U.S. patent application number 09/767075 was filed with the patent office on 2002-03-14 for intramedullary nail.
Invention is credited to Fujiwara, Hiroo.
Application Number | 20020032445 09/767075 |
Document ID | / |
Family ID | 18724258 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020032445 |
Kind Code |
A1 |
Fujiwara, Hiroo |
March 14, 2002 |
Intramedullary nail
Abstract
A lag screw for connecting a bone portion separated from the
femur, by fracture, to the main portion thereof is fixedly secured
in the separated bone portion and extends through main portion of
the femur. A nail member is installed in the femur in order to fix
the lag screw to the femur. The lag screw is secured in the nail
member by a set screw inserted into an outer end of the nail
member. In order to prevent the rotation of the separated bone
portion about the lag screw, an auxiliary connector is inserted
through the nail member between the lag screw and the set screw.
The lag screw is clamped by the set screw via a spacer for
transmitting a clamping force.
Inventors: |
Fujiwara, Hiroo;
(Kurashiki-shi, JP) |
Correspondence
Address: |
Paul & Paul
2900 Two Thousand Market Street
Philadelphia
PA
19103
US
|
Family ID: |
18724258 |
Appl. No.: |
09/767075 |
Filed: |
January 22, 2001 |
Current U.S.
Class: |
606/67 ;
606/64 |
Current CPC
Class: |
A61B 17/744
20130101 |
Class at
Publication: |
606/67 ;
606/64 |
International
Class: |
A61B 017/78 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 27, 2000 |
JP |
2000-231416 |
Claims
What is claimed is:
1. An intramedullary nail comprising: a bone connector for
connecting a bone portion separated from a main portion of a bone
by fracture to said main portion, said bone connector extending
through said main portion and secured in said separated bone
portion; a nail member installed in said main portion of said bone
for fixing said bone connector to said main portion, said bone
connector extending through said nail member; a set screw inserted
into an outer end of said nail member for securing said bone
connector in said nail member; an auxiliary connector extending
through said nail member between said bone connector and said set
screw; and a spacer for transmitting a clamping force from said set
screw to said bone connector thereby to clamp said bone
connector.
2. The intramedullary nail according to claim 1, wherein said
spacer includes two legs extending in spaced relation to each
other, and wherein said auxiliary connector extends through said
nail member between said two legs.
3. The intramedullary nail according to claim 2, wherein said bone
connector has grooves formed on a peripheral surface thereof for
two legs of said spacer to engage.
4. The intramedullary nail according to claim 1, wherein said set
screw includes a boss extending toward said spacer, said boss
passing through said spacer to engage a groove formed on a
peripheral surface of said auxiliary connector.
5. An intramedullary nail comprising: a bone connector for
connecting a bone portion separated from a main portion of a femur,
by fracture, to said main portion, said bone connector extending
through said main portion and secured in said separated bone
portion; a nail member installed in said main portion of said femur
for fixing said bone connector to said main portion, said bone
connector slidably inserted through said nail member; a set screw
inserted into a set hole for securing said bone connector in said
nail member, said set hole formed in an outer end of said nail
member and extending longitudinally of said nail member; an
auxiliary connector extending through said nail member between said
bone connector and said set screw; and a spacer for transmitting a
clamping force from said set screw to said bone connector without
interfering with said auxiliary connector, thereby to clamp said
bone connector.
6. The intramedullary nail according to claim 5, wherein said
spacer includes two legs extending in a spaced relation to each
other, wherein said auxiliary connector extends through said nail
member between said two legs, and wherein said bone connector has
one or more groove(s) formed on a peripheral surface thereof for
said two legs to engage.
