U.S. patent application number 10/891737 was filed with the patent office on 2006-01-19 for intramedullary fixation assembly and devices and methods for installing the same.
This patent application is currently assigned to Wright Medical Technology, Inc.. Invention is credited to John T. Capo, Robert M. Fencl, Aaron C. Smith, Virak Tan, Mark J. Warburton.
Application Number | 20060015101 10/891737 |
Document ID | / |
Family ID | 35600433 |
Filed Date | 2006-01-19 |
United States Patent
Application |
20060015101 |
Kind Code |
A1 |
Warburton; Mark J. ; et
al. |
January 19, 2006 |
Intramedullary fixation assembly and devices and methods for
installing the same
Abstract
An intramedullary fixation assembly usable with different long
bone types and a guide assembly for guiding deployment of the
intramedullary fixation assembly. The intramedullary fixation
assembly includes a fixation member that has ends and a curved body
extending between the ends. The curved body of the fixation member
has a radius of curvature configured to extend through the
medullary canal regardless of the long bone anatomy. Fasteners fix
the fixation member to the bone fragments and are guided by a guide
assembly. The guide assembly includes a guide body defining
openings configured to guide the fasteners through openings defined
in the fixation member and into the bone fragments. A fixation end
of the guide body includes a pair of opposing, converging surfaces
that are configured to engage in a positive fit with an exposed end
of the fixation member accessible through the side aperture in the
first fragment.
Inventors: |
Warburton; Mark J.; (High
Point, NC) ; Fencl; Robert M.; (Cordova, TN) ;
Capo; John T.; (Hoboken, NJ) ; Tan; Virak;
(Murray Hill, NJ) ; Smith; Aaron C.; (Arlington,
TN) |
Correspondence
Address: |
ALSTON & BIRD LLP;BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
Wright Medical Technology,
Inc.
|
Family ID: |
35600433 |
Appl. No.: |
10/891737 |
Filed: |
July 15, 2004 |
Current U.S.
Class: |
606/62 |
Current CPC
Class: |
A61B 2017/0046 20130101;
A61B 17/1668 20130101; A61B 17/72 20130101; A61B 2090/062 20160201;
A61B 2017/922 20130101; A61B 17/861 20130101; A61B 17/8875
20130101; A61B 17/1659 20130101; A61B 17/848 20130101; A61B 17/1684
20130101; A61B 17/1725 20130101 |
Class at
Publication: |
606/062 |
International
Class: |
A61F 2/30 20060101
A61F002/30 |
Claims
1. An intramedullary fixation assembly for repairing any of a
plurality of human long bone types, each of the long bones defining
a medullary canal fractured into at least a first and second
adjacent bone fragments, the first bone fragment having a free end
with an articular surface thereon and defining a side aperture,
said side aperture positioned subjacent the articular surface and
extending into the medullary canal, said intramedullary fixation
assembly comprising: at least a first and second fasteners, each of
said fasteners having an elongate body with a head end and an
opposite, bone-securing end; and a fixation member having a first
end, a second end and a body extending between the first and second
ends, said body defining a first fastener opening positioned
proximate the first end and configured to allow passage of the
first fastener therethrough and into the first bone fragment, said
body defining a second fastener opening positioned proximate the
second end and configured to allow passage of the second fastener
therethrough and into the second bone fragment, and said body
having a radius of curvature at least near the first end within a
range of 1.5 to 5 inches to allow passage of the fixation member
through the side aperture of the first bone fragment and into the
medullary canal until the first end of the fixation member is
positioned adjacent the side aperture and within a portion of the
medullary canal defined within the first bone fragment, and the
second end of the fixation member is positioned within a portion of
the medullary canal defined within the second bone fragment,
wherein the bone fragments are from any of the plurality of human
long bone types.
2. An intramedullary fixation assembly of claim 1, wherein the body
continuously curves from its first end to its second end.
3. An intramedullary fixation assembly of claim 1, wherein the
radius of curvature is defined by a centerline extending from the
first end to the second end.
4. An intramedullary fixation assembly of claim 3, wherein the body
includes a smoothly curving concave and convex sides configured to
facilitate passage of the fixation member through the side aperture
and into the medullary canal.
5. An intramedullary fixation assembly of claim 4, wherein at least
one of the first and second ends is tapered.
6. An intramedullary fixation assembly of claim 2, wherein the
radius of curvature is with a range of about 2.6 to 3.4 inches.
7. An intramedullary fixation assembly of claim 1, wherein the
fixation member includes a tilt.
8. An intramedullary fixation assembly of claim 1, wherein at least
one of the fasteners is a bi-cortical fastener having a threaded
shaft with a wider diameter than the bone-securing end and
separated from the bone-securing end by a non-threaded shaft
portion.
9. An intramedullary fixation assembly of claim 1, wherein the
second end includes a tail portion having a relatively smaller
diameter than the body.
10. An intramedullary fixation assembly of claim 9, wherein the
tail portion includes a pair of spaced arms defining a split
configured to receive a fastener, and wherein insertion of the
fastener forces the spaced arms apart.
11. An intramedullary fixation assembly of claim 1, wherein at
least one of the first and second ends has a taper and wherein the
body has a continuous curvature extending between the ends.
12. An intramedullary fixation assembly of claim 1, wherein the
first end of the body includes additional fastener openings
extending at divergent angles with respect to the first fastener
openings.
13. An intramedullary fixation assembly of claim 12, wherein the
fastener openings at the first end of the body extend at an
inclination angle matched to the articular surface.
14. An intramedullary fixation assembly of claim 13, wherein the
first end of the fixation member defines a surface configured to
extend under and support the articular cartilage.
15. An intramedullary fixation assembly of claim 14, wherein the
body defines an exposed end surface accessible through the side
aperture and having the first fastener opening extending
therethrough.
16. An intramedullary fixation assembly of claim 15, wherein the
surface extending under the articular cartilage is at about a right
angle to the exposed end surface.
17. An intramedullary fixation assembly of claim 16, wherein the
fixation member is configured to extend from a metaphysis of the
long bone to the diaphysis of the longbone without extending into
the epiphysis of the longbone, thereby avoiding damage to the
articular cartilage.
18. A bi-cortical bone fastener for use with a fixation member
defining a fixation member opening having a diameter, said bone
fastener comprising: a first bone-securing shaft portion having
threads configured for fixation into a first layer of bone, said
first bone-securing shaft portion having a maximum diameter smaller
than the fixation member opening diameter; a mid-shaft portion
adjacent the bone-securing shaft portion and configured to extend
into the fixation member opening, said mid-shaft portion having a
maximum diameter greater than the maximum diameter of the
bone-securing shaft portion; and a second bone-securing shaft
portion adjacent the mid-shaft portion and opposite the first
bone-securing shaft portion, said second bone-securing shaft
portion having threads configured for fixation into a second layer
of bone, said second bone-securing shaft portion having a maximum
diameter greater than the diameter of the mid-shaft portion.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is related to the use of orthopedic
fixation devices and devices for installing the same, and in
particular, to intramedullary fixation devices and guides for
facilitating installation and fixation of the same.
