CA2189643A1

CA2189643A1 - Joint resurfacing system

Info

Publication number: CA2189643A1
Application number: CA002189643A
Authority: CA
Inventors: Jeffrey C. Felt
Original assignee: Individual
Current assignee: Advanced Bio Surfaces Inc
Priority date: 1994-05-06
Filing date: 1995-05-04
Publication date: 1995-11-16
Also published as: EP0830114B1; ATE221759T1; EP0830114A1; EP0830114A4; WO1995030388A1; US5556429A; DE69527725D1; JP2007111546A; AU2470195A; ES2182902T3; US5795353A; DE69527725T2; JPH10500038A

Abstract

A system for resurfacing orthopedic joints by arthroscopic means. The system involves a method that includes the delivery of curable biomaterial, and the use of minimally invasive means to prepare an injury site. and then deliver, cure and shape a curable biomaterial at the site of injury.

Description

WO gS/30388 2 ~ 8 ~ 6 4 3 P~
JOINT RESURFACING SYSTEM
TECHNICAL FIELD
S The present invention relates to methods. a~a~n.cPc materials and systems for the repair of ' ' ' ' injury, and in particular, for bone and cartilage repair and .
BACE~GROUND OF l~k ~NV~ION
The ' ' ' I system is subject to injury caused by traumatic events as weU
as by a number of diseases, such as ~ ~ ' and rheumatoid a~thritis.
Repair of comnective tissue of the ' ' ' ' system is commonly performed using materials such as natural or synthetic tendons and ligaments. loint repair and - r iS typically 1 , ' ' ' using metal and/or polymeric implants and devices.
Such devices are typically fixated into existing bone by means of bone plates, adhesives, screws, and the like.
Total joint l~r' ' is indicated under conditions in which the cartilage surface between the bones forming a joint has .~ .,1 Often it has !~, ~ tO a point where there is significant pain during Inrnm~tifm. as weU as during translation and rotation of joint . ; This d.,6.,~ c joint disease is commonly treated by a techrlique known as joint surface ~y6~c~ which involves Ic, ' of the ori~inal surfaces with artificial weight bearing materials in the form of implants.
EIip l~,"l.. ,~,.. i ~enerally involves the . ' of a femoral component in the form of a baU mounted on a shaft, together with an acetabular component in the form of a socket imo which the ball sits.
Total knee ~cplac~ t is somewhat more difficult than hip Ir~ because of the complex loading pattern of the knee. The tibial component of a total knee1. . '~~ is fixed in the canceUous bone of the tibia. The femoral component is typically fixed to the conical bone of the femoral shaft using a suitable cement.
The tibial ponion of a knee prosthetic device generally involves the insertion of a broad plateau region covering the tibia, after bone of the c~hchr~n~l plate is removed.
Tn most designs. a composite material is provided, involving a metal suppon underlying a po~ymeric, or ~ ~er-~i 'o~

