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Description  |
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FIELD OF THE INVENTION
The present invention generally concerns catheterization. In particular, it
concerns methods and apparatus for providing catheterization, through bone
material, into cavities in animals, including humans. In preferred
applications, catheterization is provided into joint cavities, for
therapeutic treatment.
BACKGROUND OF THE INVENTION
For a variety of reasons, therapeutic access to internal cavities of
animals, including humans, has been desirable. Herein the term
"therapeutic access" will generally be understood to refer to access to
the cavity from a remote location, for any of a variety of reasons. For
example, the access may be desired in order to introduce therapeutic
material into the cavity; in order to remove material from the cavity;
and, in order to obtain access to the cavity with mechanical means such as
an orthoscopic filament or laser surgery tool. The term "therapeutic
access" is intended to include within its meaning access to treat
conditions, study conditions, inhibit the onset of physical problems, etc.
There are a wide variety of reasons why access has been desirable, in both
human and veterinary medicine. Herein the description will primarily focus
on treatments of humans, and the focus of attention will be on joint
cavities. Further, conditions of particular interest to the techniques and
apparatus described herein are arthritic conditions; however it will be
understood that: many of the methods and apparatus described herein may be
applied to a wide variety of animals and not just humans; some of the
techniques may be utilized for access to cavities other than joint
cavities; and, some of the treatment methods described herein may be
utilized for therapy other than treatment of arthritic conditions.
Again, a particular area in which the methods and apparatus described
herein may be of use, is in the treatment of arthritis. More than 37
million individuals in the United States suffer from the broad category of
joint diseases known collectively as arthritis. Among the more common of
these conditions are: osteoarthritis, which is prevalent among elderly;
and, rheumatoid arthritis, which tends to occur in relatively young men
and women. When the pain associated with the conditions cannot be
controlled by conservative treatments methods, and/or when function cannot
be readily restored, joint replacement is often the presently prescribed
treatment method. Approximately 120,000 hip replacements and 70,000 knee
replacements are performed each year in the United States.
While joint replacement operations are generally successful for short term
relief, loosening of implants and erosion of articulating surfaces pose
problems over the long-term. As a result there have been ongoing efforts
to improve joint prostheses. However, it is also desirable to develop
treatment methodologies that avoid joint replacement or at least postpone
its necessity.
Research has indicated that access to synovial fluid of a diseased joint
could be a key factor in the development of new treatment methodologies.
In particular, the nature of the synovial fluid has been linked to joint
disease. A study of changes in the synovial fluid could provide
information useful in long-term diagnoses and treatment and access to a
joint for direct application of drugs and/or lubricants therein can lead
to more effective modes of treatment for arthritic disease.
Cuevas et al., Biochem. Biophys. Res. Comm., 156, 611 (1988), incorporated
herein by reference, reported that administration of fibroblast growth
factor directly into injured joints of rabbits for 20 days promoted repair
of the damaged cartilage; while no evidence of damage repair was seen in
control animals which received intra-articular saline infusions. Such
studies support the contention that access to synovial fluid may be of
considerable therapeutic value.
A typical conventional means of orthopedic joint access for fluid drainage
and acute drug therapy has been by percutaneous hypodermic needle
insertion. Studies during which artificial synovial fluid has been
injected as an experimental treatment include the reports found in:
Leardini et al., Clinical Trials Journals, Vol. 24, p. 341 (1987); Namiki
et al., International Journal of Clinical Pharmacology, Theory and
Toxicology. Vol. 20, p. 501 (1982); Grecomoro et al., Phramatherapeutica,
Vol. 5., p. 137 (1987); and, Bragantini et al., Clinical Trials Journal,
Vo. 25, p. 333 (1987). The previous four recited articles are incorporated
herein by reference. In general, the articles report that one to three
intra-articular injections per week of 20-40 mg (milligrams) of hyaluronic
acid temporally relieved arthritis pain in some patients. However, two of
the studies (Namikini et al. and Leardini et al.) report that the
injections either produced pain lasting a few hours (3.3-4.7% incidence
rate) or swelling which lasted a few days (1.0-2.5 % incidence rate).