[0003] 2. Description of Related Art
[0004] Long bone fractures are fairly common in the elderly
population, often due to the onset of osteoporosis. Long bone
fractures may be reduced by the use of assorted conventional bone
plates. For example, a bone plate may be attached to the outside
surface of two adjacent fragments of a long bone and then secured
by inserting bone screws through openings in the bone plate.
Problems may arise with such bone plates, however, in that the soft
tissues covering the bone plates may become irritated by passage or
movement over the bone plates.
[0005] An alternative to bone plates are intramedullary nails or
rods that extend through a medullary canal defined within the
fractured long bone. The nails or rods are typically fastened to
the fractured portions of the long bones with bone screws. The
nails or rods are placed into the medullary canal by insertion
through a hole which is drilled into one end of the long bone. For
instance, to reduce a fractured femur with an intramedullary rod or
nail, a hole is drilled through the articular cartilage between the
condyles to provide access for the rod. Because the intramedullary
nails or rods are contained within the medullary canal, they avoid
the problems with soft tissue associated with plates. However,
insertion of these rods through holes in the ends of the longs
bones requires damaging the articular cartilage on the ends of the
long bones.
[0006] U.S. Pat. No. 6,527,775 to Warburton ("the '775 patent"),
which is hereby incorporated herein in its entirety by reference,
describes an intramedullary fixation device used to reduce a distal
fracture of the radius. As shown in FIG. 3A of the '775 patent, the
intramedullary fixation device 25 includes an elongated axially
extending rod 26 with a distal portion 27 and a proximal portion
28. The fixation device also includes a distal fixation member 30
and proximal fixation members 35. The distal fixation member
extends through the distal portion of the rod and into a distal
fracture fragment 18. The proximal fixation members extend through
the proximal portion of the rod and the portion of the radius
proximal the fracture line. The '775 patent describes avoiding end
insertion of the rod through the cartilage of the distal radius by
using a laterally positioned bone window 16 defined in the distal
fracture fragment.
[0007] Although the '775 patent discloses an intramedullary
fixation device for reducing a distal radius fracture without
insertion through cartilage on the end of the distal radius, other
long bones, such as the humerus, femur and tibia are also often
fractured and require repair.
[0008] Therefore, it would be advantageous to have a fixation
device for all long bones that is insertable into the medullary
shaft of the long bones. It would also be advantageous if the
fixation device were capable of insertion without damaging the
articular cartilage of the long bones.
BRIEF SUMMARY OF THE INVENTION
[0009] The present invention addresses the above needs and achieves
other advantages by providing an intramedullary fixation assembly
usable with different long bone types and a guide assembly for
guiding deployment of the intramedullary fixation assembly. The
intramedullary fixation assembly includes a fixation member that
has ends and a curved body extending between the ends. The curved
body of the fixation member has a radius of curvature extending
from a first end configured to extend between a side aperture
defined in a first fragment through the medulary canal and into a
second fragment, regardless of the type of the long bone. Fasteners
are used to fix the fixation member to the bone fragments and are
guided by a guide assembly. The guide assembly includes a guide
body defining openings configured to guide the fasteners through
openings defined in the fixation member and into the bone
fragments. A fixation end of the guide body includes a pair of
opposing, converging surfaces that are configured to engage in a
positive fit with an exposed end of the fixation member accessible
through the side aperture in the first fragment. Advantageously,
the positive fit facilitates accurate positioning of the guide body
and, as a result, of the fixation member fasteners.
[0010] In one embodiment, the present invention includes an
intramedullary fixation assembly for repairing any of a plurality
of long bone types. Each of the long bones defines a medullary
canal fractured into at least a first and second adjacent bone
fragments. The first bone fragment has a free end with an articular
cartilage surface and defines a side aperture. The side aperture is
positioned subjacent the articular cartilage surface of the first
bone fragment and extends into the medullary canal. Included in the
intramedullary fixation device are a plurality of fasteners (e.g.,
a first fastener and a second fastener) each having an elongate
body with a head end and an opposite, bone-securing end. A fixation
member of the intramedullary fixation device includes a first end,
a second end and a curved body extending between the first and
second ends. The curved body defines at least one fastener opening
positioned proximate the first end and configured to allow passage
of the first fastener therethrough and into the first bone
fragment. Also defined by the curved body is a second fastener
opening positioned proximate the second end and configured to allow
passage of the second fastener therethrough and into the second
bone fragment. The curved body has a radius of curvature extending
from the first end that is configured to allow passage of the
fixation member through the side aperture of the first bone
fragment and into the medullary canal until the first end of the
fixation member is positioned adjacent the side aperture, and
within a portion of the medullary canal defined within the first
bone fragment, and the second end of the fixation member is
positioned within a portion of the medullary canal defined within
the second bone fragment. In this manner, the fixation assembly can
be used to reduce and secure a fracture of any of the various types
of human long bone types.
[0011] In one aspect, the curved body has a smooth, continuous
curvature that extends from its first end to its second end. The
radius of curvature is preferably defined by a centerline extending
from the first end to the second end. Also, the curved body
preferably includes smoothly curving concave and convex sides
configured to facilitate passage of the fixation member through the
side aperture and into the medullary canal. Also, the first and
second ends may be tapered to facilitate insertion through the side
aperture and into the medullary canal.
[0012] In another aspect, the same radius of curvature extending
from the first end can be used for a plurality of lengths for the
curved body, allowing the design to be extended to various long
bone types. Preferably, the radius of curvature extending from the
first end ranges from between 1.5 to 5 inches, and more preferably,
about a radius of curvature of approximately 2 to 4 inches, or 2.6
to 3.4 inches.
[0013] In another embodiment, the present invention includes a
guide assembly for facilitating placement of a plurality of bone
fasteners of an intramedullary fixation assembly through predefined
locations on a fixation member of the intramedullary fixation
assembly. The fixation member extends through a medullary canal
defined within a long bone and has an exposed end accessible
through a side aperture defined by the long bone. Included in the
guide assembly is at least one guide fastener configured to extend
into the exposed end of the fixation member so as to be secured to
the fixation member. A guide body includes a fixation end and
defines a plurality of fastener guide openings. These guide
openings are configured to orient the bone fasteners extending
through the guide openings with the predefined locations on the
fixation member. The fixation end defines an opening configured to
allow passage of the guide fastener through the guide body and into
the exposed end of the fixation member. The fixation end includes
at least one pair of surfaces positioned opposite each other and
generally extending in a converging direction. These surfaces are,
as a result, configured to engage in a positive fit with the
exposed end of the fixation member when the guide body is secured
thereto with the guide fastener. This positive fit reduces the
motion between the guide body and the fixation member, thereby
improving the ability of the guide openings to accurately guide the
bone fasteners through the predetermined locations on the fixation
member.
[0014] As an example of the surfaces used for a positive fit, the
pair of surfaces may be portions of a convex surface or prong
configured to extend within a concave surface defined within the
exposed end of the fixation member. Preferably, the convex surface
is configured to reach a positive fit prior to full contact between
the remaining (non-convex and non-concave) surfaces of the fixation
end and the exposed end. In yet another aspect, there may be
additional pairs of surfaces or prongs configured for a positive
fit, including second, third and fourth pairs of surfaces spaced
from each other in a cruciform configuration.