w0 9s/30388 2 1 8 9 6 4 3 P~
A wide array of malerials have been described for use it~ the II~f~ fA~lUlC of medical implants. See generaliy. Chapter I, in ~ tt ' 1` Medical Devices and Tissue F..; ~ An Inte~rated Apl7roach. Frederick H. Siiver. ed., Chapman and Haii, 1994. Such materiais generally fall imo the categories of metais, polymers, ceramics, 5 and composite materiais.
A recent article entitled ~New Challenges in Biomateriais", Science, 263:1715-li20 (1994), Peppas et ai., provides a useful overview of the current state of the att in '- The article describes a number of materials currently useci for orthopedic , including metais (iron, cobait, amd titanium), degradable polymers, seif-10 reinforced c.. .~ of pol~61~"ui;c acid, stronger polymers such as pol~.'atld ceramic materiais such as hJJ~u~ titv and certain glasses.
Elsewhere, for inst~mce at page 1719, the Peppas et ai. articie refers to the potential usefulness of polymers that can be triggered to undergo a phase change. The ,lticle itseif does not identify such polymers, but instead postuiates that maoerials that are 15 initially iiquid might be - ' ' through a minimaiiy invasive surgical device and then triggered to soiidify or gel in the presence of ultraviolet iight, visible iight, or ionic change in vivo. As an example of this approach the article cites an article of Hili-West, et ai., Obstet. Gynecol. 83(1):59-64 (1994).
The Hill-West et al. article, in turn, describes the use of a; '~
20 resorbable hydrogel barrier for preventing pu,lutJv~ ve adhesions in animals. The article describes the formation of the hydrogel barrier in situ by l ' 7i '~ v a solution of a u...ùlv~ul,.. ~IC~JVl,~lllv. using W light. The hydrogel barrier is not described as beitlg useful in weight-bearing, orthopedic l.l.~ c and in fact, was completely resorbed within 7 days after arrlif~
There are a number of drawbacks associated with the I l c and related methods presently employed for orthopedic ~l,l.l; -:;.~ and in particular joint repair and One such drawback is that these methods generally involve invasive surgery, i.e., resecting tissue in order to gain access to the injury site. In tum, invasive surgery typically involves up to 7 to 10 days of l ~ with the costs associated therewith.
A related drawback of an arthrotomy involves the need to cut through skin, nerves, vessels. muscles. Iigaments. tendons, and/or joint capsules. Certain procedures .
wog5/30388 2 1 89 643 P~
.
can also require the use of eithe; general or spinal anesthesia. They may also require blood j r and significant recovery time a , -' by post-surgical pain and discomfort. Lastly, prolonged physical therapy is typically required to strengthen operative areas and prevent, ~s. Such therapy can often last up to six weeks or 5 more.
It would be particularly useful to be able to repair such injuries in a manner that avoided such invasive surgical procedures and the problems associated therewith.
SUM~ARY OF T~E INV~IION
~0 The present invention overcomes the drawbacks associated with the prior art by providing a method, system and related , for repairing or resurfacing the site of irljured orthopedic tissue by minimally-invasive means.
The method of the present invention comprises the steps of:
(a) providing a curable ' 1 and (b) employing minimally invasive means to:
(i) prepare the tissue injury site for receipt of the L- ';
(iu) deliver a quantity of the curable biomaterial to the prepared tissue injury site;
(iu) cure the delivered biomaterial in such a manner that the cured biomaterial is '~ retained in apposition to the prepared site; and ~Iv) contour the cured, retained biomaterial to achieve a desired: r y~JI, g that of natural tissue.
The method of the invention lends itself to a .ull--r " " system that comprises curable ~ 1, in ' with minimaUy invasive means for preparing the tissue site; deLivering the biomaterial to the prepared tissue site; curing the biomaterial in situ; and contouring the cured l I The individual ~ of such a system, and ~ ;.u~ means for deLivering and curing biomaterial in a minimaLly invasive fashion are considered novel as well.
In a preferred ~ ~ - ' t, a system is provided that comprises: (a) an ;l surgical instrument; and (b) a fluid delivery cannula capable of delivering aflowable, curable biomaterial under ~.~hlU~CU~ I--, the biomaoerial comprising a curable polymer and hydrogel.
The preferred system can be used to perform a method that comprises the steps of:

