U.S. patent application number 12/689862 was filed with the patent office on 2011-04-07 for integral, one-piece humeral head device.
This patent application is currently assigned to TORNIER, INC.. Invention is credited to R. Sean Churchill, Austin W. Mutchler.
Application Number | 20110082557 12/689862 |
Document ID | / |
Family ID | 39775558 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110082557 |
Kind Code |
A1 |
Mutchler; Austin W. ; et
al. |
April 7, 2011 |
Integral, One-Piece Humeral Head Device
Abstract
A humeral head augment device for use in a modular shoulder
prosthesis. The humeral head augment device has an external bearing
surface with at least one surface portion that includes a radius of
curvature. The radius of curvature is configured to constrain
translational movement of the implanted shoulder prosthesis when
the humeral head augment device is positioned within the shoulder
prosthesis. The humeral head augment device also includes a
coupling mechanism designed to lock the humeral head augment device
to either the stem or the humeral head, thereby ensuring proper
operational positioning of the device within the shoulder
prosthesis and allowing the implanted shoulder prosthesis to
function in a patient suffering from rotator cuff arthropathy. A
shoulder prosthesis using a humeral head augment device, a method
for assembling a shoulder prosthesis and method for using a humeral
head augment device in a shoulder prosthesis are also
disclosed.
Inventors: |
Mutchler; Austin W.;
(Warsaw, IN) ; Churchill; R. Sean; (Mequon,
WI) |
Assignee: |
TORNIER, INC.
Edina
MN
|
Family ID: |
39775558 |
Appl. No.: |
12/689862 |
Filed: |
January 19, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11688309 |
Mar 20, 2007 |
|
|
|
12689862 |
|
|
|
|
Current U.S.
Class: |
623/19.14 |
Current CPC
Class: |
A61F 2002/4018 20130101;
Y10T 29/49947 20150115; A61F 2/4014 20130101; A61F 2002/4062
20130101; A61F 2002/4037 20130101; A61F 2002/4033 20130101 |
Class at
Publication: |
623/19.14 |
International
Class: |
A61F 2/40 20060101
A61F002/40 |
Claims
1-53. (canceled)
54. An integral, one-piece humeral head device comprising: a
humeral head having an articulation surface comprising a first
portion and a second augmented portion, the first portion
comprising a first radius of curvature and the second portion
comprising multiple radii of curvature; and a tapered post
extending from the humeral head and configured to engage a
bone.
55. The device as recited in claim 54, wherein the first radius of
curvature and the multiple radii of curvature lie in a plane.
56. The device as recited in claim 55, wherein the plane comprises
a medial plane.
57. The device as recited in claim 54, wherein the first radius
comprises a single radius.
58. The device as recited in claim 54, wherein the first portion
comprises a glenoid-bearing portion, and the second portion
comprises a acromion-bearing portion.
59. The device as recited in claim 54, wherein the first portion
and the second portion comprise articulating surfaces.
60. The device as recited in claim 54, wherein the second portion
comprises multiple portions, each of the multiple portions
comprising one of the multiple radii.
61. The device as recited in claim 60, wherein at least one of the
multiple portions constrains translation of an implanted
device.
62. The device as recited in claim 61, wherein at least one of the
multiple portions constrains superior translation of the implanted
device.
63. The device as recited in claim 62, wherein at least one of the
multiple portions constrains superior translation of the implanted
device during abduction of a device recipient's arm.
64. The device as recited in claim 60, wherein the second portion
comprises two portions, each of the two portions comprising one of
the multiple radii.
65. The device as recited in claim 60, wherein the second portion
comprises greater than two portions, each of the greater than two
portions comprising one of the multiple radii.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of pending U.S.
application Ser. No. 11/688,309 filed on Mar. 20, 2007, now U.S.
Pat. No. ______, the disclosure of which is included by reference
herein in its entirety.
TECHNICAL FIELD
[0002] The present invention relates generally to orthopaedic
implants. More particularly, the present invention relates to a
shoulder replacement prosthesis and the method of use for treating
rotator cuff arthropathy.
BACKGROUND OF THE INVENTION
[0003] Deterioration of an individual's rotator cuff may lead to
the need to undergo a shoulder arthroplasty procedure. In severe
cases, a person's humeral head may translate in a more superior
direction during abduction of their effected arm resulting in the
superior surface of the humeral head articulating with both the
inferior surface of the acromion and the acromioclavicular joint.
Articulation between these two bones could lead to accelerated
destruction of the humeral head and erosion of the acromion and the
acromioclavicular joint.
[0004] It was generally accepted practice for orthopedic surgeons
to treat individuals with compromised rotator cuffs using standard
sized shoulder stem prosthesis with oversized humeral heads to
reestablish the joint space created by the bone loss. Humeral head
bipolar prostheses have also been utilized by surgeons to address
the stability problems associated with rotator cuff tear
arthropathy. Both of these treatment modalities led to the
overstuffing of the joint space and a resultant reduced range of
motion for the effected arm of the individual. Several non-implant
surgical techniques have been used with limited success in an
attempt to address the rotator cuff tear arthropathy, including
surgically smoothing the greater tubercle. Unfortunately, the
individual still experienced reduced range of motion and joint pain
because of the bone on bone contact.
