U.S. patent application number 11/421972 was filed with the patent office on 2007-12-13 for system and method for inserting an implant.
Invention is credited to Gabriel Surma.
Application Number | 20070288096 11/421972 |
Document ID | / |
Family ID | 38822906 |
Filed Date | 2007-12-13 |
United States Patent
Application |
20070288096 |
Kind Code |
A1 |
Surma; Gabriel |
December 13, 2007 |
SYSTEM AND METHOD FOR INSERTING AN IMPLANT
Abstract
An implant includes a body configured to be implanted at least
partially within a bone canal. The body has a proximal end, a
longitudinal axis and a cavity located at the proximal end. The
cavity is configured to mate with an insertion tool and defines a
cavity axis that is not parallel to the longitudinal axis of the
implant.
Inventors: |
Surma; Gabriel; (Winona
Lake, IN) |
Correspondence
Address: |
PHILIP S. JOHNSON;JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
38822906 |
Appl. No.: |
11/421972 |
Filed: |
June 2, 2006 |
Current U.S.
Class: |
623/22.4 |
Current CPC
Class: |
A61F 2002/4062 20130101;
A61F 2002/4681 20130101; A61F 2002/3625 20130101; A61F 2002/305
20130101; A61F 2/36 20130101; A61F 2220/0033 20130101; A61F 2/3676
20130101; A61F 2/367 20130101; A61F 2002/30795 20130101; A61F
2002/4635 20130101; A61F 2/4607 20130101; A61F 2002/4628 20130101;
A61F 2220/0025 20130101; A61F 2002/30367 20130101; A61F 2002/30322
20130101; A61F 2250/0026 20130101; A61F 2002/30354 20130101 |
Class at
Publication: |
623/22.4 |
International
Class: |
A61F 2/32 20060101
A61F002/32 |
Claims
1. An implant, comprising: a body configured to be implanted at
least partially within a bone canal, the body having a proximal
end, a longitudinal axis and a cavity located at the proximal end,
wherein the cavity is configured to mate with an insertion tool,
and the cavity defines a cavity axis that is not parallel to the
longitudinal axis of the implant.
2. The implant of claim 1, wherein the cavity axis and the
longitudinal axis intersect to form an offset angle of between 5
degrees and 55 degrees.
3. The implant of claim 2, wherein the offset angle is about 40
degrees.
4. The implant of claim 1, further comprising a neck extending from
the body, and wherein the cavity is located laterally relative to
the neck.
5. The implant of claim 1, wherein the cavity includes at least one
feature configured to mate with the distal tip of an insertion
tool.
6. The implant of claim 5, wherein the at least one feature
includes at least one of a dimple and a shoulder.
7. The implant of claim 1, wherein the cavity is generally circular
when viewed in a cross-section taken perpendicular to the cavity
axis.
8. The implant of claim 1, wherein the bone canal is the femoral
canal and the implant is a hip implant.
9. An implant system, comprising: an implant comprising a body
having a proximal end, a longitudinal axis, and a cavity, the
cavity having a cavity axis that is not parallel to the
longitudinal axis of implant; and a tool for assisting in the
implantation of the implant having a distal end configured to mate
with the cavity.
10. The system of claim 9, wherein the tool has a distal portion
and further comprising a cantilevered spring arm that extends from
the distal portion of the tool, the arm being configured to
frictionally engage the cavity of the implant when the arm is at
least partially disposed therein.
11. The system of claim 10, wherein the cavity has a dimple, and
the arm includes a feature configured to be at least partially
disposed within the dimple when the distal end of the tool is
engaged with the cavity.
12. An implant system, comprising: an implant comprising a body
having a proximal end, a longitudinal axis, and a cavity; and a
tool for assisting in the implantation of the implant comprising a
distal end configured to mate with the cavity, the distal end
having an axis that is not parallel to the longitudinal axis of the
body when the tool is mated with the implant.
13. A method of implanting an implant at least partially within a
bone, the bone having a bone axis, comprising the steps of:
providing a system comprising an implant comprising a body, the
body having a proximal end, a distal end, a longitudinal axis and a
cavity located at the proximal end, wherein the cavity defines a
cavity axis that is not parallel to the longitudinal axis of the
implant, and a tool for assisting in the implantation of the
implant comprising a shaft having a distal end configured to mate
with the cavity and a proximal end, the proximal end including a
strike plate attached thereto; creating a void in a bone;
introducing the distal end of the implant into the void, whereat
the longitudinal axis of the implant is not aligned with the bone
axis; engaging the distal end of the tool into the cavity of the
implant; striking the strike plate to thereby rotate the
longitudinal axis of the implant toward the bone axis until the
longitudinal axis of the implant is substantially aligned with the
bone axis; and disengaging the distal end of the tool from the
cavity of the implant.