.... .... .. ... . ... .. _ .. _ _ wo gs/30388 2 1 8 9 6 ~ 3 Pcrlusgs/oss97 (a) providing a flowable, curable biomalerial comprising a curable polymer and hydrogel;
(b) preparing the tissue injury site by operation of the .~II;llU:l-UUi~ instrumem. and under ~ U~.U~ V.`~
(c) preparing a tissue access site and inserting and~ directing the delivery cannula through the tissue access site to the site of tissue injury;
(d) deLivering a quantity of the curable biomaterial through the cannula to the prepared site;
(e) curir~g the delivered biomaterial by minimaDy invasive means and in a mannersuch that the cured biomaterial is retained in apposition to the prepared site; and (f) contouring the cured biomaterial to achieve a desired ~,u~l~ " that of natural tissue.
In an altemative i ~ " the cured. shaped biomaterial can be treated or modified in order to improve one or more desirable properties, for instautce, it caut be coated with a pemmanent interface material in order to improve the ~ . ' ' y or coefficient of friction of the final implant.
DETAILED DESCRIErIION
As used herein the following words and oemms shall have the mearlings ascribed below:
"L In refers to a material tha~ is capable of being introduced to the site of an orthopedic tissue injury by minimally invasive means, and there be cured or otherwise modifled in order to cause it to be retained in a desired position and c 'i, GeneraDy such ' ' are flowable in their uncured fomm, meaning they are of sufficient viscosity to allow their delivery through a cannula of on the order of about 2 mm to about 6 mm inner diameter, and preferably of about 3 mm to about Smm innerdiameur. Such ' ;~ls are also curable, meaning that they can be cured or otherwise modified, in situ, at the tissue site, in order to undergo a phase or chemical change sumcient to retain a desired position and '_ ~mirltmally invasive means~ refers IO surgical means, such as: ' u~uuic surgicalmeans. that can be ~ without the need to resect tissue in order to gain access to a site of orth~edic i~u~.

w0 9s/30388 2 i 8 9 6 4 3 P~
'IAulLu~uui~ surgical instrument~ shall refer to the controllers and associated hardware and software necessary for performing ~u~ iu~ hu,.u~ic surgery;
"delivery cannula" shaD mean a cannula capable of being operated in a minimaDy invasive fashion under ,~lLu~u,u;c ~ together with associated connective S tubing and containers for the operable and fluid attachment of the cannula tû a source of biomaterial for the storage, delivery, and recovery of '. l' of the present invention;
According to a preferred ' t, a liquid phase p~JI.~ h~l~ub_l composite is applied through a cannula under A~ f ~ The composite is cured and lû contoured in situ to effectively resurface a daunaged joint. The cured pol~ h~d.ub_l composite exhibits physical/chemical . ~ analogous to those of human cartilage, and ~' - an optimal ' - of such properties as load bearing, shear stress resistance, impact absorption, and wear I~ The surface of the cured composite can optionaDy be modifled after curing and coMouring, e.g., in order to 15 reduce its coefficient of friction.
In a preferred ~ ' ' t, the method of the present invention comprises the step of providing a curable biomateria] comprising a curable polymer and hydrogel - r - ' suitable for use in the present invention include those materials that are capable of being delivered by means of a cannula, as described herein, and cured 20 in situ in order to form a, ~ - l material for bone or cartilage.
Natural cartilage is a llu.. .A~,UIA~. structure found in various parts of the body, and particularly articular cartilage, which exists as a finely granular matrix forming a thin on the surfaces of joints. Its narural elasticity enables it to break the force of while its mr -' affords ease and freedom of movement. In terms of 25 thickness, cartilage tends to take on the shape of the articular surface on which it lies.
Where this is convex, the cartilage is thickest at the center, where the greatest pressure is received. The reverse is generaDy true in the case of concave articular surfaces.
Preferred ' ' are intended to mimic many of the physical-chemical .1- -.A. ~ of natural cartilage. Preferred I - '- are composites of two or more 30 individual materials, and ~ UL.II.~ those comprising two phase systems formed from a polymeric matrix and a hydrogel filler.