[0015] The present invention has many advantages. For example, the
invention has many attributes that facilitate its use for different
types of human long bone. Maintaining a constant radius of
curvature of a first end of the curved body allows for different
sized long bones and different types of long bone to be
accommodated merely by extending the arc further to produce a
greater "hook" on increasing sizes of fixation members. This
overcomes the increase in not only the length of the long bone, but
also the increase in distance between widened end and width of the
medullary canal, facilitating its use on different and larger types
of long bones. It has also been determined that use of a radius of
curvature in the ranges of 1.5 to 5 inches facilitates use with
different types of long bone, especially when the curved body
curves continuously along its length and the ends are tapered for
easy insertion. The use of a cruciform shape and positive fit or
wedge effect used for the concave indentations and the prongs
provides rotational and translational stability of the fixation
member when attached to the guide assembly. In addition, the
positive fit or wedge effect operates to center and reduce
micro-motion between the targeting guide and the rest of the guide
assembly.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0016] Having thus described the invention in general terms,
reference will now be made to the accompanying drawings, which are
not necessarily drawn to scale, and wherein:
[0017] FIG. 1 is a perspective view of a long bone fracture
repaired using an intramedullary fixation assembly of one
embodiment of the present invention;
[0018] FIG. 2 is an elevation view of the long bone fracture and
intramedullary fixation assembly of FIG. 1;
[0019] FIG. 3 is a side elevation view of a fixation member of the
intramedullary fixation assembly of FIG. 1;
[0020] FIG. 4 is another side elevation view of a fixation member
of the intramedullary fixation assembly of FIG. 1;
[0021] FIG. 5 is another side elevation view of a fixation member
of the intramedullary fixation assembly of FIG. 1;
[0022] FIG. 6 is another side elevation view of a fixation member
of the intramedullary fixation assembly of FIG. 1;
[0023] FIG. 7 is a sectional view of the fixation member of FIG.
6;
[0024] FIG. 8 is a sectional view of the fixation member of FIG.
6;
[0025] FIG. 9 is a sectional view of the fixation member of FIG.
6;
[0026] FIG. 10 is a sectional view of the fixation member of FIG.
6;
[0027] FIG. 11 is a sectional view of a portion of the fixation
member and a pair of bone fasteners of the intramedullary fixation
assembly of FIG. 1;
[0028] FIG. 12 is a sectional view of one of the bone fasteners
shown in FIG. 11;
[0029] FIG. 13 is a side elevation view of a fixation member of
another embodiment of the present invention, including a stem
extending from one of its ends;
[0030] FIG. 14 is another side elevation view of the fixation
member of FIG. 13;
[0031] FIG. 15 is a plan view of a head end of one of the bone
fasteners shown in FIG. 11;
[0032] FIG. 16 is a side elevation view of the bone fastener shown
in FIG. 15;
[0033] FIG. 17 is a sectional view of the bone fastener shown in
FIG. 15;
[0034] FIG. 18 is a plan view of a head of a k-wire for use as a
bone fastener in another embodiment of an intramedullary fixation
assembly of the present invention;
[0035] FIG. 19 is a sectional view of the k-wire shown in FIG.
18;
[0036] FIG. 20 is a side elevation view of an outrigger frame of a
guide assembly of another embodiment of the present invention shown
in FIG. 53;
[0037] FIG. 21 is a plan view of the outrigger frame of FIG.
20;
[0038] FIG. 22 is another side elevation view of the outrigger
frame of FIG. 20;
[0039] FIG. 23 is plan view of a targeting guide of the guide
assembly of the present invention shown in FIG. 53;
[0040] FIG. 24 is a side elevation view of the targeting guide of
FIG. 23;
[0041] FIG. 25 is another plan view of the targeting guide of FIG.
23;
[0042] FIG. 26 is a sectional view of the targeting guide of FIG.
25;
[0043] FIGS. 27-30 are various views of the targeting guide of
another embodiment of the present invention;
[0044] FIG. 31 is a side elevation view of a screw-in drill guide
which is part of the outrigger frame of FIG. 20;
[0045] FIG. 32 is a sectional view of the screw-in drill guide of
FIG. 31;
[0046] FIG. 33 is a side elevation view of a drill guide of another
embodiment of the present invention;
[0047] FIG. 34 is a sectional view of the drill guide of FIG.
33;
[0048] FIG. 35 is a side elevation view of a screw guide of a guide
assembly as shown in FIG. 59;
[0049] FIG. 36 is a sectional view of the screw guide of FIG.
35;
[0050] FIG. 37 is a side elevation view of guide member of the
outrigger frame shown in FIG. 20;
[0051] FIG. 38 is a sectional view of the guide member of FIG.
37;
[0052] FIGS. 39 and 40 show a perspective view of attachment of a
set of four prongs on the guide member of FIG. 37 within a set of
four recesses defined in an end of the fixation member shown in
FIG. 6;
[0053] FIG. 41 is an enlarged view of the prongs and recesses of
FIG. 39 forming an interference fit;
[0054] FIGS. 42 and 43 show a side elevation view of a fastener
driving drill bit of another embodiment of the present
invention;
[0055] FIG. 44 is a side elevation of a drill bit of another
embodiment of the present invention;
[0056] FIG. 45 is a plan view of a hand driver of another
embodiment of the present invention;
[0057] FIG. 46 is a side elevation view of the hand driver of FIG.
45;
[0058] FIG. 47 is a sectional view of a cannulated drill bit of
another embodiment of the present invention;
[0059] FIG. 48 is a side elevation view of a trialing broach
assembly of another embodiment of the present invention;
[0060] FIG. 49 is a side elevation of a handle of the trialing
broach assembly shown in FIG. 48;
[0061] FIG. 50 is a side elevation view of a depth indicator of
another embodiment of the present invention;
[0062] FIG. 51 is a sectional view of the depth indicator of FIG.
50;
[0063] FIG. 52 is a perspective view of the trialing broach
assembly of FIG. 48 show inserted into a long bone;
[0064] FIG. 53 is a perspective view of the fixation member of FIG.
