U.S. patent application number 12/898937 was filed with the patent office on 2012-04-12 for system and method of bone preparation.
This patent application is currently assigned to HOWMEDICA OSTEONICS CORP.. Invention is credited to Vincent Alipit, Michael C. Ferko.
Application Number | 20120089146 12/898937 |
Document ID | / |
Family ID | 45925719 |
Filed Date | 2012-04-12 |
United States Patent
Application |
20120089146 |
Kind Code |
A1 |
Ferko; Michael C. ; et
al. |
April 12, 2012 |
SYSTEM AND METHOD OF BONE PREPARATION
Abstract
The invention includes a system, method and kit for preparation
of a bone. One aspect of the present invention is a bone
preparation system comprising a cutting instrument and a guiding
element. The cutting instrument includes a distal attachment
feature and a distal region. The guiding element includes a
proximal attachment feature and a guiding surface. When the
proximal attachment feature of the guiding element is engaged with
the distal attachment feature of the cutting instrument, the
cutting instrument can pivot about the proximal attachment feature
until the distal region contacts the guiding surface.
Inventors: |
Ferko; Michael C.; (Warwick,
NY) ; Alipit; Vincent; (Nanuet, NY) |
Assignee: |
HOWMEDICA OSTEONICS CORP.
Mahwah
NJ
|
Family ID: |
45925719 |
Appl. No.: |
12/898937 |
Filed: |
October 6, 2010 |
Current U.S.
Class: |
606/87 |
Current CPC
Class: |
A61B 17/1659 20130101;
A61B 17/164 20130101; A61B 17/17 20130101; A61B 17/1617
20130101 |
Class at
Publication: |
606/87 |
International
Class: |
A61B 17/56 20060101
A61B017/56 |
Claims
1. A bone preparation system comprising: a cutting instrument
including a first attachment feature and a first region; and a
guiding element including a second attachment feature and a guiding
surface, wherein the second attachment feature is engaged with the
first attachment feature so that the cutting instrument can rotate
and pivot about the guiding element, contact between the first
region and the guiding surface determining the amount of pivot of
the cutting instrument about the guiding element.
2. The bone preparation system of claim 1, wherein the first
attachment feature is a distal attachment feature and the first
region is a distal region; and the second attachment feature is a
proximal attachment feature.
3. The bone preparation system of claim 2, wherein the distal
region includes a distal end and a distal surface.
4. The bone preparation system of claim 1, wherein the guiding
surface extends 360 degrees around the second attachment
feature.
5. The bone preparation system of claim 1, wherein the guiding
surface extends around a portion of the second attachment
feature.
6. The bone preparation system of claim 1, wherein the guiding
surface is derived from an outer profile of an augment implant.
7. The bone preparation system of claim 6, wherein the augment
profile is derived from a pre-operative patient specific imaging
process.
8. The bone preparation system of claim 1, wherein the guiding
element includes a first end having at least one fixation
feature.
9. The bone preparation system of claim 1, wherein the guiding
element further includes an aperture for engaging a stem.
10. The bone preparation system of claim 9, wherein the stem
further includes an outer profile having a cutting feature.
11. The bone preparation system of claim 9, wherein the second
attachment feature has a central axis and the guiding element
aperture has a central axis, the stem has a central axis, wherein
the second attachment feature central axis, aperture central axis
and stem central axis are aligned.
12. The bone preparation system of claim 9, wherein the second
attachment feature has a central axis and the guiding element
aperture has a central axis, the stem has a central axis, wherein
the second attachment feature central axis is offset from the
aperture central axis, and the aperture central axis and stem
central axis are aligned.
13. The bone preparation system of claim 1, wherein the second
attachment feature is a sphere and the first attachment feature is
a spherical female indentation.
14. A method of bone preparation comprising: inserting a guiding
element into a canal of a bone; attaching a cutting instrument with
a central axis to the guiding element; preparing the bone by
pivoting the cutting instrument about the guiding element; and
removing the cutting instrument and the guiding element from the
prepared bone.
15. The method of bone preparation of claim 14, further comprising
the step of preparing the canal of the bone.
16. The method of bone preparation of claim 15, wherein the
preparing the canal step includes utilizing a reamer.
