U.S. patent application number 12/248091 was filed with the patent office on 2009-06-11 for transcutaneous prosthesis.
This patent application is currently assigned to University College London. Invention is credited to Gordon BLUNN, Justin Cobb, Allen Goodship, Paul Unwin.
Application Number | 20090149966 12/248091 |
Document ID | / |
Family ID | 9894311 |
Filed Date | 2009-06-11 |
United States Patent
Application |
20090149966 |
Kind Code |
A1 |
BLUNN; Gordon ; et
al. |
June 11, 2009 |
TRANSCUTANEOUS PROSTHESIS
Abstract
A transcutaneous prosthesis includes a first component
configured for attachment to a bone, the first component including
flutes or grooves on a surface thereof for deterring rotation of
the prosthesis within a bone; a second component adapted for
location between the bone and the skin, the second component having
a surface treatment for stimulation of fibroblastic cell
proliferation and attachment of epithelial cells; and a third
component adapted for location to extend from the skin surface and
is adapted to extend directly from the skin surface in use, the
third component having a coating of a non-stick material on an
outer surface thereof, the coating having a surface energy that is
lower than a surface energy of the first and second components and
which is low enough to deter bacterial adhesion.
Inventors: |
BLUNN; Gordon; (Royston,
GB) ; Cobb; Justin; (London, GB) ; Goodship;
Allen; (Wheathamstead, GB) ; Unwin; Paul;
(Radlett, GB) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
University College London
London
GB
|
Family ID: |
9894311 |
Appl. No.: |
12/248091 |
Filed: |
October 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11306584 |
Jan 3, 2006 |
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12248091 |
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10311589 |
Apr 28, 2003 |
7014661 |
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PCT/GB01/02771 |
Jun 22, 2001 |
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11306584 |
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Current U.S.
Class: |
623/23.44 ;
606/279; 606/86A; 623/23.51 |
Current CPC
Class: |
A61F 2002/009 20130101;
A61F 2/0077 20130101; A61F 2/54 20130101; A61F 2002/0081 20130101;
A61F 2002/30879 20130101; A61L 27/28 20130101; A61F 2/3094
20130101; A61F 2/78 20130101; A61F 2002/30322 20130101; A61F
2310/0058 20130101; A61F 2310/00604 20130101; A61F 2002/0086
20130101; A61C 8/0012 20130101; A61F 2002/30838 20130101; A61F
2/2814 20130101; A61F 2002/30558 20130101; A61F 2002/3093 20130101;
A61F 2002/30224 20130101; A61F 2002/7887 20130101; A61F 2250/0073
20130101; A61F 2/30767 20130101; A61L 2430/02 20130101; A61F
2002/30561 20130101; A61F 2002/30574 20130101; A61F 2310/00976
20130101; A61F 2002/30604 20130101; A61F 2002/30785 20130101; A61F
2002/30929 20130101; A61C 8/0006 20130101; A61F 2002/30878
20130101; A61F 2250/0074 20130101; A61C 8/0018 20130101; A61F
2002/30845 20130101; A61L 27/303 20130101; A61F 2250/0026 20130101;
A61F 2/30749 20130101; A61F 2230/0069 20130101; A61F 2310/00796
20130101; A61F 2002/30225 20130101; A61L 27/34 20130101; A61F 2/60
20130101; A61L 27/34 20130101; C08L 89/00 20130101 |
Class at
Publication: |
623/23.44 ;
606/279; 606/86.A; 623/23.51 |
International
Class: |
A61F 2/28 20060101
A61F002/28; A61B 17/86 20060101 A61B017/86; A61F 2/78 20060101
A61F002/78 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 23, 2000 |
GB |
0015479.9 |
Claims
1. A transcutaneous prosthesis which comprises: a first component
having means for attachment to a bone, a second component adapted
for location between the bone and the skin, the second component
having a surface treatment for stimulation of fibroblastic cell
proliferation and attachment of epithelial cells; and a third
component adapted for location to extended directly from the skin
surface in use, whereby the outer surface of the third component
has a surface energy that is lower than a surface energy of at
least the second component and which is low enough to deter
bacterial adhesion.
2. A prosthesis according to claim 1 wherein the components are
integrally formed and have different surface treatments.
3. A prosthesis according to claim 1, wherein the first component
has a surface treatment which stimulates bone growth and osseous
integration.
4. A prosthesis according to claim 1, wherein the second component
has a micro-pitted surface.
5. A prosthesis according to claim 1, wherein the surface of the
second component carries a protein coating.
6. A prosthesis according to claim 1, wherein the second component
extends outwardly from the first and third components.