[0005] Recent developments in the shoulder arthroplasty field
involve the design of modular humeral heads that are configured to
include a glenoid bearing portion and an extended acromion bearing
portion. Problems that have been seen with these types of designs
is excessive post-operative translation in the superior direction
because of the previous bone loss and the use of a single radius of
curvature for the two bearing portions. Another problem encountered
with the extended bearing modular humeral heads is the head being
incorrectly rotated when the prosthesis is assembled in the
operating room. The malrotation may cause the humeral head to be
positioned in a less then optimal location relative to the acromion
during arm abduction.
SUMMARY OF THE INVENTION
[0006] Advancement of the state of orthopaedic implants and the
treatment of rotator cuff tear arthropathy is believed desirable.
The present invention satisfies the need for improvements to the
shoulder replacement implant used to treat patients suffering from
a torn rotator cuff or other soft tissue injuries by providing a
modular humeral head augment device for coupling to a shoulder
prosthesis.
[0007] The present invention provides in one aspect, a humeral head
augment device. The humeral head augment device includes an
external bearing surface that is configured with at least one
surface portion having a radius of curvature that is designed to
constrain translational movement of the implanted shoulder
prosthesis to which the humeral head augment device is connected.
The humeral head augment device has a coupling mechanism that
connects the humeral head augment device to either the stem or the
humeral head components of the shoulder prosthesis.
[0008] The present invention provides in another aspect, a modular
shoulder prosthesis that includes a humeral head that has an
articulation surface and an interior surface from which a connector
extends and a stem component that includes a second connector that
engages the humeral head and secures the two components together.
The shoulder prosthesis further includes a humeral head augment
device that has an external bearing surface with at least one
surface portion having a radius of curvature and a coupling
mechanism that is configured to connect the humeral head augment
device to either the stem or humeral head. When the humeral head
augment device is attached to the implanted shoulder prosthesis,
the at least one radius of curvature of the external bearing
surface functions to constrain translation of the shoulder
prosthesis post-operatively.
[0009] The present invention provides in yet another aspect, a
shoulder prosthesis system. The shoulder prosthesis system includes
a plurality of humeral heads, each having an articulation surface
and an interior surface that has a connector extending from it. In
addition, the system includes a plurality of stems, the stems each
having a proximal end that includes a connector for engaging the
connector disposed on the interior surface of the humeral head. The
shoulder prosthesis system further includes a plurality of humeral
head augment devices, each humeral head augment device having an
external bearing surface that is configured with at least one
surface portion that has a radius of curvature. Each of the humeral
head augment devices also include a coupling mechanism that
operates to connect the humeral head augment device to either one
of the plurality of stems or one of the plurality of humeral heads.
When assembled within the shoulder prosthesis, the humeral head
augment device functions to constrain translational movement of the
shoulder prosthesis following implantation.
[0010] The present invention provides in another aspect, a method
for using a humeral head augment device in a shoulder prosthesis.
The method includes the step of providing a shoulder prosthesis,
the shoulder prosthesis includes a humeral head and a stem which
are configured to be coupled together. The method further includes
providing a humeral head augment device, the humeral head augment
device has at least one surface portion which is configured to have
a radius of curvature. The radius of curvature being selected to
constrain translation of the implanted shoulder prosthesis
following positioning of the humeral head augment device within the
shoulder prosthesis. The method also includes the step of coupling
the humeral head augment device within the shoulder prosthesis
utilizing a coupling mechanism. The coupling mechanism connects the
humeral head augment device to either the stem component or the
humeral head component.
[0011] Further, additional features and advantages are realized
through the techniques of the present invention. Other embodiments
and aspects of the invention are described in detail herein and are
considered a part of the claimed invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
objects, features and advantages of the invention are apparent from
the following detailed description taken in conjunction with the
accompanying drawings in which:
[0013] FIG. 1 is a side elevational view of one embodiment of a
shoulder prosthesis with a humeral head augment device in operable
position, in accordance with an aspect of the present
invention;
[0014] FIG. 2 is a side elevational, exploded view of the shoulder
prosthesis with humeral head augment device of FIG. 1, in
accordance with an aspect of the present invention;
[0015] FIG. 3 is distal perspective view of the shoulder prosthesis
with humeral head augment device of FIG. 1, in accordance with an
aspect of the present invention;
[0016] FIG. 4 is a perspective view of one embodiment of a humeral
head augment device, in accordance with an aspect of the present
invention;
[0017] FIG. 5A is a perspective view of the humeral head augment
device of FIG. 4, showing a motion control member configured as a
rail, prior to being coupled to a proximal end of a stem, in
accordance with an aspect of the present invention;
[0018] FIG. 5B is a perspective view of the humeral head augment
device of FIG. 4, showing an alternative motion control member
configured as a pin, prior to being coupled to the proximal end of
the stem, in accordance with an aspect of the present
invention;
[0019] FIG. 5C is a perspective view of the humeral head augment
device of FIG. 4, showing an alternative motion control member
configured as a tab, prior to being coupled to the proximal end of
the stem, in accordance with an aspect of the present
invention;
[0020] FIG. 6 is a lateral elevational view of the proximal end of
the stem coupled to a humeral head augment device, in accordance