Besides the incidence of pain (and/or swelling) associated with treatment
through use of hypodermic needles to provide percutaneous insertion, other
potential problems and limitations are presented by this conventional
technique. Examples of these are briefly discussed herein. The list is not
intended to be considered as exhaustive.
If percutaneous hypodermic injection is to be utilized, then therapy
extending over a substantial period of time would require subjecting the
patient to a plurality of painful injections. This not only increases pain
and discomfort to the patient, but also requires the patient to frequently
return for treatment to a medical facility, increasing cost and
inconvenience.
Another problem with this method of therapy is that treatment on a
continuous basis, i.e. through continuous infusion, is not readily
feasible. Further, the size of bolus which may be given in any given
treatment will be severely limited by the size of the cavity and/or
patient comfort.
Also, each injection may need to be precisely located, for maximum
therapeutic effect. This may be difficult to achieve. The needle injection
itself may cause damage, or provide a site of infection. For example, if
the joint of concern is the knee joint, the cavity (or fluid containing
capsule) is defined by bone structure and membrane. Generally, needle
insertion would require piercing of the membrane. Thus, damage to the
integrity of the capsule is involved, and infection may set in. The
problem is exacerbated should a plurality of injections be necessary.
The studies of the four references discussed above were carried out on knee
joints. Treatment of hip, wrist and finger joints would typically involve
more technically difficult percutaneous needle puncture (in the case of
the hip) or likely cause unacceptable trauma (in the case of the smaller
wrist joint and tiny finger joints).
What has generally been needed has been a more convenient and effective
method for obtaining therapeutic access to an internal cavity such as a
joint cavity. Apparatus for conducting such methods have also been needed.
SUMMARY OF THE INVENTION
The present invention generally concerns methods and apparatus for therapy.
The invention particularly concerns therapy for treatment of material in
cavities in animals, including humans, wherein the cavity is an internal
cavity at least partially defined by the surface of a bone in association
therewith.
In certain preferred applications, the methods concern therapy for
treatment of a bone joint in an animal, the bone joint having a cavity
including fluid retained therein by means of a retaining membrane. This
preferred application of the invention includes a step of selectively
introducing therapeutic material into the cavity without piercing the
retaining membrane. In preferred applications this is conducted by
introducing therapeutic material into the cavity by means of delivering
the therapeutic material through an access channel provided in a bone in
contact with, or association with, the cavity. This may be done, for
example, by drilling a hole through the bone, and introducing the
therapeutic material therethrough. A preferred apparatus for introduction
to the therapeutic material is described. In certain preferred methods,
material introduced is selected from the group consisting of:
hydrocortisone and related steroids; hyaluronic acid (lubricant);
phenylbutazone; sodium salicylate; benzyl salicylate (anti-inflammatory
agents); orgoteins; lidocaine (analgesics); fibroblast growth factor
(growth factors) and, mixtures thereof.
A preferred embodiment of the present invention may be generally
characterized as providing therapeutic access to an internal joint cavity
of an animal, the cavity being defined at least in part by bone material.
The preferred method generally includes steps of providing an access
channel through the bone material defining the joint cavity, the access
channel terminating in fluid flow communication with the cavity; and,
providing fluid flow access with the access channel, from a remote
location. As explained herein, the term "therapeutic access" in this
context is meant to refer to access for any of a variety of reasons, not
merely to introduce material into the cavity. For example, the access may
be provided in order to remove material from the cavity, or in order to
provide a preferred point of introduction of a mechanical device (or
portion of a medical device) into the cavity. The term "therapeutic" in
this context is meant to include access for any of a variety of means
including treatment, inhibition of deterioration, investigation
(examination) and/or experimentation.
