WO2000023009A1

WO2000023009A1 - Apparatus for percutaneous interposition balloon arthroplasty

Info

Publication number: WO2000023009A1
Application number: PCT/US1999/024467
Authority: WO
Inventors: John T. Frauens
Original assignee: Frauens John T
Priority date: 1998-10-21
Filing date: 1999-10-21
Publication date: 2000-04-27
Also published as: EP1123068A1; CA2347977A1; AU1317700A; JP2002538850A

Abstract

The current invention is a method and apparatus (300) for percutaneous interposition balloon arthroplasty. The method comprises the steps of entering a joint (10), introducing a deflated balloon (200) within the joint, and inflating the balloon (300) with a filler solution. The apparatus of this invention is a balloon (300) suitable for percutaneous interposition arthroplasty, comprising an outer shell (210) and a filler solution. The balloon (300) may further comprise a filling solution that comprises a condensed phase composition, a gas composition, and any mixtures thereof.

Description

APPARATUS FOR PERCUTANEOUS INTERPOSITION BALLOON ARTHROPLASTY

FIELD OF THE INVENTION This invention relates to a method and apparatus for performing arthroplastic surgery for the interposition of balloons within joints. Specifically, this invention relates to a method and apparatus for performing percutaneous interposition balloon arthroplasty for the repair of

movable and mixed articulating joints in the body.

BACKGROUND OF THE INVENTION

There are three basic classifications of joints of the human body: synarthroidal, amphiarthroidal, and diarthroidal. Synarthroidal joints provide immovable articulations;

amphiarthroidal joints provide mixed articulations; and diarthroidal joints provide movable articulations. Healthy fibrocartilage and hyaline cartilage within the joint provide a weight bearing function and allow painless articulation of amphiarthroidal and diarthroidal joints.

Primary osteoarthritis is a debilitating disease that affects amphiarthroidal and diarthroidal joints. The changes that occur with primary osteoarthritis involve altered biomechanical, biochemical, histologic and metabolic characteristics of the cartilage, synovial fluid and bone. Initially, these changes affect the articular cartilage and eventually affect the

surrounding perichondral tissues in a cascade of events. Articular cartilage comprises 70-

80% water and functions as a weight bearing surface by its unique interaction between the water and cartilage matrix. There are many theories concerning how articular cartilage

functions as a weight bearing surface which include hydrodynamic, boundary, elastohydrodynamic and squeeze film lubrication. However, it is known that the viscoelastic properties contribute to the multiple functions of articular cartilage, including its weight bearing function. The viscoelastic properties of cartilage are due to an intricate tight meshwork of interlacing collagen fibers that physically ensnare the large macromolecules of proteoglycan. For example, in a typical case of osteoarthritis of the hip joint, the femoral head

remains covered with fibrocartilage over a third to two-thirds of its surface, but in the superior weight bearing region, the lining tissue becomes considerably thinner, although intact throughout. Where thin, the lining tissue is partly fibrocartilage, and partly fibrous,

displaying focal areas of cystic degeneration. However, where fibrocartilage is present, the

thickness of the membrane between the femoral cup, cacetabulum, and the bone does not generally exceed 2 mm.

To treat osteoarthritis effectively, procedures are needed for repairing amphiarhroidal and diarthroidal joints that prevent the disintegration of fibrocartilage and that restore the

viscoelastic properties of articular cartilage for an indefinite period of time. Historically, repair of the joint was conducted by disintegration of the diseased tissue

followed by fibrous repair. However, this method has significant disadvantages, even when accompanied by conventional arthroplasty.

Orthopedic surgeons who specialize in total joint arthroplasties have been uncomfortable with performing resections of an entire joint. In the hip joint, for example, the

entire acetabulum down to the intra-pelvic bone and the proximal femur would have to be resected. Sections of the proximal femur that are resected in this procedure include the

femoral head, neck and intramedullary bone of the upper half of the femur. However, the pathology in primary osteoarthritis is initially and primarily isolated to the articular cartilage.

Thus, the resected tissue is many times greater than the surface area actually responsible for

the patient's symptoms.