7. An intramedullary nail comprising: a bone connector for
connecting a bone portion separated from a main portion of a bone
by fracture to said main portion, said bone connector extending
through said main portion and secured in said separated bone
portion; a nail member installed in said main portion of the bone
for fixing said bone connector to said main portion, said bone
connector extending through said nail member; a set screw inserted
into an outer end of said nail member for securing said bone
connector in said nail member; and an auxiliary connector extending
through said nail member and arranged in a position where said
auxiliary connector is free from said set screw.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an intramedullary nail used
for an intramedullary nailing procedure.
[0003] 2. Description of the Related Art
[0004] The intramedullary nail is mainly used for treating a
fracture of the proximal portion of the femur such as an
intertrochanteric fracture or a subtrochanteric fracture by pulling
the proximal bone portion, separated from the femur by the
fracture, to the femur to compress and fix them.
[0005] The intramedullary nail includes a nail member inserted into
the femur from one end thereof, and a lag screw extending through
the nail member and connected to the bone portion separated by the
fracture. The lag screw includes engaging means for engaging the
separated bone portion at the forward end thereof, and is fixedly
supported on the nail member by a set screw inserted into a
threaded hole formed in the outer end of the nail member. The nail
member is formed with a through hole extending diagonally across
the proximal portion thereof so that the forward end of the lag
screw inserted into the through hole may be screwed into the bone
portion separated by fracture such as the caput of bone positioned
at a diagonally upward side.
[0006] In the treatment of the fractured proximal portion of the
femur, the first step is to insert the nail member in the proximal
end of the femur and install it in the medullary cavity thereof.
Then, a locking screw can be inserted, if necessary, such that it
extends across the medullary cavity and the distal portion of the
nail member thereby fixing the nail member at a predetermined
position in the femur. As the next step, the engaging means
(threaded portion) at the forward end of the lag screw is passed
through the through hole of the nail member into the portion of the
caput of bone positioned more proximal than the fractured portion
thereby to secure the separated caput to the lag screw. After that,
the separated caput of the femur is pulled by the lag screw in such
a manner as to press the separated caput against the main portion
of the femur. When the caput of the femur comes to be positioned
adjacent to the main portion thereof, the set screw is inserted
into a threaded fixing hole of the nail member so that the forward
end of the set screw engages the peripheral surface of the lag
screw thereby to secure the lag screw to the nail member.
[0007] However, the separated portion of the bone such as the
fractured caput, which is secured only to a single bone connector
such as a lag screw, is liable to rotate about the bone connector.
The rotation of the separated bone portion hinders the separated
bone portion from being coapted to the main portion of the bone.
Therefore, this can result in a problem that the healing time of
the fracture is increased or that the fracture line is displaced
before the separated bone portion is coapted to the main portion.
In the case where the degree of rotation is high, the muscle
surrounding the separated portion of the bone such as the caput may
be damaged.
[0008] In order to prevent such a rotation of a separated bone
portion, it is required to connect the separated bone portion of
the femur and the main portion thereof by additionally providing an
auxiliary connector extending across the nail member to the
separated bone portion. However, the auxiliary connector cannot
pass across through the nail member because of the presence of a
set screw extending longitudinally inside of the nail member from
one end thereof for securing the bone connector to the nail
member.
SUMMARY OF THE INVENTION
[0009] Accordingly, it is an object of the present invention to
obviate the problem in the prior art described above to provide an
intramedullary nail allowing a bone connector and an auxiliary
connector to be inserted into a nail member for preventing the
rotation of a bone portion separated from a main portion of a femur
by fracture and located on the proximal side of the fractured
portion, thereby to promote the healing of the fractured
portion.
[0010] In order to achieve the object described above, in
accordance with a first aspect of the present invention, there is
provided an intramedullary nail which includes a bone connector for
connecting a bone portion separated from a main portion of a bone
by fracture to the main portion, the bone connector extending
through the main portion and secured in the separated bone portion;
a nail member installed in the main portion of the bone for fixing
the bone connector to the main portion, the bone connector
extending through the nail member; a set screw inserted into an
outer end of the nail member for securing the bone connector in the
nail member; an auxiliary connector extending through the nail
member between the bone connector and the set screw; and a spacer
for transmitting a clamping force from the set screw to the bone
connector thereby to clamp the bone connector.
