measuring the contact pressure
along at least two points within the intra-articular space, for
example, the lateral and medial condyles, a cut may subsequently be
made across the femur 10, such that after realignment of the bone
pieces, the intra-articular pressure about the lateral and medial
aspects of the knee joint substantially approaches a desirable
ratio within a physiologic tolerance.
[0061] Although the present invention contemplates the use of the
pressure transducer in order to determine the angle of correction,
it should be appreciated that other methods may also be employed.
Examples include but are not limited to, radiographic means, visual
means, MRI, laser, and bone scans. These and other similar
visualization methods are adequate, so long as they permit the
actual amount of correction in the deformed bone to approach a
physiologic tolerance.
[0062] Once the contact pressure has been determined, saw blade 60
may be inserted into the slot 44 of guide 40, and into the partial
oblique cut on the femur 10 at a position distal to the loosely
secured bone anchor, for instance, bone anchor 162. The partial
oblique cut is then completed across the femur 10 to form two bone
pieces. It should be appreciated that each of the resulting bone
pieces includes a portion of the tunnel 36, and is held in position
relative one another by the bone anchor and the support structure
30. Looking now at FIG. 9A, the bone pieces may be pivoted relative
to one another about the bone anchor 162 by the precisely geared
goniometer 34 until a desired angle of alignment is reached, for
instance, an angle which conforms to the amount of correction
previously determined. In this manner, a precise degree of
correction and alignment between the bone pieces may subsequently
be achieved. Once the correction and alignment have been obtained,
the bone anchor 162 is tightly secured against the femur 10 at cut
71 (FIG. 9B), so that the bone pieces may be pulled against one
another. The bone anchor 162, when secured through the tunnel 36,
acts to pull the bone pieces in a direction transverse to the cut
71 so that the bone pieces may remain in approximation and
alignment. Although reference has been made to the bone anchor 162,
it should be understood that bone anchors 152 or 72 may also be
used.
[0063] To ensure that alignment between two bone pieces is
maintained and no subsequent translational movement will occur,
multiple bone anchors 162 may be secured through the femur 10 along
the cut 71 (FIGS. 10A-B and 11A-B). To form the tunnels that will
accommodate the additional bone anchors, referring now to FIG. 18,
an apparatus 180 is employed. Apparatus 180, in one embodiment of
the invention, includes a pair of parallel substantially
cylindrical members 182, configured so that either may be
positioned within the opening 70 of goniometer 34. The members are
coupled to one another by a connector 185. Each member 182 may
include a protrusion 184, similar to protrusion 1465 illustrated in
FIG. 14B, for engaging slot 75 in goniometer 34 to prevent the
apparatus 180 from rotating during formation of the tunnel 36
and/or passageways 130. When one cylindrical member 182 is placed
within the opening 70, the other cylindrical member 182 is
preferably extended by connector 185 beyond the goniometer 34 for
subsequently guiding a coring reamer into the femur 10. The
connector 185 may be adjustable in order to vary the distance
between members 182 and thus between the tunnels formed. Each
cylindrical member 182 is provided with an inner diameter designed
to accommodate either cylindrical guide 145 or guide 146, discussed
above in connection with FIGS. 14A-B. In an embodiment, the member
182 that is not to be positioned within the opening 70 of the
goniometer 34 may be substituted with a ring. The ring is
preferably sufficiently rigid and includes an inner diameter that
is capable of accommodating the either guide 145 or guide 146. The
procedure previously described may thereafter be employed, that is
drilling a tunnel through the femur, placing a bone anchor through
the tunnel, and securely tighten the bone anchor against the
femur.
[0064] When securing with additional bone anchors 162, the support
structure 30 and/or the goniometer 34 may be provided with a
locking mechanism (not shown) so that the alignment between the
bone pieces may be maintained prior to the placement of the
additional bone anchors 162 into the femur 10. In one embodiment of
the invention, at least two bone anchors 162 are used. The location
and number of the additional bone anchors 162, to a certain extent,
are limited only by the size of the bone. FIG. 11A illustrates a
configuration wherein a total of five bone anchors 162 are
positioned in the femur 10. The use of multiple bone anchors
provides added rigidity to the cut and resistance to translational
movement between the bone pieces, such that the support structure
30 may subsequently be removed. In addition, as the fixation is
sufficiently secured, no external fixators, for instance,
transfixion screws, lag screws, and similar devices will be
needed.
[0065] Although the above described methods are directed to femoral
osteotomy, the same methods are applicable to tibial osteotomy. It
is contemplated that the sequence of steps outlined above would be
followed. However, unlike the femoral osteotomy, the tibial
osteotomy is distal to the tibial tubercle and extends from a
proximal posterior position on the tibia to a distal anterior
position.
[0066] In order to achieve such a cut, referring now to FIGS.
19A-D, the support structure 30 is positioned along the anterior
surface of the tibia 190 such that the first portion 301 is distal
to the tibial tubercle 192 and the second portion 302 is proximal
to the tibial tubercle 192. The support structure 30 of FIGS. 19A-D
corresponds to the embodiment shown in FIG. 3C, and is affixed to
subcutaneously insertable pins 19 on the medial surface of the
tibia 190 by way of bars 35. In an alternate embodiment, the
support structure 30 may correspond to the embodiment shown in FIG.
3A, and may be affixed to multiple subcutaneously insertable pins
19 on the anterior surface of the tibia 190, as shown in FIG. 19B.
Furthermore, whereas in a femoral osteotomy the guide 40 is placed
on a lateral surface of the femur 10, in tibial osteotomy the guide
40 is placed of the anterior surface of the tibia 190. The position
of the guide 40, however, is distal to the opening 70 in goniometer
34 and provides a cut that traces the geometry of the posterior
surface of the tibia. More particularly, as seen from the medial
surface of the tibia 190, the cut is similar to cut 194 in FIG.
19C. Once the cut is made, the procedure described above in
connection with the femoral osteotomy may be employed to secure a
bone anchor 162 across the cut 194. Multiple anchoring pins 162
(FIG. 19D) may also be employed to ensure a secure alignment of the
tibial bone pieces. In general, a tibial osteotomy may be easier to
perform than a femoral osteotomy in terms of fixation, but slightly
more difficult in terms of cutting.
[0067] While the invention has been described in connection with
specific embodiments thereof, it will be understood that it is
capable of further modification. This application is intended to
cover any variations, uses, or adaptations of the invention and
including such departures from the present disclosures as come
within known or customary practice in the art to which the
invention pertains. For example, the above procedure may also be
used to easily fix a horizontal, spiral oblique fracture of the
humerus, as well as fractures in other bones of the body.
* * * * *