3 connected to the guide assembly of the present invention;
[0065] FIG. 54 is a perspective view of the fixation member and
guide assembly of FIG. 53, wherein the fixation member has been
positioned in the medullary canal of the fractured long bone;
[0066] FIG. 55 is a perspective view of the guide assembly and
fixation member shown in FIG. 54, wherein the guide assembly is
guiding drilling through an opening in the fixation member and into
the long bone;
[0067] FIG. 56 is a perspective view of the guide assembly and
fixation member shown in FIG. 54, wherein drilling is being guided
through another opening in the fixation member;
[0068] FIG. 57 is a perspective view of the guide assembly and
fixation member of FIG. 54 guiding placement of a bone fastener,
such as the bone fasteners shown in FIGS. 11 and 12, through the
bone and the opening in the fixation member;
[0069] FIG. 58 is a perspective view of placement of another bone
fastener using the assemblies of FIG. 57;
[0070] FIG. 59 is a perspective view of placement of yet another
bone fastener using the assemblies of FIG. 57;
[0071] FIG. 60 is a sectional view of a long bone and a fixation
member of another embodiment of the present invention, wherein the
fixation member includes a split tail;
[0072] FIG. 61 is a sectional view of a bone fastener of another
embodiment of the present invention positioned within the split
tail of the fixation member of FIG. 60;
[0073] FIG. 62 is a sectional view of a long bone and a fixation
member of another embodiment of the present invention, wherein the
fixation member includes a split tail;
[0074] FIG. 63 is a sectional view of the long bone and fixation
member of FIG. 62 wherein one arm of the split tail is threaded to
allow splaying of the split tail FIG. 64 is a side elevation view
of an impactor having a U-shaped end and fixation member defining
U-shaped slots for receiving the end of the impactor in another
embodiment of the present invention;
[0075] FIG. 65 is a sectional view of the U-shaped impactor and
slot of FIG. 64;
[0076] FIGS. 66-72 show assorted views of an S-shaped, positive fit
connection between a guide assembly and fixation member of another
embodiment of the present invention;
[0077] FIG. 73 is a side elevation view of a fixation member of
another embodiment of the present invention having a bow tilt;
[0078] FIG. 74 is a side elevation view of a fixation member of
another embodiment of the present invention having a linear offset;
and
[0079] FIG. 75 is a side elevation view of a fixation member of
another embodiment of the present invention having an angular
bend.
DETAILED DESCRIPTION OF THE INVENTION
[0080] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments of the invention are shown. Indeed,
this invention may be embodied in many different forms and should
not be construed as limited to the embodiments set forth herein;
rather, these embodiments are provided so that this disclosure will
satisfy applicable legal requirements. Like numbers refer to like
elements throughout.
[0081] An intramedullary fixation assembly 10 of one embodiment of
the present invention is shown installed in a long bone 11 of a
patient in FIGS. 1 and 2. The long bone could be any of a number of
long bones, such as a femur, tibia, radius or humerus. The fixation
assembly 10 is most suited to repairing fractures of the long bone
11 wherein the fracture is at one end near an articular cartilage
surface 12 and wherein it is desired to leave the articular surface
undisrupted during the repair. Also, the long bone includes a
widened end 13 that supports the articular cartilage surface which
tapers to a more narrow shaft 14. Extending within the shaft 14 and
a portion of the widened end 13 is a medullary canal 15. Generally,
every type of long bone will have the afore-described
characteristics, such as the shaft 14 being relatively narrower
than the end 13. However, the proportional geometry of the
different long bones will vary due to their biology and
function.
[0082] When referred to herein, the terms "different long bones,"
"various long bones," and other, related terms, do not refer to the
same type of long bone in different people, but different types of
long bones, such as a femur versus a tibia, or radius, or humerus.
In addition, the intramedullary fixation assembly could be used to
repair somewhat more complex fractures, but is shown being used to
repair a first bone fragment 16 separated from a second bone
fragment 17 by a single fracture line 18. A side aperture 19 is
defined in a lateral surface of the widened end 13, subjacent the
articular cartilage surface 12, to allow insertion of the
intramedullary fixation assembly 10.
[0083] Generally, the intramedullary fixation assembly 10 includes
an elongate fixation member 20 and a plurality of fasteners 21 that
extend through the elongate fixation member to attach it to the
long bone 11 above and below the fracture line 18 and thereby
reduce the fracture, for example as shown in FIGS. 1 and 2. The
elongate fixation member 20 preferably, when positioned within the
medullary canal 15 of the long bone 11 (regardless of its type),
has a first end 22 positioned adjacent the side aperture 19.
Extending from the first end, through the rest of the aperture and
into the medullary canal 15 of the first bone fragment 16, is a
curved body 24 (shown in broken lines in FIGS. 1 and 2) of the
fixation member 20. The curved body 24 extends to a second end 23
which is positioned within the medullary canal 15 of the second
bone fragment 17. Advantageously, a radius of curvature of the
curved body 24 is selected to promote smooth insertion of the
curved body through the side aperture 19 and into the medullary
canal 15 despite differences in the width of the widened end 13 and
the shaft 14 and medullary canal 15 between the various types of
long bone 11.
[0084] For example, one embodiment of the fixation member 20 of the
present invention is shown in FIGS. 3-14. The first end 22 of the
fixation member 20 has two intersecting flat surfaces, including an
exposed first end surface 27 that is accessible through the side
aperture 19 and an adjacent first end surface 28 that is at a right
angle to the exposed surface, as shown in FIG. 4. The second end 23
of the fixation member 20 has a rounded profile with a radius of
about 0.08 inches, as shown in FIG. 4, and edges rounded to about a
0.06 inch radius, as shown in FIG. 5.
[0085] The curved body 24 of the fixation member 20 includes a
convex side 29 and a concave side 30 that are on opposite sides of
the curved body. The sides have radii of curvature with a similar
center, but the center of the convex side changes so that the sides
converge in a slight taper as they extend to the second end 23, as
shown in FIG. 4. For instance, the radius of curvature of the
concave side 30 is about 3.12 inches and the radius of curvature of
the convex side 29 is about 3.36 inches near the first end 22 when
measured from a first center 31 positioned about 2.14 inches from
the plane of the adjacent first end surface 28 and about 2.47
inches from the plane of the exposed first end surface 27. But, the
radius of curvature of the convex side 29 shifts to about 2.68
inches at a second center 32 that is positioned about 1.89 inches
from the plane of the adjacent first end surface 28 and about 1.5
inches from the plane of the exposed first end surface 27.
[0086] Notably, this shift produces the taper near the second end
23 of the fixation member 20. Also notable is that maintaining a
constant radius of curvature near the first end 22 of the curved
body 24 allows for different sized and different types of long
bones to be accommodated merely by extending the arc further to
produce a greater "hook." This overcomes the increase in not only
the length of the long bone 11, but also the increase in distance
between widened end 13 and width of the medullary canal 15,
facilitating its use on different and larger types of long bones.
If measured from the centerline of the curved body 24, the radius
of curvature can actually be constant between the sides 29, 30 and
the ends 22, 23 regardless of the amount of taper. This radius of
curvature can also be maintained while the arc length of the curved
body 24 is extended to account for increased length of the long
bone 11 and increased offset between the side aperture 19 and the
position of the medullary canal 15. As a result, an entire kit of
fixation members could have the same radius of curvature but be
usable in different types and lengths of long bones.
[0087] A second pair of opposite, side surfaces 33 extend between
the convex side 29 and concave side 30, as shown in FIGS. 3 and 5.
Similar to the convex side 29 and concave side 30, the side
surfaces 33 taper slightly toward each other as they extend from
the first end 22 to the second end 23 of the curved body 24.
However, the side surfaces 33 in the illustrated embodiment are
relatively planar, as opposed to the curved shape of the sides 29,
30. Advantageously, the taper of the sides 29, 30, 33, the
continuous curve of the curved body 24 between the ends 22, 23 and
the rounded profile of the second end 23 help to facilitate
insertion through the side aperture 19 and into the medullary canal
15. Note that the term "continuous" differs from "constant" in
reference to curvature herein in that a continuous curvature is not
necessarily a constant curvature. In addition, the use of radii of
curvature within about the ranges cited above, with variations of
about 1.5 to 5 inches, allow the fixation member 20 to be employed
in different (preferably human) long bones with only variations in
the overall length of the fixation member.