It is further a method according to the present invention to provide
selected therapeutic access to a cavity in an animal wherein the cavity is
defined at least in part by bone surface, when the method is generally
characterized by steps of: providing an access channel through a bone
having a surface in association with the cavity, the access channel being
provided in fluid flow communication with the cavity; securing a tap
arrangement within the access channel, the tap arrangement having internal
flow channel provided in fluid flow communication with the cavity; and,
providing a cannula arrangement, or fluid flow arrangement with the tap
arrangement internal flow channel. By this method, material can be
inserted into or withdrawn from the cavity, by transport through the
cannula arrangement and tap arrangement. In preferred applications, the
tap arrangement will have been secured to the cannula arrangement prior to
the insertion of the tap arrangement within the animal.
It is noted that the access channel may be provided simultaneously with the
securing of the tap arrangement, for example if the tap arrangement is
driven into the bone as a wedge, or drill bit.
Methods according to the present invention may be utilized to provide
access to a variety of cavities, preferred applications being for
treatment of arthritis for example in knee joint cavities, hip cavities
and/or wrist and finger cavities.
In preferred applications, an infusion pump arrangement and/or medical
access port are provided in fluid flow communication with the cannula
arrangement, for medical access to the cavity. A variety of types of
infusion pump arrangements and access ports may be utilized, and several
are referenced herein, in the detailed descriptions. With such an
arrangement selected control of material within the cavity is facilitated.
The present invention also includes within its scope the provision of an
apparatus or arrangement for providing therapeutic access to a cavity in
an animal, for example a human, when the cavity is defined, at least in
part, by a surface of a bone adjacent the cavity. The preferred apparatus
generally comprises: an implantable (biologically compatible) tap
arrangement constructed and arranged for anchoring in the bone; and, a
cannula arrangement secured to the tap arrangement and having an external
conduit in fluid flow communication with the tap arrangement. Preferably,
the tap arrangement has an internal longitudinal channel extending
therethrough, and the cannula arrangement includes an end extension
positioned within the tap arrangement longitudinal channel. For preferred
applications, the tap arrangement comprises a screw-like construction,
having a threaded shank portion for anchoring in the bone. Alternate
arrangements, however, may be utilized.
Preferably the cannula arrangement comprises an implantable (biologically
compatible) flexible conduit, that can be readily secured subcutaneously
in the subject. This will provide for ease of movement, and more efficient
operation.
A preferred tool for implanting preferred apparatus according to the
present invention is also provided. The tool generally includes a shank
portion having an end adapted for secure mating with a portion of the tap
arrangement; and, a longitudinal slot for receipt of the cannula
arrangement therein. Preferably the tool includes means for secure
gripping thereof, for example a handle portion. Herein the apparatus is
generally referred to, in some instances, as a "bone catheter" for
convenience.
Another application of the invention will be apparent from the detailed
descriptions. In particular, the tap arrangement may be provided in
communication with an interior of a bone, rather than a natural cavity.
Thus, therapeutic access to a bone interior can be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings constitute a part of the specification and include exemplary
embodiments of the methods, techniques and apparatus disclosed herein. The
drawings are meant to be exemplary only, and not otherwise limiting. It
will be understood that in some instances relative material thicknesses,
and component sizes, may be shown exaggerated to facilitate understanding.
FIG. 1 is a schematic perspective view of a subject of the methods of the
present invention.
FIG. 2 is an enlarged fragmentary schematic view of a joint in an animal
treated according to the methods of the present invention.
FIG. 3 is a perspective view of an apparatus according to the present
invention.
FIG. 4 is an enlarged fragmentary view of a portion of the apparatus shown
in FIG. 3.
FIG. 5 is a cross-sectional view of a portion of the apparatus shown in
FIG. 4, the cross-section being taken generally along line 5--5, FIG. 4.
FIG. 6 is a cross-sectional view taken generally along line 6--6, FIG. 4.
FIG. 7 is a perspective view of a combination catheter apparatus according
to the present invention and device for use in mounting the catheter
apparatus in a subject, according to methods of the present invention.
FIG. 8 is a fragmentary cross-sectional view of an alternate arrangement of
the present invention, FIG. 8 being generally analogous to the view of
FIG. 5.
FIG. 9 is a graph representing data derived from an experiment described
herein.