[0011] In accordance with a second aspect of the present invention,
there is provided an intramedullary nail which includes a bone
connector for connecting a bone portion separated from a main
portion of a femur by fracture to the main portion, the bone
connector extending through the main portion and secured in the
separated bone portion; a nail member installed in the main portion
of the femur for fixing the bone connector to the main portion, the
bone connector slidably inserted through the nail member; a set
screw inserted into a set hole for securing the bone connector in
the nail member, the set hole formed in an outer end of the nail
member and extending longitudinally of the nail member; an
auxiliary connector extending through the nail member between the
bone connector and the set screw; and a spacer for transmitting a
clamping force from the set screw to the bone connector without
interfering with the auxiliary connector, thereby to clamp the bone
connector.
[0012] In accordance with a third aspect of the present invention,
there is provided an intramedullary nail which includes a bone
connector for connecting a bone portion separated from a main
portion of a bone by fracture to the main portion, the bone
connector extending through the main portion and secured in the
separated bone portion; a nail member installed in the main portion
of the bone for fixing the bone connector to the main portion, the
bone connector extending through the nail member; a set screw
inserted into an outer end of the nail member for securing the bone
connector in the nail member; and an auxiliary connector extending
through the nail member and arranged in a position where the
auxiliary connector is free from the set screw.
[0013] In the intramedullary nail described above, the spacer
includes two legs extending in spaced relation with each other, and
the auxiliary connector extends through the nail member between the
two legs. Preferably, the bone connector has grooves formed on a
peripheral surface thereof for the two legs of the spacer to
engage.
[0014] In the above-mentioned intrammedullary nail, the set screw
may include a boss extending toward the spacer, which boss passes
through the spacer to engage a groove formed on a peripheral
surface of the auxiliary connector.
[0015] Since the auxiliary connector extending through the nail
member between the bone connector and the set screw is provided and
the spacer for transmitting the clamping force is interposed
between the set screw and the bone connector, the auxiliary
connector extending to the separated bone portion through the nail
member prevents the rotation of the separated bone portion. Also,
the clamping force of the set screw inserted to the outer end of
the nail member is transmitted to the bone connector over the
auxiliary connector via the spacer, thereby permitting the bone
connector to be secured in the nail member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above and other objects, features, and advantages of the
present invention will be made more apparent from the following
description of the preferred embodiments thereof with reference to
the accompanying drawings, wherein:
[0017] FIG. 1 is a partly sectional perspective view of one
embodiment of an intramedullary nail according to the present
invention;
[0018] FIG. 2 is a partly sectional view illustrating the whole
intramedullary nail shown in FIG. 1 used to fix the fractured
portions of the femur;
[0019] FIG. 3 is a sectional view of the nail member shown in FIG.
1;
[0020] FIG. 4 is a perspective view of one embodiment of a spacer
for transmitting a clamping force;
[0021] FIG. 5 is a partly sectional view of the intramedullary nail
for explaining the principle on which the clamping force is applied
by a set screw to a lag screw via the spacer and by which the
rotation of the lag screw is prevented;
[0022] FIG. 6 is a sectional view taken along line VI-VI of FIG. 5;
and
[0023] FIG. 7 is a partly sectional perspective view of another
embodiment of an intramedullary nail according to the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Preferred embodiments of an intramedullary nail according to
the present invention will be described below with reference to the
accompanying drawings.
[0025] FIG. 1 is a partly sectional perspective view of one
embodiment of an intramedullary nail according to the present
invention, and FIG. 2 is a partly sectional view illustrating the
whole intramedullary nail shown in FIG. 1 used to fix the fractured
portions of the femur. FIG. 3 is a sectional view of the nail
member shown in FIG. 1.