~ wossl3o388 P~l/l .~

Common polymeric materials for use in rnedical devices include, for example, polyvinyl chlorides, pol~,h~h,,~. s~ryrenic resins, POIYUIU~UJIV~
poiyesters, Ih.."",~ elaslomers, polyw~ . a.,ylu~ ' ' - styrene ("ABS") resinS, acryiics, pvlru.~ cs, nylons. slyrene a.,ly' ' and ceLiulosics.
5 See, for example, "Guide to Medical Plastics", pages 41-78 in Medical Device &Di:~vnnctin In~hlct~y~ Aprii, 1994, the disclosure of which is i , ' herein by reference.
Suitable matrix materiais for use in the presenl invention are those polymeric materiais that proYide an optimal ~ ' of properties reiating to their I r .
0 ~inrli~tinn and in viYo use. In the uncured state, such properties include ~ ;ly and the abiiity to be stably soeriiized and stored. In the course of applying such materiai, such properties include hydrogel: . ' ' y and capacity, flowabiiity, and rn vivocurability. In the cured state, such propenies include moldabiiity, cured strength (e.g., tensiie and CO.."J~ ;;C), elongation to break, and 1- , ' "~y. Examples of suitable matrix materiais include, but are not iimited to, silicone polymers and pul~. ' polymers.
In a preferred; ~ " ~, the matrix is formed of a silicone polymer, i.e., polymer containing a repeating siiicon-oxygen backbone together with orgaluc R groups attached to a significant portion of the silicon atoms by siiicon-carbon bonds. See generally, "Siiicones", pages 1048-1059 in Concise IG~ IVV~i;~ of Polymer Science and r Eds. Mark et al., Wiley and Sons, 1990, the disclosure of which is i._o~l ' herein by reference.
Silicone polymers are . ~;~liy avaiiable in at least three generai classes, namely as IIU~ UIJ~ , siLicone random polymers. and siLicone-organic (block) copolymers. T~ , ly ~ in the form of pvl~." ' yl siioxanes are preferred, and constitute the iargest volume of llu,,~v,uuly produced today.
In an aiternative preferred ~ L " t, the matrix is formed of a pol~.
polymer. Pol~ ' e.g, Ih, ,~ l;, pulyul~ ' ("TPU"), are typicaliy prepared using three reactan~s: an isocyana~e, a long-chain macrodiol, and a short-chain diol e:;~ender. The isocyanale and long-chain diol form a "soft" segmem, whiie the isocyanate and short-chain diol forrn a "hard" segment. It is the interaction of soft and hard segments that determines and provide the polymer with rubber-iike properties.

