U.S. patent application number 14/575367 was filed with the patent office on 2015-04-09 for canal sizer and associated method.
The applicant listed for this patent is DEPUY SYNTHES PRODUCTS, LLC. Invention is credited to ANDREW M JACOBS, CHARLES W JAGGERS, THOMAS M VANASSE, GORDON R YOUNG.
Application Number | 20150100061 14/575367 |
Document ID | / |
Family ID | 34435755 |
Filed Date | 2015-04-09 |
United States Patent
Application |
20150100061 |
Kind Code |
A1 |
VANASSE; THOMAS M ; et
al. |
April 9, 2015 |
CANAL SIZER AND ASSOCIATED METHOD
Abstract
An instrument for measuring the medullary canal of a long bone
in order to determine the proper size for a stem centralizer is
provided. The instrument includes an elongated central portion
defining opposed first and second ends and a contact portion. The
contact portion extends from the first end or the second end of the
elongated central portion. The contact portion has a contact area
for contact with the medullary canal and defines a relief area for
providing clearance between the instrument and the medullary
canal.
Inventors: |
VANASSE; THOMAS M;
(THOMASTON, CT) ; JACOBS; ANDREW M; (FORT WAYNE,
IN) ; YOUNG; GORDON R; (FORT WAYNE, IN) ;
JAGGERS; CHARLES W; (WARSAW, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DEPUY SYNTHES PRODUCTS, LLC |
RAYNHAM |
MA |
US |
|
|
Family ID: |
34435755 |
Appl. No.: |
14/575367 |
Filed: |
December 18, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12697680 |
Feb 1, 2010 |
8945131 |
|
|
14575367 |
|
|
|
|
10717404 |
Nov 19, 2003 |
|
|
|
12697680 |
|
|
|
|
Current U.S.
Class: |
606/102 |
Current CPC
Class: |
A61F 2002/4631 20130101;
A61B 5/4504 20130101; A61F 2002/30617 20130101; A61F 2002/3625
20130101; A61F 2002/4615 20130101; A61F 2002/4659 20130101; A61F
2002/4077 20130101; A61F 2/389 20130101; A61F 2002/30616 20130101;
A61F 2250/0097 20130101; A61B 17/88 20130101; A61B 90/06 20160201;
A61F 2/36 20130101; A61F 2002/365 20130101; A61F 2/3662 20130101;
A61B 2017/00544 20130101; A61B 90/94 20160201; A61F 2002/4662
20130101; A61F 2/4607 20130101; A61F 2250/0064 20130101; A61B
5/1076 20130101; A61F 2/30723 20130101; A61B 2017/00539 20130101;
A61F 2/4614 20130101; A61B 2090/061 20160201; A61F 2002/3631
20130101; A61F 2002/3611 20130101; A61F 2002/4658 20130101; A61F
2/4657 20130101; A61F 2/30724 20130101; A61F 2002/3071 20130101;
A61F 2250/0089 20130101; A61F 2/3676 20130101; A61B 2090/062
20160201; A61B 17/164 20130101; A61F 2/3859 20130101 |
Class at
Publication: |
606/102 |
International
Class: |
A61B 17/88 20060101
A61B017/88 |
Claims
1. An instrument for measuring the medullary canal of a long bone
in order to determine the proper size for a stem centralizer, said
instrument comprising: an elongated central portion defining
opposed first and second ends; and an arcuate contact portion
extending from the first end of said elongated central portion,
said contact portion having a contact area including an outer
periphery, having a circumference, for contact with the medullary
canal and defining a relief area for providing clearance between
the instrument and the medullary canal, wherein the relief area is
recessed from the outer periphery of the contact area, such that
the relief area interrupts the outer periphery of the contact area,
and the relief area does not extend around the entire circumference
of the outer periphery; wherein said contact portion comprises a
plurality of contact areas for contact with the medullary canal and
defines a plurality of relief areas for providing clearance between
the instrument and the medullary canal and said contact portion has
2 to 6 contact areas for contact with the medullary canal and has 2
to 6 relief areas.
2. (canceled)
3. (canceled)
4. (canceled)
5. The instrument of claim 1, wherein said contact portion has 4
equally spaced apart contact areas for contact with the medullary
canal and has 4 equally spaced apart relief areas.
6. The instrument of claim 1, wherein said elongated central
portion is generally cylindrical.
7. The instrument of claim 1, wherein said contact portion is
generally pear shaped.
8. The instrument of claim 1, wherein said elongated central
portion includes a plurality of spaced apart marks corresponding to
at least one of a metric dimension and an inch dimension.
9. An instrument for measuring the medullary canal of a long bone
in order to determine the proper size for a stem centralizer, said
instrument comprising: an elongated central portion defining
opposed first and second ends; a first arcuate contact portion
extending from the first end of said elongated central portion,
said first contact portion having a contact area including an outer
periphery, having a circumference, for contact with the medullary
canal and defining a relief area for providing clearance between
the instrument and the medullary canal, wherein the relief area is
recessed from the outer periphery of the contact area, such that
the relief area interrupts the outer periphery of the contact area,
and the relief area does not extend around the entire circumference
of the outer periphery, wherein said contact portion comprises a
plurality of contact areas for contact with the medullary canal and
defines a plurality of relief areas for providing clearance between
the instrument and the medullary canal and said contact portion has
2 to 6 contact areas for contact with the medullary canal and has 2
to 6 relief areas; and a second arcuate contact portion extending
from the second end of said elongated central portion, said second
contact portion having a contact area including an outer periphery,
having a circumference, for contact with the medullary canal and
defining a relief area for providing clearance between the
instrument and the medullary canal, and the relief area does not
extend around the entire circumference of the outer periphery,
wherein said contact portion comprises a plurality of contact areas
for contact with the medullary canal and defines a plurality of
relief areas for providing clearance between the instrument and the
medullary canal and said contact portion has 2 to 6 contact areas
for contact with the medullary canal and has 2 to 6 relief
areas.
10. (canceled)
11. (canceled)
12. The instrument of claim 9, wherein at least one of said first
contact portion and said second contact portion has 4 equally
spaced apart contact areas for contact with the medullary canal and
has 4 equally spaced apart relief areas.
13. The instrument of claim 9, wherein said elongated central
portion is generally cylindrical.
14. The instrument of claim 9, wherein at least one of said first
contact portion and said second contact portion is generally pear
shaped.
15. The instrument of claim 9, wherein said elongated central
portion includes a plurality of spaced apart marks corresponding to
at least one of a metric dimension and an inch dimension.