[0026] Referring to FIGS. 1 and 2, the intramedullary nail 10
according to the present invention includes a rod-shaped nail
member 16 inserted into the inner cavity (medullary cavity) 14 of a
femur 12 from one end of the femur 12, and a lag screw 22, i.e. a
bone connector for connecting to the main portion of the femur 12 a
bone portion 20 separated from the main portion of the femur 12 by
the fracture along a fracture line 18.
[0027] Specifically, referring to FIG. 3, the nail member 16
includes a proximal portion 16b, an distal portion 16c longer than
the proximal portion 16b, and a bent portion 16a located at a
boundary between them. As best shown in FIG. 3, the proximal
portion 16b is formed with two through holes, a main through hole
24 and an auxiliary through hole 26, extending in parallel
diagonally across the nail member 16 in the neighborhood of the
bent portion 16a of the nail member 16. The proximal portion 16b of
the nail member 16 is formed in a large size sufficient to
accommodate the through holes 24, 26, while the distal portion 16c
is formed in a small size suitable for the shape of the inner
cavity (medullary cavity) 14 of the femur 12 in order to facilitate
the insertion of the distal portion 16 into it. Fixing through
holes 28 extending orthogonal to the axis of the distal portion 16c
are formed at an end of the distal portion 16c of the nail member
16. Locking screws 30 are inserted across the shaft of the femur 12
(the body of the femur 12) into the fixing through holes 28 in
order to securely fix the nail member 16 to the shaft of the femur
12.
[0028] In the embodiment of the intramedullary nail 10 shown in
FIGS. 1 and 2, the bone connector is the lag screw 22. The lag
screw 22 has engaging means 32 such as a threaded portion at the
forward end thereof for engaging the bone portion 20 separated from
the main portion of the femur 12, and the proximal portion of the
lag screw 22 is formed with a plurality of grooves 34 extending on
the peripheral surface thereof along the axis of the lag screw 22
(in the lag screw 22 shown in FIGS. 1 and 2, four grooves 34 are
disposed on the peripheral surface of the lag screw 22 at intervals
of 90.degree. around the axis of the lag screw 22). The lag screw
22 is inserted into the femur 12 with the engaging means 32 thereof
directed ahead, and further slidably inserted into the main through
hole 24 of the nail member 16 thereby to penetrate into the
separated bone portion 22. Thus, the lag screw 22 is fixedly
secured in the separate bone portion 20 by causing the engaging
means 32 at one end of the lag screw to engage the separated bone
portion 20. Finally, the separated bone portion 20 is fixed to the
main portion of the femur 12 by securing the other end of the lag
screw 22 to the main through hole 24 of the nail member 16
installed in the femur 12.
[0029] The intramedullary nail 10 according to the present
invention further includes an auxiliary connector 36 slidably
inserted through an auxiliary through hole 26 located in the nail
member 10 as shown in FIGS. 1 and 2. The auxiliary connector 36,
like the lag screw 22, i.e. the bone connector, is arranged in such
a position as to pass through the main portion of the femur 12
while being passed into the separated bone portion 20 thereof.
[0030] The auxiliary connector 36 and the bone connector arranged
in this way form two fixed axles extending from the nail member 16
to the separated bone portion 20 thereby to prevent the separated
bone portion 20 from rotating about the bone connector (the lag
screw 22). However, the auxiliary connector 36 can be used for
other purposes than preventing the rotation of the separated bone
portion 20.
[0031] A set hole 38, which extends longitudinally in the nail
member 16 from one end thereof across the auxiliary through hole 26
to the main through hole 24 and has at least a portion threaded, is
formed at the outer end (proximal end) of the nail member 16. A set
screw 42 is screwed into the set hole 38 for applying the clamping
force to the lag screw 22 inserted into the main through hole
24.