7. A prosthesis according to claim 6, wherein the second component
has through-holes.
8. A prosthesis according to claim 1, where the third component
carries a coating comprising a fluoro- or silicon polymer.
9. A prosthesis according to claim 1, wherein the third component
carries a coating comprising diamond like carbon.
10. A prosthesis according to claim 1, wherein the third component
includes a frangible or detachable linkage which permits an
external component to detach in the event that an unusually high
load is applied to the prosthesis.
11. A prosthesis according to claim 1, in which the third component
is adapted for connection to an artificial limb or digit.
12. A prosthesis according to claim 5, wherein the protein coating
is fibronectin or laminin.
13. A prosthesis according to claim 1, wherein the surface of the
second component carries a hydrated calcium phosphate coating.
14. A prosthesis as claimed in claim 13, wherein the hydrated
calcium phosphate coating is a coating of hydroxy apatite.
15. A prosthesis as claimed in claim 1, wherein the surface energy
of the third component is a surface energy level of a non-stick
material such as a fluoro or silicone polymer or diamond-like
carbon.
16. A prosthesis as claimed in claim 1, wherein the outer surface
of the third component has a coating of a non-stick material.
17. A prosthesis as claimed in claim 1, wherein the first component
is shaped for implantation into a bone.
18. A prosthesis as claimed in claim 6, wherein the second
component extends in an outward direction perpendicular to the
first and third components.
19. A prosthesis according to claim 6, wherein the second component
extends in an outward direction perpendicular to the first and
third components, in plate like form.
20. A prosthesis according to claim 6, wherein the second component
is mushroom shaped.
21. A prosthesis according to claim 7, wherein the second component
has first set of through holes of a first size and a second set of
through holes of a second size.
22. A transcutaneous prosthesis which comprises: a first component
having means for attachment to a bone; a second component adapted
for location between the bone and the skin, the second component
having a surface treatment for stimulation of fibroblastic cell
proliferation and attachment of epithelial cells; and a third
component adapted for location to extend directly from the skin
surface in use, wherein the second component is located between the
first and third components in use, the third component having an
outer surface comprising a non-stick material, wherein the outer
surface has a surface energy which is low enough to deter bacterial
adhesion.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 11/306,584, filed Jan. 3, 2006, which is a
continuation of U.S. application Ser. No. 10/311,589, filed on Apr.
28, 2003, which is now U.S. Pat. No. 7,014,661, which is a national
stage filing of PCT/GB01/02771, filed on Jun. 22, 2001, which
claims the priority of GB 0015479.9, which was filed on Jun. 23,
2000.
FIELD OF THE INVENTION
[0002] This invention relates to transcutaneous prosthesis and
includes a method of fitting a prosthesis having a transcutaneous
component to a patient.
BACKGROUND OF THE INVENTION
[0003] Amputation of limbs or digits can occur due to trauma or
because of surgical removal. Examples of trauma include loss of
fingers in machinery accidents, loss of limbs in car accidents or
as a result of land mine explosions. Surgical removal can also be
indicated as a result of cardiovascular disease, diabetes and
cancerous tumours to the bone or soft tissues.
[0004] After amputation, it is common to fit an external
endo-prosthetic device that is attached to the body via by a skin
interface. This commonly involves the manufacture of a custom-made
socket which is secured to the stump using straps or clamps. A
number of disadvantages arise from the use of such endo-prosthetic
devices. For example:
[0005] (1) Skin is not a satisfactory high load bearing structure
and often breaks down under load, becoming inflamed and
uncomfortable and, in severe cases, pressure sores are formed which
are difficult to heal.
[0006] (2) Changes in the shape of the stump may mean that a new
custom-made socket is required.
[0007] (3) The use of sockets for receiving the stump are commonly
sweaty and uncomfortable.
[0008] (4) Where a joint is involved, the external prosthesis is
usually moved by muscle groups situated at a distance from the
attached prosthesis and therefore motion is inefficient and
unnatural.
OBJECTS AND SUMMARY
[0009] A major object of the present invention is to provide a
prosthesis which overcomes some or all of the above
disadvantages.
[0010] According to one aspect of the present invention there is
provided a transcutaneous prosthesis which comprises a first
component shaped for implantation into a bone, a second component
intended for location between the bone and the skin, the second
component having a surface treatment for stimulation of
fibroblastic cell proliferation and attachment of epithelial cells
and a third component intended for location exterior to the skin
surface having a low surface energy which deters bacterial
adhesion.