17. The method of bone preparation of claim 16, wherein the
inserting step includes engaging the guiding element with the
reamer.
18. The method of bone preparation of claim 15, further comprising
the step of inserting a prosthetic implant into the prepared
bone.
19. The method of bone preparation of claim 14, further comprising
the step of rotating the cutting instrument about the central
axis.
20. The method of bone preparation of claim 19, further comprising
the step of pivoting the cutting instrument about the guiding
element.
21. The method of bone preparation of claim 14, further comprising
the step of imaging of the bone of a patient.
22. The method of bone preparation of claim 21, further comprising
the step of developing a patient specific implant based on the
pre-operative imaging of the bone of a patient.
23. A bone preparation kit comprising: an augment implant for the
metaphyseal region of a long bone; and a guiding element including
a guiding surface, wherein the guiding surface is derived from an
outer profile of the augment implant.
24. The bone preparation kit of claim 23, wherein the augment
implant includes a geometry based on pre-operative patient
imaging.
25. The bone preparation kit of claim 23, wherein the guiding
surface includes a distal end having at least one fixation
feature.
26. The bone preparation kit of claim 23, wherein the guiding
element further includes an aperture designed to engage a stem.
27. The bone preparation kit of claim 26, wherein the stem is a
reamer.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a bone reaming system, and
more particularly, to an apparatus and method for preparing
specific geometries in the metaphyseal region of long bones.
[0002] Orthopedic surgery has been prevalent in recent years and
the number of joint arthroplasty procedures is projected to grow
exponentially in the future. Total knee replacement (TKR) is an
example of joint arthroplasty. In TKR, the end surfaces of the
femoral and tibial bones are resected and replaced with implants
that may be made from metal, ceramic, polyurethane, or some
combination thereof. In this procedure, the femoral and tibial
implants may be fixed to the bone using cement, cementless biologic
fixation or other known fixation means. While good TKR survivorship
has been reported, it is known that these procedures may fail for
reasons including incorrect alignment, loosening, osteolysis,
infection, and the like. If a TKR procedure fails, a revision TKR
procedure may be required.
[0003] In revision TKR, the primary implant components typically
need to be removed, leaving defects or voids in the metaphyseal
regions of the long bones on which they were implanted. Defects may
be the result of removing the implants, the cement, other fixation
means such as screws, or bone regions compromised by infection. The
void size and geometry are unique for each patient and it is
critical to augment these defect regions to ensure proper
structural support for revision TKR implants.
[0004] In these revision TKR procedures, the augments available to
address these bone defects are generally offered in limited sizes
and shapes which do not consider the unique defect geometries of a
particular patient. At least in part, the limitation of augment
offerings is due to inability of current preparation instrument
systems to prepare complex and non-uniform geometries. Thus, it is
common place for patients to have excessive bone removed from their
specific defect region in order to receive standard augment
prostheses. Moreover, in some cases, an impaction based preparation
technique such as broaching is used to prepare a bone defect region
during revision surgery. Given that the bone in the defect region
is already compromised, this impaction technique may lead to bone
fractures which further worsen the patient condition and require
addition intervention.
[0005] Therefore there exists a need for bone preparation system
that will allow for complex and non-uniform geometries to be
created during a preparation of the bone using non-impaction
means.
BRIEF SUMMARY OF THE INVENTION
[0006] One aspect of the present invention is a bone preparation
system comprising a cutting instrument and a guiding element. The
cutting instrument includes an attachment feature and a first
region. The guiding element includes an attachment feature and a
guiding surface. When the attachment feature of the guiding element
is engaged with the distal attachment feature of the cutting
instrument, the cutting instrument can rotate and pivot about the
guiding element. Contact between the first region and the guiding
surface determines the amount of pivot of the cutting instrument
about the guiding element.
[0007] Alternate embodiments of the bone preparation system may
include any of, or any combination of the following: the cutting
instrument attachment feature is a distal attachment feature and
the first region is a distal region, the guiding surface attachment
feature is a proximal attachment feature; the distal region of the
cutting instrument may be comprised of a distal end and a distal
surface; the guiding surface of the guiding element may extend 360
degrees around or around a portion of the attachment feature of the
guiding element; the guiding surface may be derived from an outer
profile of an augment implant which may be derived from a
pre-operative patient specific imaging process; the guiding element
may further include an aperture designed to engage a stem wherein
the stem may include a cutting feature; the central axis of the
guiding element, aperture and stem have various alignments; or the
attachment feature of the guiding element may be a sphere and the
distal attachment feature is a spherical female indentation.