[0032] Further, in order to allow a guide rod (not shown) to be
used for facilitating the insertion into the inner cavity 14 of the
femur 12, an inner hole for the guide rod 44 may be formed along
the longitudinal axis of the nail member 16 as shown in FIG. 3. In
such a case, the set hole 38 in the proximal portion 16b of the
nail member 16 constitutes a part of the inner hole for the guide
rod 44.
[0033] In the intramedullary nail 10 according to the present
invention, the auxiliary connector 36 extends through the nail
member 16 at a location between the set screw 42 screwed into the
outer end of the nail member 16 and the lag screw 22, i.e. a bone
connector. Therefore, in order to allow the set screw 42 to apply a
clamping force to the lag screw 22 over the auxiliary connector 36,
a spacer 46 for transmitting a clamping force is interposed between
the set screw 42 and the lag screw 22.
[0034] FIG. 4 is a perspective view of one embodiment of the spacer
46. FIG. 5 is a partly sectional view of the intramedullary nail
for explaining the principle on which the clamping force is applied
by the set screw to the lag screw 22 via the spacer 46 and the
rotation of the lag screw 22 is prevented. FIG. 6 is a sectional
view taken along line VI-VI of FIG. 5.
[0035] The spacer 46 shown in FIG. 4 includes a body 46a and two
legs 46b extending from the body 46a in spaced relation with each
other.
[0036] As shown in FIG. 5, when the set screw 42 is placed on the
spacer 46 inserted into the set hole 38 and is screwed into it, the
set screw 42 engaged with the threaded portion of the set hole 38
abuts against the body 46a. Thus, the set screw 42 pushes down the
whole of the spacer 46 and the lower ends of the legs 46b come into
engagement with the grooves 34 of the lag screw 22, thereby
securing the lag screw 22 in the nail member 16 while at the same
time preventing the rotation of the lag screw 22. Even in the case
where the grooves 34 are not formed on the periphery surface of the
lag screw 22, the lag screw 22 can be secured in the nail member 16
by being clamped between the nail member 16 (particularly the
surface of the main through hole 24) and the spacer 46 due to the
friction between the lower ends of the legs 46b of the spacer 46
and the peripheral surface of the lag screw 22.
[0037] The auxiliary connector 36 inserted into the auxiliary
through hole 26, on the other hand, can pass through the nail
member 16 by way of the space defined between the two spaced legs
46b of the spacer 46. As shown in FIG. 5, preferably, the diameter
of the portion of the set hole 38 in the neighborhood of the main
through hole 24 is rendered smaller than that of the portion
thereof engaged by the set screw 42, and guide grooves 48 for the
legs 46b are formed on the inner surface of the set hole 38 as
shown in FIG. 6. Such guide grooves 48 can prevent the spacer 46
from being rotated by the rotation of the set screw 42 when the set
screw 42 is screwed into the set hole 38. Also, the portion of the
set hole 38 where the diameter thereof changes defines a shoulder
50 as shown in FIG. 3, thereby limiting the downward movement of
the body 46a of the spacer 46. Thus, the movable range of the
spacer 46 is limited such that the lower ends of the legs 46b are
suspended in the main through hole 24 even when the spacer 46 moves
to its lowest position. This enables the forward end of the leg
screw 22 to come into contact with the legs 46b of the spacer 46
during the insertion of the lag screw 22, thereby moving the spacer
46 upward.
[0038] In the case where it is desirable to securely hold the
auxiliary connector 26 in the nail member 16, a boss 52 may be
formed at the forward end of the set screw 42 and inserted through
an opening 54 formed in the body 46a of the spacer 46 to abut
against the auxiliary connector 36, as shown in FIG. 1. In this
way, the set screw 42 is inserted in the set hole 38 and engaged
with the threaded portion thereof, so that the boss 52 of the set
screw 42 comes into contact with the auxiliary connector 36, which
makes it possible to securely hold the auxiliary connector 36 in
the nail member 16. Further, in order to prevent the rotation of
the auxiliary connector 36, a longitudinally extending groove may
be formed on the auxiliary connector 36 to be engaged by the boss
52 of the set screw 42.