14. The method of claim 13, wherein the providing step comprises
providing a tool that has a distal portion that includes a
cantilevered spring arm that extends from the distal portion, and
the arm being configured to frictionally engage the cavity of the
implant when at least partially disposed therein, and wherein the
engaging step comprises engaging the arm with the cavity.
15. The method of claim 14, wherein the providing step comprises
providing an implant that includes a dimple within the cavity, and
providing a tool that includes a raised surface on a distal end of
the cantilevered spring arm configured to at least partially engage
the dimple when the distal end of the tool is engaged with the
cavity, and wherein the engaging step comprises engaging the raised
surface with the dimple.
16. The method of claim 15, wherein the cantilevered spring arm and
the cavity of the implant are configured to permit disengagement of
the tool and the implant when a force ranging from approximately
one-quarter of a pound to five pounds is exerted proximally along
the longitudinal axis of the tool.
17. The method of claim 13, wherein the bone axis is a long bone
axis.
18. The method of claim 17, wherein the implant is a hip implant,
the long bone axis is the femoral axis, and the creating step
comprises the step of sparing the greater trochanter.
19. A method of implanting an implant at least partially within
tissue, wherein the tissue includes an implant target position
having a target axis and a tissue feature that intersects the
target axis, comprising the steps of: providing a system comprising
an implant comprising a body, the body having a proximal end, a
distal end, a longitudinal axis and a cavity located at the
proximal end, wherein the cavity defines a cavity axis that is not
parallel to the longitudinal axis of the implant, and a tool for
assisting in the implantation of the implant comprising a shaft
having a distal end configured to mate with the cavity and a
proximal end; creating a pathway from a tissue surface to a target
position within the tissue; inserting the distal end of the implant
into the pathway; engaging the distal end of the tool with the
cavity of the implant; manipulating the tool to move the implant to
the target position without impinging on the tissue feature; and
disengaging the distal end of the tool from the cavity of the
implant.
20. The method of claim 19, wherein the manipulating step comprises
one of rotating or translating the implant.
21. The method of claim 19, wherein the target axis is the femoral
axis of the femur, the tissue feature is the greater
trochanter,
22. The method of claim 19, wherein the tool includes a strike
plate attached at the proximal end of the tool, and the
manipulating step comprises impacting the strike plate.
Description
[0001] This invention relates to a method of and system for
implanting an implant, more particularly implanting a hip implant
at least partially within the femoral canal.
[0002] Orthopaedic surgeons, as with other specialities, have been
driven to perform their surgery through smaller and smaller
incisions in an attempt to minimize damage to tissue that surrounds
the surgical site, to thereby decrease blood loss and recovery
time. In orthopaedics, particularly, it is recognized that sparing
a patient's bone is preferred whenever possible during surgery. In
hip replacement surgery, a surgeon can attempt to spare the upper
part of the femur (greater trochanter) by using a small incision
surgical technique that employs a short hip implant.
[0003] An issue that occurs during this surgery is the difficulty
in using an insertion feature of the implant that is positioned on
the lateral-superior aspect of the implant. The feature is located
at this position due to the compromise between accessibility of the
feature and the mechanical strength requirements imposed on the
implant. Currently available straight, in-line impactors and
implant insertion features are positioned coincident with or
parallel to the long (or longitudinal) axis of the implant. When
the surgeon attempts to finally seat the implant using the
insertion feature, the position of the insertion feature can cause
the impactor to interfere with the mass of the greater trochanter.
As a result of this difficulty, the surgeon may not completely seat
the implant, thereby compromising the biomechanics of the joint
space and potentially leading to implant subsidence and/or
dislocation.
BRIEF SUMMARY OF THE INVENTION
[0004] The present invention addresses the shortcomings of the
prior art by providing an improved method of and system for
inserting and impacting an implant.
[0005] The preferred embodiment of the implant system allows the
insertion of a short implant using the `around the corner` surgical
technique. This technique aims to minimize the damage to the
greater trochanter by broaching around the medial curve of the
femur and under the greater trochanter. The insertion feature
located on the implant is designed to mate with the
inserter/impactor tool in a way that allows for rotational control
of the implant but is also removable using a low force. The system
addresses the problem of greater trochanter impingement by both
angling the insertion feature with respect to the long axis of the
implant and curving the impactor to travel around the greater
trochanter during the "around the corner" insertion motion.