-wo 9sl303x8 2 1 8 9 6 4 3 P~J'~' . ~'~ ~ 7 1 During melt processing. the l,ol~u,~ ` chains are linear and assume the into which they are formed, such as by injection molding. or in the case of the present invention, by .1l ' u~. uuic ~rrlir~tifm On cooling, the hard segments forln ordered domains held together by hydrogen bonding. These domains act as cross-links to 5 the linear chains, making the material similar to a cross-linked rubber.
Those skilled in the att, in view of the preseM invention, will appreciate the mamler in which the choice of isocyanate, macrodiol, and chain extender can be varied to achieve a wide diversity of properties. Preferred TPU's for medical use are presently based on the use of a Jii~u1~ wch as ~'i, ' ~' ' J;;~u._~ (nMDln), a 10 glycol such as pul.~. ' jl.,.,.. ether glycol, and a diol such as 1,4-butanediol.
Hydrogels suiuble for use in composites of the present invention are water-corluinitlg gels, i.e., polymers ~ by hyJIu,uhili~ i~y and insolubility in water.
See, for insunce, ~Hydrogels", pages 458-459 in Concise r~ lu~/~L ûf Polymer rl~ and r . Eds. Mark et al., Wi]ey and Sons, 1990, the disclosure of 15 which is ill~,UI~ ' herein by reference. Although their use is optiona~ in the present invention, the inclusion of hydrogels is highly preferred since they tend to contribute a number of desirable qualities. By virtue of their h~ , ' ' . water-conuining nature, hydrogels assist the cured composite with load bearing capabilities of the curedcomposite. They also tend to decrease frictional forces on the composite and add thermal 20 elasticity.
In a preferred c ~- ' t~ the hydrogel is a ftne, powdery synthetic hydrogel.
Suitable hydrogels exhibit an optimal ' of such properties as ~ y with the matrix polymer of choice, and ~ , ' 'y.
Suitable hydrogels swell to an . - ' volume in water, but preserve their 25 shape. Synthetic hydrogels suitable for use in forming a composite of the present invention include those based on ' ~ , and acrylic esters, (meth)a~.l ~' hydrogels, and those based on N-vinyl-2-~,.~1l. ' ' Preferred hydrogels include those formed from monomeric hydroxyalkyl acrylates and I~ ' . copolymerized with a suitable cross-linking agent, such as ethylene 30 ~ y` ("EDMA~).
In a palticularly preferred ' ' the matrix polymer is a siloxane (i.e., silicone polymer). and preferably one selected from the group consisting of alpha, omega-wosS/30388 2189643 r ~l dibydroxy-poly(~" J' ' ) and poly( ' J~.'-' ) with 0.2 mol% of ~ ,L.I..h~l-siloxane units. Dispersed as the hydrogel component in the preferredpolymer is 15% to 30% (by weight based on the weight of the uncured composite) of a lightly cross-linked hydrogel aggregate. A preferred hydrogel aggregate is formed by 2-h~dlu~ yl ~ .L~ .~' ~IA) cross-linked by ethylene ~ , (EDMA) at a of 2 %-5 % by weight, based on the weight of the hydrogel.
Those skilled in the art wiD appreciate the marlner in which hydrogel/matrix and can be altered based on their intended arp'~ inn For instance, a stiffcr composite with a low hydrogel . e.g.,--10% based on 10 the fioal weight of the composite, would be suitable for ~ al disc ., ' Depending, for instance, on their intended .. ' . - - ' wiD prefer;tbly corltain a hydrogel phase at a, of between about 15 and 50 weight percent, arld preferably between about 10 and about 50 weight percent, and preferably between about 15 and about 30 weight percent, based on the weight of the ' of matrix and hydrogel.