with an aspect of the present invention;
[0021] FIG. 7A is a cross-section, side elevational view of the
proximal end of the shoulder prosthesis of FIG. 6 taken along line
7-7, showing a locking mechanism of a coupling mechanism configured
as an expanding pin, in accordance with an aspect of the present
invention;
[0022] FIG. 7B is a cross-section, side elevational view of the
proximal end of the shoulder prosthesis of FIG. 6 taken along line
7-7, showing an alternative locking mechanism of a coupling
mechanism configured as a threaded screw, in accordance with an
aspect of the present invention;
[0023] FIG. 7C is a cross-section, side elevational view of the
proximal end of the shoulder prosthesis of FIG. 6 taken along line
7-7, showing another alternative locking mechanism of a coupling
mechanism configured as a threaded screw and cylindrical post, in
accordance with an aspect of the present invention;
[0024] FIG. 7D is a cross-section, side elevational view of the
proximal end of the shoulder prosthesis of FIG. 6 taken along line
7-7, showing yet another alternative locking mechanism of a
coupling mechanism configured as a male-female locking taper, in
accordance with an aspect of the present invention;
[0025] FIG. 7E is a cross-section, side elevational perspective
view of the humeral head augment device of FIG. 6 taken along line
7-7, showing a further alternative locking mechanism of a coupling
mechanism configured as a threaded screw and dual cylindrical
posts, in accordance with an aspect of the present invention;
[0026] FIG. 8 is a perspective view of an alternative humeral head
augment device with a relief disposed on the posterior side
extending from the medial side to the lateral side of the
alternative humeral head augment device, in accordance with an
aspect of the present invention;
[0027] FIG. 9 is a perspective view of a shoulder prosthesis with
the alternative humeral head augment device of FIG. 8, coupled in
operable position to the proximal end of a stem, in accordance with
an aspect of the present invention;
[0028] FIG. 10 is a side elevational view of an alternate
embodiment of a humeral head augment device, wherein the device is
a one-piece humeral-acromion head, in accordance with an aspect of
the present invention; and
[0029] FIG. 11 is a side elevational view of an alternative
embodiment of a humeral head augment device, wherein the device is
a one-piece humeral-acromion head resurfacing implant, in
accordance with an aspect of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0030] Generally stated, disclosed herein is a humeral head augment
device and a shoulder prosthesis that includes as a component, a
humeral head augment device. Further, described herein is a method
for using a humeral head augment device with a shoulder prosthesis
that may limit post-operative translateral movement for patients
suffering from rotator cuff arthropathy.
[0031] As depicted in FIGS. 1 and 2, the general arrangement of a
shoulder prosthesis 10 for use with a humeral head augment device
40, in accordance with an aspect of the present invention, includes
a humeral head 30, a stem 20 and a humeral head augment device 40.
In this detailed description and the following claims, the words
proximal, distal, anterior, posterior, medial and lateral are
defined by their standard usage for indicating a particular part of
a bone or prosthesis according to the relative disposition of the
natural bone or directional terms of reference. For example,
"proximal" means the portion of a prosthesis nearest the torso,
while "distal" indicates the portion of the prosthesis farthest
from the torso. As for directional terms, "anterior" is a direction
towards the front side of the body, "posterior" means a direction
towards the back side of the body, "medial" means towards the
midline of the body and "lateral" is a direction towards the sides
or away from the midline of the body.
[0032] With reference to FIGS. 1 and 2, stem 20 includes a proximal
end 14, a distal end 15 and a longitudinal axis 16. A taper cavity
17 (see FIGS. 7A-E) is located on the medial side of proximal end
14 of stem 20. As shown in FIGS. 7A-E, taper cavity 17 is defined
by a female taper 18 with a center axis 27 which is angled relative
to longitudinal axis 16. Female taper 18 is configured to decrease
radially when moving from the medial opening 19 of taper cavity 17
to the taper cavity bottom 28. Although not shown, it is
contemplated that proximal end 14 may include a tapered post as an
alternative to taper cavity 17, with both taper embodiments
functioning to connect stem 20 to humeral head 30. As shown in
FIGS. 3, 5A, 5B, 5C, and 6, proximal end 14 of stem 20 typically
includes stability fins 23 located generally along the medial,
anterior and posterior sides. Fins 23 may be straight or tapered
and include numerous through holes 24 for fixation purposes.
Positioned adjacent to medial opening 19 of taper cavity 17 is a
support collar 25. The plane in which the proximal surface 26 of
collar 25 lies is substantially normal to taper center axis 27.
Collar 25 typically functions to provide support for stem 20
against the resected proximal surface of a patient's humerus.
Additional functionality of collar 25 may include supporting
humeral head 30 and provide motion control of humeral head augment
device 40. As seen in FIG. 3, the shape of collar 25 may be
designed to match the dimensions of the resected proximal humerus.
It is contemplated that collar 25 may also have a circular, oval or
oblong shape. It is not shown, but should be understood that
proximal end 14 of stem 20 may not include collar 25 or
alternatively, collar 25 may be modular, thereby allowing the
operating surgeon at the time of implantation of shoulder
prosthesis 10 to either attach or remove collar 25.
[0033] The distal shaft 21 of stem 20 may be integral to proximal
end 14 or modular in design, allowing for a plurality of distal
shafts 21 that are configured with varying lengths and diameters to
be attached. Distal shaft 21 may include an assortment of bone or
cement fixation mechanisms 22 along the outer surface of distal
shaft 21. These may include, but are not limited to fins, flat
surfaces, channels and cavities. Although not shown, distal shaft
21 may be coated with promoters of bone in-growth, including but
not limited to porous coating, TCP, HA, metal mesh or other surface
treatment sprays. The cross-section of distal shaft 21 is generally
circular, although other shaped cross-sections are contemplated
including, but not limited to hexagonal, trapezoidal, oval or
polygonal.
