U.S. patent application number 09/854958 was filed with the patent office on 2001-09-13 for radial head implant system including modular implant and modular radial head locking instrument.
This patent application is currently assigned to Wright Medical Technology, Inc.. Invention is credited to Grusin, Nathaniel Kelley, Johnson, James A., King, Graham J. W., Patterson, Stuart D., Terrill-Grisoni, Lauralan, Theis-Handwerker, Maureen.
Application Number | 20010021876 09/854958 |
Document ID | / |
Family ID | 23532659 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010021876 |
Kind Code |
A1 |
Terrill-Grisoni, Lauralan ;
et al. |
September 13, 2001 |
Radial head implant system including modular implant and modular
radial head locking instrument
Abstract
A modular radial head system including a modular implant for
replacing the head of the proximal end of a radius and for
articulating with the capitellum of a humerus. The modular implant
includes a modular head and an modular stem. The system further
includes a modular radial head locking instrument for locking the
modular head and the modular stem of the modular implant to one
another. The locking instrument includes a first jaw, a second jaw,
and a control mechanism for urging the first and second jaws
together to provide offset axial compression of the modular head
and the modular stem of the modular implant.
Inventors: |
Terrill-Grisoni, Lauralan;
(Cordova, TN) ; Grusin, Nathaniel Kelley;
(Memphis, TN) ; Patterson, Stuart D.; (Winter
Haven, FL) ; Theis-Handwerker, Maureen; (Germantown,
TN) ; Johnson, James A.; (London, CA) ; King,
Graham J. W.; (London, CA) |
Correspondence
Address: |
Larry W. McKenzie
Walker, McKenzie & Walker, P.C.
Suite 434
6363 Poplar Avenue
Memphis
TN
38119-4896
US
|
Assignee: |
Wright Medical Technology,
Inc.
Arlington
TN
38002
|
Family ID: |
23532659 |
Appl. No.: |
09/854958 |
Filed: |
May 15, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09854958 |
May 15, 2001 |
|
|
|
09388093 |
Sep 1, 1999 |
|
|
|
Current U.S.
Class: |
623/20.11 ;
606/99 |
Current CPC
Class: |
A61F 2002/30616
20130101; A61F 2230/0069 20130101; A61F 2002/30332 20130101; A61F
2/4637 20130101; A61F 2002/30143 20130101; A61F 2002/4666 20130101;
A61F 2220/0033 20130101; A61F 2002/3827 20130101; A61F 2002/30691
20130101; A61F 2220/0025 20130101; A61F 2002/30479 20130101; Y10S
623/911 20130101; A61F 2002/30787 20130101; A61F 2310/00029
20130101; A61F 2002/30785 20130101; A61F 2002/30604 20130101; A61F
2/4657 20130101; A61F 2002/30878 20130101; A61F 2250/0064 20130101;
A61F 2/4684 20130101; A61F 2/4605 20130101; A61F 2002/30233
20130101; A61F 2002/30505 20130101; A61F 2230/0017 20130101; A61F
2/3804 20130101; A61F 2230/0006 20130101; A61F 2002/30113
20130101 |
Class at
Publication: |
623/20.11 ;
606/99 |
International
Class: |
A61F 002/38 |
Claims
1. A modular radial head system comprising: (a) a modular implant
for replacing the head of the proximal end of a radius and for
articulating with the capitellum of a humerus; said implant
including a modular head having a first lock member, and including
an modular stem having a second lock member for coacting with said
first lock member of said modular head to lock said modular head
and said modular stem together; and (b) a modular radial head
locking instrument for locking said modular head and said modular
stem of said modular implant to one another; said modular radial
head locking instrument including a first jaw, a second jaw, and a
control mechanism for urging said first and second jaws together;
said first jaw having a distal end adapted to engage a portion of
said modular stem and having a proximal end; said second jaw having
a distal end adapted to engage a portion of said modular head and
having a proximal end; said control mechanism engaging said
proximal ends of said first and second jaws to provide offset axial
compression of said modular head and said modular stem.
2. The system of claim 1 in which said distal end of said first jaw
of said modular radial head locking instrument has a slot for
receiving a portion of said modular stem; and in which said distal
end of said second jaw of said modular radial head locking
instrument has a centering means for receiving and positioning said
modular head.
3. The system of claim 1 in which said offset axial compression
provided by said control mechanism is load controlled.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of pending U.S. patent
application Ser. No. 09/388,093, filed Sep. 1, 1999.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to implantable
orthopaedic prostheses and more particularly to a system including
modular radial head implants, sizers for trial reduction of the
joint, and instrumentation for preparing the radial head,
implanting the sizers, assembling the implants, etc.
[0004] 2. Information Disclosure Statement: Prostheses for
replacing or repairing the radial head are well known in the prior
art. The Sorbie-Questor.RTM. Total Elbow System includes a radial
head component having a metal base and a polyethylene articulating
surface cap molded onto the metal base. The Swanson Titanium Radial
Head Implant is a one-piece implant manufactured from commercially
pure titanium that features nitrogen ion implantation for increased
surface hardness, and is provided in five different sizes to meet
various operative requirements.