[0008] Another aspect of the present invention is a method of bone
preparation. Here, a guiding element is inserted into the canal of
a bone and a cutting instrument is attached to the guiding element.
The bone is prepared by pivoting the cutting instrument about the
guiding element. The cutting instrument and guiding element are
removed from the prepared bone.
[0009] Alternate embodiments of the method bone preparation system
may include any of, or any combination of the following methods:
preparing the canal of the bone using a reamer, engaging the
guiding element with the reamer, inserting a prosthetic implant
into the prepared bone, rotating the cutting instrument about the
central axis, pivoting the cutting instrument about the guiding
element, imaging of the patient, or developing a pre-operative
patient specific implant based on the imaging of the bone of a
patient.
[0010] A further aspect of the present invention is a bone
preparation kit comprising an augment implant and a guiding
element. The augment implant is for the metaphyseal region of a
long bone. The guiding element includes a guiding surface where the
guiding surface is derived from an outer profile of the augment
implant.
[0011] Alternate embodiments of the bone preparation kit may
further comprise any of the following: the augment implant includes
a geometry based on patient imaging, the guiding surface includes a
distal having at least one fixation feature, the guiding element
further includes an aperture designed to engage a stem.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The present invention will be better understood on reading
the following detailed description of non-limiting embodiments
thereof, and on examining the accompanying drawings, in which:
[0013] FIG. 1 is a perspective view of a bone preparation system in
accordance with one embodiment of the present invention.
[0014] FIG. 2 is an exploded view of the bone preparation system
shown in FIG. 1.
[0015] FIG. 3 is an enlarged perspective view of a portion of a
cutting instrument included in the bone preparation system shown in
FIG. 1.
[0016] FIG. 4 is a perspective view of a guiding element included
in the bone preparation system shown in FIG. 1.
[0017] FIG. 5 is a perspective view of an alternate embodiment of a
guiding element.
[0018] FIG. 6 is a perspective view of a tibial augment in
accordance with one embodiment of the present invention.
[0019] FIG. 7 is a perspective view of tibial baseplate implant in
accordance with one embodiment of the present invention.
[0020] FIG. 8 is a perspective view of the tibial augment shown in
FIG. 6 assembled with the tibial baseplate implant shown in FIG.
7.
[0021] FIG. 9 is a view illustrating the relationship of the
geometry of the tibial augment shown in FIG. 6 to the bone
preparation system shown in FIG. 1.
[0022] FIG. 10 is another view illustrating the relationship of the
geometry of the tibial augment shown in FIG. 6 to the bone
preparation system shown in FIG. 1.
[0023] FIG. 11 is a perspective view of an alternate embodiment
bone preparation system in accordance with the present
invention.
[0024] FIG. 12 is a perspective view of a guiding element included
in the bone preparation system shown in FIG. 11.
[0025] FIG. 13 is a cross-sectional view of a tibial bone with a
portion of the bone preparation system shown in FIG. 1 included
therein.
[0026] FIG. 14 is a cross-sectional view of a tibial bone with the
bone preparation system shown in FIG. 1 included therein.
[0027] FIG. 15 is a cross-sectional view of a tibial bone with the
construct shown in FIG. 8 implanted thereon.
DETAILED DESCRIPTION
[0028] As used herein, the term "distal" means more distant from
the heart and the term "proximal" means closest to the heart. The
term "inferior" means toward the feet and the term "superior" means
towards the head. The term "anterior" means towards the front part
of the body or the face and the term "posterior" means towards the
back of the body. The term "medial" means toward the midline of the
body and the term "lateral" means away from the midline of the
body.