[0034] As seen in FIGS. 1 and 2, humeral head 30 of shoulder
prosthesis 10 includes an outer articulation surface 31.
Articulation surface 31 has a substantially spherical contour that
is typically comprised of one radius of curvature 33R, though
multiple radius of curvatures may be incorporated into articulation
surface 31 and are contemplated for treatment of unique clinical
situations. As shown in FIGS. 1 and 2, preferably, articulation
surface 31 extends to an angle .alpha. that is about 180 degrees.
It is contemplated that angle .alpha. may be less than 180 degrees
or greater than 180 degrees depending upon a patient's anatomical
features and clinical application. Articulation surface 31
terminates at the intersection with an underside skirt 32 that is
positioned around the full circumference of humeral head 30.
Although not shown, at least one hole may be positioned proximate
to skirt 32, allowing for securement of soft tissue for joint
stabilization purposes. Intersecting skirt 32 is a substantially
planar interior surface 34 that is positioned essentially opposite
articulation surface 31 (see FIGS. 7A-7E). Extending from interior
surface 34 in substantially perpendicular direction is a second
connector shaped as a tapered post 35. As illustrated in FIGS.
7A-7E, tapered post 35 is sized and dimensioned to decrease
radially from the post base 36 to the post end 37. Tapered post 35
is located generally in the center of interior surface 34 and is
positioned and designed to mate with taper cavity 17 of proximal
end 14. Although not shown, is should be understood to those
skilled in the art that tapered post 35 may be eccentrically
located on interior surface 34 allowing the operating surgeon to
rotate and orient humeral head 30 to provide for optimal
post-operative joint stabilization. Further, it is also
contemplated that interior surface 34 may include a tapered cavity
as an alternative to taper post 35, with both taper embodiments
functioning to connect humeral head 30 to stem 20. When connected
to stem 20, interior surface 34 of humeral head 30 may abut or
alternatively, be positioned proximate to collar 25 and augment
device 40.
[0035] When properly coupled to stem 20 of an implanted shoulder
prosthesis 10, the convex, generally spherical shape of
articulation surface 31 is configured to articulate either with a
glenoid implant or the patient's natural glenoid. Radius of
curvature 33R of humeral head 30 may range in size from 15 mm to 45
mm, with a more detailed range being between 19 mm to 30 mm. Radius
of curvature 33R is configured and dimensioned to and allow for
three degrees of motion for an implanted shoulder prosthesis 10,
including rotational movement and translational or sliding movement
in the superior-inferior direction and anterior-posterior
direction.
[0036] As depicted in FIG. 4, humeral head augment device 40
includes a generally convex external bearing surface 41 that
includes at least one radius of curvature that may be different
than radius of curvature 33R of humeral head 30. External bearing
surface 41 may be divided into two portions, the first portion 42
being located in the medial aspect of external bearing surface 41
and a second portion 43 being positioned in the lateral aspect of
the external bearing surface 41. It should be understood to those
skilled in the art that external bearing surface 41 may also be
constructed of a single portion with a corresponding single radius
of curvature for the entire external bearing surface 41. It should
also be understood that external bearing surface 41 may further
include greater than two portions with corresponding multiple
radius of curvatures.
[0037] For example purposes, FIGS. 1 and 2 show that first portion
42 and second portion 43 have different radius of curvatures. The
radius of curvature 44R of first portion 42 is usually greater than
the radius of curvature 45R of second portion 43. The basis for the
multiple radius of curvatures for external bearing surface 41 of
humeral head augment device 40 is to limit or constrain the amount
or degree of superior translation that may occur within implanted
shoulder prosthesis 10 during abduction of a patient's arm. Radius
of curvature 44R of first portion 42 may also be greater than
radius of curvature 33R of articulation surface 31. Again, this
geometric mismatch results in implanted shoulder prosthesis 10
being constrained from excessive superior translation when a
patient's arm is taken through a full range of motion including
abduction. Such constraint on superior movement is critical for
patients suffering from deficient rotator cuffs caused by tears or
soft tissue weakening and eroded bony structures, including the
acromion and acromioclavicular joint. Humeral head augment device
40 may be modular in design, thus radius of curvatures 44R, 45R may
have varying values ranging from 15 mm to infinity or be configured
as a straight line segment. Mixing and matching values for radius
of curvatures 44R, 45R as to each other and in combination with
radius of curvature 33R allows the operating surgeon to optimize
the desired shoulder joint range of motion provided by the
implanted humeral head 30 in conjunction with humeral head augment
device 40 with the presented anatomic structures of a patient. For
example, it is contemplated that in some clinical cases radius of
curvature 44R may be less than radius of curvature 45R and equal to
radius of curvature 33R, thereby allowing more superior translation
of shoulder prosthesis 10 during abduction. A further alternative
may also be for humeral head augment device 40 to include only a
single radius of curvature that is different than radius of
curvature 33R of humeral head 30. For another clinical case it may
be desirable for radius of curvatures 44R, 45R to be equal to each
other, but greater than radius of curvature 33R, thus significantly
restricting shoulder prosthesis 10 from any degree of superior
translational movement. It should be understood to those skilled in
the art that in yet another clinical case, it may be preferred that
radius of curvatures 33R, 44R and 45R be equal to each other,
thereby resulting in little or no geometric restriction of shoulder
prosthesis 10 and a uniform and consistent radius of curvature for
articulation surface 31 and external bearing surface 41.
[0038] FIG. 1 shows first portion 42 and second portion 43 being
tangent to each other. This geometric relationship between first
portion 42 and second portion 43 is essential to enable shoulder
prosthesis 10 to move in a smooth and unrestricted or continuous
manner while the patient's arm moves through a complete range of
motion. Further, as seen in FIG. 1, articulation surface 31 is
usually tangent to first portion 42, again to allow a patient to
experience smooth and unrestricted or continuous movement of their
implanted shoulder prosthesis 10.
[0039] FIG. 6 shows the distal, lateral aspect of humeral head
augment device 40. Positioned along the distal peripheral edge of
humeral head augment device 40 may be at least one hole 55 that the
operating surgeon may use for soft tissue attachment purposes. It
should be understood to those skilled in the art that several holes
may be located along the anterior, posterior and lateral peripheral
edge providing various locations for soft-tissue securement.
[0040] As seen in FIGS. 7A-7D, humeral head augment device 40
includes an internal surface 46 that has a medial aspect 47 and a
lateral aspect 48. When humeral head augment device 40 is operably
positioned within shoulder prosthesis 10, medial aspect 47
typically contacts or is proximate with the superior surface of
proximal end 14. Extending from medial aspect 47 is at least one
locking mechanism 52 that is received by an associated at least one
locking mechanism 53. Locking mechanisms 52, 53 act together as a
coupling mechanism 54 to secure or couple humeral head augment
device 40 to proximal end 14 of stem 20. FIG. 1 depicts the
placement of humeral head augment device 40 as being generally
lateral to longitudinal axis 16. As a result of the modularity of
humeral head augment device 40 relative to stem 20, humeral head
augment device 40 may also be placed in other operable positions
relative to longitudinal axis 16 depending upon the clinical needs
of the patient and resulting intraoperative assessment, including
being positioned neutral, medial anterior or posterior to
longitudinal axis 16.
[0041] As shown in the cross-section view in FIG. 7A, locking
mechanism 52 includes an expanding screw or pin device 60 extending
through a collared cylindrical hole 64 in medial aspect 47. As
expanding screw or pin 60 is threaded into receiving cavity 61 of
associated locking mechanism 53 that is positioned within proximal
end 14, expanding screw or pin device 60 engages receiving cavity
61 resulting in the securement of humeral head augment device 40 to
stem 20.
[0042] FIG. 7B is a cross-section view of humeral head augment
device 40 that shows an alternative coupling mechanism 54,
consisting of a threaded screw 62 and a threaded hole 63. Locking
mechanism 52 includes a threaded screw that extends through a
collared cylindrical hole 65 in medial aspect 47. Associated
locking mechanism 53 consists of threaded hole 63 positioned in
proximal end 14. In operation, threaded screw 62 is inserted into
the hole and engages the corresponding threads of threaded hole 63
causing humeral head augment device 40 being fixed to stem 20.
[0043] A further example of coupling mechanism 54 is shown in a
cross-section view of humeral head augment device 40 at FIG. 7C.
Locking mechanism 52 consists of at least one cylindrical post 66
extending from medial aspect 47 of internal surface 46. The
associated locking mechanism 53 includes a corresponding at least
one cylindrical hole 68 configured and dimensioned to receive at
least one post 66 and a threaded set screw 67 that is inserted into
a threaded hole 69 that projects from cavity bottom 28 of taper
cavity 17 and intersects hole 68 at an angle relative to
longitudinal axis 16. Alternative coupling mechanism 54 functions
by having at least one post 66 fully inserted into at least one
hole 68 with medial aspect 47 contacting or being proximate the
superior surface of proximal end 14 with threaded set screw 67
being inserted into threaded hole 69 that when fully engaged,
threaded set screw 67 pressingly fixates post 66 into hole 68.
[0044] Cross-section view of humeral head augment device 40 at FIG.
7D depicts yet a further alternative coupling mechanism 54. Locking
mechanism 52 typically includes a male conical taper 70 projecting
from medial aspect 47 of internal surface 46. Male conical taper 70
is oriented about normal relative to medial aspect 47. Associated
locking mechanism 53 is a female conical taper 71 that is sized and
dimensioned to receive male conical taper 70. Female conical taper
71 is positioned within proximal end 14 with a centerline that is
almost normal to the superior surface of proximal end 14. In use,
alternative coupling mechanism 54 is a taper lock connection formed
by the engagement of male conical taper 70 and female conical taper
71 that results in humeral head augment device 40 being secured to
stem 20. It should be understood to those skilled in the art that
this alternative coupling mechanism 54 may be reversed in that male
conical taper 70 could extend from proximal end 14 and female
conical taper 71 could be located within medial aspect 47 of
humeral head augment device 40.
[0045] A cross-sectional view of humeral head augment device 40
showing another example of a coupling mechanism 54 is seen at FIG.
7E. Locking mechanism 52 consists of at least two substantially
parallel cylindrical posts 72 extending from medial aspect 47 of
internal surface 46. The associated locking mechanism 53 includes
at least two substantially parallel cylindrical holes 73 that are
generally configured and dimensioned to receive at least two posts
72 and a threaded set screw 74 that is inserted into a threaded
hole 75 that projects from cavity bottom 28 of taper cavity 17 and
intersects both of the at least two substantially parallel
cylindrical holes 73 at an angle relative to longitudinal axis 16.