BRIEF SUMMARY OF THE INVENTION
[0005] The present invention provides a modular radial head system
including a modular implant for replacing the head of the proximal
end of a radius and for articulating with the capitellum of a
humerus. The modular implant includes a modular head and an modular
stem. The system further includes a modular radial head locking
instrument for locking the modular head and the modular stem of the
modular implant to one another. The locking instrument includes a
first jaw, a second jaw, and a control mechanism for urging the
first and second jaws together to provide offset axial compression
of the modular head and the modular stem of the modular
implant.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0006] FIG. 1 is a top plan view of a modular head of the preferred
embodiment of a modular radial head implant of the present
invention.
[0007] FIG. 2 is a sectional view substantially as taken on line
2-2 of FIG. 1.
[0008] FIG. 3 is side elevational view of the modular head of FIG.
1.
[0009] FIG. 4 is bottom plan view of the modular head of FIG.
1.
[0010] FIG. 5 is a top plan view of a modular body of the preferred
embodiment of a modular radial head implant of the present
invention.
[0011] FIG. 6 is a side elevational view of the modular body of
FIG. 5.
[0012] FIG. 7 is a top plan view of a modular head of the preferred
embodiment of a modular radial head sizer of the present
invention.
[0013] FIG. 8 is a sectional view substantially as taken on line
8-8 of FIG. 7.
[0014] FIG. 9 is side elevational view of the modular head of FIG.
7.
[0015] FIG. 10 is a sectional view substantially as taken on line
10-10 of FIG. 9.
[0016] FIG. 11 is bottom plan view of the modular head of FIG.
7.
[0017] FIG. 12 is a top plan view of a modular body of the
preferred embodiment of a modular radial head sizer of the present
invention.
[0018] FIG. 13 is a sectional view substantially as taken on line
13-13 of FIG. 12, on a somewhat enlarged scale.
[0019] FIG. 14 is a side elevational view of the modular body of
FIG. 12.
[0020] FIG. 15 is a sectional view substantially as taken on line
15-15 of FIG. 14.
[0021] FIG. 16 is a top plan view of a preferred embodiment of a
modular body sizer insertion instrument of the present
invention.
[0022] FIG. 17 is a side elevational view of the modular body sizer
insertion instrument of FIG. 16.
[0023] FIG. 18 is a plan view of a preferred embodiment of a
modular head sizer insertion instrument of the present
invention.
[0024] FIG. 19 is a top plan view of a preferred embodiment of a
modular radial head broach of the present invention.
[0025] FIG. 20 is a side elevational view of the modular radial
head broach of FIG. 19.
[0026] FIG. 21 is a sectional view substantially as taken on line
21-21 of FIG. 20, on a somewhat enlarged scale.
[0027] FIG. 22 is an elevational view of a preferred embodiment of
a modular radial head radius crank planer of the present invention,
with portions thereof broken away to shown internal structure.
[0028] FIG. 23 is a plan view of a portion of the radius crank
planer substantially as taken on line 23-23 of FIG. 22, on a
somewhat enlarged scale.
[0029] FIG. 24 is an elevational view of a portion of the radius
crank planer substantially as taken on line 24-24 of FIG. 23, on a
somewhat enlarged scale.
[0030] FIG. 25 is an elevational view of a preferred embodiment of
a modular radial head locking instrument of the present invention,
with portions thereof broken away for clarity.
[0031] FIG. 26 is a sectional view substantially as taken on line
26-26 of FIG. 25.
[0032] FIG. 27 is a sectional view substantially as taken on line
27-27 of FIG. 25.
[0033] FIG. 28 is a sectional view of the proximal end of a radius,
having a fractured neck.
[0034] FIG. 29 is a sectional view similar to FIG. 28, but with the
head and a portion of the neck of the proximal end of the radius
excised, and showing the head of a modular radial head broach of
the present invention being used to prepare the medullary canal of
the proximal end of the radius.
[0035] FIG. 30 is a sectional view similar to FIG. 29, but showing
the medullary canal of the proximal end of the radius prepared for
implantation.
[0036] FIG. 31 is a sectional view similar to FIG. 30, but showing
the stem of the modular body of the modular radial head sizer of
the present invention inserted into the medullary canal, and
showing the planer portion of the modular radial head radius crank
planer of the present invention being slipped onto the stem.
[0037] FIG. 32 is a sectional view similar to FIG. 31, but showing
the planer portion of the modular radial head radius crank planer
fully positioned on the stem of the modular body of the modular
radial head sizer.
[0038] FIG. 33 is a sectional view substantially as taken on line
33-33 of FIG. 32.
[0039] FIG. 34 is a sectional view similar to FIG. 32, but showing
the modular radial head radius crank planer removed from the stem,
and showing the modular head of the modular radial head sizer
screwed onto the modular sizer head insertion tool and being
slipped onto the boss of the modular body of the modular radial
head sizer.
[0040] FIG. 35 is a sectional view similar to FIG. 34, but showing
the modular head fully inserted onto the boss, and showing modular
head sizer insertion instrument of the present invention engaging
the flats of the neck portion of the stem of the modular body of
the modular radial head sizer.
[0041] FIG. 36 is a sectional view similar to FIG. 35, but showing
the modular body sizer insertion instrument and modular head sizer
insertion instrument fully mounted on the respective modular body
and modular head, and showing the modular body and modular head
rotated 90.degree. with respect to one another and locked
together.