DETAILED DESCRIPTION OF THE INVENTION
As required, detailed descriptions of methods, techniques and apparatus of
the invention are presented herein. The descriptions are intended to be
exemplary only, and to provide support for the general methods and
apparatus claimed. The descriptions are not intended to be limiting, but
rather as a basis for support of the claims.
In general, the methods of the present invention concern providing
therapeutic access to an internal cavity of an animal, including humans,
wherein that cavity is defined at least in part by a bone surface; that is
wherein the cavity is adjacent a bone. In general, the method concerns
obtaining access to the cavity in a manner which does not involve
undesirable piercing or rupture of a membrane associated with enclosing
the cavity (if there is one). The method generally comprises providing an
access channel through a bone in contact with the cavity, the access
channel terminating in fluid flow communication with the cavity; and,
delivering the therapeutic material into the cavity by transport through
the access channel. Specific details concerning the applications and the
methods, and the particular therapeutic agents that may be introduced into
the cavity, are described hereinbelow. First, the apparatus will be
generally described.
PREFERRED APPARATUS FOR USE IN METHODS ACCORDING TO THE PRESENT INVENTION
For purposes of facilitating understanding of the apparatus, it will be
described herein as applied in association with a human knee. More general
applications, at other body cavities in humans, and other animals, will be
apparent from the description. As previously indicated, the apparatus may
be anchored for access to an interior of a bone, rather than a cavity.
In general there are a variety of reasons why therapeutic access to such a
cavity may be desired; and, the term "therapeutic access" is meant to
include any of a variety of reasons for such access. For example, the term
is intended to include within its scope: access in order to deliver
therapeutic material or agent to the cavity; access in order to remove
material from the cavity; and, access in order to provide a mechanical
means such as orthoscopic filament and/or surgical fiber into the cavity.
The term "therapeutic" and variants thereof in this context is meant to
include access for treatment, examination and/or experimentation. Herein,
for simplicity, description will generally focus on examples involving
introduction of material to the cavity or removal of material from the
cavity.
In the schematic of FIG. 1, a subject 1 (in phantom) is depicted having a
first apparatus 5 according to the present invention provided in
communication with his right knee 6; and, a second apparatus 7 according
to the present invention implanted for communication with his left knee 8.
Herein, apparatus such as 5 and 7 will sometimes be referred to as
"orthopedic catheters" or "bone catheters". In general, differences
between the system involving apparatus 5 and the system involving
apparatus 7 relate to means provided for access to an anchored end of the
apparatus, and therapy. These will be discussed in more detail
hereinbelow. Initially, however, detailed descriptions with respect to
those features concerning apparatus 5 and 7 that are similar are
presented. With respect to this, attention is directed to FIG. 2.
In FIG. 2, a schematic representation of bone joint 15 treatable according
to the methods of the present invention, with apparatus of the present
invention, is illustrated. In FIG. 2, joint 15 is shown provided with an
apparatus 16 according to the present invention. The apparatus 16 of FIG.
2 may correspond to either of apparatus 5 and 7, FIG. 1 (in phantom). The
joint 15 of FIG. 2 may be a human knee joint, as depicted in FIG. 1.
However, it may be another type of joint such as a hip joint, wrist joint,
finger joint, etc.; and, it may be a joint of an animal other than a
human. More generally, the cavity being treated may be a joint cavity, as
shown; however, it may be another type of internal cavity adjacent a bone.
Referring to FIG. 2, joint 15 comprises a joint cavity 20, defined by bones
21 and 22. The cavity is further defined by membrane or membrane surfaces
24 and 25 attached to the bones, and enclosing cavity 20. The enclosed
cavity 20 may be referred to as the joint capsule.
It will be understood that the schematic of FIG. 2 is highly simplified,
relative to the actual depiction of a joint. Ligaments, etc. for example,
are not depicted. Also, precise relative size of depicted components is
not indicated. In general, cavity 20 defined by membrane sections 24 and
25 and surfaces of bones 21 and 22 includes therein synovial fluid 30. As
previously discussed in the background section, conditions involving
deterioration of joint operation have been, in some instances, linked to
the nature of, or condition of, the synovial fluid 30.