Alternative coupling mechanism 54 functions by typically having at
least two posts 72 fully inserted into the at least two holes 73
resulting in medial aspect 47 abutting or being proximate to the
superior surface of proximal end 14 with threaded set screw 74
being inserted into threaded hole 75 that when fully engaged,
threaded set screw 74 urges posts 72 outwardly, thereby pressingly
locking posts 72 within holes 73.
[0046] It should be noted that it is further contemplated that each
of the above described coupling mechanisms 54 may be utilized to
secure humeral head augment device 40 to humeral head 30. Although
not shown, it should be understood to those skilled in the art that
humeral head augment device 40 may be secured to humeral head 30
utilizing a locking mechanism disposed on the seating surface 49 of
humeral head augment device 40 and an associated locking mechanism
positioned on interior surface 34 of humeral head 30. Possible
locking mechanism may include, but are not limited to interlocking
tapers, expanding set pins, extending posts and threaded fixation
screws.
[0047] Humeral head augment device 40 may also include seating
surface 49, an antirotation surface 50 and a motion control member
51. As described above, following the securement of humeral head
augment device 40 to stem 20, a properly sized humeral head 30 may
be attached to stem 20 utilizing a taper lock arrangement.
Following attachment of humeral head 30 to stem 20, seating surface
49 will typically abut or be positioned proximate to interior
surface 34. Located between seating surface 49 and medial aspect 47
of internal surface 46 is antirotation surface 50. Antirotation
surface 50 is oriented substantially perpendicular relative to
seating surface 49.
[0048] As shown in FIGS. 5A-5C, when humeral head augment device 40
is coupled to proximal end 14, antirotation surface 50 may contact
a superior section 76 of collar 25. Extending from the central
portion of antirotation surface 50 is motion control member 51.
[0049] FIG. 5A depicts one embodiment of motion control member 51
that is generally t-shaped or a "rail" like projection 77 that
extends from antirotation surface 50. Superior section 76 of collar
25 has been modified to receive motion control member 51 by
including a corresponding cavity or indentation of a similar shape
to motion control member 51.
[0050] An alternative motion control member 51 is shown in FIG. 5B
as a cylindrical post 78 extending from antirotation surface 50.
Again, when humeral head augment device 40 is fixed to stem 20,
post 78 extends into a corresponding cylindrical hole located on
superior section 76.
[0051] Yet, a further alternative embodiment of motion control
member 51 is seen in FIG. 5C, where motion control member 51 is a
rectangular tab 79. Tab 79 projects into a correspondingly shaped
cavity located in superior surface 76 when humeral head augment
device 40 is coupled to stem 20. It should be understood to those
skilled in the art that additional embodiments of the motion
control member are contemplated herein, including but not limited
to screws, pins, flanges and keys. It is further understood that,
all embodiments of motion control member 51 are designed to
function to inhibit any rotational or other movement between the
coupled humeral head augment device 40 and stem 20. Eliminating or
reducing any motion assists to ensure proper positioning of
external bearing surface 41 relative to the anatomic bony
structures following the implantation of shoulder prosthesis 10 and
to humeral head 30.
[0052] FIG. 8 shows one alternative embodiment of humeral head
augment device 80. For some clinical cases, operating surgeons
desire to maintain healthy and intact posterior soft tissue
structures surrounding the shoulder joint, more specifically, soft
tissue structures that comprise the rotator cuff. In these
situations, a clinician may choose to utilize alternative humeral
head augment device 80. Alternative humeral head augment device 80
includes a unitary body that has a posterior side 81, a medial side
82 and a lateral side 83. To accommodate the posterior soft tissue
of the rotator cuff structure, external bearing surface 41 disposed
on posterior side 81 is partially relieved or may be totally
removed. The resultant relief 84 may extend from medial side 82 to
lateral side 83. Alternatively, although not shown, relief 84 may
extend only for a portion of posterior side 81 with relief
originating either proximate to medial side 82 or proximate to
lateral side 83. The remaining portions of external bearing surface
41 remaining intact. Relief 84 will not compromise or impact any of
the articulation functionality of external bearing surface 41 that
has been described herein. As seen in FIG. 9, alternative humeral
head augment device 80 attaches to proximal end 14 in the same
manner as has been described previously and is operably positioned
in the same location on stem 20 as detailed above, allowing
alternative humeral head augment device 80 to interface and
function with humeral head 30 in the same or similar way as
described for humeral head augment device 40 herein. Further, at
least one hole 55 may be positioned along the distal, lateral or
anterior aspect of humeral head augment device 80 to facilitate
soft tissue securement at various locations along the peripheral
rim.
[0053] The embodiment of shoulder prosthesis 10 described herein
may be modular in design, thereby allowing the operating surgeon to
choose from a system of multiple differently sized and shaped
components, including stems 20, humeral heads 30 and humeral head
augment devices 40. The shoulder prosthesis system provides the
operating surgeon with the flexibility to mix, match, and implant
the appropriate sized and configured shoulder prosthesis to the
presented anatomic structures. The system typically is comprised of
a series or plurality of stems comprised of various lengths and
cross-sectional sizes. Each stem having a proximal end 14 that may
be connected to humeral head 30 and humeral head augment device 40.