Traditionally, osteoarthritis of the hip has been treated in one of two ways: arthroplasty utilizing foreign substances of non-animal origin, and other methods that ameliorate pain and disability in osteoarthritis of the hip. Arthroplastic procedures that

consist of interposing membranes, metallic cups, or other inserts to sustain the joint space

until new joint spaces can regenerate have been extensively used in the prior art.

Cup or mould arthroplasty has commonly been used to treat degenerative arthritis of the hip joint. This procedure consists of denuding the femoral head and the acetabulum to bleeding bone, and reshaping them into a ball and socket joint with a metallic cup interposed

between the two surfaces. The aim of mould arthroplasty is the formation of smooth glistening fibrocartilage around the periphery of the articular surface and hyaline cartilage in the central portion. Smith-Petersen concluded that, in response to physiologic stresses of friction and intermittent pressure of movement and supported weight-bearing, the repairing tissue will mold into smooth fibro-cartilage and in some instances to hyaline cartilage. M.N.

Smith-Petersen, 21 J. Bone & Joint Surg. 269 (1939). Other inventors used mould arthroplasty with varying degrees of success. P'ean and Chlumsky were the first to utilize foreign materials in arthroplasty, the former in human joints, while the latter experimented with an array of metal plates and films of celluloid, rubber, and collodion; Sir Robert Jones

successfully utilized a strip of gold foil to cover the reconstructed head of the femur; Pupovac

used magnesium plates; and Rehn was the first to use cup arthroplasty when he inserted a previously molded cap-like appliance of steel into the acetabular side of the hip joint. Paul H. Harmon, 76 Surg. Gyn. Obst. 347 (1943). Smith-Perterson utilized cups of various materials: glass, viscaloid, pyrex glass, bakelite, and vitallium. M.N. Smith-Peterson, J. M. J. Bone Surg., 18: 869 (1936). Vitallium was the most successful material used in cup arthroplasty.

However, cup arthroplasty caused severe trauma in patients and showed poor formation of hyaline cartilage. Other approaches have been used to repair disease of joints in the human body. For

instance, in the vertebral column, a collapsible plastic bladder-like prosthesis with the same

shape as the nucleus pulposis of an intervertebral disc is delivered via a stem into the space

between the vertebrae. U.S. Pat. No. 3,875,595 (Froning). A method and apparatus has been described for the repair of tissue in the vertebral column, such as fibrocartilage, using a bladder-like prosthesis device that can be inserted into the disc space and thereby infused with biomaterial to distract the space and provide a permanent replacement disc. However, this method addresses only prosthetic placement in the vertebral column. PCT Pat. App. No.

WO 97/26847 (Felt, et al). In yet another case, an arthroscopically implantable prosthetic device consisting of a pair of multi-compartment rings shaped to fit into a joint and filled with a polymeric substance is used to restore function to a diseased joint. U.S. Pat. No.

5,344,459 (Swartz).

What is needed is a method and apparatus for restoring the function of movable and

mixed articulating joints and for repairing fibrocartilaginous tissue and restoring the

viscoelastic properties of articular cartilage in amphiarthroidal joints such as the hip for an indefinite period of time. SUMMARY OF THE INVENTION

The current invention provides a method and related materials for percutaneous interposition arthroplasty, comprising the steps of entering the joint with a probing device, introducing a deflated balloon within the joint, and inflating the balloon. Moreover, this method may further comprise the step of distending and debriding the joint prior to

introducing the deflated balloon, the step of keeping ligaments (e.g., the ligamentum teres)

intact, the step of resecting the ligaments, the step of closing the puncture wound, and the step of removing the balloon. Combinations of these steps are considered part of this invention.

In addition, this invention is a balloon suitable for percutaneous interposition arthroplasty and comprising an outer shell and a filler solution. The filler solution may be a condensed phase composition, a gas composition, or mixtures of gases and condensed phases.

Condensed phase compositions include, but are not limited to, polymers, curable condensed compositions, gels, resins, liquids, and solutions. This group further includes, for example, silicone-gel, saline solution, and soybean oil. Gas phase compositions may include, but are

not limited to, air, nitrogen, oxygen, argon, carbon dioxide, and mixtures thereof. The balloon may be any shape, may have multiple compartments, may be capable of withstanding

significant pressures, and may be relatively impenetrable. Combinations of filler solution materials are considered part of this invention.

The interposition of a balloon may also facilitate the repair or reformation of the cartilage tissue on the surfaces of the bones of the joint. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows primary osteoarthritis of the hip joint. Figure 2 shows hip joint distention and arthroscopic placement. Figure 3 shows balloon introduction.

Figure 4 shows balloon inflation. Figure 5 shows interposition balloon arthroplasty.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method and related devices for repairing joints and surrounding tissues by minimally invasive means. In particular, the invention provides a method and related materials for using minimally invasive means to repair and reconstruct tissue such as fibrocartilage, particularly fibrocartilage associated with diarthroidal and amphiarthroidal joints. The method involves using minimally invasive means to prepare the site of pathology, and distending a joint site in situ in order repair the damaged joint.

The method comprises the steps of: a. performing surgery to enter the joint; b. using a minimally invasive means to remove damaged or diseased

material from a narrowing joint space and nearby tissues; c. introducing at least one deflated balloon to a cavity; and d. inflating the balloon. Arthroscopy has revolutionized knee surgery but has been of minimal use, for example, when it comes to hip pathology. However, arthroscopy is applicable to the hip joint. The hip joint is well suited for balloon arthroplasty because the hip is accessible percutaneously without disturbing its blood supply. Furthermore, the joint can be significantly distended by releasing its inherent negative pressure, resulting in a relatively uncomplicated surgical process as the space between the acetabular fossa and the head of the

femur can serve as a suitable cavity for the delivery and inflation of a balloon. The surfaces of the acetabular fossa, the femoral head and surrounding tissues can be treated or covered

with a suitable material in order to enhance their integrity and use as a cavity. Moreover, the

ligamentum teres may be preserved or resected to ensure a permanent replacement procedure.

The ligamentum teres is vital only in infancy and childhood. By adulthood, the primary blood supply to the femoral head is through the anterior and posterior femoral circumflex arteries. As a result, the ligamentum teres can be resected with balloon insertion

while maintaining the blood supply through the circumflex arteries. The advantage of preserving the ligamentium teres is to add to the stability of the femur.

The procedure consists of, first, making an appropriate incision. Then, through a probing device such as an orthoscope, the hip joint is entered, distended and debrided. Depending on the circumstances, the ligamentum teres may be preserved. The debriding step

is optional. Then, through a probing device, a deflated balloon may be introduced within the

joint and distended similar to the fashion in which a breast implant is filled with saline. The arthroscopic introducer-inflator may be removed and the puncture wound(s) closed. Rehabilitation for such a procedure is relatively minimal. The advantages include joint space restoration with restoration of viscoelastic dynamics. Additionally, a total hip replacement

would remain viable if the procedure should fail. Moreover, a surgeon could wait for a

predetermined period of time and then remove the balloon implant if desired. This procedure permits the femoral head to be resurfaced (with the balloon or,

subsequently, by repair or reformation of the cartilage) without dislocating the hip which in

some circumstances would disrupt the blood supply, thereby causing avascular necrosis. The procedure, therefore, allows full access to the femoral head for complete resurfacing while maintaining the primary blood supply. Surgeons could reduce total hip arthroplasty with its inherent risks and complications to a brief, percutaneous, out-patient procedure with minimal risk plus maintenance of anatomy should a formal hip resection and replacement be required later on. Similar procedures could be used for balloon arthroplasty in other joints.

PREPARING THE JOINT SPACE AND INSERTING A BALLOON

The description of the preparation of the joint space and insertion of a balloon are

described for the hip joint. Similar procedures can be used for balloon arthroplasty of other joints. Figure 1 shows primary osteoarthritis of the hip joint. This may be characterized, in

part, by a narrowing joint space 10, cartilage loss 20, and thickening joint capsule 30. The

narrowing joint space 10 is the space between the head of the femur 40 and the acetabular

fossa 50. Other symptoms may exist and are well known to those in the art.

The procedure for balloon arthroplasty contains the following steps as appropriate.

(i) Assessment of the extent of osteoarthritis.

(ii) Distension of the joint. (iii) Orthoscopy into the joint space.

(iv) Optional removal and/or cleaning of destroyed tissue.

(v) Delivery of a deflated balloon. (vi) Inflation of the balloon.

(vii) Optional deflation/removal of the balloon.

Performing the surgery for entering the hip joint can be carried out using techniques

well within the skill of those in the art. The narrowing joint space 10 may be viewed, for

instance, by remote visualization techniques such as fiberoptic visualization. The integrity of the hip and femur can be assessed, and optionally, repaired, for example, by the application of a biocompatible patching material, such as a fibrin glue.

Figure 2 shows hip joint distention and arthroscopic placement. In some patients, joint distention is unnecessary. However, if a surgeon desires, distention may be achieved by mechanical displacement of the femur with respect to the acetabular fossa. The joint space

10 can be distended prior to and/or during either the preparation and/or delivery of the

balloon. Distension can be accomplished by any suitable means, including by mechanical

and/or hydrostatic means. A surgeon can employ external traction. An orthoscope 100 may

be inserted into the cavity 110 formed by distending the narrowed joint space 10. The

deflated balloon may then be placed into the distended cavity. If required, the destroyed pelvic and femur related tissue such as fibrocartilage may be removed and cleaned prior to inserting the deflated balloon. The remaining, repaired tissue

and bone matter serve as a support for an inflated balloon. The head of the femur 40 engages

a balloon 300 like a penile condom. The ligamentum teres may be preserved, so as to allow

any balloon to occupy the cavity, 110, except for the void around the ligamentum teres. See,

for example, Figure 5. Once the damaged material has been removed and the remaining joint tissues repaired, the joint space 10 may be used as a cavity 110 to contain a delivered balloon.

The joint space 10, including any repaired portions is created to be of sufficient dimension to allow a deflated balloon to be delivered and distended. By the use of distension, the joint

space 10 can be sufficiently re-established to achieve any desired final dimension and

position. The means used to accomplish distension (for example, another balloon or other

mechanical devices) may also form at least one barrier (for example, a cavity 110) for the

balloon. The narrowed joint space 10 may be easily distended by the use of one or more

inflatable balloons. When inflated, a balloon provides rigid walls that are capable of

expanding the joint space 10. An inflatable balloon provides sufficient strength and

dimensions and can be prepared using conventional materials. In use, the deflated balloon

can be delivered to the narrowed joint space 10 and inflated to separate the space 10. For

example, a balloon may be inserted with an orthoscope. Under certain circumstances, distension prior to the insertion of the inflatable balloon is unnecessary.

Once positioned within the cavity 110, Figure 4 shows that the orthroscope 100 may

be used to inflate a balloon by injecting a suitable filler solution (not shown) to create an

inflated balloon 300. Depending on the application, the same or different orthoscope may be

used for insertion of the deflated balloon 200, and for inflating the deflated balloon 200. For

example, an orthroscope 100 may be inserted into the space 10 to deliver an deflated balloon and a second probing device used to inflate the deflated balloon.

A suitable gas (for example, nitrogen, carbon dioxide, oxygen, argon, etc.) may be delivered in order to inflate the balloon in situ. Positioning of the balloon may be facilitated

by the use of ancillary means, such as using a C-arm cine , or by self-effecting means embodied within the balloon or the delivery apparatus. Suitable materials for preparing balloons of the present invention, for example, are those that may be used for balloon angioplasty. Suitable materials provide an optimal combination of such properties as compliance, biostability and biocompatability, and mechanical characteristics such as elasticity and strength. Balloons can be in any suitable form, including those having at least one layer and having at least one compartment when expanded. A useful balloon device will include the balloon (optionally having a plurality of lumens), a delivery probing device, and fluid or gas pressure means. An orthoscope may be used as a probing device.

Examples of suitable balloon outer shell 210 materials include, but are not limited to,

polyolefin copolymers, polyethylene, polycarbonate, and polyethylene terephthalate. Such polymeric materials can be used in either unsupported form, or in supported form, for

example, by the integration of polyethylene terephthalates or other fibers.

Balloons can also take several forms, depending on how the balloon is to be delivered and inflated. A single, thin walled balloon can be used, for instance, to contact and form a

barrier along the joint surface. A balloon can be provided that occupies less than the entire volume of the cavity 110. The balloon may be, for instance, in the shape of a cylinder or a

collapsed, bell tent.

Any portion, region or surface of the outer shell of the balloon 210 may be treated

with friction modifying coatings or other materials to improve or otherwise alter the physical

or chemical properties. A balloon of the present invention can be inflatably attached (for example, provided

in an releasable and deflated or inflated configuration) within or upon the end of a probing

device, in order to be inserted into the space 10 or cavity 110. Moreover, the balloon may be inserted using minimally invasive means, and remote visualization methods including

fiberoptic visualization.

Once within the space 10 or cavity 110, the balloon can be finally positioned and delivered. The balloon may be self-venting, in that whatever volume of gas may be present within the balloon and shaft at the time of insertion can be displaced by the filler solution and vented through the balloon walls, for example, to the surrounding tissue. The balloon may be evacuated by the application of suction or vacuum to the shaft. Some or all of the gas present within the shaft and/or balloon may be vented through the balloon material by the deliver of a

filler solution. As the filler solution fills the balloon and displaces the gas the filler solution also serves to inflate the balloon to a desired extent, and in a suitable position within the

cavity 110 sufficiently distended, the filler solution may be cured, or permitted to fully cure,

in situ in order to retain the balloon and filler solution permanently in place. This step is

optional and depends upon the filler solution.

The balloon may be fabricated from natural or synthetic materials, including but not limited to, polymeric materials, such as films or membranes, and woven or nonwoven fabrics or meshes. Balloons that will not permit the effusion or diffusion of liquids, gels, solids, other condensed compositions and gases can be fabricated as one or more layers comprising such materials, and/or with one or more regions or portions of differing properties.

The materials used to fabricate balloons may provide an optimal combination of such

properties as biocompatability, biodurability, strength, wall thickness, wettability with a filler solution, puncture resistance, compliance, flexibility, modulus of elasticity, stress/strain curve

yield point, burst pressure, maximum inflation, Young's modulus, shear modulus, and the ability to be easily fabricated and sterilized. Examples of suitable balloon materials include, but are not limited to, solid polymeric materials such as membranes. Polymeric materials may be provided with suitable venting

holes. Suitable polymeric materials include, but are not limited to, elastomeric and other materials commonly used for angioplasty and related application, and include polyurethanes,

polyolefins, polyamides, polyvinyl chlorides, and polyethylene terephthalates, as well as various copolymers, combinations and permutations thereof.

Balloon materials are available commercially for use in filtration and other

applications, and include cloth and mesh formed of polymeric materials such as polyester,

polypropylene and nylon threads. A material may be reinforced, for example, with woven glass or fine fibers of other materials, to provide added strength or other desirable properties. Such materials can be selected to provide an optimal combination of such properties as strength, mesh opening, thread diameter, mesh count, percent open area, and cost. Examples

of suitable materials are commercially available and include, but are not limited to, nylon screen cloth, such a nylon mesh.

The balloons themselves may be fabricated by a variety of means. The balloon may be formed as a continuous (for example, unitary) and non-interrupted (for example, seamless) form. The balloon may be fabricated from a plurality of generally sheet-like portions, which

can be assembled and sealed together. Sealing may be accomplished by any suitable means, including by the use of adhesives, sewing, RF bonding, heat sealing, impulse sealing, and any

combination thereof. Once sealed, the balloon may be turned inside out in order to provide the sealed seam on the interior of the resultant balloon.

The balloon may be fabricated to assume any desired shape upon inflation, for

example, a generally oval shape, or the shape of a kidney bean, in order to approximate the natural anatomical shape of the space 10. The balloon may provide major surfaces for

contacting the principal surfaces of the joint, for example, the head of the femur 40 and

acetabular fossa 50. The balloon may further provide wall portions for contact with other

tissue.