According to the present invention, therapeutic access is provided to
cavity 20 by means of a preferred apparatus 16. More specifically, a bore
or channel 34 is provided in a bone associated with a cavity 20, for the
illustration of FIG. 2, bone 21. Channel 34 is driven through bone 21, and
terminates at opening 35 in fluid flow communication with capsule 20. It
will be understood that therapeutic access to cavity 20, therefore, is
provided by means of channel 34 and opening 35. This access is provided
without piercing of membrane sections 24 and 25, since the access
generally comprises a bore driven directly through one of the bones, i.e.
bone 21. The precise, preferred, location of the bore will depend upon the
particular cavity involved, the nature of the adjacent bones, and the
preference of the surgeon. A wide variety is possible.
According to the invention, therapeutic access through channel 34 is
preferably provided by means of apparatus 16. Apparatus 16 includes two
principal components comprising: a tap arrangement 40; and, a conduit or
cannula arrangement 41. Tap arrangement 40 provides means for by which
cannula arrangement 41 is anchored in fluid flow communication with cavity
20, i.e. in channel 34. Apparatus 16 will be better understood by
reference to FIG. 3.
Referring to FIG. 3, apparatus 16 depicted therein, in perspective,
includes tap arrangement 40 and cannula arrangement 41. Preferably cannula
arrangement 41 comprises an elongate flexible cannula having an internal
lumen, bore or flow through channel 42, extending longitudinally
therethrough. While a variety of materials may be utilized for cannula
arrangement 41, preferably the arrangement comprises a flexible conduit of
biologically compatible material such as silicone rubber or
polyurethane/silicone rubber copolymer. Such materials are available for
example under the designation SILASTIC Tubing from Dow Corning, and MOxMed
of Portage, Wis. The tap arrangement 40 generally provides for anchoring
of cannula arrangement 41, in fluid flow communication with the cavity or
capsule. The term "tap" in this context is not meant to indicate any
particular direction of fluid flow.
Tap arrangement 40 includes means for anchoring within a bone, and in
particular within a channel formed in the bone, as described above with
respect to FIG. 2. For the preferred arrangement of FIG. 3, tap
arrangement 40 comprises a hollow screw member 45 having a longitudinal
channel 46 (FIG. 5) extending therethrough. Screw member 45 generally
comprises a head portion 49, and a shank portion 50. The shank portion 50
is provided with external threads 51 for use in anchoring tap arrangement
40 to a bone, for example, as shown in FIG. 2 to an internal surface of
bore or channel 34. For the preferred embodiment shown, FIG. 3, shank
portion 50 is threaded throughout its entire length.
Attention is now directed to FIGS. 4 and 5, wherein tap arrangement 40 is
shown in greater detail. Referring to FIG. 4, cannula arrangement 41 is
shown in fluid flow communication with internal bore 46 of tap arrangement
40. Thus, the internal channel of cannula 41 communicates through tap
arrangement 40, to tip 53 thereof. Referring to FIG. 5, for the preferred
embodiment, an extension 55 of cannula arrangement 41 is threaded (i.e.
projects) completely through channel 46 of screw member 45, so that an end
56 of cannula arrangement 41 is adjacent or substantially flush with end
53 of screw member 45. In preferred embodiments this arrangement is
provided, since in general for presently available materials, silicone
rubber or the like from which cannula arrangement 41 is preferably formed
tends to be non-thrombogenic, to a greater extent than preferred,
relatively rigid, materials from which screw arrangements such as screw
member 45 would be formed. Providing the soft, flexible, biologically
compatible silicone rubber type material in the vicinity of end 53 will
thus tend to inhibit closing or blocking thereof, or overgrowth. It will
be understood, however, that a wide variety of arrangements may be
utilized.
For the preferred arrangement shown in FIG. 5, extension 55 of cannula
arrangement 41 is shown secured to tap arrangement 40 by means of adhesive
layer 58. A variety of biologically compatible, and relatively stable,
adhesives, may be utilized including an implant grade room temperature
vulcanizing silicone rubber adhesive, such as available from Dow Corning
as a medical SILASTIC elastomer. Alternate methods of securing may also be
used.