The shoulder prosthesis system further includes a plurality of
different sized humeral heads 30. Each of humeral heads 30 may have
a different sized radius of curvature 33R for the respected
articulation surface 31. Having a plurality of differing sized and
curved humeral heads 30 allows the operating surgeon the ability to
more closely match humeral head 30 with the articulating surface of
a natural glenoid or a prosthetic glenoid. Each of the plurality of
humeral heads 30 will typically include tapered post 35 or another
like connector. Additionally, the shoulder prosthesis system will
have a plurality of humeral head augment devices 40. Again, the
plurality of humeral head augment devices 40 gives the operating
surgeon the ability to reestablish shoulder joint stability and
provide pain relief without compromising post-operative limb range
of motion. Each of the plurality of humeral head augment devices 40
will include the structural features which have been discussed
previously herein. The plurality of humeral head augment devices 40
in the system may each have the same or different sized radius of
curvatures 44R, 45R for the respected first portion 42 and second
portion 43 of external bearing surface 41, and with respect to
humeral head 30, radius of curvatures 44R, 45R may be the same or
different sized as compared to radius of curvature 33R, thereby
allowing the operating surgeon the ability to customize shoulder
prosthesis 10 intraoperatively to address motion control, joint
stability and soft-tissue deficiencies. Each of the plurality of
humeral head augment devices 40 may include a coupling mechanism 54
to allow for securement to one of the plurality of stems 20 in the
system and a motion control member 51 that ensures proper alignment
of humeral head augment device 40 relative to humeral head 30 and
stem 20.
[0054] FIG. 10 shows a further alternative embodiment of the
humeral head augment device. A one-piece humeral-acromion head 300
is seen with the humeral head augment device being integral to the
humeral head. As depicted at FIG. 10, humeral-acromion head 300
includes an outer articulation surface 301. Articulation surface
301 has a generally curved contour that may be comprised of
multiple radius of curvatures. It should be understood to those
skilled in the art that articulation surface 301 may also be
comprised of a single radius of curvature. For example purposes
only, FIG. 10 illustrates articulation surface 301 to be comprised
of multiple radius of curvatures, 302R, 303R with articulation
surface 301 extending to an angle .beta. that may range from 180
degrees to 270 degrees depending upon a patient's anatomic features
and clinical circumstances. As discussed previously herein for
humeral head 30, humeral-acromion head 300 also includes a tapered
post 305 that is similar in structure to tapered post 35. For the
sake of brevity and redundancy, the specific structural
characteristics of tapered post 305 will not be discussed again as
they are essentially the same as those of tapered post 35 of
humeral head 30. Tapered post 305 does function to couple
humeral-acromion head 300 to stem 20.
[0055] As seen in FIG. 10, articulation surface 301 may consist of
at least two portions, a glenoid bearing portion 310 and an
acromion bearing portion 320. When properly coupled to stem 20,
glenoid bearing portion 310 is configured to articulate with a
glenoid implant or the patient's natural glenoid. Radius of
curvature 302R is configured and dimensioned to allow for three
degrees of motion for an implanted shoulder prosthesis. In
addition, acromion bearing portion 320 is configured to articulate
with the patient's natural acromion allowing for multiple degrees
of motion. Glenoid bearing portion 310 will have at least one
radius of curvature 302R that may range in size from 15 mm to 45 mm
with a more detailed range being between 19 mm to 30 mm.
[0056] For example purposes only, as seen in FIG. 10, acromion
bearing portion 320 includes at least one radius of curvature 303R.
It should be understood to those skilled in the art that acromion
bearing portion 320 may be constructed of multiple different sized
radius of curvatures. Generally, radius of curvature 303R is
differently sized than radius of curvature 302R. The specific size
relationship between 302R and 303R (e.g., greater than, less than,
or equal) will be dependent upon the presented clinical
circumstances and the preference of the operating surgeon.
[0057] Acromion bearing portion 320 of humeral-acromion head 300
may be configured to include a relief on the posterior side. As has
already been described previously herein, the relief is provided to
allow for the placement of intact rotator cuff soft tissue
structures. Although not shown, the relief may span the entire
posterior side or, alternatively, only a portion of the posterior
side of acromion bearing portion 320.
[0058] It is also further contemplated, and as described previously
herein, humeral-acromion head 300 may include at least one hole
positioned along the peripheral rim of both the glenoid bearing
portion 310 and acromion bearing portion 320. The hole or holes may
be positioned and sized to allow for soft tissue attachment to
provide for joint stabilization.
[0059] FIG. 11 shows yet a further alternative embodiment of a
humeral head augment device. A humeral-acromion resurfacing implant
400 is seen with the humeral head and the humeral head augment
device being a one-piece construct. As shown at FIG. 11,
resurfacing implant 400 includes an outer articulation surface 401.
Articulation surface 401 has a generally curved contour that may be
comprised of multiple radius of curvatures. It should be understood
to those skilled in the art that articulation surface 401 may also
be comprised of a single radius of curvature. For example purposes
only, FIG. 11 illustrates articulation surface 401 to be comprised
of multiple radius of curvatures, 402R, 403R with articulation
surface 401 extending to an angle A that may range from 180 degrees
to 270 degrees depending upon a patient's anatomic features and
clinical circumstances. Resurfacing implant 400 also includes a
tapered post or stem 430 that extends from the undersurface of
resurfacing implant 400 and is inserted into the surgically
prepared proximal humerus to secure the implanted resurfacing
implant 400 to the bone.