A balloon may be provided with one or more orientation markers, in order to permit the surgeon to determine the optimal orientation of the balloon in situ. Suitable orientation

markers include, but are not limited to, the placement of detectable markers or indications within or upon the balloon material and/or probing device, the marking or indications themselves being detectable by minimally invasive means, for example, by fiberoptic

visualization, interoperative magnetic resonance imaging (MRI), ultrasound, and laser radiation.

The deflated balloon may be positioned within the space 10 or cavity 110 following preparation. As described hereinabove, mechanical distension of the space can be used as well, for example, either while inserting and/or positioning a balloon and/or during inflation

of a balloon with filler solution.

Once in place within the cavity 110, the balloon may be filled by having the probing

device connected to a filler solution delivery device capable of delivering filler solution through the probing device and into the balloon under sufficient pressure. When in the form

of a curable polymer, the filler solution may begin to cure as it leaves the mixing chamber of

the delivery device. Saline, as a filler solution, will never cure. If a curing filler is chosen,

the cure rate of the biopolymer may be controlled, in combination with the dimensions and other conditions of the distension means, in order to provide sufficient time for the filler solution to expand the balloon before final curing occurs. Noncuring materials may change viscosity upon entering the cavity 110. Such changes may result from different pressures,

temperatures or both. In some cases, the phase of filler solution may change, for example, from gas to liquid or solid to liquid or gel, etc. The progress of inflating may be monitored,

for example, by C-arm cine or interoperative MRI.

"Cure" and inflections thereof, will refer to any change in the physical properties of a

material by chemical reaction or vulcanization. Curing may occur with the aid of any combination of heat, chemicals, catalysts, and energy, such as. but not limited to, light and

ultrasound. When used with regard to the method of the invention, for instance, "curable" can refer to uncured biomaterial, having the potential to be cured in vivo (as by the application of a suitable energy source), as well as to a biomaterial that is in the process of curing, as with a biomaterial formed at the time of delivery by the concurrent mixing of a plurality of biomaterial components.

Figure 5 shows interposition balloon arthroplasty upon completion. The balloon 300

becomes semi-circular shaped balloon 400, which encompasses the head of the femur 40.

The balloon can be left in place for a fixed period of time, and then removed by a similar procedure, or the balloon may be permanent. The balloon was constructed so that it would

form a semicircular shape and as it was distended would obtain stability by "locking" over the

expanse of the head-neck angle. The balloon may leave the ligamentum teres undisturbed.

FILLER SOLUTIONS Natural cartilage is a non-vascular structure found in various parts of the body.

Articular cartilage tends to exist as a finely granular matrix forming a thin incrustation on the surfaces of joints. The natural elasticity of articular cartilage enables it to break the force of concussions, while its smoothness affords ease and freedom of movement. Filler solutions

are intended to mimic many of the physical-chemical characteristics of natural tissue. Filler solutions can be provided as one component systems, or as two or more

component systems that can be mixed prior to or during delivery, or at the site of repair. Generally, fillers are flowable, meaning they are of sufficient viscosity to allow their delivery

into the balloon. The fillers may be heated or subject to pressure changes to aid flowing.

Moreover, the fillers may be solvated in a liquid, gel, or other condensed phase composition to aid flowing into the balloon with or without temperature or pressure changes. Suitable fillers may comprise gas phase compositions which include, but are not limited to, air, nitrogen, oxygen, argon, carbon dioxide, other inert gases, and mixtures thereof.

Filler solutions may be homogeneous (i.e., providing the same chemical-physical parameters throughout), or they can be heterogeneous. Filler solutions may be used that provide implants having varying regions of varying or different physical-chemical properties.

Common polymeric materials for use in medical devices include, but are not limited to, polyvinyl chlorides, polyethylenes, styrenic resins, polypropylene, thermoplastic

polyesters, thermoplastic elastomers, polycarbonates, acrylonitrilebutadiene-styrene ("ABS")

resins, acrylics, polyurethanes, nylons, styrene acrylonitriles, and cellulosic.

Suitable filler solutions are those polymeric materials that provide a suitable combination of properties relating to their device application and in vivo use. Such properties include, but are not limited to, processability and the ability to be stably sterilized and stored.