[0042] FIG. 37 is a sectional view substantially as taken on line
37-37 of FIG. 35.
[0043] FIG. 38 is a sectional view similar to FIG. 36, but showing
the modular body sizer insertion instrument and modular head sizer
insertion instrument removed therefrom, and illustrating a trial
reduction of the proximal end of the radius and the capitellum of
the humerus.
[0044] FIG. 39 is a sectional view similar to FIG. 38, but showing
the modular radial head sizer removed from the radius, showing the
stem of the modular body of the modular radial head implant of the
present invention being placed into the medullary canal of the
radius, and showing the modular head of the modular radial head
implant being placed onto the boss of the modular body thereof.
[0045] FIG. 40 is a sectional view similar to FIG. 39 but showing
the modular radial head locking instrument of the present invention
engaging the modular radial head implant to lock the modular head
and modular body thereof together.
[0046] FIG. 41 is a sectional view similar to FIG. 40, but with the
modular radial head locking instrument removed, with the modular
head and modular body locked together, and illustrating a reduction
of the proximal end of the radius and the capitellum of the
humerus.
DETAILED DESCRIPTION OF THE INVENTION
[0047] The preferred embodiment of the system of the present
invention is used for replacing or resurfacing the radial head of
an elbow joint. However, it should be understood that the system of
the present invention could be used for other joints, with
modifications to accommodate the particular size and anatomical
shape and positioning, etc., without changing the essential
structure and operation of the system of the present invention.
[0048] The system of the present invention includes a modular
radial head implant 11 (see, in general, FIGS. 39-41) for replacing
the head H of the proximal end P of a radius R in the event the
neck N of the proximal end P of the radius R has a fracture F (see,
in general, FIG. 28), or the head H otherwise needs to be replaced.
The modular radial head implant 11 includes a modular head 13 (see,
in general, FIGS. 1-4) and a modular body 15 (see, in general,
FIGS. 5 and 6).
[0049] The modular head 13 includes a proximal end 17 having a
slight concavity 19 therein for articulation with the capitellum C
of a humerus (see FIG. 41). The modular head 13 has a distal end 21
and an outer wall 23 extending between the proximal and distal ends
17, 21 thereof. The outer wall 23 of the modular head 13 preferably
curves outwardly slightly between said proximal and distal ends 17,
21 thereof as clearly shown in FIGS. 2 and 3 with the modular head
13 forming a circular disc with a barrel-shaped outer wall. The
modular head 13 thus substantially reproduces the anatomical
articular geometry of the head H, or proximal end P, of a radius R.
The modular head 13 includes a first lock member 25. The first lock
member 25 preferably has a cavity 27 with a female taper. For
example, the sides of the cavity 27 preferably taper inwardly from
the distal end 21 of the modular head 13 a combined total of
approximately 3.degree. as indicated by the arrow 29 in FIG. 2.
[0050] The modular body 15 includes a distal end 31 for engaging
the proximal end P of the radius R (see FIGS. 39-41), and a
proximal end 33. The modular body 15 includes a second lock member
35 for coacting with the first lock member 25 of the modular head
13 to lock the modular head 13 and the modular body 15 together.
The distal end 31 of the modular body 15 preferably has an
elongated stem 37 for extending into the medullary canal MC of the
proximal end P of the radius R (see FIGS. 39-41). The proximal end
33 of the modular body 15 preferably has an enlarged boss or
platform 39 for fitting into the cavity 27 of the first lock member
25 of the modular head 13. The platform 39 preferably has a male
taper for coacting with the female taper of the cavity 27 of the
first lock member 25 of the modular head 13 to lock the modular
head 13 and the modular body 15 together. For example, the sides of
the platform 39 preferably taper outwardly from the proximal end 33
of the modular body 15 a combined total of approximately 3.degree.
as indicated by the arrow 41 in FIG. 6, and the platform 39 is
preferably sized so as to tightly fit into the cavity 27 so that
the male and female tapers will securely lock together when the
modular head 13 and modular body 15 are forcibly brought together
as will now be apparent to those skilled in the art. The modular
body 15 has a drainage passage 43 allowing fluid trapped between
the first and second lock members 25, 33 to drain out. The drainage
passage 43 preferably consists of a hole or aperture 45 extending
through the platform 39 from the proximal end 33 of the modular
body 15, through the platform 39 to a point exterior of the stem 37
as clearly shown in FIG. 6. Preferably, the modular body 15 has a
plurality of spaced drainage passages 43 through the platform 39 as
shown in FIG. 5.
[0051] The modular head 13 and modular body 15 may be constructed
in various manners and out of various materials as will now be
apparent to those skilled in the art to substantially reproduce
anatomical articular geometry. Thus, for example, the modular head
13 and modular body 15 can each be machined or otherwise
constructed as a one-piece, integral unit out of a medical grade,
physiologically acceptable material such as a cobalt chromium
molybdenum alloy or the like, in various sizes to fit a range of
typical patients, etc. The modular head 13 and modular body 15 are
preferably highly polished. Preferably, the modular radial head
implant 11 includes a plurality of different size modular heads 13
and bodies 15 for allowing different size modular radial head
implants 11 to be assembled from individual heads 13 and bodies 15.