- Composites of the present invention can also include other optional adjuvants and additives, such as stabiliers, fillers, . ;...;.1 - ~ catalysts, pl~.tiri7,.rc, pigments, and lubricants, to the e%ent such optional ingredients do not diminish the utility of the for its intended purpose.
Cured polymer-hydrogel composites ' an optimal ' of physical/chemical properties",.u~;, ..l~l.~ in terms of their ~ ' stability, dissolution stability, 1~ r'~ and physical I r , e.g., physical propenies such as density, thickness, and surface roughness, and mechanical propenies such as load-bearing strength, tensile strength, static shear strength, fatigue of the anchor points, 25 impact absorption, wear ~ and surface abrasion. Such ~Ir~ can be evaluated using procedures commonly accepted for the evaluation of natural tissue and joirlts, as weD as the evaluation of' '~
In panicular, preferred composite materials, in the cured form, exhibit mechanical properties ~.uu" ' ,, those of the natural tissue that they are intended to replace. For 30 instance, preferred cured composites exhibit a load beartng strength of between about 50 and about 200 psi (pounds per square inch), and preferably between about 100 and about 150 psi. Such composites also exhibit a shear stress of between about 10 and 100 psi, .. .. . . : _ _ w0 ss/30388 2 1 8 9 6 4 3 P~
and preferably between about 30 and 50 p5i, as such units are typically determined in tùe evaluation of natural vissue and joints.
Preferred ' lc are also stable under conditions used for ~n.rjli7Arinn and av,li~iu"~ly are stable on storage and in the course of delivery. They are also capable of 5 flowing through a delivery cannula to an in vivo locavion, and being cured in situ, as by exposure to an energy source such as ultraviolet light or by chemical reaction. Thereafter the cured biomaterial is suitably amenable to shaping and contouring, by the use of ~ v,,~ d~v~l or custom designed A Ihu:,~,ul~h tools or Over the course of their use in the body the cured, contoured biomaterial exhibits ~h~
10 prvperties suitable for use in extended in vivo li, As arlother step of the method of the invention, the tissue injury site is prepared for receipt of the ' ~ Tbose skilled in the art will appt~cciate the manner inwhich computer analysis of ' ' ' ' bone mass can allow the operator to customi_ethe mechanical properties of the polymer-hydrvgel composite to match the adjacent 15 ' ' ' ' bone. This can be , ' ' ' by adjusting the si_e of the hydrvgel aggregates and by changing the percentage of the hydrogel in the polymer composite.
In a preferred method, the patient is ftrst prepped and draped as per rvutine Vl ' procedure. The first area to by resurfaced is then positioned ~
arld facing upright. If the opposing bone requires resurfacing the joiM can be 20 Ic~u~i~iu..cJ after the initial application has cured. This will allow gravity to assist in filling the anchor points and ~' ' -1, the liquid composite evenly over the surface to be covered. Based on the present d~crrirtil n all the necessary maneuvers will typically be carried out using only two or thrcee access portals.
The surface to be bonded is first cleaned of ~ y synovia and frayed or 25 damaged cartilage using a laser knife and/or other such as an shaver. The surface is then be prepared in order to imprvve its ability to accept and retain ' ' For instance, the ' ' ' ' bone is roughened by a burr and any osteophytes removed, also by the ùse of a burr. The bone is then irrigated to remove debris and the site suctioned dry. The bone can also be abraded in order to roughen its 30 suOace. or it can be coated with a suitable cement ~r ot~er interface material.