Operation of apparatus 16 will be further understood by reference to FIG.
2. Screw member 45 is shown driven into bore 34. By means of cannula
arrangement 41, fluid flow communication with cavity 20 (i.e. therapeutic
access to cavity 20) is provided. Preferably, screw member 45 is driven
far enough so that it projects beyond a surface of bone 22, at port 35, a
sufficient distance to inhibit bone overgrowth, but not so far as to
inhibit joint operation; for example, it should not contact or interfere
with the moving condyle surfaces. In some applications, not shown, a
"head" of the top arrangement may be countersunk.
Preferred manners in which an arrangement similar to arrangement 16 may be
utilized, will be further understood by reference back to FIG. 1. In the
right leg of the subject shown in FIG. 1, apparatus 5 is shown anchored by
means of tap arrangement 63 in the right knee 6 of the subject 1. It will
be understood that tap arrangement 63 will have been positioned, for fluid
flow communication with the joint cavity. Apparatus 5 includes a cannula
arrangement 64 in fluid flow communication with tap arrangement 63, and
hence the cavity. Cannula arrangement 64 may be as previously described,
and will preferably have been surgically positioned subcutaneously, i.e.
under the skin of subject 1. The cannula arrangement includes an end 65,
remote from tap arrangement 63. End 65 is adapted for access by a medical
technician (or others) to ultimately obtain therapeutic access to the
cavity at tap arrangement 63.
For the arrangement shown in FIG. 1, end 65 is attached to a medical access
port or port arrangement 68 which terminates at a selected location for
access. It will be understood that in a variety of manners, means may be
attached to (or provided in association with) access port 68 for
convenient therapeutic access to the cavity in fluid flow communication
with the tap arrangement 63. For example aspiration means may be attached
to (or coupled with) the port 68, to aspirate or remove fluid from the
remote cavity. Alternatively, fluid infusion means may be attached to (or
coupled with) port 68, to inject or infuse material into the cavity.
Devices for irrigation of the cavity may be used. It will also be seen
that cannula arrangement 64 provides a convenient physical passageway,
directed into the remote cavity, so that the end of an object such as a
needle, fiber optic or laser surgery optic could, if desired, be readily
directed into the cavity by means of the cannula arrangement 64.
A wide variety of medical access ports that could be adapted for use in
applications described herein are known. The various types include: single
lumen bolus injection ports; multi-lumen bolus injection ports; and,
multi-catheter bolus injection ports. Included among commercially
available ports are the Port-A-Cath available from Pharmacia Deltec of St.
Paul, Minn.; I NFUEE-A-PORT, available from Shiley Infusaid (Pfizer),
Norwood, Mass.; and, LifePort, available from Strato Medical of Beverly,
Mass. These and other conventional ports, or ports yet to be developed,
may be utilized with apparatus according to the present invention. In
general, the various ports will have a variety of means for attachment to
a lumen or cannula arrangement, such as cannula arrangement 64. It will be
understood that the end 65 of cannula arrangement 64 will be selected so
as to be adapted for the particular connection to be made. An example of
this is illustrated in FIG. 3, whereat end 70 is adapted for secure to
male connector 72. A variety of means may be utilized to provide for
secure attachment including: a suture-type connection; a restrictive
elastic portion in end 70; adhesives; male./female connectors, etc.
In some applications it may be preferable to provide apparatus according to
the present invention in fluid flow communication with an implanted pump.
An example of this is illustrated in FIG. 1 with respect to apparatus 7.
Apparatus 7 includes a tap arrangement 80 anchored within a bone of knee
8, for fluid flow communication with a joint cavity or capsule thereat.
Apparatus 7 includes cannula arrangement 81 in fluid flow communication
with tap arrangement 80, and thus the associated cavity. The tap
arrangement 80 and cannula arrangement 81 of apparatus 7 may be as
previously described.
For arrangement 7, cannula arrangement 81 is shown having remote end 84
provided in fluid flow communication with pump arrangement 85. The pump
arrangement 85 is shown surgically implanted at the abdomen of subject 1.