Thus, for example, modular heads 13 may be provided with 5
different head diameters ranging between 20 and 28 millimeters in 2
millimeter increments, and with 3 different head heights ranging
between and 13 millimeters in 2 millimeter increments. Modular
bodies 15 may be provided with 5 different stem diameters ranging
between 5.5 and 9.5 millimeters in 1 millimeter increments, and
with 3 different stem lengths ranging between 20 and 24 millimeters
in 2 millimeter increments. The various heads 13 and bodies 15 are
preferably universally modular, so that all of the bodies 15 will
work with all of the heads 13, and vice versa.
[0052] The system of the present invention includes a modular
radial head sizer 2.11 (see, in general, FIGS. 34-38) for allowing
a trial reduction of the elbow joint to help determine the proper
size modular radial head implant 11 to use as will now be apparent
to those skilled in the art. The modular radial head sizer 2.11
includes a modular head 2.13 (see, in general, FIGS. 7-11) and a
modular body 2.15 (see, in general, FIGS. 12-15).
[0053] The modular head 2.13 includes a proximal end 2.17 having a
slight concavity 2.19 therein for articulation with the capitellum
C of a humerus (see FIG. 38) during trial reduction of the modular
radial head sizer 2.11. The modular head 2.13 has a distal end 2.21
and an outer wall 2.23 extending between the proximal and distal
ends 2.17, 2.21 thereof. The outer wall 2.23 of the modular head
2.13 preferably curves outwardly slightly between said proximal and
distal ends 2.17, 2.21 thereof as clearly shown in FIGS. 8-10 with
the modular head 2.13 forming a circular disc with a barrel-shaped
outer wall. The modular head 2.13 thus substantially reproduces the
anatomical articular geometry of the head H, or proximal end P, of
a radius R. The modular head 2.13 has a cavity 2.27 for lockably
receiving a portion of the modular body 2.15 as will hereinafter
become apparent, and has a side entrance opening 2.28 to the cavity
2.27 through the outer wall 2.23. The modular head 2.13 preferably
has an internally threaded aperture or cavity 2.29 extending into
or through the outer wall 2.23. As indicated in FIGS. 9 and 10, the
threaded cavity 2.29 may be directly opposite the side entrance
opening 2.28.
[0054] The modular body 2.15 includes a distal end 2.31 for
engaging the proximal end P of the radius R (see, in general, FIGS.
31, 32, 34-36 and 38), and a proximal end 2.33. The distal end 2.31
of the modular body 2.15 preferably has an elongated stem 2.37 for
extending into the medullary canal MC of the proximal end P of the
radius R (see FIGS. 31, 32, 34-36 and 38). The proximal end 2.33 of
the modular body 2.15 preferably has an enlarged boss or platform
2.39 for fitting into the cavity 2.27 of the modular head 2.13. The
platform 2.39 is adapted to be inserted through the side entrance
opening 2.28 of said modular head 2.13 into the cavity 2.27 of the
modular head 2.13.
[0055] The modular radial head sizer 2.11 preferably includes lock
means 2.47 (see, in general, FIG. 37) for locking the modular head
2.13 and modular body 2.15 together after the platform 2.39 of the
modular body 2.15 is inserted into the cavity 2.27 of the modular
head 2.13 through the side entrance opening 2.28 of the modular
head 2.13. The lock means 2.47 preferably includes ball-and-detent
type means for locking the modular head 2.13 and modular body 2.15
together when the platform 2.39 of the modular body 2.15 is
inserted into the cavity 2.27 of the modular head 2.13 through the
side entrance opening 2.28 of the modular head 2.13 and rotated.
The ball-and-detent type means may be any typical operation and
construction now apparent to those skilled in the art such as a
true ball-and-detent lock including a ball-and-spring means 2.51 in
the opposite ends of the platform 2.39 as clearly shown in FIG. 13,
and coacting detents or apertures 2.53 in the modular head 2.13 on
opposite sides of the cavity 2.27 as clearly shown in FIG. 8 spaced
90.degree. from the side entrance opening 2.28 so that the modular
head 2.13 and modular body 2.15 will be locked together when the
platform 2.39 of the modular body 2.15 is inserted into the cavity
2.27 of the modular head 2.13 through the side entrance opening
2.28 of the modular head 2.13 and rotated 90.degree. as will now be
apparent to those skilled in the art.
[0056] The proximal end or neck 2.55 of the stem 2.37 immediately
adjacent the platform 2.39 of the modular body 2.15 preferably has
at least two opposite flats 2.57 on the exterior thereof located
parallel to the flat sides of the platform 2.39 for reasons which
will hereinafter become apparent. The neck 2.55 may have three sets
of opposite flats 2.57 to provide a hexagonal cross section, or
equivalent keyway type geometry, as clearly shown in FIG. 15.