In the course of applying such material, such properties include in vivo flowability and moldability. The filler solution may comprise a thermosetting polyurethane polymer based on a

suitable combination of isocyanates, long chain polyols, and short chain (low molecular

weight) extenders and/or crosslinkers. Suitable components are available commercially and

are each may be used in the highest possible grade, for example, reagent or analytical grade or higher. Examples of suitable isocyanates include, but are not limited to, 4,4'-diphenyl methane diisocyanate ("MDI"), and 4,2'-diphenylmethane diisocyanate, including mixtures thereof, as well as toluene diisocyanate ("TDI"). Examples of suitable long chain polyols

include, but are not limited to, tetrahydrofuran polymers such as poly(tetramethylene oxide) ("PTMO"). Examples of suitable extenders/crosslinkers include, but are not limited to, 1,4- butanediol and trimethylol propane, and blends thereof. Such performance may be evaluated using procedures commonly accepted for the evaluation of natural tissue and joints. Curing is unnecessary, for example, for oils (carbon or

silicon based), water, saline solution, gels, resins and other condensed phases which may possess an optimal combination of physical chemical properties. Suitable gels, for example,

include silicone gels. Suitable oils include, for example, soybean oils. Filler solutions of the present invention may further include adjuvants and additives,

such as stabilizers, fillers, antioxidants, catalysts, plasticizers, pigments, and lubricants, to the

extent such ingredients do not diminish the utility of the composition for its intended purpose.

Filler solutions may be stable under conditions used for sterilization and stable on storage and in the course of delivery. They may be capable of flowing through a delivery

device to an in vivo location, and/or being cured in situ, as by exposure to an energy source such as light or by chemical reaction. Thereafter, a cured filler solution may be amenable to shaping and contouring. Uncured filler solutions may be shaped and contoured to the extent that the balloon and filler solution will allow.

One or more catalysts may be incorporated into one or more components of the

curable filler solutions in order to cure the filler solution in the physiological environment within a desired length of time. Curable filler solutions may be able to cure within about 5 minutes or less.

Means may be employed to improve the biostability, for example, the oxidative and/or hydrolytic stability, of the filler solution, thereby extending the life of the implant. Suitable

means for improving biostability include the use of aliphatic macrodiol such as hydrogenated polybutadiene (HPDI). By judicious choice of the corresponding diisocyanate (for example, MDI) and chain extender (for example, ethylenediamine), those skilled in the art will be able to achieve the desired packing density or crystallinity of the hard segments, thereby improving the hydrolytic stability of the cured polyurethane.

Filler solutions may be provided as a plurality of components, for example, a two-part

polyurethane system, may be mixed at the time of use using suitable mixing techniques, such as those commonly used for the delivery of two-part adhesive formulations. A suitable mixing device involves, for instance, a static mixer having a hollow tube having a segmented, helical vein running through its lumen. A two-part polyurethane system can be mixed by forcing the respective components through the lumen under pressure.

The foregoing description is intended to be illustrative of the invention, but is not to be considered as comprehensive or limiting of its scope.

Claims

What is claimed is:

1. A method of treating joint disease using percutaneous interposition arthroplasty, comprising the steps of:

a. using minimally invasive means to enter a joint space; b. introducing a deflated balloon within a joint space; and c. inflating the balloon.

2. The method of claim 1 , further comprising the step of distending a joint space prior to introducing a deflated balloon.

3. The method of claim 1 , further comprising the steps of: a. distending a joint space prior to introducing a deflated balloon; and b. using minimally invasive means to remove damaged or diseased material from

a joint space and nearby tissues.

4. The method of claim 1, further comprising the step of examining and determining the

integrity of the damaged tissue.

5. The method of claim 1, wherein the inflated balloon facilitates the repair or reformation of cartilage on one or more surfaces of the joint.

6. The method of claim 1, wherein the inflated balloon helps restore the viscoelastic dynamics of a joint space.

7. The method of claim 1, further comprising the step of covering joint surfaces and surrounding tissue in order to enhance the integrity of the joint.