wo gs/30388 2 1 8 9 6 4 3 - -In a preferred ~ hu~ , anchoring points are created in the supponing join~tissue. For instance, invened T-shaped (1) altchor points can be cut into the ' ' I bone using speciaUy designed ~..i u~uu;~ drill bits or by laser means.
If only a small patch is needed only one or two anchor points may be sufficient,providing the number and _ of points is sumcient to prevent rotational or ' movement of the cured ' If a larger area of canilage is being replaced, then six to nine anchor points may be ncccssary. The number, size and location of sites can be daermined on a case by case basis, by balancing the need to retain the cured biomaterial in permanent _ 1, with the natural tissue, with the need to avoid undue trauma or damage to the structural integrity of the natural tissue itself. Additional or other meatls~ for instance thc use of cements, can also be used to enhance the permanent ~ _ _ of the cured biomaterial with the natural joint tissue.
For instance, the prepared bone surface, including the anchor sites, can be treated with high molecular weight hyaluronic acid. This will improve adhesion of the polymer and act to inhibit r~ and local u~twuulu~;S. High molecular weight hyaluronic acid has also been shown to be an effective stimulator of osteophytes (i.e., bone-forming cclls) as well as an inhibitor of T ' I al-l). As an IL-I inhibitor, the acid will tend to decrease the i '' y response in the area around the new insert.
As another step of the invention, a desired quantity of the curable biomaterial is delivered by minimally invasive means to the prepared site. Uncured I i, either in bulk or in the form of separate reaclive ~ can be stored in suitable storage containers, e.g., sterile, teflon-lined metal canisters. The biomaterial can be delivered, as with a pump, from a storage canister to the delivery cannula on demand. Biomaterial can be delivered in the form of a single . e.g., including both polymer matrix and hydrogel, or can be delivered in the form of a plurality of . , or ingredients.
For instance, polymer matrix and hydrogel can be separately stored and suitably mixed or combined either in the course of delivery or at the injury site itsehf.
An example of a delivery system that can serve as a model for the delivery of uncured ' '- is one presently sold by Dyonics, Inc. as the "InteliJET Fluid r~ _ System". This system involves the a low pressure, high flow rate delivery w0 ss/3038s 2 1 8 9 ~ ~ 3 r~
of saline to a site, and combines delivery with suction that is ~ "~, adjusted to specific blade styles.
In terms of its component parts, a preferred delivery system of the present invention wiD typicaDy include a motor drive unit, with a remote controller, associated tube sets, a nonscope inflow delivery camnula, having "r ~ fluid dynamics pressure and flow rate ~ 'j , an energy source for curing, for the flush, vacuum, waste canister, overflow jars.
The application cannula wiD then be inserted into the joint and under v;~u~l;~liùll from the fiberoptic scope the polymer composite will be appGed to the ' ' ' I bone.
The flow of the liquid phw polymer composite will be conttolled by the operator via a foot pedal connected to the pumping mechanism on the polymer canister. The liquid phw polymer composite wiD flow from the tip of the application catheter to fill the anchor points and ~ ' . '~, cover the ~ ' ' ' ' bone.
As another step of the invention, the delivered biomaterial is cured by minimaDyinvasive means and in such a manner that the cured biomaterial is retained in apposition to the prepared site. As described herein, the biomaterial can be cured by any suitable means, either in a single step or in stages as it is delivered. Preferred ' ' are curable by the application of ultraviolet light, making them particularly amenable to a system that delivers such light by minimally invasive means.
When a suff~cient amount of uncured biu~ul~ has been delivered, pol~...~,.i~liùll can be initiated by any suitable means, e.g., by the use of an ultraviolet light source at the tip of the application camnula. After the composite has cured the surface can be contoured as needed by other The joint wiD then be irrigated and the removed from the portals.
Using the preferred composite materials described herein it is envisioned that there may be some natural migration of the hydrogel component to the composite surface in the course of curing. This migration will tend to produce a net positive charge across the surface of the composite. This positive charge, in turn, wiD tend to bind negatively charged hyaluronic acid, which is a compound that naturaDy ocwrs in the joint (ptoduced by Type A ~,~,,ùviuu~:ui,). While not intending to be bound by theory, it would appear that the result of such binding will produce a lubricating effect to the surface of the composite. Since the hyaluronic acid is a normal product of the synovial lining ceD it wossl30388 2 1 89643 r~l,L.. 7/
will be l~"" ~ ' - ' A synthetic hydrophilic bilayer may altL~ i be applied to reduce the coefficient of friction funher.
The steps of preparing the joint surface and contouring the cured ' l as described herein, can be r . ' ' ' using .u..~ iu..~ hlu~-u,ui- instruments and tools. Stryker, Inc., Zimmer, Inc. and Dyonics, Inc. for instance, produce a wide array of ~ U:lLU~ surgical blades and : P~ . products are described in Dyonics' U.S. Patent Nos. 4,274,414, 4,2û3,444, 4,705,038, 4,842,578, 4,834,729,and 4,983,179, the disclosure of each of which is i , ' herein by reference.
In yet another step of the present invention, the cured, retained biomaterial iscontoured to achieve a desired r ' ~ that of natural tissue.
The preferred Cûmposite is heat moldable, allowing for sculpting with a probe that car~ be introduced through an ~;' . portal. Such a probe will typically have a retractable, flat spatula-shaped end. The tip of the spatula can be heated to about 100 degrees centigrade, at which: . ~ the surface of the composite can be sculpted to the desired contour. As the composite c0015, it wiD have sumcient memory to retain the shape it was given.
If unusual wear occurs in a given area, the implant can later be resculpted to cover the worn area without the need to repeat the entire process described above. Instead, the heat probe can simply be re-inserted under the: ' U~U,U;L visualization and the insert remolded to provide adequate size or properties in the needed area.
The steps described herein can be performed or combined in any suitable fashion.For instance, it is ~ , ' ' that the delivery, curing and contouring of biomaterial can be - . " ' ' ' 1~, and in a single step, for instance, by the use of a mold that retains a biomaterial in a desired shape as it is delivered and cured.Optionally, and preferably, the final biomaterial can be subjected to further physica]/chemical ' ' , e.g., in order to enhance i~
' ~ . ' ' :~" and Ihe like. For instance, calcitonin and y inhibiting molecules such as Interleuken I inhibitors can be attached to the bone composite surface to prevent local o~.~u,uu~u~;~ and local A ' y response which cause loosenmg.
Similarly, the surface of the cured composite can optionally be modifled in order to reduce the coefficient of friction.