[0057] The modular head 2.13 and modular body 2.15 may be
constructed in various manners and out of various materials as will
now be apparent to those skilled in the art to substantially
reproduce anatomical articular geometry. Thus, for example, the
modular head 2.13 and modular body 2.15, except for the
ball-and-spring means 2.51, can each be machined or otherwise
constructed as a one-piece, integral unit out of a medical grade,
physiologically acceptable material, in various sizes to fit a
range of typical patients, etc. Preferably, the modular radial head
sizer 2.11 includes a plurality of different size modular heads
2.13 and bodies 2.15 for allowing different size modular radial
head sizers 2.11 to be assembled from individual heads 2.13 and
bodies 2.15. Thus, for example, modular heads 2.13 may be provided
to conform to the modular heads 13 of the modular radial head
implants 11 with 5 different head diameters ranging between 20 and
28 millimeters in 2 millimeter increments, and with 3 different
head heights ranging between 9 and 13 millimeters in 2 millimeter
increments. Likewise, modular bodies 2.15 may be provided to
conform to the modular bodies 15 of the modular radial head
implants 11 with 5 different stem diameters ranging between 5.5 and
9.5 millimeters in 1 millimeter increments, and with 3 different
stem lengths ranging between 20 and 24 millimeters in 2 millimeter
increments. The various heads 2.13 and bodies 2.15 are preferably
universally modular, so that all of the bodies 2.15 will work with
all of the heads 2.13, and vice versa.
[0058] The system of the present invention includes modular radial
head sizer insertion instrumentation for use in inserting the
modular radial head sizer 2.11 into the elbow joint. The
instrumentation including a modular sizer head insertion tool 3.13
and a modular sizer body holding tool 3.15 (see, in general, FIGS.
16-18).
[0059] The modular sizer head insertion tool 3.13 includes an
elongated body 3.17 having a first end 3.19 and a second end 3.21.
The first end 3.19 of the elongated body 3.17 of the modular sizer
head insertion tool 3.13 includes a grip portion 3.23. The second
end 3.21 of the elongated body 3.17 of the modular sizer head
insertion tool 3.13 includes a threaded stud 3.25 for screwing into
the threaded cavity 2.29 in the outer wall 2.23 of the modular head
2.13 of the modular radial head sizer 2.11.
[0060] The modular sizer body holding tool 3.15 includes an
elongated body 3.27 having a first end 3.29 and a second end 3.31.
The first end 3.29 of the elongated body 3.27 of the modular sizer
body holding tool 3.15 includes a grip portion 3.33. The second end
3.31 of the elongated body 3.27 of the modular sizer body holding
tool 3.15 has a mouth 3.35 with two opposite and parallel jaws 3.37
for engaging the flats 2.57 of the neck portion 2.55 of the stem
2.37 of the modular body 2.15 of the modular radial head sizer 2.11
to allow the modular sizer body holding tool 3.15 to hold the
modular body 2.15 of the modular radial head sizer 2.11 against
rotation. The elongated body 3.27 preferably has a double bend 3.39
between the first and second ends 3.29, 3.31 as clearly shown in
FIG. 17 to provide enhanced finger clearance adjacent the grip
portion 3.33 as will hereinafter become apparent.
[0061] The modular sizer head insertion tool 3.13 and modular sizer
body holding tool 3.15 may be constructed in various manners and
out of various materials as will now be apparent to those skilled
in the art. Thus, for example, the modular sizer head insertion
tool 3.13 and modular sizer body holding tool 3.15 can each be
machined or otherwise constructed as a one-piece, integral unit out
of a medical grade or the like in various sizes to fit the
respective modular head 2.13 and modular body 2.15 of the modular
radial head sizer 2.11.
[0062] The system of the present invention includes a modular
radial head broach 4.11 (see, in general, FIGS. 19-21) for use in
preparing the medullary canal MC of the proximal end P of the
radius R to receive the proper size modular radial head implant 11.
The modular radial head broach 4.11 includes an elongated body 4.13
having a first end 4.15 and a second end 4.17. The first end 4.15
of the elongated body 4.13 includes a grip portion 4.19, either
formed as a part thereof or attached thereto, and especially formed
to be hand-gripped. The second end 4.17 of the elongated body 4.13
includes a cutting head 4.21 for shaping and enlarging the proximal
end of the medullary canal MC. The elongated body 4.13 is
preferably bent adjacent the cutting head 4.21 as indicated by the
arrow 4.23 in FIG. 20, and the cutting head 4.21 is relatively
short (shorter than the corresponding implant stem) to allow easy
joint access and facilitate introduction into the medullary canal
MC. The cutting head 4.21 preferably has a blunt, rounded tip 4.25
to protect the capitellum cartilage and prevent soft tissue
disruption upon introduction to the joint space. Gentle cutting
teeth 4.27 are formed on the sides of the cutting head 4.21 from
longitudinal flats cut on the circumference of the cutting head
4.21, spaced every 30.degree..
[0063] The modular radial head broach 4.11 may be constructed in
various manners and out of various materials as will now be
apparent to those skilled in the art. Thus, for example, the
elongated body 4.13 and cutting head 4.21 can be machined or
otherwise constructed as a one-piece, integral unit out of a
stainless steel or the like, in various sizes to fit a range of
typical patients, etc. The grip portion 4.19 may be machined or
otherwise constructed as a separate unit out of Radel polymer or
the like and press fitted or otherwise joined to the first end 4.15
of the elongated body 4.13. Preferably, the system of the present
invention includes a series of modular radial head broaches 4.11
having different size cutting heads 4.21 for allowing the medullary
canal MC to be prepared with different internal diameters to
receive different size stems 37 of different size modular bodies
15, etc. Thus, for example, modular radial head broaches 4.11 may
be provided to conform to the modular bodies 15 of the modular
radial head implants 11 with 5 different stem diameters ranging
between 5.5 and 9.5 millimeters in 1 millimeter increments.