8. The method of claim 2, or 3 where the distending step is achieved by mechanical means.

9. The method of claim 2, or 3 where the distending step is achieved by hydrostatic means.

10. The method of claim 1, where the minimally invasive means to enter a joint space are orthoscopic.

11. The method of claim 3, where the minimally invasive means to remove damaged or diseased material from a joint space and nearby tissues are orthoscopic.

12. A method of treating joint disease of the hip using percutaneous interposition

arthroplasty, comprising the steps of: c. using minimally invasive means to enter a hip joint space; d. introducing a deflated balloon within a hip joint space; and e. inflating the balloon.

13. The method of claim 12, further comprising the step of distending a hip joint space

prior to introducing a deflated balloon.

14. The method of claim 12, further comprising the steps of: a. distending a hip joint space prior to introducing a deflated balloon; and

b. using minimally invasive means to remove damaged or diseased material from a hip joint space and nearby tissues.

15. The method of claim 12, further comprising the step of examining and determining the integrity of the damaged tissue.

16. The method of claim 12, wherein the inflated balloon facilitates the repair or reformation of cartilage on one or more surfaces of the hip joint.

17. The method of claim 12, wherein the inflated balloon helps restore the viscoelastic dynamics of a hip joint space.

18. The method of claim 12, further comprising the step of covering joint surfaces and surrounding tissue in order to enhance the integrity of the joint.

19. The method of claim 12, wherein the balloon covers the femoral head.

20. The method of claim 12, wherein the ligamentum teres remains undisturbed.

21. The method of claim 12, wherein the ligamentum teres is resected.

22. The method of claim 13, or 14 where the distending step is achieved by mechanical means.

23. The method of claim 13, or 14 where the distending step is achieved by hydrostatic

means.

24. The method of claim 12, where the minimally invasive means to enter a joint space are orthoscopic.

25. The method of claim 14, where the minimally invasive means to remove damaged or diseased material from a joint space and nearby tissues are orthoscopic.

26. The method of claim 12, where the joint disease is osteoarthritis.

27. A method of repairing a hip joint without dislocating the hip using percutaneous interposition balloon arthroplasty, comprising the steps of: c. using minimally invasive means to enter a hip joint space; d. introducing a deflated balloon within a hip joint space; and e. inflating the balloon.

28. The method of claim 1, or 12 wherein the balloon is semicircular.

29. The method of claim 1, or 12 wherein the balloon is inflated using orthoscopic means.

30. The method of claim 1, or 12 wherein the balloon is inflated with a filler solution.

31. The method of claim 30, wherein the filler solution is selected from at least one

member of a group consisting of polyvinyl chlorides, polyethylenes, styrenic resins, polypropylene, thermoplastic polyesters, thermoplastic elastomers, polycarbonates, acrylonitrilebutadiene-styrene resins, acrylics, polyurethanes, nylons, and styrene acrylonitriles

32. The method of claim 30, wherein the filler solution comprises a thermosetting

polyurethane polymer.

33. The method of claim 30, wherein the filler solution is selected from at least one member of a group consisting of gels and oils.

34. The method of claim 30, wherein the filler solution is selected from at least one member of a group consisting of carbon dioxide, oxygen, and nitrogen.

35. The method of claim 30, wherein the filler solution is selected from at least one member of a group consisting of inert gases.

36. The method of claim 30, wherein the filler solution is curable.

37. The method of claim 1, or 12 wherein the balloon comprises an outer shell.

38. The method of claim 37, wherein the outer shell comprises at least one member of a

group consisting of PVC, polyurethane, polyethylene terephalate and polycarbonate.

39. A balloon suitable for percutaneous interposition arthroplasty, comprising an outer shell.

40. The balloon of claim 39, wherein the outer shell comprises one member selected from

a group consisting of PNC, polyurethane, polyethylene terephalate, and polycarbonate.

41. The balloon of claim 39, wherein the balloon is semicircular.

42. The balloon of claim 39, wherein the balloon is capable of withstanding pressures of at least 500 pounds per square inch.

43. The balloon of claim 39, wherein the balloon is capable of withstanding pressures of at least 500 pounds per square inch.