[0039] FIG. 7 is a perspective view of another embodiment of an
intramedullary nail 10 according to the present invention which is
similar to that shown in FIG. 1 except that the bone connector is
of such a type that the compression force can be easily exerted on
the separated portion of bone.
[0040] The bone connector shown in FIG. 7 includes a sleeve 56
inserted into the main through hole 24 of the nail member 16, and
the lag screw 22 is inserted into the sleeve 56. The proximal end
of the lag screw 22 is formed with a threaded hole (not shown) in
the axial direction, and the forward end of the pulling screw 58
for pulling the lag screw 22 is inserted into the same threaded
hole. The head of the proximal end of the pulling screw 58 is in
contact with the annular shoulder formed on the inner surface of
the proximal end of the sleeve 56. By rotating the pulling screw
58, the lag screw 22 can be pulled in such a direction as to pull
the separated bone portion 20 toward the remainder (main portion)
of the femur 12 and apply a compression force to it. The peripheral
surface of the sleeve 56 shown in FIG. 7 is serrated to enhance a
frictional engagement with the spacer 46. Alternatively, the
peripheral surface of the sleeve 56 can of course be formed with
grooves, like the lag screw 22 shown in FIG. 1, which are adapted
to engage the legs 46b of the spacer 46.
[0041] Components of the intramedullary nail described above are
preferably made of pure titanium, a titanium alloy, the
cobalt-nickel alloy or a similar biocompatible material.
[0042] In the shown embodiment, the spacer 46 is shown as a
separate member from the set screw 42. However, the set screw 42
and the spacer 46 may be integrated with each other.
[0043] A method of using the intramedullary nail 10 shown in FIG. 1
will be now described.
[0044] The femur 12, as shown in FIG. 2, includes a caput 60 at an
end thereof and an inner cavity (medullary cavity) 14 in the shaft
thereof. The fracture related to the caput 60 of the femur 12 is
liable to occur in the neck portion of caput 60 having a thin root,
for example, at the position indicated by the fracture line 18
shown in FIG. 2. In the case of such a fracture, if the separated
bone portion (caput 60) is fixed by a single bone connector like
the lag screw 22 as in the prior art, the separated bone portion 20
could rotate about the bone connector (i.e. the lag screw 22),
often having an adverse effect on the healing of the fractured
portion. In view of this, the intramedullary nail 10 according to
the invention is provided with an auxiliary connector 36
substantially parallel to the axis of a bone connector, and the
separated bone portion 20 and the main portion of the femur 12 are
connected and fixed to each other by use of these two
connectors.
[0045] First, after a guide rod (not shown) is inserted into the
femur 12 along the inner cavity 14 thereof, a hole is formed in the
femur 12 by drilling along the guide rod. The nail member 16 is
inserted into the inner cavity 14 while being guided by the guide
rod until it reaches a predetermined position as shown in FIG. 2.
Then, by passing the locking screws 30 across the shaft of the
femur 12 through the fixing through holes 28, the nail member 16 is
fixed at a predetermined position of the femur 12. After the nail
member 16 is fixed at a predetermined position, the guide rod is
removed from the inner cavity 14 of the femur 12.
[0046] As the next step, a guide pin (not shown) is inserted from
the side wall of the femur 12 into the forward end of the caput 60
across the femur 12 through the main through hole 24 of the nail
member 16. After drilling a hole in the femur 12 along the guide
pin, the lag screw 22 is inserted into the femur 12 through the
main through hole 24 of the nail member 16 with the engaging means
(threaded portion) 32 of the lag screw 22 directed forward while
being guided by the guide pin until the engaging means 32 of the
lag screw 22 reaches the separated bone portion 20 (caput 60).