[0060] As seen in FIG. 11, articulation surface 401 may consist of
at least two portions, a glenoid bearing portion 410 and an
acromion bearing portion 420. Following implantation, glenoid
bearing portion 410 is configured to articulate with a glenoid
implant or the patient's natural glenoid. Radius of curvature 402R
is configured and dimensioned to and allow for three degrees of
motion for an implanted shoulder prosthesis. In addition, acromion
bearing portion 420 is configured to articulate with the patient's
natural acromion allowing for multiple degrees of motion. Glenoid
bearing portion 410 will have at least one radius of curvature 402R
that may range in size from 15 mm to 45 mm with a more detailed
range being between 19 mm to 30 mm.
[0061] For example purposes only, as seen in FIG. 11, acromion
bearing portion 410 includes at least one of curvature 403R. It
should be understood to those skilled in the art that acromion
bearing portion 410 may be constructed of multiple different sized
radius of curvatures. Generally, radius of curvature 403R is
differently sized (e.g., greater than, less than, or equal) than
radius of curvature 402R with the specific size relationship being
dependent upon the presented clinical circumstances and preference
of the operating surgeon.
[0062] Acromion bearing portion 420 of resurfacing implant 400 may
be configured to include a relief on the posterior side. As has
already been described previously herein, the relief is provided to
allow for the placement of intact rotator cuff soft tissue
structures. Although not shown, the relief may span the entire
posterior side or, alternatively, only a portion of the posterior
side of acromion bearing portion 420.
[0063] It is also further contemplated, and as described previously
herein, resurfacing implant 400 may include at least one hole
positioned along the peripheral rim of both the glenoid bearing
portion 410 and acromion bearing portion 420. The hole or holes may
be positioned and sized to allow for soft tissue attachment to
provide for joint stabilization.
[0064] The method of assembling shoulder prosthesis 10 includes
obtaining a plurality of humeral heads 30 with each humeral head 30
including articulation surface 31, interior surface 34 and a
connector for attaching humeral head 30 to stem 20. The method
further includes obtaining a plurality of stems 20, each stem 20
having a shaft with a distinct cross-section, a proximal end 14 and
distal end 15 with a second connector member for engaging humeral
head 30. It is understood that the method includes the step of
obtaining a plurality of humeral head augment devices 40 with each
of the plurality of humeral head augment devices 40 having external
bearing surface 41 with the structural and functionality
characteristics described previously herein and coupling mechanism
54. The method may also include the step of assembling one humeral
head 30 with one stem 20 and one humeral head augment device 40.
Each of these separate components being chosen from the plurality
of the respective components contained within a shoulder implant
system. The method further includes the steps of employing the
coupling mechanism to connect the selected humeral head augment
device 40 to the selected stem 20, or alternatively, to the
selected humeral head 30. The method may also include the step of
engaging the two corresponding connectors of humeral head 30 and
stem 20 respectively, resulting in the assembly of shoulder
prosthesis 10.
[0065] The surgical technique for implantation of a shoulder
prosthesis is well known in the art. The method for using a humeral
head augment device 40 in a shoulder prosthesis 10 includes,
providing a shoulder prosthesis that may include a modular humeral
head 30 and a stem 20 that are designed to be coupled to each other
by a mechanical coupling mechanism. The method may further include
providing a humeral head augment device 40 for attachment to either
stem 20 or humeral head 30. Humeral head augment device 40 includes
external bearing surface 41 that may include a first portion 42 and
second portion 43 with respected radius of curvatures 44R, 45R.
Radius of curvatures 44R, 45R may be of different values to
constrain translational movement of shoulder prosthesis 10
post-operatively. Humeral head augment device 40 further may
include coupling mechanism 54 that is configured to connect humeral
head augment device 40 to either stem 20 or humeral head 30.
Coupling mechanism 54 allows the operating surgeon to assemble
humeral head augment device 40 to stem 20 either prior to
implantation into the humerus or following stem 20 being seated
into the resected proximal humerus. Humeral head augment device 40
also may include motion control member 51 that maintains accurate
orientation of humeral head augment device 40 relative to stem 20
and humeral head 30. Ensuring correct positioning of humeral head
augment device 40 relative to the other modular components of
shoulder prosthesis 10 will facilitate post-operative joint
stability and proper articulation of the humeral head 30 and
humeral head augment device 40 with the natural glenoid, a
prosthetic glenoid or the natural acromion.
[0066] It should be understood by those skilled in the art that the
surgical method may include sequentially implanting stem 20 into
the prepared proximal aspect of the patient's humerus prior to
coupling humeral head augment device 40 to stem 20 or
alternatively, to humeral head 30 with the final step being to
connect the selected humeral head 30 to stem 20. The sequence of
assembly of shoulder prosthesis 10 as described herein may be
different depending upon the given clinical situation and whether
humeral head augment device 40 is attached to humeral head 30 or
stem 20. At the discretion of the operating surgeon, humeral head
augment device 40 may be coupled to stem 20 or to humeral head 30
on the "back table" prior to the complete assembly and placement of
shoulder prosthesis 10 within the patient's resected humerus.
Ultimately, the shoulder prosthesis 10 assembly steps for the
method of using a humeral head augment device 40 in shoulder
prosthesis 10 and the final sizing combination of stem 20, humeral
head 30 and humeral head augment device 40 will vary depending upon
the preference of the operating surgeon in combination with the
clinical needs of the patient.
[0067] Although the preferred embodiments have been depicted and
described in detail herein, it will be apparent to those skilled in
the relevant art that various modifications, additions and
substitutions can be made without departing from its essence and
therefore these are to be considered to be within the scope of the
following claims.
* * * * *