[0064] The system of the present invention includes modular radial
head radius crank planer 5.11 for use in preparing the proximal end
P of the radius R to receive the modular radial head implant 11.
The modular radial head radius crank planer 5.11 provides a "bit
and brace" style hand-powered instrument to provide central axis
loading with off-axis, bi-directional rotation to provide planing
action for the resected end of the radius R. The modular radial
head radius crank planer 5.11 includes an elongated shaft 5.13
having a first end 5.15 and a second end 5.17, a handle or knob
5.19 for mounting to the first end 5.15 of the shaft 5.13, a
cutting head 5.21 for mounting to the second end 5.17 of the shaft
5.13, and a grip member 5.23 for mounting to the shaft 5.13 between
the first and second ends 5.15, 5.17 thereof (see, in general, FIG.
22). The cutting head 5.21 has an elongated arm 5.25 terminating in
a cutting or planer portion 5.27. The cutting or planer portion
5.27 is in the form of a flat disk with a plurality of cutting
teeth 5.29 on one side and a center slot 5.31 for mating with the
neck portion 2.55 of the stem 2.37 of the modular body 2.15 of a
modular radial head sizer 2.11. As shown in FIG. 23, the direction
of the cutting teeth 5.29 preferably changes 30.degree. every
60.degree.. The profile of the cutting teeth 5.29 is preferably
created from {fraction (1/16)} inch (0.15875 centimeter) diameter
ball ended slots spaced 0.070 inch (0.1778 centimeter) along the
face of the cutting or planer portion 5.27. The shaft 5.13 is
off-set as indicated by the arrow 5.33 in FIG. 22 so that a
longitudinal axis 5.35 passing through the handle or knob 5.19 will
pass through the center of the cutting or planer portion 5.27 as
clearly indicated in FIG. 22.
[0065] The modular radial head crank planer 5.11 may be constructed
in various manners and out of various materials as will now be
apparent to those skilled in the art. Thus, for example, the
elongated shaft 5.13, handle 5.19 and cutting head 5.21 can be
machined or otherwise constructed out of a stainless steel or the
like, in various sizes to fit a range of typical patients, etc. The
grip member 5.23 may be machined or otherwise constructed as a
separate unit out of Radel polymer or the like and rotatably
positioned on the shaft 5.13. The cutting head 5.21 is preferably
modular for replacement due to wear, etc.
[0066] The system of the present invention includes a modular
radial head locking instrument 6.11 for use in locking a selected
modular head 2.13 and a selected modular body 2.15 of the modular
radial head implant 11. The modular radial head locking instrument
6.11 preferably includes an adapted femoral head extractor
instrument 6.13 or the like such as the femoral head extractor
instrument (No. 5014) manufactured and/or sold by Immedica, Inc. of
871 Mountain Avenue, Springfield, N.J. 07081. The locking
instrument includes a first jaw 6.15, a second jaw 6.17, an
elongated body 6.19, and a lever arm 6.21 or the like adapted to
cause the first and second jaws 6.15, 6.17 to move toward one
another (see, in general, FIG. 25). The first jaw 6.15 is adapted
to engage the underside of the platform 39 of a modular body 15 of
the modular radial head implant 11, and the second jaw 6.17 is
adapted to engage the proximal end 17 of a modular head 13 of the
modular radial head implant 11 as clearly shown in FIG. 40. A soft
pad 6.23 manufactured out of plastic or the like is preferably
provided on the jaw 6.17 to provide a soft interface with the
proximal end 17 of the modular head 13 of the implant 11 to prevent
implant damage. The first jaw 6.15 preferably has a distal end with
a slot 6.25 therein for receiving a portion of the proximal end P
of the radius R and/or the stem 37 of the modular body 15 of the
modular implant 11. A portion of the first jaw 6.15 adjacent the
slot 6.25 preferably forms a raised lip 6.26 for engaging the
underside of the platform 39 of a modular body 15 of the modular
radial head implant 11. The second jaw 6.17 preferably has a distal
end with a modular centering means for receiving and positioning
the modular head 15 of the modular implant 11. The modular
centering means preferably consist of a curved wall 6.27 on the pad
6.23 to engage and position the proximal end 17 of the modular head
15 of the modular implant 11. The locking instrument 6.11 thus
allows offset axial compression of the modular head 13 and modular
body 15 of the implant 11. The instrument 6.13 may include the
typical screw adjustment and force gauge mechanism 6.29, allowing
the offset axial compression to be load controlled so that the
required load is delivered to assemble the implant 11, but
additional load is contraindicated or not allowed to avoid
instrument damage.
[0067] The modular radial head locking instrument 6.11 may be
constructed in various manners and out of various materials as will
now be apparent to those skilled in the art. As hereinabove stated,
the working mechanism of the locking instrument 6.11 preferably
consist of an adapted Immedica femoral head extractor. The first
and second jaws 6.15, 6.17 can be machined or otherwise constructed
out of a stainless steel or the like. Several different size pads
6.23 (i.e., pads 6.23 with different size curved walls 6.27 to
correspond to modular heads 15 having different diameters) may be
machined or otherwise constructed as separate units out of Ultem
polymer or the like corresponding to the different implant sizes,
etc.