[0088] There may be some adaptations of the fixation member 20
beyond extension of the arc length, such as through the application
of a tilt. The tilt would generally not be in the curvature defined
by the convex and concave sides 29, 30 to accommodate curvature in
different long bones. For example, a volar tilt may be used to
accommodate the volar tilt in the saggital plane of the human
radius. In this instance, volar tilt facilitates better filling of
the medullary canal of the distal radius and can improve
stabilization of the fixation member 20. Generally, the tilt can be
accomplished, for example, through the use of a radial bow, as
shown in FIG. 73, a linear offset, as shown in FIG. 74, or an
angular bend, as shown in FIG. 75. The radial bow ranges from about
4 to 8 inches (100 to 200 mm) of curvature. The linear offset is
about 2 to 5 mm and the angular bend is about a 10.degree. to
20.degree. angle.
[0089] To allow passage of the fasteners 21 through the fixation
member, a plurality of fastener openings are defined in the
fixation member. These fastener openings include a side aperture
accessible fastener opening 34, a pair of fastener openings 35
extending between the curved convex side 29 and concave side 30,
and fastener openings 36 extending between the side surfaces 33.
The fastener opening 34 extends from the exposed first end surface
27 (which is accessible through the side aperture 19 when the
fixation member 20 is installed) through a portion of the curved
body 24 and to the convex side 29, as shown in FIGS. 4 and 5. The
fastener opening 34 includes a guide portion 38 and a fastener head
portion 39 that is generally more narrow than the guide portion.
Both of the portions are threaded, as shown in FIGS. 7 and 8, to
facilitate a secure fit by the fasteners 21 and various
installation devices, as will be described in more detail below.
Defined around the periphery of the guide portion 38 of the
fastener opening 34 are four concave channels, recesses or
indentations 40. These indentations are arranged in a cross, or
cruciform, shape each radiating out from the fastener opening 34
and spaced 90.degree. from each other. As will be described in more
detail below, the concave indentations 40 serve to provide for a
secure, positive fit with a guide assembly 50.
[0090] The pair of fastener openings 35 which extend between the
sides 29, 30 extend through the curved body 24 nearer the first end
22 so as to be within the first bone fragment 16, as shown in FIG.
5. Each of the fastener openings also has a threaded fastener
portion 39 similar to the fastener opening 34, but a non-threaded
guide portion 38, as shown in FIGS. 9 and 10. These fastener
openings 35 extend at different, divergent angles than each other
and the orientation of the fastener opening 34 which is relatively
orthogonal with respect to the exposed first end surface 27 and the
convex side 29, as shown in FIGS. 3. As a result, the fastener
openings of the present invention (such as the fastener openings
35) need not all be aligned with the axis of the fixation
member.
[0091] These different angles improve fixation by allowing angled
insertion of the fasteners into different portions of the first
bone fragment 16, as shown in FIGS. 1 and 2. In addition, the
angles of the fastener openings 34, 35 may be configured so that
the fasteners extend subjacent to the articular cartilage for
improved fixation. Generally, this will require the fastener
openings 34, 35 to extend at some acute angle, such as an angle
between about 50.degree. and 85.degree. (depending on the origin of
the fastener opening), and preferably about 60.degree. to
70.degree., with respect to the fixation member body. Basically,
these angles are to match the inclination angle of the articular
surface so as to provide a buttress effect for the articular
cartilage. For instance, the ulnar inclination angle of the
articular cartilage on the radius is about 23.degree. (resulting in
a 67.degree. fastener opening angle). The buttress effect is also
improved by the sub-chondral placement of the first end surface 28
that is adjacent and at a right angle with respect to the exposed
first end surface 27 so as to underlie the articular cartilage.
[0092] In the illustrated embodiment shown in FIGS. 4 and 6, three
fastener openings 36 are defined in the curved body 24 at a
position nearer the second end 23 of the fixation member 20. The
two outer ones of the fastener openings 36 are configured to
receive threaded fasteners 21, similar to the fastener openings 34,
35, but the center one of the fastener openings 36 is configured to
receive a relatively smaller diameter k-wire fastener 41, as shown
in FIG. 6. Preferably, the larger of the fastener openings 36 are
not threaded to allow a slip fit of the threaded fasteners 21
without damaging the threads, as will be described below.
[0093] The threaded fasteners 21 are shown in greater detail by
FIGS. 15-17 and the k-wire fastener 41 by FIGS. 18 and 19. Each of
the fasteners 21, 41 is shown as being driven by a Phillips-type,
or cruciform-type, head (FIGS. 15, 17 and 18), but may be
configured for mating with a driver in any number of ways, such as
with an Allan-type head or flat head. Each of the illustrated
threaded fasteners 21 includes a head 42, a threaded shaft 43, a
non-threaded shaft portion 45 and a bone-securing end 44, as shown
in FIG. 16. The head 42 of each of the threaded fasteners 21 has a
larger diameter than its shaft 43, so as to prevent the threaded
fastener from passing through tapped openings in the first layer of
cortical bone. However, the diameter of the head 42 is still small
enough to pass through a screw guide 51, or other guide, positioned
by the guide assembly 50 within the guide portion 38, as will be
described in more detail below.
[0094] When the threaded fasteners 21 are inserted through the
openings 34, 35 and into the first bone fragment 16, the head is
configured to reside in the guide portion 38, the threaded shaft 43
in the threaded fastener portion 39 and the bone-securing layer is
configured to attach to the distant layer of cortical bone opposite
the side aperture 19 and subjacent the articular cartilage surface
12, as shown in FIGS. 1 and 2. When inserted through the openings
36 and into the second bone fragment 17, the threaded shaft 43 is
configured to attach to the first layer of cortical bone, the
non-threaded shaft portion 45 is configured to reside in the
openings 36 in a slip fit and the bone-securing end 44 is
configured to attach to the distant layer of cortical bone opposite
the first layer of cortical bone, as shown in FIG. 11. The fastener
head 42 is configured to abut the first layer of cortical bone, and
may have a rounded shape to minimize irritation of the overlying
tissues, as shown in FIG. 12. Notably, when used in the openings
36, the threaded fasteners 21 become bi-cortical screws, firmly
attaching to two layers of cortical bone. As another option, the
non-threaded shaft 45 may include a chamfer 63 to help locate the
screw in the openings 36 as it is advanced through the fixation
member 20.
[0095] The bone-securing end 44 preferably has threads and an outer
diameter that is smaller than the minimum, trough diameter of the
threads on the threaded shaft 43 and the diameter of the
un-threaded shaft portion to prevent the bone-securing end from
locking up or fretting the threads when passing through the
fastener portion 39. A neck 46 on each of the threaded fasteners 21
also prevents lockup by providing space between the threaded
fastener shaft 43 and fastener head 42, as shown in FIGS. 16 and
17. As shown in FIG. 19, the k-wire fastener 41 also includes a
fastener head 42, a neck 46, a threaded shaft 43 and a non-threaded
shaft portion 45, but its bone securing end 44 is not threaded for
easier insertion as the first fastener.
[0096] During installation, the threaded shaft 43 of one of the
threaded or k-wire fasteners 21, 41 mates with the threaded
fastener portion 39 of its respective one of the fastener openings
34, 35 and 36 and the bone-securing end 44 extends into the long
bone 11 for a secure fit, as shown in FIGS. 1 and 2. It should be
noted that although two types of fasteners are described herein
that are preferred, other types of fasteners may also be employed,
including other types of wires, screws, etc., and still be within
the purview of the present invention as long as some portion of the
fastener secures itself to the fixation member 20 and another
portion to the long bone 11.
[0097] FIGS. 20-30 illustrate the guide assembly 50 of the present
invention that is used to position the screw guide 51, a screw-in
drill guide 52 and a plurality of other drill guides 53, shown in
FIGS. 31-36. The guide assembly 50 includes an outrigger frame 54
having a curved, hook-shaped body 55 including a first end 56 for
positioning fasteners 21 within the first end 22 of the fixation
member 20 and the first bone fragment 16, and a second end 57 for
positioning fasteners within the second end 23 of the fixation
member and the second bone fragment 17, as shown in FIGS.
20-22.
[0098] The outrigger frame 54 also includes a guide member 58 that
has a truncated pyramid shape and extends from a flat surface of
the first end 56 of the hook-shaped body 55, as shown in FIGS. 20
and 22. The guide member 58 tapers as it extends outward from the
hook-shaped body and ends in four prongs 59, as shown in FIGS.
37-40. Each of the prongs 59 has a rounded shape with opposing edge
surfaces 60 angled toward each other (i.e., they are generally
converging) as they extend outwards from the end of the truncated
pyramid shape. These converging surfaces are spaced so as to fit
into similarly shaped, but somewhat smaller, concave indentations
40 in a positive, or interference, type fit, as shown in FIGS.
39-41. The guide member 58 and its subjacent portion of the
hook-shaped body 55 define a stepped opening 61, as shown in FIG.
38, that is sized to receive the screw-in drill guide 52 (shown in
FIGS. 31 and 32). The stepped opening 61 includes shoulders 62 that
prevent the passage of the screw-in drill guide 52.
[0099] The screw-in drill guide 52 includes a burled knob 65, an
elongate shaft 66, a tapered shoulder 67 and a threaded tip 68. The
burled knob provides 65 a gripping surface for tightening the
screw-in drill guide 52 and its relatively large diameter acts as a
stop against passage of the screw-in drill guide through the
stepped opening 61 when inserted therein and tightened. The
elongate shaft 66 extends from the burled knob and tapers at the
tapered shoulder 67 down to the diameter of the threaded tip 68.
This shape allows passage of the threaded tip through and out of
the stepped opening 61 so that the threaded tip 68 can be advanced
into the threads of the guide portion 38 of the fastener opening
34. Defined within the screw-in drill guide 52 is a guide opening
that extends from the burled knob 52 through to the threaded tip 68
and includes a large diameter portion 70 that tapers to a small
diameter portion 71 near the threaded tip, as shown in FIG. 32.
This change in diameter helps to concentrically center the
fasteners 21 as they are advanced through the screw-in drill guide
52 and into the fastener opening 34 defined in the fixation member
20, as will be described below.
[0100] When the threaded tip is advanced into the threads of the
guide portion 38, the guide member 58 and its prongs 59, which are
also spaced in a cruciform or cross pattern similar to the
indentations 40, are advanced into the indentations, as shown in
FIG. 40. The cruciform pattern, combined with the positive fit,
firmly locks the outrigger frame 54 to the fixation member 20
before and during guidance of insertion of the various fasteners
21, 41. This firm attachment guards against relative motion of the
guide assembly 50 with respect to the fixation member 20, so that
misalignment of the guides 51, 52, 53 is reduced even with just a
single point of attachment of the guide assembly to the fixation
member.
[0101] The cruciform shape and positive fit are particularly
effective at restricting rotation between the guide assembly and
fixation member, which can be a problem due to the relative length
and cantilevered configuration of the guide assembly and fixation
member, especially on the larger long bones such as the tibia and
femur. It should be noted, however, that the positive fit of the
prongs 59 in the concave indentations 40 could be accomplished in
other ways, such as by having the indentations on the guide member
58 instead of the exposed first end surface 27 of the fixation
member 20.
[0102] In addition, different numbers and configurations of the
prong and indentation arrangement are also possible to achieve a
firm positive fit, even though the cruciform arrangement is
preferred for reducing rotational motion. For instance, the
positive or press fit may be implemented or facilitated, as shown
for example in FIG. 41, by slightly over-sizing a male fitting
portion (e.g., the prongs 59) with respect to a female portion
(e.g., the concave indentations 40) so that the angled opposing
surfaces (e.g., converging edge surfaces 60) are in contact and the
tip of the male portion, and other remaining flat surfaces have
minimal contact to allow the angled surfaces to wedge into each
other.
[0103] Returning to a discussion of the first end 56 of the
hook-shaped body 55 of the outrigger frame 54, the first end 56
further supports two screw guides 51 that are integrally connected
to, and extend from, the first end of the hook-shaped body, as
shown in FIGS. 20-22. These screw guides 51 are cylindrical tubes
that define openings extending therethrough and are oriented so as
to have an axis collinear and aligned with the axes of the of the
pair of openings 35 defined in the curved body 24 of the fixation
member 20. Preferably, the screw guides 51 are oriented so that the
fasteners 21 extend at an angle into the first bone fragment 16
right below the articular cartilage surface 12, as shown in FIGS. 1
and 2. In addition to the screw guides 51, the first end 56 also
includes a handle mount 37 defining a threaded opening.
[0104] Referring now to the second end 57 of the hook-shaped body
55, there is supported a channel member 72 of the outrigger frame
54 that extends away from the second end of the hook-shaped body.
The channel member 72 has an elongate rectangular shape, as shown
by FIGS. 21 and 22, and includes a pair of channel arms 73
extending away and along the length of the rectangular shape, as
shown in FIGS. 20 and 21. Each of the arms defines an angled
surface 74 extending toward the other one of the arms and the arms
are spaced from each other and parallel so as to define a channel.
Extending into the channel defined between the arms 73 is a stop
75. In addition, the second end 57 and the channel member 72 define
a locking member opening 76 that extends into the channel between
the arms 73. The locking member opening 76 is sized and includes
threads to receive advancement of a locking member 77, as shown in
FIGS. 20 and 22. The locking member includes its own burled knob 78
to facilitate its advancement and also has a frusto-conical shaped
distal locking tip 79 that extends out of the locking member
opening 76 and into the channel between the arms 73 when the
locking member 77 is fully advanced, as shown in FIGS. 20 and
21.