[0006] While the issue of navigating a short implant in a hip
procedure is described in some detail below, it is contemplated
that the implant system can be used in any method where an implant
needs to be inserted or positioned in a non-axial fashion. For
example, a similar method and system can be used to implant humeral
implants. The invention is also not necessarily limited to
implantation of long-bone implants. The system can be employed
wherever the insertion path of the implant benefits from being out
of axis of the ultimate location of the implant.
[0007] According to the present invention a short hip implant
includes a body configured to be implanted at least partially
within the femoral canal. The body has a proximal end, a
longitudinal axis and a cavity located at the proximal end. The
cavity is configured to mate with an insertion tool, and defines a
cavity axis that is not parallel to the longitudinal axis of the
implant.
[0008] According to another aspect of the present invention a hip
implant system includes a short hip implant having a body with a
proximal end, a longitudinal axis, and a cavity. The cavity has a
cavity axis that is not parallel to the longitudinal axis. The
system also includes a tool for assisting in the implantation of
the implant that has a distal end configured to mate with the
cavity.
[0009] According to another aspect of the present invention a hip
implant system includes a short hip implant having a body with a
proximal end, a longitudinal axis, and a cavity. The system also
includes a tool for assisting in the implantation of the implant
that has a distal end configured to mate with the cavity. The
distal end has an axis that is not parallel to the longitudinal
axis of the body when the tool is mated with the implant.
[0010] A method of implanting a short implant at least partially
within a bone, wherein the bone has an axis, is also provided. The
method includes the steps of (a) providing a system including an
implant having a body with a proximal end, a distal end, a
longitudinal axis and a cavity located at the proximal end, the
cavity being configured to mate with an insertion tool and defining
a cavity axis that is not parallel to the longitudinal axis of the
implant, and a tool for assisting in the implantation of the
implant, the tool including a shaft having a distal end configured
to mate with the cavity and a proximal end, the proximal end
including a strike plate attached thereto; (b) creating a void in
the bone; (c) introducing the distal end of the short implant into
the void, whereat the longitudinal axis of the implant is not
aligned with the bone axis; (d) engaging the distal end of the tool
into the cavity of the implant; (e) striking the strike plate to
thereby rotate the longitudinal axis of the implant toward the bone
axis until the longitudinal axis of the implant is substantially
aligned with the bone axis; and (f) disengaging the distal end of
the tool from the cavity of the implant.
[0011] A method of implanting an implant at least partially within
tissue, wherein the tissue includes an implant target position
having a target axis and a tissue feature that intersects the
target axis, is also provided. The method includes the steps of (a)
providing a system including an implant that has (i) a body, the
body having a proximal end, a distal end, a longitudinal axis and a
cavity located at the proximal end, wherein the cavity defines a
cavity axis that is not parallel to the longitudinal axis of the
implant, and (ii) a tool for assisting in the implantation of the
implant comprising a shaft having a distal end configured to mate
with the cavity and a proximal end; (b) creating a pathway from a
tissue surface to a target position within the tissue; (c)
inserting the distal end of the implant into the pathway; (d)
engaging the distal end of the tool with the cavity of the implant;
(e) manipulating the tool to move the implant to the target
position without impinging on the tissue feature; and (f)
disengaging the distal end of the tool from the cavity of the
implant.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] These and other features, advantages and benefits will be
made apparent through the following descriptions and accompanying
figures, where like reference numerals refer to the same features
across the various drawings.
[0013] FIG. 1 shows a side view of a short hip implant engaged with
a tool for assisting in the implant of the hip implant according to
one embodiment of the invention;
[0014] FIG. 2 shows a to scale, cross-sectional view of the tool of
FIG. 1;
[0015] FIGS. 3A and 3B show a close-up view of the distal end of
the tool of FIG. 1, respectively, disengaged and engaged with the
proximal end of the implant of FIG. 2;
[0016] FIG. 4 shows a schematic view of the implant being inserted
into the femur in three stages according to one embodiment of the
invention; and
[0017] FIGS. 5A-5C show a schematic view of the implant being
inserted into the femoral canal in three stages according to one
embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Referring to the drawings, FIG. 1 shows a hip implant system
according to the invention, generally referred to as reference
numeral 10. The hip implant system includes a short hip implant 20
and a tool 30 for assisting in the implantation of implant. Implant
20 includes a distal end 21, a proximal end 22, a stem 23 extending
from proximal end 22, and an insertion cavity 24 formed in proximal
end 22 (FIG. 3A). Tool 30 has a shaft 31, having a proximal end 32
and a distal end 40, a strike plate 33 connected to proximal end 32
and grip 34 extended from a medial portion 39 of shaft 31. Tool 30
is approximately 25 cm in length.