[0068] The surgical procedure or technique for using the modular
radial head system of the present invention can vary as will now be
apparent to those skilled in the art. The preferred surgical
technique preferably includes the following steps:
[0069] 1. Expose the radio-capitellar joint through a Kocher
incision between the anconeus and extensor carpi ulnaris muscles.
Carefully preserve the motor branch of the radial nerve at the
radial neck N.
[0070] 2. Using a surgical saw, the radial neck N is resected to
the level of the fracture F or to the desired level of radial head
resection. The annular and collateral ligaments are preserved where
possible.
[0071] 3. Using a starter broach or awl, an opening is created in
the medullary canal MC. The appropriate modular radial head broach
4.11, based on pre-operative templating, is used to further shape
the canal MC to receive the stem 2.37 of the modular body 2.13 of
the modular radial head sizer 2.11 and the stem 37 of the modular
body 15 of the modular radial head implant 11.
[0072] 4. The stem 2.37 of the modular body 2.13 of the modular
radial head sizer 2.11 is the inserted into the prepared medullary
canal MC, and the cutting head 5.21 of the modular radial head
crank planer 5.11 is slipped over the neck portion 2.55 of the stem
2.37, and rotated back and forth around the longitudinal axis 5.35
to create a plane surface on the resected end of the proximal end P
of the radius R. The modular body 2.15 of the modular radial head
sizer 2.11 will rotate with the cutting head 5.21 of the modular
radial head crank planer 5.11. Axial force is applied to the handle
5.19 at the top of the crank planer 5.11 when the grip member 5.23
is moved in an arc about the longitudinal axis 5.35.
[0073] 5. The appropriate modular head 2.13 of the modular radial
head sizer 2.11, based on pre-operative templating, is screwed onto
the threaded stud 3.25 of the modular sizer head insertion tool
3.13. The mouth 3.35 of the grip portion 3.33 of the modular sizer
body holding tool 3.15 is placed onto the neck portion 2.55, or
keyway, of the stem 2.37 of the modular body 2.15 of the modular
radial head sizer 2.11 to hold the modular body 2.15 in place as
the modular head 2.13 of the modular radial head sizer 2.11 is
slipped onto the platform 2.39 of the modular body 2.15. The
modular sizer body holding tool 3.15 keeps the modular body 2.15
from rotating with respect to the modular head 2.13. Once the
modular head 2.13 has slipped over the platform 2.39 of the modular
body 2.15, moving the modular sizer head insertion tool 3.13 with
respect to the modular sizer body holding tool 3.15 causes the
modular head 2.13 to rotate relative to the modular body 2.15. Once
the modular head 2.13 has been rotated 90.degree. (or a
quarter-turn) relative to the modular body 2.15, the modular head
2.13 and modular body 2.15 will be locked together via the
ball-and-detent means. Unscrew the modular sizer head insertion
tool 3.13 and remove the modular sizer body holding tool 3.15, and
perform trial reduction with the modular radial head sizer 2.11 in
place. Good contact between the concavity 2.19 of the proximal end
2.17 of the modular head 2.13 and the capitellum C, and smooth
rotation should be noted on passive flexion and rotation of the
forearm.
[0074] 6. If the trial reduction is not acceptable, applicable
procedural stems 2-5, above, are repeated and trials chosen as
appropriate.
[0075] 7. Once sizing has been determined to be acceptable, the
modular sizer head insertion tool 3.13 is reattached to the modular
head 2.13, and the modular sizer body holding tool 3.15 is placed
back into the neck portion 2.55, or keyway, of the stem sizer. The
modular head 2.13 is unlocked from the modular body 2.14 by
rotating the modular head 2.13 a quarter turn, or 90.degree.,
relative to the modular body 2.15 again, and the modular head 2.13
is removed from the joint space. The modular body 2.15 is then
removed from the joint space and the joint thoroughly
irrigated.
[0076] 8. The appropriate size of modular body 15 is selected and
placed into the radial canal MC. The appropriate size of modular
head 13 is selected and prepared for implantation. Using finger
control, the modular head 13 is placed into the joint space with
the female taper of the cavity 27 of the modular head 13 over the
male taper of the platform 39 of the modular body 15. At this
point, the modular head 13 and modular body 15 are not locked
together, but are in position to be locked together.
[0077] 9. Based on head implant size, the appropriate assembly tool
head insert 6.23 is placed onto the second jaw 6.17 of the modular
radial head locking instrument 6.11. The lever arm 6.21 of the
modular radial head locking instrument 6.11 is opened out away from
the instrument body 6.19. Using the screw mechanism 6.29 on the
instrument body 6.19, the jaws 6.15, 6.17 of the locking instrument
6.11 are adjusted to the approximate head height as denoted by
graduations on the shaft, etc. The distal ends of the jaws 6.15,
6.17 are placed into the joint space so that the proximal end 17 of
the modular head 13 of the implant 11 is resting on the plastic pad
6.23 of the jaw 6.17, and the platform 39 of the modular body 15 of
the implant 11 is resting on the jaw 6.15 as clearly shown in FIG.