Pump arrangement 85 may be utilized to preferably deliver therapeutic
material through cannula arrangement 81 into the cavity at the knee, in a
variety of manners. For example, it may be provided with means for
continuous infusion or selected infusion at intermittent intervals.
A variety of pump arrangements may be utilized as arrangement 85. These
would include electronically programmable pump arrangements and single
infusion rate pumps. It should also be apparent that pump-port
combinations may also be used.
Some pump arrangements readily adaptable for use in systems according to
the present invention are commercially available. Included among these are
the Infusaid pump available from Shiley (Pfizer), Norwood, Mass.; the
SynchroMed pump available from Medtronic, Minneapolis, Minn. Other pumps
utilizable in systems according to the present invention include the
spring pumps of U.S. Pat. Nos. 4,718,893 and 4,772,263, incorporated
herein by reference.
As previously suggested with respect to ports, a variety of proximal end
fittings in end 84 of cannula arrangement 81 may be utilized, for
adaptation in connection to a variety of pump arrangements. Connection
means, for example, such as suture connections, adhesives, restrictive
elastic materials and/or male/female interlocking connectors may be
utilized.
Referring again to FIG. 4, tap arrangement 40 may be manufactured from a
variety of materials. In general what is required is: a material which is
biologically compatible and implantable; and, a material which is
relatively rigid and thus anchorable in a manner insuring connection
without likely collapse or plugging of the channel end cannula 41. It is
foreseen that among the more desirable materials for use in preparing tap
arrangement 40 are materials from which conventional bone screws are
preferably made, for example titanium and stainless steel. Other materials
which may be utilized include: various plastics; various other metals and
metal alloys; and, ceramics.
For the arrangement shown in FIGS. 1-6, the tap arrangements have been
illustrated with a threaded shank, for anchoring via screwing into a
channel in the bone. Other means for securing the tap arrangement in place
may be utilized including: wedge arrangements, adhesives and the like. In
general, what is required is a secure anchor, to protect against problems
from the arrangement coming loose or unsecured. An advantage to the
threaded arrangements shown is that they may be readily removed, should
bone overgrowth justify redrilling a portion of the bone.
The specific dimensions of components of an arrangement according to the
present invention will depend, of course, upon the particular application.
The arrangement utilized in the experiments described herein, and
generally utilizable in a human knee, include a tap arrangement having: a
shank diameter of about 0.3-0.6 cm; an overall length of about 1.0-4.0 cm;
and, an internal bore of about 0.05-0.2 cm. The length of the cannula
arrangement will depend upon the selected preferred location for the
distal end, for example the location of the port and/or pump. It is
foreseen that apparatus according to the present invention may be
miniaturized, for use in wrist or finger joints.
Referring to FIG. 8, an alternate arrangement for anchoring the cannula
within the tap arrangement is provided. Referring to FIG. 8, an apparatus
86 is depicted in cross-section, comprising tap arrangement 87 and cannula
arrangement 88. These are generally as previously described, except tap
arrangement 87 includes an internal recess 89 therein filled with adhesive
material 89a. The adhesive material 89a may be set, after cannula 88 is
put in place, to facilitate anchoring of cannula arrangement 88 within tap
arrangement 87.
It will be understood that the ends of arrangements according to the
present invention, for example tips 53 and 56, FIG. 5, may be provided
with a variety of designs. It is foreseen that specific shapes, etc. may
be preferred, to: provide for lack of irritation to the patient or
material within an associated capsule; to inhibit likelihood of blockage
through bone overgrowth or clotting, etc.; and/or to facilitate anchoring
in position. The arrangements illustrated in FIGS. 5 and 8 are intended to
be exemplary only, with respect to this.
Methods for Securing Systems According to the Present Invention in Place
A variety of surgical methods may be utilized to put apparatus according to
the present invention in place. In general preferred methods involve a
step of providing a bore or channel in a bone, for securing the tap
arrangement. Typically this will involve drilling a bore or channel
through the bone, to provide a channel having an end in fluid flow
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