[0019] FIG. 1 depicts distal end 40 of tool 30 at least partially
disposed in cavity 24 of implant 10. Distal end 40 is configured to
mate with cavity 24 such that implant 10 may be securely held
during the implant procedure, which as is described in more detail
below, includes the steps of inserting and impacting via a "round
the corner" surgical technique.
[0020] Referring to FIG. 2, tool 30 is shown in cross-section. A
top surface 35 of strike plate 33 is rounded to permit plate 33 to
be impacted at multiple locations as implant 10 is inserted into
its ultimate position. As is described in greater detail below, the
surgical technique for one embodiment of the invention requires a
"round the corner" approach that permits the implant to be inserted
while avoiding contact with the greater trochanter. To facilitate
this requirement, strike plate 33 is rounded at a medial end 33a
allowing impaction of implant 20 in a lateral direction at an
oblique angle "around the corner" to a position inline with the
axis of the femur. Further impaction can then be performed on a
flat portion at lateral end 33b of plate 33 to seat implant 20 to
the correct depth within the proximal femur.
[0021] Strike plate 33 has a counter-sunk bore 36 that extends from
top surface 35 distally toward shaft 31 of tool 30. Bore 36 is
configured to accept a portion of an alignment member 50 (FIG. 4).
In a preferred embodiment, bore 36 is approximately 9 mm. The
interface between tool 30 and alignment member 50 is preferably a
clearance fit, which allows for easy operation of the alignment
member and encourages intra-operative use of the alignment member,
as its use consumes no additional time during surgery. The axis of
bore 36 preferably is designed to be parallel with the implant axis
when implant 10 is finally positioned in situ.
[0022] Grip 34 is fixed relative to shaft 31 and is shaped such
that it complements the shape of the instrument body and provides
the surgeon comfort and control when gripped during the method.
Shaft 31 is preferably in the shape of an s-curve, so as to
increase visualisation of the wound while clearing patient anatomy.
That is, distal end 40 is not aligned with proximal portion 32 so
as to provide the surgeon with a clear view of distal end 40 so as
make the use of smaller incisions more practicable.
[0023] Referring to FIGS. 3A and 3B, the insertion feature is shown
in detail in a disengaged position and an engaged position,
respectively. Only the proximal portion 22 of implant 20 is
depicted in FIGS. 3A and 3B. In accordance with the invention,
cavity 24 has an axis C that is not aligned with the longitudinal
axis L of implant 10. In a preferred embodiment, axis C is offset
from longitudinal axis L by angle A, which ranges from 5 degrees to
55 degrees. More preferably, angle A ranges from 15 to 45 degrees.
Most preferably angle A is about 40 degrees. Distal portion 25 of
cavity 24 is preferably circular in cross section and preferably is
approximately 9 mm in diameter. Cavity 24 includes a slot 26 that
communicates with distal portion 25 and a dimple 27, each
configured to accept features of insertion/impact tool 30. In a
preferred embodiment, the distance from the center of dimple 27 to
the bottom of cavity 24 is approximately 13 mm. Slot 26 is
preferably 3.5 mm in width and need not run the full depth of the
cavity.
[0024] Distal end 40 of tool 30 includes a distal tip 41 that is
circular in cross-section and configured to engage distal portion
25 of cavity 24. Distal tip 41 is designed to transmit the
impaction force from strike plate 33 to implant 20. Distal end 40
also includes a rib 42 which is configured to engage slot 26 of
cavity 24. Rib 42 permits the surgeon to control the orientation of
implant 10 as it permits implant 20 to have only one orientation
with respect to insert/impactor tool 30 during operation. Distal
end 40 also includes a cantilevered spring arm 43, which preferably
extends from distal end 40 at a location circumferentially
displaced from the location of rib 42. In a most preferred
embodiment rib 42 is located on the opposite side of distal end 40
from arm 43. Arm 43 includes a male feature or protrusion 44, which
is preferably a spherical protrusion, designed to frictionally
engage female feature or dimple 27 of implant 20. Frictional
engagement of protrusion 44 with dimple 27 ensures that the implant
remains attached while navigating through soft tissues. This design
of attachment ensures that tool (or instrument) 30 is easily
removed from implant 20 following final impaction. The spring arm
43 is designed so that at least one-quarter pound is required to be
exerted to remove distal portion 40 from implant 20.