40. Final hand tightening of the assembly tool jaws 6.15, 6.17 is
performed to eliminate any space between the jaws 6.15, 6.17 and
the implant components. The lever arm 6.21 of the locking
instrument 6.11 is brought toward the instrument body 6.19 until an
audible click is heard, or other equivalent load controlled
feedback is experienced. This feedback (click or equivalent)
denotes that the 2000N-assembly force has been reached.
Additionally, the load can be visually verified on the force gauge
6.29 located on the instrument body 6.19. Continuing to apply load
to the instrument 6.11 and implant 11 beyond the 2000N force may
result in breakage of the instrument 6.11 or damage to the implant
11. If adequate joint space is available due to extensive fracture,
etc., the implant 11 may alternatively be assembled in the same
manner outside the body. The two implant components 13, 15 are
placed into the jaws 6.15, 6.17 of the locking instrument 6.11, the
jaws 6.15, 6.17 are tightened onto the implant components 13, 15,
then the 2000N-assembly load is applied to the two components 13,
15 by forcing the lever arm 6.21 toward the assembly tool body
6.19.
[0078] 10. The locking instrument 6.11 is removed from the joint
space. The capsule, ligaments, and the anconeus and extensor carpi
ulnaris muscles are sutured in layers with non-absorbable sutures,
burying the knots.
[0079] As thus constructed and used, the preferred embodiment of
the present invention provides:
[0080] (A) a modular radial head implant in which (1) the stem
(body) and head components are modular; (2) the stem (body) and
head components are assembled by a short 3.degree. taper; (3) the
components are highly polished and not fixed in bone (i.e., the
implant is allowed to rotate, pivot and piston slightly); (4) the
modular head reproduces the anatomical articular geometry; (5) the
stem (body) components have drainage holes to allow for fluids
trapped between the male and female tapers to drain out, thus
improving the assembly; (6) the stem (body) and head components can
be assembled intraoperatively (in vivo) or on back table; and (7)
stem (body) and head components are universally modular--all stem
(body) components work with all head components;
[0081] (B) a modular radial head sizer in which (1) the stem (body)
and head components are modular; (2) the stem (body) and head
components are assembled in a side loading manner via a slot and a
groove, and rotated slightly to lock together; (3) the stem (body)
components have two opposite flats under the platform or boss for
coacting with a tool to keep the stem (body) from rotating as the
head is rotated for locking; (4) the head component has a screw
hole for receiving an insertion instrument to rotate the head
component with respect to the stem (body) component to achieve
locking; and (5) the head component has a slot that mates with the
platform or boss of the stem (body) component, and a retaining
groove that the platform (boss) spins in to capture the stem (body)
component;
[0082] (C) modular radial head sizer insertion instrumentation
consisting of a head sizer insertion tool and a stem sizer tool,
and in which (1) the head tool has a threaded tip to rotate the
head once it has been slipped onto the stem sizer; (2) the stem
tool has a mouth with parallel flats which engage the parallel
flats on the stem sizer to hold the stem sizer while the head sizer
is rotated and locked onto the stem sizer; and (3) the stem sizer
tool has a double bend to allow for finger space between the stem
and head sizer handles to achieve the desired motion;
[0083] (D) a modular radial head broach, or series of broaches, in
which (1) the broaches are left-hand cutting instruments used to
shape the intermedullary canal of the proximal radius for the
different size stem diameters of the modular radial head implants;
(2) the broaches are much shorter than the implant stems and have
bent shafts to allow easier joint access; (3) the ends of the
broaches are blunt in order to prevent soft tissue disruption upon
introduction to the joint space; (4) the cutting teeth are created
from longitudinal flats cut on the circumference of the tool spaced
every 30.degree.; and (5) the cutting teeth cut when rotated
counterclockwise and impact bone chips when rotated clockwise;
[0084] (E) a modular radial head radius crank planer consisting of
a "Bit and brace" style hand-powered instrument to provide central
axis loading with off-axis bidirectional rotation to provide
planing action, in which (1) a portion of the crank planer is
modular for replacement due to wear; (2) planer teeth are placed on
one side of a flat disk, tooth direction changes 30.degree. every
60.degree. around the disk, and tooth profile is created from
{fraction (1/16)} inch (0.15875 centimeter) diameter ball ended
slots spaced 0.070 inch (0.1778 centimeter ) along disk; and (3)
the disk portion of the planer has a center slot for mating with
the stem sizing instruments to facilitate centralization and
perpendicularity of the planer on the radius; and
[0085] (F) modular radial head locking components (head locker and
stem locker) for fitting an adapted femoral head extractor in
which: (1) the components allow offset axial compression of the
modular radial head components; (2) modular Ultem pieces
corresponding to the different stem sizes are interchangeable with
the stem locking component; (3) the Ultem pieces provide a soft,
elevated pad to compress the stem (body) components into the head
components; (4) the head locking components incorporate a thin
plastic pad as the implant/instrument interface to prevent implant
damage; and (5) both components incorporate an I-beam shape to
provide increased resistance to deflection under load.
[0086] Although the present invention has been described and
illustrated with respect to preferred embodiments and preferred
uses therefor, it is not to be so limited since modifications and
changes can be made therein which are within the full intended
scope of the invention.
* * * * *