16. A kit for use in performing total hip arthroplasty, said kit
comprising: a plurality of instruments, each of said plurality of
instruments adapted for measuring the medullary canal of a femur,
each of said plurality of instruments including an elongated
central portion defining opposed first and second ends, and an
arcuate contact portion extending from the first end of the
elongated central portion, the contact portion having a contact
area including an outer periphery, having a circumference, for
contact with the medullary canal and defining a relief area for
providing clearance between the instrument and the medullary canal
canal, wherein the relief area is recessed from the outer periphery
of the contact area, such that the relief area interrupts the outer
periphery of the contact area, and the relief area does not extend
around the entire circumference of the outer periphery, wherein
said contact portion comprises a plurality of contact areas for
contact with the medullary canal and defines a plurality of relief
areas for providing clearance between the instrument and the
medullary canal and said contact portion has 2 to 6 contact areas
for contact with the medullary canal and has 2 to 6 relief areas; a
hip stem for implantation into the medullary canal; and a plurality
of stem centralizers for cooperation with said hip stem and for
implantation into the medullary canal, each of said plurality of
stem centralizers corresponding to one of the contact portions of
said plurality of instruments.
17. The kit of claim 16, wherein each of said instruments further
comprise a second contact portion extending from the second end of
said elongated central portion, said second contact portion having
a contact area for contact with the medullary canal and defining a
relief area for providing clearance between the instrument and the
medullary canal.
18. (canceled)
19. (canceled)
20. The kit of claim 16, wherein the elongated central portion of
each of said instruments includes a plurality of spaced apart marks
corresponding to at least one of a metric dimension and an inch
dimension.
21. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a divisional patent application of U.S. application
Ser. No. 12/697,680, filed Feb. 1, 2010, which is a divisional of
U.S. patent Ser. No. 10/717,404 of the same title and filed on Nov.
19, 2003 (now abandoned), the disclosure of which is hereby
incorporated by reference.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of
orthopaedics, and more particularly, to an instrument for use in
arthroplasty.
BACKGROUND OF THE INVENTION
[0003] A joint within the human body forms a juncture between two
or more bones or other skeletal parts. The ankle, hip, knee,
shoulder, elbow and wrist are just a few examples of the multitude
of joints found within the body. As should be apparent from the
above list of examples of joints, many of the joints permit
relative motion between the bones. For example, the motion of
sliding, gliding, hinge or ball and socket movements may be had by
a joint. For example, the ankle permits a hinge movement, the knee
allows for a combination of gliding and hinge movements and the
shoulder and hip permit movement through a ball and socket
arrangement.
[0004] The joints in the body are stressed or can be damaged in a
variety of ways. For example, gradual wear and tear is imposed on
the joints through the continuous use of a joint over the years.
The joints that permit motion have cartilage positioned between the
bones providing lubrication to the motion and also absorbing some
of the forces direct to the joint. Over time, the normal use of a
joint may wear down the cartilage and bring the moving bones in
direct contact with each other. In contrast, in normal use, a
trauma to a joint, such as the delivery of a large force, from an
accident, for example, an automobile accident, may cause
considerable damage to the bones, the cartilage or to other
connective tissue such as tendons or ligaments.
[0005] Arthropathy, a term referring to a disease of the joint, is
another way in which a joint may become damaged. Perhaps the best
known joint disease is arthritis, which is generally referred to a
disease or inflammation of a joint that results in pain, swelling,
stiffness, instability, and often deformity.
[0006] There are many different forms of arthritis, with
osteoarthritis being the most common and resulting from the wear
and tear of a cartilage within a joint. Another type of arthritis
is osteonecrosis, which is caused by the death of a part of the
bone due to loss of blood supply. Other types of arthritis are
caused by trauma to the joint while others, such as rheumatoid
arthritis, Lupus, and psoriatic arthritis destroy cartilage and are
associated with the inflammation of the joint lining.
[0007] The hip joint is one of the joints that is commonly
afflicted with arthropathy. The hip joint is a ball and socket
joint that joins the femur or thighbone with the pelvis. The pelvis
has a semispherical socket called the acetabulum for receiving a
ball socket head in the femur. Both the head of the femur and the
acetabulum are coated with cartilage for allowing the femur to move
easily within the pelvis. Other joints commonly afflicted with
arthropathy include the spine, knee, shoulder, carpals,
metacarpals, and phalanges of the hand. Arthroplasty as opposed to
arthropathy commonly refers to the making of artificial joint. In
severe cases of arthritis or other forms of arthropathy, such as
when pain is overwhelming or when a joint has a limited range of
mobility, a partial or total replacement of the joint with an
artificial joint may be justified. The procedure for replacing the
joint varies, of course, with the particular joint in question, but
in general involves replacing a terminal portion of an afflicted
bone with a prosthetic implant and inserting a member to serve as a
substitute for the cartilage.
[0008] The prosthetic implant is formed of a rigid material that
becomes bonded with the bone and provides strength and rigidity to
the joint and the cartilage substitute members chosen to provide
lubrication to the joint and to absorb some of the compressive
forces. Suitable materials for the implant include metals, and
composite materials such as titanium, cobalt chromium, stainless
steel, ceramic and suitable materials for cartilage substitutes
include polyethylene. A cement may also be used to secure the
prosthetic implant to the host bone.
[0009] A total hip replacement, for example, involves removing the
ball shaped head of the femur and inserting a stem implant into the
center of the bone which is referred to as the medullary canal or
marrow of the bone. The stem implant may be cemented into the
medullary canal or may have a porous coated surface for allowing
the bone to heal directly to the implant. The stem implant has a
neck and a ball shaped head which are intended to perform the same
functions as a healthy femur's neck and a ball shaped head. The
polyethylene cup is inserted into the acetabulum and has a socket
for receiving the head on the stem implant.
[0010] One challenge in the proper positioning of the prosthesis
during surgery is the proper position of the stem axially and
rotationally. Improper positioning has been shown to limit the
patient's range of motion by inducing improper leg length,
inadequate lateral stem offset and non-anatomical version of the
stem. Inadequate pressurization of the cement within the femoral
canal has also been documented as a potential cause of improper
cement technique.
[0011] Centralization of the stem within the cement mantle is also
critical for success. Non-uniform or excessively thin cement
mantles can induce high cement stress and subsequent cracks that
may cause failure at the cement-stem-bone interfaces. The cement
debris, due to abrasions, has also been shown to produce excessive
third-body wear of polyethylene acetabular components as well as
potentially induce osteolytic reactions and bone resorptions that
may lead to stem loosening.