[0011] The prosthesis provided by the present invention is thus an
intra-osseous transcutaneous prosthesis (ITAP) and has a number of
advantages. For example, the first component is attached directly
to load-bearing parts of the bony skeleton such that load is
transmitted through bone. This means that the patient is able to
apply much more power to the prosthesis. Also, motion and
perception of movement is more natural because of the bone
attachment. Moreover, because the skin takes no part in
transmitting the load from the bone to the external part of the
prosthesis, there is no pressure on the skin surface which would
cause inflammation or discomfort.
[0012] The first component is formed with some suitable means for
preventing rotation of the component in the bone which may comprise
flutes or grooves or functionally similar shaped surfaces. These
surfaces may be shaped to fit the profile of the intramedullary
cavity, where present. Also, the first component is preferably
provided with a surface treatment which encourages osseous
integration. Suitable surface treatments include hydroxyapatite
which is a hydrated calcium phosphate. The surface may also be
formed with small apertures or pits to encourage integration
between the bone and the first component. Where micro pits are
formed in the surface, these may be of the order of 20 to 500
microns in size, preferably 20 to 100 microns.
[0013] The second component extends between the bone and the
epithelial surface. This component is provided with a surface
treatment for stimulating fibrous tissue ingrowth. Again, this
component may be treated with an hydroxyapatite or aluminium oxide
coating and the coating treated with materials which encourage the
adhesion of epithelial cells to the second component. This
component may also have a coating which is porous to encourage soft
tissue ingrowth materials which encourage such growth include
adhesion promoting proteins such as fibronectin or laminin. In
order to aid adhesion of the fibrous tissue to the second
component, the hypodermis is preferably surgically removed during
the procedure of installing the prosthesis. The goal is to attach
the skin to the implant to prevent movement of the skin and shear
forces separating epithelial cells at the interface and underlying
dermis and thereby permitting infection to enter between the skin
and the prosthesis.
[0014] The third component comprises the exterior part of the
prosthesis and this has a low surface energy which deters bacterial
adhesion. A low surface energy can be achieved by coating this part
of the prosthesis with a non-stick material such as a diamond-like
carbon, a fluorinated polymer or a silicone polymer.
[0015] The prosthesis may be made up from separate components
connected together, or two or more of the components may be formed
integrally and given appropriate surface treatments.
[0016] The external component will preferably include a safety
device comprising a linkage which breaks under an unusual load such
as, for example, one caused by the patient falling. This will allow
the external component to detach from the skeletal and
transcutaneous component without causing damage to the bone or to
the skin. An additional feature which will protect the fixation of
an intramedullary post is an external device which limits torque
transmitted to the adjustable fixation. The torque transmitted may
be adjustable so that with time, the transmitted torque can be
increased, as the internal component integrates with the bone.
[0017] In a further preferred embodiment of the present invention
the second component may be provided so as to extend outwardly from
the first and third components in a manner that increases the
external surface area of the second component. The second component
may also be provided with through holes which further increase the
external surface area and allow growth of tissue through the second
component. This has been found to advantageously facilitate the
integration of the component with fibrous tissue growth.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The invention is illustrated by the accompanying drawings in
which:
[0019] FIGS. 1 and 2 are diagrammatic views through part of a
deer's antler and skull;
[0020] FIG. 3 is a diagrammatic part section showing a
transcutaneous prosthesis in accordance with the invention, fitted
to a patient.
[0021] FIG. 4 is a perspective view of a preferred embodiment of a
prosthesis in accordance with the present invention drawn on a
larger scale compared with FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Referring to the drawings, the present invention was in part
stimulated by study of the skin-bone interface around red deer
antlers. This is a unique structure and may be thought of as a
biological model for a transcutaneous implant. The deer antler at
periods of the year is very heavily loaded during the rut.
Histological examination indicates that the layer of skin
epithelial cells become thinner as the epithelial layer approaches
the antler, such that at the antler-skin interface an epithelial
skin layer is only about one cell thick. The dermis is intimately
attached to the bone (pedicle) interface. The attachment is
achieved through a series of "Sharpeys fibres" which attach to the
dermis and to the bone and prevent differential skin movement.
Antlers do not normally become infected and the bone structure is
invaginated with small pores measuring 18 to 40 microns in
diameter. This helps the interface between the dermis and the bone
to resist shear stresses. These features are shown in FIGS. 1 and 2
of the accompanying drawings.
[0023] The prosthesis of the present invention is shown in FIG. 3
and may be considered an artificial analogue of the deer's antler.