[0029] Referring to the drawings, FIGS. 1-2 illustrate one
embodiment bone preparation system 10 including a stem 20, guiding
element 30 and a cutting instrument 40. The stem 20 has a distal
end 21, proximal end 22 and a central axis 26. The stem 20 is
designed to fit within the intramedullary canal of a long bone, for
example, the tibia (shown in FIGS. 12 and 13). The stem 20 may
include features such as an outer profile 23, depth references 24
and attachment geometries 25 for interfacing with other
instruments. The attachment geometries 25 are designed to allow for
assembly with other instruments as well as to provide rotational
constraint during subsequent bone preparation, which will be
further described. In the embodiment shown, a powered reaming
instrument, which is not shown but is known in the art, would
interface with the attachment geometries 25 and rotate the stem 20
about its central axis 26 within the intramedullary canal. Further,
in this embodiment, outer profile 23 is a cutting surface that
prepares the intramedullary canal as the stem 20 rotates. In an
alternate embodiment, the stem 20 may have a smooth outer profile
23 dimensioned to reference a previously prepared intramedullary
canal. Further in this alternate embodiment, the attachment
geometries 25 may allow interface with an insertion-extraction
instrument. In one or more embodiments, depth references 24 may be
located anywhere on stem 20 and serve as an indicator of location
to the user.
[0030] The cutting instrument 40 has a distal end 41, a proximal
end 42 and a central axis 47. Cutting instrument 40 may include
features such as an outer profile 43, a depth reference 44 and
proximal attachment geometries 45 for interfacing with other
instruments. Outer profile 43 preferably contains a cutting
geometry and may have a single diameter throughout the cutting
region. In alternate embodiments, outer profile 43 may have a
non-constant diameter, stepped diameter or other geometric
configuration to allow variable bone preparation. In the embodiment
shown, cutting instrument 40 is a reamer and a powered reaming
instrument would interface with the proximal attachment geometries
45 to rotate the reamer about central axis 47 to prepare the bone.
In other embodiments, other instruments may interface with
attachment geometries 45 to allow for rotational bone preparation,
such as devices facilitating manual rotation. Further, in alternate
embodiments, cutting instrument 40 may be a burr or other cutting
geometry that rotates in order to prepare bone.
[0031] Depth reference 44 serves as a location indicator to the
user and can take the form or engraved marks, steps, or the like.
In the particular embodiment shown in FIGS. 1 and 2, depth
reference is a step. Further, there may be multiple depth
references 44 on the cutting instrument 40. FIG. 3 further
illustrates the distal region of cutting instrument 40, which
includes a distal surface 48 and a distal end 41. In the embodiment
shown the attachment feature 46 is a spherical female indentation
designed to engage with a male feature of guiding element 30
(described below). The stem 20, guiding element 30 and cutting
instrument 40 are constructed of known instrument or implant
material, such as stainless steel or titanium.
[0032] FIG. 4 illustrates, in more detail, guiding element 30,
which includes a distal end 31 and proximal end 32. Distal end 31
may have an aperture 33 including an aperture central axis 37.
Preferably, aperture 33 is designed to interface over proximal end
22 of stem 20, thereby engaging attachment geometries 25. When
engaged, central axis 26 of stem 20 is aligned with the aperture
central axis 37. In the depicted embodiment, guiding element 30
also preferably includes an alignment feature 36 taking the form of
an engraved line which allows for orientation reference of the
guiding element 30 as it is assembled with stem 20. Of course, in
other embodiments, alignment feature 36 may be different elements,
including, a notch, protrusion, or the like. Also in other
embodiments, guiding element 30 may include a structure designed to
affix it with stem 20. For example, a ball/detent or male/female
connection may be employed.
[0033] Guiding element 30 in FIG. 4 also includes a proximal
attachment feature 34 designed to interface with attachment feature
46 of a cutting instrument 40. In the embodiment shown, the
proximal attachment feature 34 is a protrusion having a spherical
geometry and includes an attachment feature central axis 38 that is
aligned with aperture central axis 37. In an alternate embodiment
shown in FIG. 5, attachment feature central axis 38a may be offset
and therefore not aligned with the aperture central axis 37a.
Further regarding guiding element 30, proximal attachment feature
34 and attachment feature 46 may be other known mechanisms used for
removable attachment. In addition, while attachment features 34 and
46 are shown as male and female elements, respectively, this may be
the opposite in other embodiments. In other words, cutting
instrument 40 could include a male attachment feature, while
guiding element 30 includes a female attachment feature.