[0025] Referring to FIGS. 4 and 5A-5C, the described implant system
allows the insertion of a short implant using the `around the
corner` surgical technique. The goal of this technique is to
minimize the damage to the greater trochanter of the hip by
broaching around the medial curve of the femur M and under the
greater trochanter GT. The invention addresses the problem of
greater trochanter impingement by both angling the insertion
feature with respect to the long axis of the implant L and curving
the impactor to travel around the greater trochanter CT during the
"around the corner" insertion motion.
[0026] System 10 is used as follows. The surgeon controls implant
20 with tool 30. Implant 20 is held in an engaged position with
tool 30 by spring arm 43, which includes a male feature 44 that is
disposed in a corresponding female feature 27 of implant 20. The
surgeon controls the orientation of implant 20 by rib 42, which
engages slot 26 of implant 20. Once a void is created in bone by
broaching or another method known in the art, distal end 21 of
implant 20 is positioned at the opening in the void. Referring to
FIG. 5A, tool 30 can be engaged with implant 20 prior to or at this
stage in the method.
[0027] When the surgeon desires to impact strike plate 33 to
encourage implant 20 to assume the correct implant position, the
surgeon engages distal end 40 of tool 30 with cavity 26 of implant
20. Referring to FIG. 5B, the surgeon then repeatedly impacts
strike plate 33 at proximal end 32 of tool 30. As the surgeon
impacts tool 30, implant 20 rotates about the medial curve of the
femur M and under the greater trochanter GT as shown in FIGS. 5A-5C
and in shadow FIG. 4. As implant 20 rotates, the longitudinal axis
L of implant 20 rotates toward femoral axis F. The implant is
correctly positioned when the longitudinal axis L of implant is
substantially aligned with femoral axis F.
[0028] Referring to FIG. 4, once the surgeon believes that implant
20 has achieved its optimal position in the proximal femur, the
position of implant 20 can be assessed by attaching alignment
member 50 to tool 30 via the bore 36 in the plate 33. Member 50
includes a first arm 51 that engages with bore 36, a second arm 52
that extends at a right angle from first arm 51 and a third arm
that extends at a right angle from second arm 52 in a direction
parallel to first arm 51. In this way, third arm 53 can be aligned
with the femoral axis of the leg to visually confirm that implant
20 is in the correct position. If implant 20 is misaligned, the
surgeon can continue to impact plate 33 to correct the alignment or
exert a torsional force on tool 30 to correct the varus/valgus
orientation, e.g.
[0029] Removal of tool 30 from implant 20 is performed by pulling
proximally on the proximal end of tool 30 with a force great enough
to overcome spring arm 43. The force can be designed to range from
one-quarter pound to five pounds. Excessive force is not required
and as such the position of implant 20 in the proximal femur is not
altered.
[0030] While the issue of navigating a short implant in a hip
procedure is described in some detail herein, it is contemplated
that the implant system can be used in any method where an implant
needs to be inserted or positioned in a non-axial fashion. For
example, a similar method and system can be used to implant humeral
implants. Moreover, the invention is not necessarily limited to
implantation of long-bone implants. The system can be employed
wherever the insertion path of the implant benefits from being out
of axis of the ultimate location of the implant.
[0031] System 10 of the invention, for example, can be used to
navigate an implant to final position without impingement on
defined bone feature or specific tissue structure that a surgeon
wishes to spare, wherein the bone feature or specific tissue
structure is located in a position that intersects an implant axis
at a location proximal to the final position of the implant.
Typically, in this situation, an implant would follow an axial path
to its final position, one aligned with the implant axis. Utilizing
the system of the invention, the surgeon can retain the bone
feature that would otherwise need to be removed or at least damaged
in providing a path for the implant, by inserting the implant along
a non-axial path. In the preferred embodiment, implant 20 is
navigated to a position wherein implant longitudinal axis L is
aligned with femoral axis F, but the path taken is non-axial. That
is, rather than delivering implant 20 by impacting implant 20 along
an axis parallel (if not coincident) with implant axis L, implant
20 is impacted along a cavity axis C which is not parallel to
implant longitudinal axis L. As a result, the path taken by implant
20 is curved rather than straight, and the greater trochanter bone,
that would otherwise be sacrificed or at least damaged by contact
with the implant if implant 20 took an axial path to its final
position, is spared any damage. This same concept can be used to
spare other bone features by the surgeon.
[0032] Specific construction details that are not shown are
believed to be within the purview of those of ordinary skill in the
art. The present invention has been described herein with reference
to certain preferred embodiments. These embodiments are offered as
illustrative, and not limiting, of the scope of the invention.
Certain modifications or alterations may be apparent to those
skilled in the art without departing from the scope of the
invention, which is defined by the appended claims.
* * * * *