The prosthesis comprises a first component (1) which is inserted
into the intramedullary canal of a bone (2). Component (1) is
formed with longitudinally extending cutting flutes which engage in
the bone as the prosthesis is inserted into the intramedullary
canal and resists rotation. The surface of the component (1) may be
coated with a material to encourage osseous integration such as a
hydroxy apatite material and/or be micro-pitted. The second
component (4) extends from the end of the bone to the surface of
the skin. This component may be cylindrical as drawn, or could be
flattened to a mushroom shape, thereby increasing the surface area
over which the soft tissue can be attached. Component (4) is given
a surface treatment to encourage attachment of the epithelial to
the implant. Such surface treatments include giving the surface a
micro-pitted structure and/or coating the surface with adhesion
proteins such as laminin or fibronectin which encourage fibrous
growth into the surface of the component (4) of the prosthesis.
[0024] Prior to installing the prosthesis, the hypodermis is
preferably surgically removed. Further, a surface is provided on
the second component which is porous and promotes fibrous tissue
ingrowth. Suitable materials for coating the surface include
alumina oxide ceramics and hydroxy apatite. This surface,
preferably after being given a porous surface treatment, is coated
with an adhesion promoting protein, e.g. by spraying the prosthesis
with a solution of the adhesion-promoting protein, by dipping the
prosthesis in a concentrated solution of the protein and freeze
drying, or by dipping into a sterile solution of the
adhesion-promoting protein prior to implantation
[0025] The removal of the hypodermis surgically during the
amputation and installation procedure assists in stimulating
attachment of the skin to the implant and thereby prevents shear
forces on the skin separating the epithelial cells at the
interface.
[0026] The third component (5) of the prosthesis extends from the
skin and is given a non-stick surface on its exterior portion.
Suitable materials include fluorinated polymers such as
polytetrafluoroethylene, siliconized polymers and diamond like
carbon. The presence of a non-stick surface discourages bacteria
from attaching to the prosthesis and helps to prevent infection.
The non-stick surface may be applied to the exterior portion of the
third component (5) using the technique of chemical vapour
deposition (CVD). The use of CVD is well known in the art for
applying a surface of diamond-like carbon. When applying a surface
layer of diamond, as disclosed in EP-B-0545 542 the method
generally involves providing a mixture of hydrogen or oxygen gas
and a suitable gaseous carbon compound such as a hydrocarbon,
applying energy to that gas to dissociate the hydrogen into atomic
hydrogen or the oxygen into atomic oxygen and the carbon into
active carbon ions, atoms or CH radicals and allowing such active
species to deposit on the substrate to form diamond. The energy to
cause dissociation may be provided in a number of ways common to
the art, for example by hot filament or by microwave source. A
non-stick surface of fluorinated polymer or silicone polymer may be
applied to the third component by polymerising a monomer or
prepolymer in contact with the component.
[0027] It may be convenient to apply the low energy surface
treatment to the third component while masking the remaining
components of the prosthesis. Also, the second component of the
prosthesis may be treated with the adhesion-promoting protein after
applying the low energy surface to the third component, and it may
be desirable to mask the third component while applying the
adhesion-promoting protein.
[0028] The third component may be connected to an artificial limb
or digit. For example, in the case of a replacement finger or part
finger, the first component may be implanted into the remaining
bone with the second component instituting the transcutaneous
portion, and the third component extending beyond the severed
stump. An artificial digit or part digit can then be attached to
the third component.
[0029] The prosthesis may be implanted either in a one-stage
procedure or in a two-stage procedure where the first component is
implanted into the bone and allowed to integrate before the
transcutaneous part is attached.
[0030] There is shown in FIG. 4 a further preferred embodiment of
the present invention wherein the second component (4) is extended
in an outward direction perpendicular to the first and third
components in a plate like form. This feature provides the second
component (4) with a large surface area which advantageously
facilitates the integration of the second component (4) with
fibrous tissue growth. As also shown in FIG. 4, through holes (6)
may be provided in the plate like extension of the second component
(4), which further increase the external surface area and also
allowing tissue to grow through the second component further
facilitating integration. Although the above description refers to
a series of components, it will be appreciated that each component
may be a portion of an integral element manufactured from a single
piece of material. It is, however, preferred that a frangible
linkage is provided between the third and second components or
between the second and first component, so that in the event that a
high load is applied to the third component, or to a member
attached thereto, the linkage will fair so as to protect the
implanted bone from injury.
[0031] While the present invention has been described with
particular reference to the provision of a prosthesis for
replacement of lost digits or limbs, the invention is also
applicable to other prosthesis which extend through the skin, e.g.
dental implants.
[0032] Although only preferred embodiments are specifically
illustrated and described herein, it will be appreciated that many
modifications and variations of the present invention are possible
in light of the above teachings and within the purview of the
appended claims without departing from the spirit and intended
scope of the invention.
* * * * *