[0105] Also included in the guide assembly 50 is a targeting guide
80 (as shown in FIGS. 23-26) that is configured to support and
orient the drill guides 53 and screw guides 51 that are used to
guide insertion of the fasteners 21, 41 through the fixation member
20 and into the long bone 11. Different targeting guides 80 can
also be used for different sized fixation members 20 (e.g., as
shown in FIGS. 27-30), and can be employed in right and left handed
configurations depending on the type of long bone being treated and
the orientation of the side aperture 19. The targeting guide
includes a guide portion 81 and a slide attachment portion 82. The
guide portion 81 defines a plurality of guide openings 83 sized for
the passage of screw guides 51 or drill guides 53 sized for
threaded fasteners 21 or for the smaller diameter k-wire fasteners
41. The guide openings 83 are positioned along an arc (as shown in
FIGS. 23 and 25) to correspond to the placement of the openings 36
through the side surfaces 33 of the curved body 24 so as to guide
the fasteners 21, 41 into the openings 36. Optionally, one of the
smaller diameter openings 83 may be placed to orient insertion of
one of the k-wire fasteners 41 external to the fixation member 20
to avoid additional holes in the fixation member and provide for
temporary securing of the guide assembly 50.
[0106] The slide attachment portion 82 is generally rectangular and
defines a pair of slots 84 that extend to one edge of the side
attachment portion. As is shown in FIG. 26, these slots are defined
by a pair of angled, opposing surfaces 85. In addition, at about a
midpoint along one edge of the slide attachment portion 82 is
defined a circular centering divot 86 with sloped sides, as shown
in FIGS. 24 and 26. During attachment of the targeting guide 80 to
the channel member 72, the pair of slots 84 of the slide attachment
portion 82 are inserted between the channel arms 73 until
approximately at the end of travel of the slots. Then, the locking
member 77 is advanced in the opening 76 until the locking tip 79
enters the centering divot 86. The sloped sides of the centering
divot 86 interact with the sloped edges of the locking tip 79 which
forces the targeting guide 80 to center and forms a relatively
tight, positive fit. Once the locking tip 79 bottoms within the
centering divot 86, further advancement of the locking tip pushes
the angled, opposing surfaces 85 of the slots against the angled
surfaces 74 of the channel arms 73. This also has the effect of
centering the targeting guide 80 between the channel arms 73 and
also forms a relatively tight, positive fit. In this manner, a
positive fit is used once again to ensure tight assembly of the
parts and accurate guidance for the insertion of various fasteners
21, 41.
[0107] As shown in FIGS. 33-36, each of the screw and drill guides
51, 53 include a grip flange 48 at one end of an elongate shaft 49
that defines teeth 47 at its other end. Defined within the elongate
shaft 49 of the drill guide is a guide shaft opening that tapers
from a wider to narrower diameter near the teeth 47, as shown in
FIG. 34. This corresponds with the dual diameter drill bit 90 shown
in FIG. 44, wherein the larger diameter of the drill bit prevents
travel of the drill bit beyond the shoulder defined within the
shaft 49 of the drill guide 53 so as to prevent drilling past a
selected depth for safety. The elongate shaft 49 of the screw guide
51 also defines a guide shaft, but this guide shaft has a constant
diameter because, as described above, the fasteners 21, 41 are
restrained by the structure of the fixation member 20 from
advancing too far.
[0108] During use the drill guides 53 are first inserted into the
guide openings 83 of the guide portion 81 of the targeting guide
and are advanced until the teeth 47 contact skin or bone (so as to
prevent rotation of the guides). A pilot hole is drilled using the
drill bit 90 guided by the drill guides 53. Then, the drill guides
53 are removed and screw guides 51 are inserted in the guide
openings 83 until the teeth 47 contact skin or bone. The selected
one of the threaded or k-wire fasteners 21, 41 are advanced at the
end of a driver 91 (as shown in FIGS. 42 and 43) until penetrating
the fixation member 20 through one of the openings 36 and into the
long bone 11 (in this case the second bone fragment 17). The driver
91 or drill bit 90 may be advanced using power or by hand, such as
by a hand driver 92, as shown in FIGS. 45 and 46.
[0109] During installation of the intramedullary fixation assembly
10, a k-wire is inserted into a lateral side of the widened end 13
of the long bone 11 subjacent the articular cartilage surface 12
and used to guide a cannulated drill bit 94, as shown in FIG. 47.
The cannulated drill bit clears the side aperture 19 and a
conventional bone awl (not shown) is used to open the medullary
canal 15 of cancellous bone.
[0110] A trialing broach 95, as shown in FIGS. 48 and 52, is
pushed, twisted, hammered, etc., into the long bone 11 through the
side aperture 19 to approximate the size of the fixation member 20.
The trialing broach includes a handle 98 and an awl point 99. The
handle 98 includes a head 100 that facilitates gripping and
hammering at one end and a threaded connector 101 at the other end,
as shown in FIG. 49. This threaded connector is similar to the
threaded tip 68 of the screw-in drill guide allowing the exchange
of the awl point 99 with other awl points of different sizes, each
having threaded opening at one end similar to the threaded opening
34 on the fixation member 20. Preferably, the awl point 99 has some
type of teeth or cutter (as shown symbolically by the cross-hatch
pattern 96) to aid in bone removal and sizing.
[0111] Advantageously, the trialing broaches 95 may eliminate the
need for many awls and cutting tools. However, other conventional
tools, such as reamers and awls could also be employed to clear
bone. Each of the broaches 95 may also include a depth indicator,
such as the notch 97 shown in FIG. 48, that indicates the correct
depth for that size of fixation member 20. The depth indicator or
notch 97 may include the use of fluorescent paint so as to be
easily visually detectable.
[0112] Once the side aperture 19 has been formed and the medullary
canal 15 cleared and sized, an appropriately sized fixation member
20 is selected based on the various above-described measurements.
The handle 98 of the trialing broach 95 is removed from the awl
point 99 and attached to the threaded opening defined in the handle
mount 37 via the threaded connector 101 on the handle, as shown in
FIG. 53. Then, the outrigger frame 54 of the guide assembly 50 is
attached to the fixation member. In particular, the screw-in drill
guide 52 is extended through the stepped opening 61 of the guide
member 58 and its threaded tip 68 is advanced into the threaded
opening 34 of the guide assembly. This assembly mates the prongs 59
with the concave indentations 40, thereby locking out micro-motion
and rotation between the outrigger frame 54 and the fixation member
20, as shown in FIGS. 39 and 40.
[0113] After fixation of the outrigger frame 54, the targeting
guide 80 is attached to the channel member 72 by sliding the
channel arms 73 within the pair of slots 84 on the guide portion 81
until the targeting guide is against the stop 75. Then, the locking
member 77 is advanced in the opening 76 until the locking tip 79
enters the centering divot 86. The sloped sides of the centering
divot 86 interact with the sloped edges of the locking tip 79 which
forces the targeting guide 80 to center and forms a relatively
tight, positive fit. Once the locking tip 79 bottoms within the
centering divot 86, further advancement of the locking tip pushes
the angled, opposing surfaces 85 of the slots against the angled
surfaces 74 of the channel arms 73.