[0012] One device utilized to assist in the centralization of the
stem is a centralizer or spacer. Centralizers or spacers are
provided for fitting to the distal end of a femoral hip replacement
stem in order to keep the implant stem away from the internal
surface of the cavity of the bone in which this stem is to be
inserted.
[0013] In the case of stems which are cemented in the bone cavity
there is a space between the stem and the internal surface of the
cavity of the bone in which the cement is placed. Controlling the
position of the stem within the surrounding bone cement mantle is
vital to long-term survivability of the replacement joint. Cement
can be deposited in the bone cavity and then the stem may be
inserted with the centralizer attached to the stem. Alternatively,
the centralizer may be inserted into the cavity and the stem later
inserted against the centralizer. It is important to try to obtain
an even and intact cement mantle around the stem.
[0014] In addition to the purpose of the centralizer to properly
position the stem, the centralizer may be designed to serve a
second purpose, that is to separate the cement from the blood and
other body fluids within the medullary canal of the bone. Such
separation of cement and medullary canal fluids is exasperated by
the more recent use of external pressure to assure the complete
filling of the bone cavity with cement.
[0015] Known centralizers are in the form of caps which fit over
the distal end of the stem and centralizers which are fixed inside
of a drilled end of a stem. Centralizers are also known which are
of ring form which can have a tapered inner surface corresponding
to the tapered surface of the distal stem of the femoral stem on
which the centralizer is located.
[0016] Centralizers or spacers in the form of a cap for insertion
on the end of a hip stem with fins or wings extending outwardly
from the cap which are adapted to fold circumferentially and
inwardly toward the body portion of the cap.
[0017] Cemented stem systems generally utilize two components
distal to the stem, a centralizer and a cement plug. The
centralizers usually have fins that protrude into the cement mantle
around the stem.
[0018] Due to variations in the age, gender, and size of a patient,
a wide variety of distal centralizers are available for use in the
medullary canal of a patient. The proper or optimum size from the
available variety of sizes of the centralizer must be selected by
the surgeon. When implanting a cemented stem, a surgeon has to make
an educated guess using for example x-rays and templating to
determine the proper sized distal centralizer to use.
[0019] Due to the two-dimensional nature of x-rays and templating,
and the three-dimensional shape of the centralizer, such techniques
are crude and inaccurate. Such techniques may require the removal
of the first chosen centralizer and a second centralizer used or
may result in a less than ideal centralizer being utilized.
[0020] Attempts have been made to provide for a more accurate way
of determining the proper size for centralizer for the surgeon to
use on a particular patient. For example, a canal sizer has been
developed by Zimmer Holding, Inc., Warsaw, Ind.; sold as the IM
Sizer, which provides for a plug having a round cross-section. This
device may have a tendency to get caught in the distal canal before
its proper position is reached. Also, this device is adapted for
only one particular brand and style of orthopedic implant.
[0021] The present invention is adapted to overcome at least one of
the aforementioned shortcomings of the prior art.
SUMMARY OF THE INVENTION
[0022] The present invention provides for a one-piece canal sizer
for use in selecting a distal centralizer for use in joint
arthroplasty. The one-piece sizer includes a central shaft and
opposed measuring tips. According to one aspect of the present
invention, the measuring tips have a shape corresponding to that of
the corresponding centralizer.
[0023] According to another aspect of the present invention, a
second measurement tip is connected to the sizer on the end opposed
to the first measuring tip.
[0024] According to yet another aspect of the present invention,
the measuring tips include spaced apart contact and relief areas to
assist in the ease of inserting the canal sizer.
[0025] According to yet another aspect of the present invention,
the canal sizer may include indicia in the form of, for example,
spaced apart marks denoting the depth in which the canal sizer has
been inserted. Such markings are useful in determining the proper
size of implant stem to utilize.
[0026] According to one embodiment of the present invention, there
is provided an instrument for measuring the medullary canal of a
long bone in order to determine the proper size for a stem
centralizer. The instrument includes an elongated central portion
defining opposed first and second ends and a contact portion. The
contact portion extends from the first end of the elongated central
portion. The contact portion has a contact area for contact with
the medullary canal and defines a relief area for providing
clearance between the instrument and the medullary canal.
[0027] According to another embodiment of the present invention
there is provided an instrument for measuring the medullary canal
of a long bone in order to determine the proper size for a stem
centralizer. The instrument includes an elongated central portion
defining opposed first and second ends and a first contact portion
extending from the first end of the elongated central portion. The
first contact portion has a contact area for contact with the
medullary canal and defines a relief area for providing clearance
between the instrument and the medullary canal. The instrument also
includes a second contact portion extending from the second end of
the elongated central portion. The second contact portion has a
contact area for contact with the medullary canal and defines a
relief area for providing clearance between the instrument and the
medullary canal.
[0028] According to still another embodiment of the present
invention there is provided a kit for use in performing total hip
arthroplasty. The kit includes a plurality of instruments. Each of
the plurality of instruments is adapted for measuring the medullary
canal of a long bone. Each of the plurality of instrument includes
an elongated central portion defining opposed first and second ends
and a contact portion. The contact portion extends from the first
end of the elongated central portion. The contact portion has a
contact area for contact with the medullary canal and defines a
relief area for providing clearance between the instrument and the
medullary canal. The kit also includes a hip stem for implantation
into the medullary canal and a plurality of stem centralizers. The
centralizers are for cooperation with the hip stem and for
implantation into the medullary canal. Each of the plurality of
stem centralizers corresponds to one of the contact portions of
said plurality of instruments.
[0029] According to a further embodiment of the present invention,
there is provided a method for providing joint arthroplasty. The
method includes the steps of resecting a long bone, preparing the
medullary canal of a long bone, providing a plurality of
instruments for measuring the medullary canal of the long bone,
each of the instruments including an elongated central portion
defining opposed first and second ends, and a contact portion
extending from the first end of the elongated central portion, the
contact portion having a plurality of contact areas for contact
with the medullary canal and defining a plurality of relief areas
for providing clearance between the instrument and the medullary
canal. The method also includes the steps of inserting one of the
plurality of instruments into the canal, providing a plurality of
centralizers for implanting into the medullary canal of the long
bone, each of the plurality of centralizers corresponding to one of
the plurality of instruments, determining the appropriateness of
the one of the plurality of instruments, inserting the one of the
plurality of centralizers corresponding to the one of the plurality
of instruments into the canal, providing a stem, and implanting the
stem in the medullary canal of a long bone.