w0 95/3038~ 2 t 8 9 6 4 3 r."~m ., In a preferred ' ' ~, a computer program can be useci that is based on extsting and ideai articulation angles. The program can assist the operator in producing a component having an optitnai . ' of physicai .,I.~ct~ , for instance contour and thici~ness, in order to provide optimai aiignment of the involved joint Sitniiarly, a i~ , . ' image can be generated through the u~upc to aid the opercttor in producing the optimal thickness and contour of the polymer composite. Smaii joint ~ , e.g., for wrists and ankles, as weii as for metacarpai phaiangeai joints, proxtmal interphaiangeai joints, metatarsal phaiangeai joints, and first !, ' - . I
joints can also be develope(i.

Claims

What is claimed is:

1. A method for repairing or resurfacing the site of injured orthopedic tissue, the method comprising the steps of:
(a) providing a curable biomaterial; and (b) employing minimally invasive means to (i) prepare the tissue injury site for receipt of the biomaterial;
ii) deliver a quantity of the curable biomaterial to the prepared tissue injury site;
(iii) cure the delivered biomaterial in such a manner that the cured biomaterial is permanently retained in apposition to the prepared site; and (iv) contour the cured, retained biomaterial to achieve a desired conformation approximating that of natural tissue.

2. A method according to claim 1 wherein the curable biomaterial comprises a polymeric matrix and hyrdrogel combination.

3. A method according to claim 2 wherein the polymeric matrix is selected from the group consisting of silicone polymers and polyurethane polymers.

4. A method according to claim 1 wherein the minimally invasive means are each performed using an arthroscopic instrument.

5. A method according to claim 4 wherein the delivery step is performed under arthroscopic visualization using a cannula suitably dimensioned to deliver a flowable composite.

6. A method according to claim 1 comprising the further step of coating or modifying the surface of the contoured material with a permanent interface material in order to improve the biocompatibility or coefficient of friction of the final implant.

7. A system for repairing or resurfacing a site of injured orthopedic tissue, comprising curable biomaterial. in combination with minimally invasive means forpreparing the tissue site; delivering the biomaterial to the prepared tissue site; means for curing the biomaterial in situ; and contouring the cured biomaterial.

8. An arthrosopic instrument set comprising minimally invasive means for delivering, curing, and contouring a flowable biomaterial.

9. An instrument set according to claim 8 wherein the means comprises a cannula capable of being operated in a minimally invasive fashion under arthroscopic visualization, together with associated connective tubing and containers for the operable and fluid attachment of the cannula to a source of biomaterial for the storage, delivery, and recovery of biomaterials.

10. A system for repairing or resurfacing the site of injured orthopedic tissue, the system comprising:
(a) an arthroscopic surgical instrument;
(b) a fluid delivery cannula capable of delivering a flowable, curable biomaterial comprising a curable polymer and hydrogel.

11. A method for repairing or resurfacing the site of injured orthopedic tissue, the method comprising the steps of:
(a) providing a flowable, curable biomaterial comprising a curable polymer and hydrogel;
(b) preparing the tissue injury site by operation of the arthroscopic instrument;
(c) preparing a tissue access site and inserting and directing the delivery cannula through the tissue access site to the site of tissue injury;
(d) delivering a quantity of the curable biomaterial through the cannula to the prepared site;
(e) curing the delivered biomaterial by minimally invasive means and in a mannersuch that the cured biomaterial is retained in apposition to the prepared site: and (f) contouring the cured biomaterial to achieve a desired conformation approximating that of natural tissue.

12. A method according to claim 11 comprising the further step of coating or modifying the surface of the contoured material with a permanent interface material in order to improve the biocompatibility or coefficient of friction of the final implant.