[0114] The handle 98 and guide assembly 50 are then used to slide
the fixation member 20, as facilitated by the tapered ends 22, 23
through the side aperture 19 and into the medullary canal 15, as
shown in FIG. 54. The handle 98 is then unscrewed from the handle
mount 37. As an option, the fixation member 20 may include
radio-lucent targeting indicia to aid in positioning of the
fixation member and guide assembly 50. The length of the handle 98
allows for easy readjustment of the position of the fixation member
20.
[0115] Smaller guide openings 83 on the targeting guide 80 are used
to place a temporary k-wire fastener 41, such as by using the
smaller opening falling outside of the fixation member 20. This
allows for a temporary fixation into both the first and second bone
fragments 16, 17. The drill guides 53 are placed into the
appropriately sized openings 83. The dual-diameter drill bit 90 is
advanced into the drill guides 53, the screw guides 51 connected to
the hook-shaped body 55 (if necessary) and the guide member 58 to
form pilot holes in the long bone 11, as shown in FIGS. 55 and
56.
[0116] The depth of these holes are then tested using a depth gauge
102, as shown in FIGS. 50 and 51. The depth gauge 102 may also
employ fluorescent paint to ensure clear readability, such as on
measurement numbers and hash marks 103. The depth measurements
facilitate selection of fasteners 21, 41 of the appropriate length.
If necessary, the drilled holes are then tapped (not shown) to
prepare them for insertion of threaded fasteners 21. After tapping,
the drill guides 53 are replaced with the screw guides 51 (if
necessary) and the threaded fasteners 21 are advanced through the
aligned openings 34, 35, 36 in the fixation member 20 and the long
bone 11 so as to connect the bone fragments 16, 17, as shown in
FIGS. 57, 58 and 59. The guide assembly 50 and handle 98 can then
be removed by removal of the temporary k-wire fastener 41 and the
screw-in drill guide 52.
[0117] In another embodiment of the present invention, the fixation
member 20 of the intramedullary fixation assembly 10 may include a
tail portion 105 extending from, or as part of, the second end 23,
as shown in FIGS. 13 and 14. The tail portion has a much smaller
diameter or thickness than the curved body 24 and is relatively
straight to conform to the straightness of the shaft 14 of the long
bone 11. The tail portion in some circumstances can improve the
tightness of fit of the fixation member 20 in the second bone
fragment 17 with its extra length. Another option for improving the
fit within the second bone fragment is to employ the use of a split
tail 106, as shown in FIG. 60. The split tail defines a slot 107
that separates the split tail into two spaced arms that are drawn
against the cortical wall and urged apart as a tapered screw 108 is
advanced through the slot, as shown in FIG. 61. Alternatively, the
slot 107 of the split tail 106 may also be placed in an opposite
plane with a threaded opening in one of the arms so that passage of
a standard screw therethrough pushes the arms apart for additional
stability, as shown in FIGS. 60 and 61. In another embodiment, the
split tail portion 105 has a spring bias due to construction from a
flexible material, such as a metal material, and wherein the split
tail is defined by a coronal slot.
[0118] In still another embodiment of the present invention, the
fixation member 20 may be shaped to accommodate a driving handle
110 by having defined in its first end 22 a pair of U-shaped slots
112 on either side of the fixation member, as shown in FIGS. 62 and
63. The driving handle 110 includes a horseshoe or U-shaped impact
end 111 that straddles the fixation member 20, inserting into the
U-shaped slots 112 wherein the rounded shapes avoid eccentric
loading while the fixation member is being driven into the
medullary canal 15. Clearance may also be defined in the guide
assembly 50 for the impact end 111 to allow the guide assembly to
remain attached during driving. As another alternative, the slots
112 may also be defined in the guide assembly 50 for driving the
fixation member 20 via its attachment to the guide assembly.
[0119] In yet another embodiment of the present invention, in lieu
of the afore-described connection between the prongs 59 and the
concave indentations 40, the guide member 58 may include a pair of
S-curved fittings 113, as shown in FIGS. 64, 65, 66 and 67, that
are configured to mate in a positive fit with S-curved slots 114
defined on the first end 22 of the fixation member 20, as shown in
FIGS. 68, 69 and 70.
[0120] The present invention has many advantages. For example, the
invention has many attributes that facilitate its use for different
types of human long bone 11 wherein the fixation device extends
from the metaphysis to the diaphysis (via the positioning of the
side aperture 19), but not through the epiphysis, so as to avoid
damaging the articular cartilage. Maintaining a constant radius of
curvature near the first end 22 of the curved body 24 allows for
different sized long bones to be accommodated merely by extending
the arc further to produce a greater "hook." This overcomes the
increase in not only the length of the long bone 11, but also the
increase in distance between widened end 13 and width of the
medullary canal, facilitating its use on different and larger types
of long bones. It has also been determined that use of a radius of
curvature in the range of 1.5 to 5 inches facilitates use with
different types of long bone 11, especially when the curved body 24
curves continuously along its length and the ends 22, 23 are
tapered for easy insertion.
[0121] The use of a cruciform shape and positive fit or wedge
effect used for the concave indentations 40 and the prongs 59
provides rotational and translational stability of the fixation
member 20 when attached to the guide assembly 50. In addition, the
positive fit or wedge effect operates to center and reduce
micro-motion between the targeting guide 80 and the rest of the
guide assembly 50. Use of the positive fit of the channel arms 73,
the locking tip 79, the slots 84 and the centering divot 86 is
capable of achieving an accuracy in the range of one hundredths of
an inch. Further, the improved positioning from the positive fit
allows the single guide assembly 50 to facilitate placement of all
of the fasteners, eliminating the need to use multiple assemblies
and select openings via X-rays or other visual or manual
method.
[0122] Use of k-wire fasteners 41 and k-wire sized guide openings
83 and openings 36 in the curved body 24 of the fixation member 20
allow the fixation member 20 and guide assembly 50 to be
temporarily fixed to the long bone 11 after reduction of the
fracture. This allows the health care personnel to use both hands
to insert the remaining fasteners 21, 41. The cannulated, screw-in
drill guide 52 with its internal guide shaft allows for insertion
of fasteners 21, 41 into both the first and second bone fragments
16, 17 without removal or reconfiguration of the guide assembly 50.
The progressively smaller diameters of the fastener head 42,
threaded shaft 43, non-threaded shaft 43 and threaded,
bone-securing end 44, and the smoothness of the non-threaded shaft,
limit fretting of the threads on the bone-securing end. The stop 75
prevents mounting of a left oriented targeting guide 80 to a
left-handed outrigger frame 54 and vice-versa for a right handed
outrigger frame. The dual diameters 70, 71 of the drill guides 53
ensure concentricity of the dual-diameter drill bit 90.
[0123] Many modifications and other embodiments of the inventions
set forth herein will come to mind to one skilled in the art to
which these inventions pertain having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. For example, the fixation member 20 may have defined on
its outer surface grooves or texture (similar to the awl point 99)
that facilitates a tight fit in the medullary canal 15 or can hold
biologic or pharmacologic materials to facilitate bone ingrowth.
Therefore, it is to be understood that the inventions are not to be
limited to the specific embodiments disclosed and that
modifications and other embodiments are intended to be included
within the scope of the appended claims. Although specific terms
are employed herein, they are used in a generic and descriptive
sense only and not for purposes of limitation.
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