[0034] The guiding element 30 may further include a guiding surface
35 designed to allow for a specified bone preparation. The geometry
of guiding surface 35 may be derived from a pre-operative scan,
such as Magnetic Resonance Imaging (MRI), Computed Tomography (CT),
X-ray or similar know technology. Here, a bone model is generated
from the pre-operative scan. The guiding surface 35 is preferably
derived from the bone model as a mathematically sweeping geometry
between multiple cross sections of a patient specific defect and
can range from zero to 360 degrees around the attachment feature
central axis 38. In an alternate embodiment, guiding surface 35 may
be derived from a standard augment implant design.
[0035] As noted above, proximal attachment feature 34 of the
guiding element 30 is preferably engaged with the attachment
feature 46 of the cutting element 40. When engaged, the attachment
feature central axis 38 intersects with the central axis 47 of the
cutting instrument 40. During bone preparation, the cutting
instrument 40 is angled until the distal end 41 or distal surface
48 of the distal region engages with the guiding surface 35, thus
establishing an outer bound for the bone preparation.
[0036] Further on the bone preparation, cutting instrument 40
rotates its central axis 47, and also pivots about proximal
attachment feature 34. Then, as either, or both the distal end 41
or distal surface 48 references the path of guiding surface 35,
thus establishing an outer bounds for the bone preparation. The
prepared bone geometry governed by guiding surface 35 is based on
an augment implant designed to fill a patient specific defect and
may be any unique geometry, including symmetric, asymmetric or
offset.
[0037] In this bone preparation system, the geometry of the bone
preparation is thusly governed by the geometry of the guiding
surface 35, which is located distal to the cutting instrument 40.
Further, the guiding surface 35 is located within the cortical
perimeters of a long bone. Also of note, the attachment feature
central axis 38 of guiding surface 35 may or may not be aligned
with the central axis 26 of stem 20 which allows for asymmetric,
offset and non-uniform preparation of the metaphyseal region of the
long bone.
[0038] The stem 20, guiding element 30 and cutting instrument 40
are illustrated in FIGS. 1-4 as independent structures. Other
embodiments of this invention may include: the stem 20 and guiding
element 30 being a single structure, the guiding element 30 and the
cutting instrument 40 being a single structure, or the stem 20,
guiding element 30 and cutting instrument 40 being a single
instrument structure.
[0039] FIG. 6 illustrates a tibial augment 60 having a distal end
61 and a proximal end 62. Tibial augment 60 is preferably utilized
to replace cancellous bone that was removed as the result of
primary TKR implant removal, infection or the like. The tibial
augment 60 is designed to provide the structural support for the
revision TKR baseplate components. It has an outer profile 63, a
central aperture 64 and a central axis 65. Central aperture 64 is
designed to interface with prosthesis such as revision TKR
baseplate component 70, as shown in FIG. 6.
[0040] As shown in FIG. 7, the tibial baseplate component 70 may
include a distal feature 71, such as a keel, and a tray component
72 that has a proximal surface 73 and a distal surface 74. FIG. 8
illustrates an example of a tibial augment 60 assembled with a
tibial baseplate component 70. A tibial augment may be assembled
with tibial baseplate component 70 using cement, mechanical
attachment or other known means.
[0041] FIG. 9 shows the relationship between the geometry of tibial
augment 60 and bone preparation system 10, in particular, the
geometrical relationship between outer profile 63 of tibial augment
60 and the guiding surface 35 of guiding element 30. Here, tibial
augment 60 has an outer profile 63 defined by an angle X1 measured
from a central axis 65. Guiding surface 35 has a geometry that
allows for a defect specific path for the cutting instrument 40.
Attachment feature 46 of cutting instrument 40 is engaged to
proximal attachment feature 34 and distal end 41 references guiding
surface 35. X2 represents an angular relationship between the
attachment feature central axis 38 and cutting instrument 40
central axis 47. Angles X1 and X2 have a mathematical relation with
respect to central axes 65 and 38.
[0042] FIG. 10 provides an overlayed perspective of the
relationship between the specific outer profile 63 of tibial
augment 60 and the outer bounds of the bone preparation governed by
the guiding surface 35. This relationship is demonstrated by
aligning the attachment feature central axis 38 and the central
axis 65 of the tibial augment 60. It is understood the mathematical
relationship relates to multi-dimensional implant structures and
may involve any unique geometry that would be different from
patient to patient.