[0030] According to yet another embodiment of the present
invention, there is provided an instrument for measuring the
medullary canal of a resected long bone in order to determine the
proper size for a stem centralizer. The instrument includes an
elongated central portion defining opposed first and second ends
and a contact portion. The contact portion extends from the first
end of the elongated central portion. The contact portion has a
shape substantially similar to the shape of the stem centralizer on
the surface opposed to the resected surface of the long bone.
[0031] The technical advantages of the present invention include
the ability to select an optimum sized cement plug centralizer for
a particular patient. For example, according to one aspect of the
present invention, a kit for use in performing total hip
arthroplasty is provided. The kit includes a plurality of
instruments. Each of the instruments is adapted for measuring the
canal of the femur. Each of the plurality of instruments includes a
contact portion. The contact portion has a contact area for contact
with the medullary canal. The kit also includes a hip stem and a
plurality of stem centralizers. The instruments serve to replicate
the stem centralizers such that the instruments are progressively
inserted into the canal until the contact portion of an instrument
is determined to be optimum. The stem centralizer corresponding to
that contact portion is then inserted as the optimum size cement
centralizer. The present invention provides for optimum sizing of
the stem centralizer for a patient.
[0032] The technical advantages of the present invention further
include the ability of an instrument to replicate a stem
centralizer. For example, according to one aspect of the present
invention, there is provided an instrument for measuring the
medullary canal of a resected long bone in order to determine the
proper size of a stem centralizer. The instrument includes a
contact portion which has a shape substantially similar to the
shape of the stem centralizer on the surface opposed to the
resected surface of the long bone. Thus, the present invention
provides for an instrument which replicates the stem
centralizer.
[0033] The technical advantages of the present invention further
include an instrument that easily passes through the canal to the
distal seating position proper for a stem centralizer. For example,
according to another aspect of the present invention, there is
provided an instrument for measuring the medullary canal of a long
bone in order to determine the proper size for a stem centralizer.
The instrument includes a contact portion having a contact area for
contacting the medullary canal and defines a relief area for
providing clearance between the instrument and the medullary canal.
Clearance between the portion of the contact portion and canal
permits the easy passage of the instrument through the canal and
avoids the build-up of pressure at the distal portion of the canal
which may prevent the free passage of the instrument. Thus, the
present invention provides for an instrument that easily passes
through the medullary canal to the distal seating position for the
stem centralizer.
[0034] The technical advantages of the present invention further
include the ability of the instrument of the present invention to
be used to assist in selecting the proper size implant for a joint
arthroplasty. For example, according to one aspect of the present
invention, an instrument for measuring the medullary canal of a
long bone is provided. The instrument is used to determine the
proper size for a stem centralizer and includes an elongated center
portion. A contact portion extends from the center portion and
includes a contact area for contacting with the medullary canal.
The elongated portion includes a plurality of spaced apart marks or
indicia. These marks or indicia when in alignment with the resected
portion of the long bone when the contact portion is fully seated
in the canal may be used to assist in determining the proper
implant to be utilized in the joint arthroplasty. Thus, the present
invention provides for an instrument that may be used to assist in
the selection of the proper implant for a joint arthroplasty.
[0035] The technical advantages of the present invention further
include the ability of the instrument of the present invention to
be used on any implant stem system. For example, according to one
aspect of the present invention an instrument for measuring the
medullary canal of a long bone is provided including a central
portion and a contact portion extending from the central portion.
The contact portion is seated into the medullary canal and the
central portion includes marks or indicia which are utilized to
assist in determining the proper implant. These marks or indicia in
one aspect of the present invention correspond to either a metric
or an inch dimension. These metric or inch dimensions may be
utilized for any implant system to determine the proper size of the
implant to be used. Thus, the present invention provides for an
instrument which may be utilized for any implant or stem system for
use in joint arthroplasty.
[0036] Other technical advantages of the present invention will be
readily apparent to one skilled in the art from the following
FIGS., descriptions and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] For a more complete understanding of the present invention
and the advantages thereof, reference is now made to the following
description taken in connection with the accompanying drawings, in
which:
[0038] FIG. 1 is a plan view of a resected proximal femur for
receiving an instrument in accordance with the present
invention;
[0039] FIG. 1A is a plan view of a resected distal femur for
receiving an instrument in accordance with the present
invention;
[0040] FIG. 1B is a plan view of a resected proximal tibia for
receiving an instrument in accordance with the present
invention;
[0041] FIG. 1C is a plan view of a resected proximal humerus for
receiving an instrument in accordance with the present
invention;
[0042] FIG. 2 is a plan view of a proximal femur showing a reamer
for use in preparing a cavity for receiving an instrument in
accordance with the present invention;
[0043] FIG. 3 is a plan view of an instrument in accordance with an
embodiment of the present invention showing an instrument having a
contact portion with a relief area;
[0044] FIG. 3A is a bottom view of the instrument of FIG. 3;
[0045] FIG. 3B is an end view of the instrument of FIG. 3;
[0046] FIG. 4 is a plan view of an instrument in accordance with
another embodiment of the present invention showing an instrument
having a pair of spaced apart contact portions with a pair of
spaced apart relief areas;
[0047] FIG. 4A is a bottom view of the instrument of FIG. 4;
[0048] FIG. 4B is an end view of the instrument of FIG. 4;
[0049] FIG. 5 is a plan view of an instrument in accordance with
yet another embodiment of the present invention showing an
instrument having a part of the contact portion similar to the
distal end of a corresponding centralizer;
[0050] FIG. 5A is a plan view of the corresponding centralizer for
use with the instrument of FIG. 5;
[0051] FIG. 6 is a plan view of an instrument in accordance with
yet another embodiment of the present invention showing an
instrument having a contact portion similar to the distal end of a
corresponding centralizer;
[0052] FIG. 6A is a plan view of the corresponding centralizer for
use with the instrument of FIG. 6;
[0053] FIG. 7 is a plan view of an instrument in accordance with
yet another embodiment of the present invention with a portion of
the instrument in position in the cavity of a proximal femur;
[0054] FIG. 8 is a plan view of the instrument of FIG. 7;
[0055] FIG. 9 is a plan view of a first end of the instrument of
FIG. 7;
[0056] FIG. 10 is a top view partially in cross section of FIG. 9
along the line 10-10 in the direction of the arrows;
[0057] FIG. 11 is a plan view of a second end of the instrument of
FIG. 7;
[0058] FIG. 12 is a top view partially in cross section of FIG. 10
along the line 12-12 in the direction of the arrows;
[0059] FIG. 13 is a plan view partially in cross section of the
instrument of FIG. 7 showing the first end of the instrument in
position in the cavity of the proximal femur;
[0060] FIG. 14 is a plan view partially in cross section of the
instrument of FIG. 7 showing the second end of the instrument in
position in the cavity of the proximal femur;
[0061] FIG. 15 is a plan view of an instrument kit according to
another embodiment of the present invention including the
instrument of FIG. 7 as well as a second instrument and a third
instrument, the second instrument and the third instrument being
similar to the first mentioned instrument, but having end portions
of different sizes;
[0062] FIG. 16 is a plan view of a prosthesis for use with the
instrument of FIG. 7; and
[0063] FIG. 17 is a flow chart of a method for performing total
joint arthroplasty in accordance with an embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0064] Embodiments of the present invention and the advantages
thereof are best understood by referring to the following
descriptions and drawings, wherein like numerals are used for like
and corresponding parts of the drawings.
[0065] Referring now to FIG. 1, a long bone in the form of femur 10
is shown for use with the instrument of the present invention. The
femur 10 includes a proximal portion 12. The proximal portion 12
includes a neck 14 from which a head 16 extends. The head 16 is
generally spherical and cooperates with the acetabulum to form a
pivoting anatomical joint. When performing joint arthroplasty, the
head 16 and neck 14 are resected from the portional proximal femur
12 along resection line 18. The resecting of the proximal femur 12
exposes medullary canal 20 of the femur 10. The femur 10 includes
an outer layer of hard dense cortical bone 22 and an inner area of
cancellous bone 24 positioned between the cortical bone 22 and the
medullary canal 20.
[0066] While the instrument of the present invention is
particularly well-suited for use in selecting a centralizer or plug
for a proximal femur, it should be appreciated that the instrument
of the present invention be used in any long bone of the human
body, for example and referring now to 1A, the distal femur 12A is
shown which includes a medullary canal 20A which is exposed along
resection line 18A.
[0067] Referring that to FIG. 1B, a proximal tibia 12B is shown.
The proximal tibia 12B includes a medullary canal 20B which is
exposed along resection line 18B.
[0068] Referring now to FIG. 1C a humerus 10C is shown. The humerus
10C includes a proximal portion 12C which includes a neck 14C from
which head 16C extends. The humerus 10C is resected along resection
line 18C to remove the neck 14C and the head 16C. The resection
line 18C exposes medullary canal 20C.
[0069] It should be appreciated that the instrument of the present
invention may be used with centralizers and plugs to centralize and
plug any and all of the medullary canal 20A of the distal femur,
the medullary canal 20B of the proximal tibia and the medullary
canal 20C of the humerus 10C.
[0070] Referring now to FIG. 2, a reamer 26 is shown in position in
the medullary canal 20 of the femur 10. The reamer 26 is utilized
to open the medullary canal 20 to permit the receiving of the
instrument of the present invention. The reamer 26 may be rotated
in the direction of arrow 28 by for example power source 30. The
power source 30 may be electrical, pneumatic or hydraulic. The
reamer 26 may include flutes 32. The flutes 32 may be tapered and
may be defined by an included angle .alpha.. The angle .alpha. also
defines the angle of the tapered opening of the medullary canal 20
for receiving the instrument of the present invention.
[0071] Referring now to FIGS. 3, 3A and 3B, and embodiment of the
present invention is shown as instrument 100. The instrument 100 is
used for measuring the medullary canal 20 of the long bone 10 in
order to determine the proper size for a canal implant 102. It
should be appreciated that canal implant 102 may be for example, a
stem centralizer or a cement plug. The instrument 100 includes an
elongated central portion 104 defining opposed first end 106 and
second end 108. The instrument 100 further includes a contact
portion 110 extending from the first end 106 of the elongated
central portion 104 of the instrument 100. The contact portion 110
includes a contact area 112 for contact with the medullary canal 20
and defines a relief area 114 for providing clearance between the
instrument 100 and the medullary canal 20.
[0072] The elongated central portion 104 may have any suitable
shape capable of supporting the contact portion 110 of the
instrument 100. For example, the elongated central portion may have
a uniform cross-section. The uniform cross-section of the said
proportion 104 may have any shape, for example triangular,
rectangular, or may have as shown in FIGS. 3, 3A & 3B the
circular saw cross-section providing for a cylindrical elongated
central portion 104.
[0073] The contact portion 110 may have any suitable shape and may,
for example, provide for a contact area 112 which is arcuate. The
arcuate contact area 112 of the contact portion 110 of the
instrument 100 may assist in the insertion of the instrument 100
into the canal 20. The contact area 112 may be defined by example a
radius R extending from origin 116 providing, for example, for
contact area 112 to be generally hemispherical. The contact portion
110 adjacent first end 106 of the central portion 104 may have any
suitable shape and may be arcuate or as shown in FIGS. 3, 3A, and
3B be generally conifrustrical. The connecting portion 118 and the
contact area 112 of the contact portion 110 may have for example, a
shape which is generally pear shaped.
[0074] The relief area 114 of the contact portion 110 may have any
shape, and may for simplicity be generally planar.
[0075] As shown in FIG. 3B, the instrument 100 may further include
a second contact portion 120 extending from the second end 108 of
the elongated center portion 104. The second contact portion 120
may have a contact area 122 for contact with the medullary canal 20
and may define a relief area 124 for providing clearance between
the instrument 100 and the medullary canal 20. The second contact
portion 120 as shown in FIG. 3B may be similar in size and shape to
the first contact portion 110. The second contact portion 120 may
be slightly larger or smaller than the first contact portion 110
and be utilized to replicate a canal implant that is either
slightly larger or slightly smaller than the canal implant for
which the first contact portion 110 is designed.
[0076] The instrument 100 may be made of any suitable durable
material and may for simplicity be of a one-piece or integral
construction. It should be appreciated, however, that the
instrument 100 may be modular having, for example, contact portions
110 and 120 being made of a separate component from the central
portion 104. The instrument 100 may be made of any suitable durable
material capable of use in a surgical procedure. Preferably, the
instrument 100 may be made of a material that is either disposable
or capable of being sterilized by standard sterilization
techniques. For example, the instrument 100 may be made of a
plastic or a metal. If made of a metal, the instrument 100 may be
made of for example, cobalt chromium alloy, stainless steel alloy,
or titanium alloy.
[0077] Referring now to FIGS. 4, 4A and 4B, another embodiment of
the present invention is shown as instrument 200. Similar to the
instrument 100 of FIGS. 3, 3A, and 3B, the instrument 200 of FIGS.
4, 4A and 4B is utilized for measuring the medullary canal 20 of a
long bone 10 in order to determine the proper size for a canal
implant. The instrument 200 is utilized for determining the proper
size of a canal implant 202. Canal implant 202 may be in the form
of, for example, a stem centralizer or a plug. Similar to the
instrument 100 of FIG. 3, the instrument 200 of FIG. 4 includes an
elongated central portion 204 defining a first end 206 and an
opposed second end 208.
[0078] Further similar to the instrument 100, the instrument 200
includes a contact portion 210 extending from the first end 206 of
the elongated central portion 204. The contact portion 210 of the
instrument 200 of FIGS. 4, 4A, and 4B is different than the contact
portion 110 of the instrument 100 in that the contact portion 210
includes a plurality of contact areas. For example, the contact
portion 210 includes a first contact area 212 and a second contact
area 213. The contact areas 212 & 213 provide for contact with
the medullary canal 20 of the long bone 10. The contact portion 210
further defines a plurality of relief areas. For example, the
contact portion 210 defines a first relief area 214 as well as a
second relief area 215. The relief areas 214 & 215 provide
clearance between the instrument and the medullary canal 20. Relief
areas 214 & 215 provide for an easier and smoother insertion of
the instrument 200 into the canal 20 as well as avoid pressure
caused by the insertion of the instrument 200 that may prevent the
proper seating of the instrument 200 in the canal 20.
[0079] The central elongated portion 204 of the instrument 200 may
have any suitable shape and may, for simplicity, be cylindrical.
The contact portion 210 as shown in FIG. 4 includes the first and
second contact areas 212 & 213 as well as the first and second
relief portions 214 & 215, respectively. It should be
appreciated that the relative size of the relief areas 214 &
215 as well as the contact areas 213 & 214 should be selected
to provide for a proper seating of the instrument 200 into the
canal 20 as well as to provide for ease of insertion of the
instrument 200 into the canal 20.
[0080] For example, as shown in FIG. 4, the relative portion of the
contact portion 210 in relief and in contact may for example be
roughly equal. Also, the first contact area 212 and the second
contact area 213 may have a similar size and for simplicity, may
have a similar shape. Similarly, the first relief area 214 and the
second relief area 215 may have similar sizes and may for
simplicity have a similar shape.
[0081] The first and second contact areas 212 & 213 may have
any suitable shape, and may as shown in FIGS. 4, 4A and 4B be
generally arcuate. The contact portion 210 may include a generally
hemispherical end portion 226 and a generally conifrustrical
intermediate portion 228. The hemispherical end portion 226 may be
defined by example, by radius RR extending from origin 216. The
first relief area 214 and the second relief area 215 may for
simplicity be plainer and may as shown in FIGS. 4A and 4B the first
relief area 214 may be parallel in space from the second relief
area 215.
[0082] It should be appreciated that the instrument 200 may include
a second contact portion similar to the contact portion 210 but
preferably may be slightly larger or smaller than the contact
portion 210. The second contact portion not shown may for example
extend from second end 208 of the central portion 204 of the
instrument 200.
[0083] Similar to the instrument 100 of FIG. 3, the instrument 200
of FIG. 4 may be integral or modular and be made of any suitable
durable material, such as those described with respect to
instrument 100.
[0084] Referring now to FIG. 5, another embodiment of the present
invention is shown as instrument 300. The instrument 300 is
utilized for measuring the medullary canal 20 of a resected long
bone 10 in order to determine the proper size of a canal implant.
For example, one such canal implant is a stem centralizer 302 (see
FIG. 5A). The instrument 300 includes an elongated central portion
304 which includes a first end 306 and an opposed second end
308.
[0085] The instrument 300 further includes a contact portion 310
extending from the first end 306 of the elongated central portion
304 of the instrument 300. The contact portion 310 has a shape
substantially similar to the shape of the stem centralizer 302 (see
FIG. 5A) on the surface of the instrument 300 opposed to the
resected surface 18 of the long bone 10.
[0086] The elongated central portion 304 may have a shape similar
to for example the elongated portion central portion 104 of the
instrument 100 of FIG. 3.
[0087] The contact portion 310 may include an end contact area 326
opposed to the resection line 18. The end contact area 326 may have
any suitable shape and may be arcuate. For example, the end contact
area 326 may as shown in FIG. 5 be generally hemispherical and
defined by radius RRR extending from center point 316. The contact
portion 310 may further include an intermediary contact area 328
extending from the end contact area 326 to the first end 306 of the
elongated central portion 304.
[0088] Referring now to FIG. 5A, stem centralizer 302 for use with
the instrument 300 is shown in greater detail. The stem centralizer
302 includes a contact portion 330 as well as an opposed stem 332.
The contact portion 330 includes a periphery 334 defined by radius
RRR extending from center point 336. The radius RRR of the
centralizer 302 is the same as the radius RRR of the contact
portion 326. The instrument 300 replicates the shape of the
periphery 334 of the centralizer 302.
[0089] Referring again to FIG. 5, the instrument 300 may further
include a second contact portion 320 similar to contact portion
310. The second contact portion 320 may extend outwardly from
second end 308 of the elongated central portion 304 of the
instrument 300.
[0090] The instrument 300 may be made of any suitable durable
material and may be made of a plastic or a metal. Preferably the
instrument 300 is made of material that may be sterilized by any
commercially available sterilization technique. The instrument 300
may be a plastic or a metal. If made of a metal the instrument 300
may be made of cobalt chromium alloy, titanium alloy or stainless
steel alloy. The instrument 300 may be integral or may be
modular.
[0091] Referring now to FIG. 6 another embodiment of the present
invention is shown as instrument 400. Instrument 400 is similar to
instrument 300 and includes an elongated central portion 404. The
central portion 404 includes a first end 406 and an opposed second
end 408. A contact portion 410 extends outwardly from first end 406
of the central portion 404.
[0092] Contact portion 410 of the instrument 400 has a shape
designed to replicate contact portion 430 of the stem centralizer
402 (see FIG. 6A). For example, the contact portion 410 includes an
end contact area 426 as well as an intermediate contact area 428
positioned between the end contact area 426 and first end 406 of
the central portion 404 of the instrument 400.
[0093] Similarly, referring to FIG. 6A, the contact portion 430 of
the centralizer 402 includes an end contact area 434 as well as an
intermediary contact area 438 positioned between the end contact
area 434 and stem portion 432 of the centralizer 402.
[0094] Referring again to FIG. 6, the instrument 400 may have any
suitable size and shape and may, similar to the instrument 100 of
FIG. 3, include a second contact portion 420 extending from second
end 408 of the instrument 400.
[0095] The instrument 400 may be made of any suitable durable
material and may for example be made of a metal or a plastic.
Preferably the instrument 400 is made of a material that may be
sterilized by conventional sterilization techniques. The instrument
400, if made of a metal, may be made of, for example, cobalt
chromium alloy, stainless steel alloy or titanium alloy. The
instrument 400 may be integral or may be modular.
[0096] Referring now to FIG. 7 another embodiment of the present
invention is shown as instrument 500. The instrument 500 is
utilized for measuring the medullary canal 20 of the long bone 10
in order to determine the proper size for a canal implant, for
example a stem centralizer. The instrument includes an elongated
central portion 504. The central portion 504 includes a first end
506 and an opposed second end 508. Contact portion 510 extends from
the first end 506 of the elongated central portion 504. The contact
portion 510 has a contact area 512 for contact with the canal and
defines a relief area 514 providing clearance for the instrument
500 in the medullary canal 20.
[0097] Referring now to FIG. 8, the instrument 500 is shown in
greater detail. As shown in FIG. 8, the instrument 500 further
includes a second contact portion 520 extending outwardly from
second end 508 of the central portion 504 of the instrument 500.
The second contact portion 520 like the first contact portion 510
includes contact area 522 as well as relief area 524.
[0098] Preferably as shown in FIG. 8, the elongated central portion
504 includes indicia 540. The indicia 540 is utilized to determine
the position of the contact portions 510 & 520 with respect to
resection line 18 of the femur 10 (see FIG. 1). The indicia 540 may
include a plurality of spaced apart marks 542. The marks 542 may
provide a visual reference for alignment with the resection line 18
(see FIG. 7). The marks 542 may be spaced apart a distance of for
example ten millimeters. The marks 542 may thus correspond to an
inch or metric dimension. For example ten millimeters is shown in
the instrument 500 of FIG. 8.
[0099] The indicia 540 may further include numerical markings 544
and alphabetical markings 546. The numerical markings 544 may
correspond to a particular dimension. For example, a metric
dimension from the resection line 18 to the contact portion 510 or
520 of the instrument 500. For example, as shown in FIG. 8, the
reference numeral 140 may be spaced a distance H from end 548 of
the first contact portion 510. As shown in FIG. 8 the dimension H
is 140 millimeters.
[0100] It should be appreciated that in order for the indicia 540
to be easily read by the surgeon the numeral 140 is shown upside
down so that the surgeon may read the dimension when the instrument
500 is inserted into the medullary canal 20 of the long bone 10.
The indicia 540 may be placed on the central portion 504 of the
instrument 500 by any suitable method, for example by stamping,
printing, or etching.
[0101] Referring now to FIGS. 9, 10, 11 and 12 the first contact
portion 510 and second contact portion 520 of the instrument 500
are shown in greater detail. Referring now to FIGS. 9 and 10, first
contact portion 510 of the instrument 500 is shown in greater
detail. As shown in FIG. 9, the first contact portion includes a
contact area 512 as well as a relief area 514. The contact area 512
as shown in FIG. 9 may include an end contact area 526 extending
from end 548 of the first contact portion 510. The end contact area
526 may be of any suitable shape and may for simplicity and to best
replicate the shape of the centralizer 502 (see FIG. 13) may have a
generally hemispherically shape defined by a radius R1 extending
from center point 516.
[0102] The first contact portion 510 may also include an
intermediate contact area 528 extending from the first contact area
526 to the first end 506 of the central portion 504 of the
instrument 500. The intermediate contact area 528 may have any
suitable shape and for simplicity as shown in FIG. 9 may be
generally conifrustrical.
[0103] While the instrument of the present invention may include a
solitary relief area and a solitary contact area as shown in FIG.
10, the instrument 500 may include a plurality of spaced apart
contact areas as well as a plurality of spaced apart relief
areas.
[0104] Relief areas and contact areas may be equally spaced about
the perimeter of the instrument 500 and may include for example 2,
3, 4, 5, 6, 7, or 8 or more alternating relief areas and
alternating contact areas. For example as shown in FIG. 9, the
instrument 500 may include four relief areas and four contact
areas. Each of the contact areas, for example contact area 550, may
have a uniform thickness of, for example, thickness T.
[0105] Referring to FIG. 10, first contact portion 510 is shown in
greater detail with the plurality of contact areas and relief areas
shown more clearly. For example, the first contact portion includes
the first contact area 550, the second contact area 552, third
contact area 554 and fourth contact area 556. Each of the contact
areas 550, 552, 554, 556 have an identical thickness of, for
example, thickness T. The outer portion 558 of the contact portions
550, 552, 554, 556 may be arcuate and defined by a radius R2.
[0106] Referring now to FIGS. 11 and 12, the second contact portion
520 of the instrument 500 is shown in greater detail. The second
contact portion 520 extends from second end 508 of the central
portion 504. The second contact portion 520 includes an end contact
area 560 as well as an intermediate contact area 562. The end
contact area 560 may have any suitable shape and may for simplicity
have a shape similar to that of the corresponding centralizer. For
example the end contact area 560 may be generally hemispherical and
defined by a radius R3 extending from center point 564.
[0107] The intermediate contact area 562 may have any shape and may
for simplicity be conifrustrical extending from the end contact
area 560 to the second end 508 of the central portion 504 of the
instrument 500. The contact areas, for example contact area 565,
may have any suitable thickness and may have a uniform thickness of
for example T-2. The thickness T-2 may be similar to the thickness
T of the contact area 512 of the first contact 510.
[0108] The second contact portion 520 may be similar to the first
contact portion 510 and may include a plurality of contact areas
and a plurality of relief areas. The contact areas and relief areas
may be symmetrically positioned about the instrument 500. For
example the second contact portion 520 may include 2, 3, 4, 5, 6,
7, 8, 9, or 10 or more spaced apart contact areas as well as a
corresponding number of spaced apart relief areas. As shown in FIG.
12, the second contact portion 520 may include a first contact area
565, a second contact area 566, a third contact area 568 and a
fourth contact area 570.
[0109] As shown in FIG. 12, the first contact area 565 may for
simplicity have a uniform thickness T-2 and have an end 572 which
is generally arcuate. For example, the end 572 may be generally
semi-circular and defined by a radius R3. It should be appreciated
that the second contact area 566, the third contact area 568 and
the fourth contact area 570 may be substantially the same as the
first contact area 565 and have end portions which are generally
hemispherical.
[0110] Referring now to FIG. 13 and FIG. 14, the end contact area
534 of the stem centralizer 502 is shown in the medullary canal 20
of the long bone 10 having a shape generally the same as the end
contact area 526 of the instrument 500.
[0111] Referring now to FIG. 13, the stem centralizer 502 has a
contact portion 530 for contact with the medullary canal 20 of the
long bone 10. The contact portion 530 of the stem centralizer 502
is designed to have the shape similar to the end contact area 526
of the first contact portion 510 of the instrument 500.
[0112] It should be appreciated that the instrument 500 may also
include the second contact portion 520 for use with a stem
centralizer not shown having a different size. The contact portion
530 of the stem centralizer 502 includes an end contact portion 534
defined by a radius R4 extending from centerline 574 stem
centralizer 502 further includes a stem 532 which matingly fits
with opening 576 in implant 540.
[0113] Referring now to FIG. 14, the instrument 500 is shown
inserted in medullary canal 20 of the long bone 10. The instrument
500 includes the end contact area 526 formed in the distal part of
first contact portion 510 of the instrument 500.
[0114] Referring now to FIG. 15 another embodiment of the present
invention is shown as kit 600. The kit 600 is for use in performing
total hip arthroplasty. The kit includes a plurality of
instruments. Each of the instruments is adapted for measuring the
medullary canal 20 of a femur 10. Kit 600, as shown in FIG. 15,
includes a first instrument 500 and a second instrument 602. It
should be appreciated that the instrument 500 may optionally
include a third instrument 604.
[0115] The kit 600 further includes a plurality of centralizers.
For example as shown in FIG. 15 the kit 600 includes a first
centralizer 502 and a second centralizer 640. It should be
appreciated that the kit 600 may include additional centralizers.
For example, and as shown in FIG. 15, the Kit 600 may include a
third centralizer 642 a fourth centralizer 644, a fifth centralizer
646 as well as a sixth centralizer 648.
[0116] Kit 600 may further include a hip stem 650 for use with one
of the stem centralizers, for example first stem centralizer 502.
It should be appreciated that the Kit 600 may include a second hip
stem 652.
[0117] As shown in FIG. 15, the kit 600 may be adapted such that
each of the instruments, 500, 602, 604 has at least one dimension
different than each of the other instruments. It should also be
appreciated that the kit 600 can also be adapted such that each of
the stem centralizers, for example stem centralizer 502, 640, 642,
644, 646 and 648 may each have a unique dimension. Further, the Kit
600 may be adapted such that each of the hip stems, for example hip
stem 650 and hip stem 652 may each have a unique dimension. It
should be appreciated by providing the plurality of instruments,
centralizers and stems, a system may be provided to accommodate a
wide variety of patient needs.
[0118] For example, as shown in FIG. 15, the instrument 500
includes a first contact portion 510 having an end contact area 534
which has dimensions similar to end contact area 620 of the first
stem centralizer 502. Similarly, the instrument 500 may include a
second contact portion 520 having an end contact area 560 having
dimensions similar to end contact area 622 of the second stem
centralizer 640. Thus the instrument 500 has a first contact
portion 510 for use with selecting the first stem centralizer 502
and a second contact portion 520 for use in selecting the second
stem centralizer 640. Similarly, the instrument 602 includes a
first contact portion 624 for use in selecting the third stem
centralizer 642 and a second contact portion 626 for use in
selecting the fourth stem centralizer 644. As shown in FIG. 15 the
first contact portion 510 includes a radius R1 which is similar to
the radius R4 of the first stem centralizer 502. The second contact
portion 520 of the instrument 500 includes a radius R5 which is
similar to the radius R6 of the second stem centralizer 640. The
first contact portion 624 of the instrument 602 includes a radius
R7 which is similar to the radius R8 of the third stem centralizer
642. The second contact area 626 of the second instrument 602
includes a radius R9 which is similar to the radius R10 of the
fourth stem centralizer 644. The third instrument 604 includes a
first contact portion 628 which includes a radius R11 which is
similar to the radius R12 of the fifth stem centralizer 646 and a
second contact portion 630 which has a radius R13 similar to the
radius R14 of the sixth stem centralizer 648.
[0119] The first contact portion 624 of the second instrument 602
corresponds with the use of the third stem centralizer 642 while
the second contact portion 626 of the second instrument 602
corresponds with the use of the fourth stem centralizer 644.
Similarly, the first contact portion 628 of the third instrument
604 corresponds to the use of the fifth stem centralizer 646 while
the second contact portion 630 of the third instrument 604
corresponds to the use of the sixth stem centralizer 648.
[0120] The position of the instrument, for example instrument 500
in the canal 20 of the long bone 10 may be utilized to determine
which of a variety of hip stems are proper for a particular
patient. For example the instrument may include the indicia 540.
Each position on the indicia 540 may represent the use of a
particular stem. For example and as shown in FIG. 15, if the
resection line 18 of the femur 10 corresponds to position x, for
example, the first hip stem 650 should be selected. Alternatively,
if the resection line 18 of the hip stem 10 corresponds to position
XX, the second hip stem 652 should be utilized.
[0121] Referring now to FIG. 16, a hip stem in the form of for
example stem 540 is shown in use in the medullary canal 20 of the
stem 10. The implant 540 includes a stem centralizer 502 connected
to distal portion 702 of the implant 540. The implant 540 may also
include a neck 704 to which a head 706 is attached.
[0122] Referring now to FIG. 17, another embodiment of the present
invention is shown as method 800. Method 800 includes a first step
802 of resecting a long bone and a second step 804 of preparing the
medullary canal of a long bone. The method 800 further includes a
third step 806 of providing a plurality of instruments for
measuring the medullary canal of the long bone. Each of the
instruments includes an elongated central portion defining opposed
first and second ends, a second contact portion extending from the
first end of the elongated central portion, the contact portions
having a plurality of contact areas for contact with the medullary
canal in defining a plurality of relief areas providing clearance
between the instrument and the medullary canal.
[0123] The method 800 further includes a fourth step 808 of
inserting one of the plurality of instruments into the canal. The
method 800 further includes a fifth step 810 of providing a
plurality of centralizers for implanting into the medullary canal
of a long bone. Each of the plurality of centralizers corresponds
to one of the plurality of instruments. The method 800 further
includes a sixth step 812 of determining the appropriateness of one
of the plurality of the instruments and a seventh step 814 of
inserting one of the plurality of centralizers corresponding to the
one of the plurality of instruments in the canal. The method
further includes an eighth step 816 of providing a stem and a ninth
step 818 of implanting the stem in the medullary canal of the long
bone.
[0124] Although the present invention and its advantages have been
described in detail, it should be understood that various changes,
substitutions, and alterations can be made therein without
departing from the spirit and scope of the present invention as
defined by the appended claims.
* * * * *