Thus, the lag screw 22 is fixedly secured in (engaged with) the
bone portion 20 by the engaging means 32. After that, the lag screw
22 is pulled in such a direction that the engaging means 32
approaches the nail member 16 to compress the fractured portions,
and the separated bone portion 20 is pulled into close proximity
with the main portion of the femur 12.
[0047] As the next step, in order to prevent the separated bone
portion from rotating about the lag screw 22, the auxiliary
connector 36 is screwed from the side wall of the femur 12 across
the femur 12 and through the auxiliary through hole 26 of the nail
member 16 to the bone portion 20. As a result, the nail member 16
installed in the shaft of the femur 12 and the separated bone
portion 20 are connected to each other by the two connectors, i.e.
the bone connector (lag screw 22) and the auxiliary connector 36,
with the result that the separated bone portion 20 cannot
rotate.
[0048] As the last step, the spacer 46 is inserted into the set
hole 38 formed at the outer end of the nail member 16, and the set
screw 42 is screwed over the spacer 46. In the process, the
auxiliary connector 36 extending laterally through the nail member
16 is adapted to pass between the legs 46b of the spacer 46. By
tightening the set screw 42, the legs 46b of the spacer 46 are
forced to come into engagement with the grooves 34 of the lag screw
22, so that the lag screw 22 is securely held in the nail member 16
while the rotation of the lag screw 22 is prevented. Specifically,
in the intramedullary nail 10 according to the invention, the
clamping force of the set screw 42 is transmitted to the lag screw
22 over the auxiliary connector 36 extending across the nail member
16 between the set screw 42 and the lag screw 22 by way of the
spacer 46 thereby to secure the lag screw 22 in the nail member 16.
The legs 46b of the spacer 46 are guided along the guide grooves 48
formed in the inner surface of the set hole 38. Therefore, the legs
46b of the spacer 46, which cannot be rotated by rotation of the
set screw 42, never interfere with the auxiliary connector 36. The
guide pin is removed after the lag screw 22 is secured in the nail
member 16.
[0049] As described above, the intramedullary nail prevents the
rotation of the separated bone portion 20 (caput 60) and the
relative displacement of the fractured portions before the
separated bone portion 20 and the main portion of the femur 12 are
fixed and the fractured portions are successfully coapted to each
other.
[0050] The present invention was described above with reference to
the intramedullary nail 10 used for fixing the fractured portions
positioned in the neighborhood of the caput 60 of the femur 12 as
an example. However, the present invention is equally applicable to
any intramedullary nail for fixing fractured portions positioned in
the neighborhood of the caput of other bones such as the
humerus.
[0051] In addition, another type of an intramedullary nail can
achieve the effect of preventing a rotation of a separated bone
portion. One embodiment of this type of the intramedullary nail may
include a bone connector extending through a femur to a bone
portion separated from a main portion of the femur and secured to
the separated bone portion for connecting the separated bone
portion to the main portion of the femur, a nail member through
which the bone connector extends and which is installed in the
femur for fixing the bone connector to the main portion of the
femur, a set screw inserted into an outer end of the nail member
for securing the bone connector to the nail member, and an
auxiliary connector extending through the nail member and arranged
in a position where the auxiliary connector is free from the set
screw (for example, under the bone connector or in a position
farther away from the set screw than the bone connector).
[0052] It will thus be understood from the foregoing description
that, according to the present invention, a separated bone portion
can be fixed to a main portion of the femur by two connectors, i.e.
a bone connector and an auxiliary connector, and therefore the
fractured portions are not displaced by the rotation of the
separated bone portion, thereby making it possible to promote the
healing of the fracture. Also, since a clamping force of the set
screw can be applied to the bone connector by a spacer for
transmitting the clamping force over the auxiliary connector
extending across the nail member at a position between the set
screw and the bone connector, secure holding of the bone connector
in the nail member is not sacrificed.
* * * * *