[0043] Guiding element 30 may be distributed as a standard
instrument, a disposable instrument or a custom single use
instrument. With a standard augment product offering, such as a
tibial augment 60, the guiding element 30 may be included as a
standard instrument in an instrument kit. Also with a standard
tibial augment 60, the guiding element 30 may be disposable
instrument, designed for a single use, and to be used with standard
stem 20 and cutting instrument 40. In an alternate scenario,
patient specific augments and may be created using scans, such as a
pre-operative MRI, CT, X-ray or any combination thereof. Then a
patient specific kit would be provided which includes, for example,
a patient specific tibial augment 60, and a guiding element 30. The
patient specific preparation would be guided thru the unique
guiding surface 35 geometry that is designed to match patient
specific augment geometry. Here, the patient specific tibial
augment and augment specific guiding element 30 may be packaged
together for a specific surgery.
[0044] FIGS. 11-12 illustrate an alternate embodiment of a bone
preparation system 100 consisting of a cutting instrument 140 and a
guiding element 130. While each are not discussed, like elements to
that of system 10 are labeled in FIGS. 11 and 12 with like
reference numerals within the 100-series of numbers. For instance,
similar to the embodiment previously described, cutting instrument
140 engages with an proximal attachment feature 134 on the guiding
element 130. The cutting instrument 140 rotates about its central
axis 147, and then pivots about attachment element 134 until either
the distal end 141 or distal surface 148 contacts guiding surface
135, thus establishing the outer bounds for the bone preparation.
The significant difference with this alternate embodiment is that
the guiding element 130 does not get assembled with a stem
component 20, but rather attaches directly to bone within the
intermedullary canal. For example if the intermedullary canal is
prepared to a certain depth using a reamer instrument or the like,
the guiding element 130 would be placed at the interface between
the prepared intermedullary bone and the unprepared intermedullary
bone where there is a natural cortical bone "shelf". Fixation
features 139 affix guiding element 130 to the bone and provides
rotational constraint during bone preparation. These fixation
features are shown as teeth, but may be other known fixation
features, such as screws, pins or the like.
[0045] A method of preparing a bone utilizing system 10 is
illustrated in FIGS. 13-15. In this method, the intermedullary
canal of tibial long bone 300 has been prepared using stem 20,
resulting in a prepared intramedullary canal region 301. This is
best shown in FIG. 13, where stem 20 remains in the prepared
central region 301. Aperture 33 and alignment feature 36 of guiding
element 30 are then removably attached with the attachment geometry
25 of stem 20, as shown in FIG. 14. Also shown in that figure, the
attachment feature of cutting instrument 40 is then assembled to
proximal attachment feature 34 of guiding element 30. Cutting
instrument 40 is then rotated about its central axis 47, thus
establishing a rotational cutting motion. The cutting instrument is
then angled, by pivoting about attachment feature central axis 38,
until distal end 41 contacts guiding surface 35. The rotating and
pivoting of cutting instrument is continued until the metaphyseal
region of the bone is prepared to receive and augment, such as
tibial augment 60.
[0046] As shown in FIG. 15, a prosthetic implant construct is then
inserted into the prepared bone, for instance, an assembled tibial
baseplate component 70 and tibial augment 60 (as described above)
with a stem implant 80. It is understood that other known implant
components such as stem extensions and offsets may further
contribute to the implant assembly. Further, the implant components
described may alternatively be inserted as individual
components.
[0047] An alternate method of preparing bone, which is not
illustrated, would involve preparing a long bone utilizing the
system depicted in FIGS. 11 and 12. Guiding element 130 would be
inserted into an already prepared central canal region 301, so that
fixation features 139 stabilize the guiding element 130. Attachment
feature 146 of cutting instrument 140 is then assembled with
proximal attachment feature 134 of guiding element 130, so that
distal end 141 references the guiding surface 135. The method
thereafter closely mirrors that described above in connection with
the use of system 10.
[0048] Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
applications of the present invention. For example, where the
tibial preparation system includes a guiding element having a
proximal attachment feature, a femoral preparation system may
include a guiding element having a distal attachment feature. It is
therefore to be understood that numerous modifications may be made
to the illustrative embodiments and that other arrangements may be
devised without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *