Joint spacer

Abstract

A joint spacer is disclosed. In one embodiment, the joint spacer is biostable and has a first side (3) comprising a raised portion (5) and a peripheral portion (6) surrounding the raised portion. The raised portion comprises a foam (1) and the foam has a porosity at the peripheral portion that is less than the porosity at the thickest point of the raised portion.

Description

Technical Field

[0001] The present invention relates to joint spacers comprising foam, methods of making joint spacers comprising foam, and methods of treating patients using such joint spacers. Background Art

[0002] Joint spacers are common medical devices in the field of orthopedics. Joint spacers separate and support the bones of a joint to relieve pain or promote healing in a desired configuration. Joint spacers can also serve as soft tissue replacements for damaged or removed tissue.

[0003] Joint spacers can be used to treat rotator cuff tears, such as large, irreparable rotator cuff tears. The goal of this type of joint spacer is to restore the biomechanics of the humeroscapulohumeral joint by lowering the humeral head and reducing subacromial friction during shoulder abduction. In addition, the joint spacer can be delivered arthroscopically via a cannula into the subacromial space, where it is deployed or inflated. Therefore, it provides a relatively quick and potentially low-risk procedure to relieve pain. A further application of joint spacers is in the knee or hip, such as an artificial meniscus in the knee.

[0004] An example of an articulator spacer used in the subacromial space is the InSpace Biodegradable Subacromial Spacer from Stryker Corp. The device is biodegradable and is designed to restore the subacromial space without the need for sutures or fixation devices.

[0005] Other applications of joint spacers are in the knee or hip joints, such as artificial menisci in the knee. The geometry of the joint spacer can vary according to a particular geometry. For example, a joint spacer used as an artificial meniscus can adopt the general shape of a biological meniscus.

[0006] Despite these advances, there remains a need for improved joint spacers, particularly those for use in the subacromial space. Summary of the invention

[0007] Current joint spacers have several potential disadvantages. First, difficulties may be encountered in fixing the joint spacer. Second, biodegradable spacers may be less popular than biostable materials due to the biological effects of degradation products in the body and the short-term effects of intervention. Third, discomfort or inflammation may occur due to friction between the joint head and the joint spacer.

[0008] To permanently fix the joint spacer in the body, a sling or other fixation method may be needed. Another option is to use a balloon or other expandable material, but these materials may still move out of place after implantation. Using sutures to fix the joint spacer also has its disadvantages, as the friction between the sutures and the joint spacer may cause tears in the joint spacer over time. Therefore, a joint spacer that can be fixed for a long time without tearing may be needed.

[0009] According to one embodiment of the present invention, the joint spacer includes a biostable support that allows tissue ingrowth. The biostable support should be strong enough in certain positions so that it can be fixed for a long time by sutures without tearing. In some embodiments, this is achieved by compression and heat setting technology, which causes the porosity of the foam to change in relation to its thickness. Porosity is defined as the percentage of void space in this article. In one embodiment, the thickness of the foam changes so that the center of the first surface of the joint spacer is thicker than its peripheral portion. Therefore, the porosity of the foam at its central position is greater than the porosity of its peripheral portion. In one embodiment, due to the greater compression of the foam at the peripheral position, the porosity of the foam at the peripheral position is smaller. The compression at the peripheral position increases, thereby reducing the porosity, increasing the tear strength of the foam, and better allowing the joint spacer to be fixed by sutures or other fixation methods.

[0010] According to one embodiment of the present invention, the joint spacer includes a first side and a second side opposite to the first side, wherein the first side includes a convex protrusion, the convex protrusion includes foam, and the foam has a porosity that decreases radially from the center of the first side to the periphery of the convex protrusion. According to one embodiment of the present invention, the joint spacer includes a first side, i.e., a side facing the joint, and a second side opposite to the first side, i.e., a side facing the bone, wherein the first side includes a convex protrusion, the convex protrusion includes foam, and the foam has a porosity that decreases radially from the center of the first side to the periphery of the convex protrusion. In one embodiment, the first side faces the bone and the second side faces the joint. The joint spacer may also include a peripheral portion surrounding the convex protrusion. The peripheral portion may have a substantially uniform thickness and / or a constant porosity distribution throughout the peripheral portion.

[0011] In one embodiment, the first side is the first articular surface and the second side is the second articular surface. In the context of the joint spacer of the present invention, the articular surface is the surface of the joint spacer facing the articular surface of the joint. For example, in the context of a meniscus implant, the first articular surface may be configured as the articular surface facing the tibial plateau, and the second articular surface may be configured as the articular surface facing the femoral condyle. In one embodiment, the first side of the joint spacer is opposite to the second side.

[0012] According to a further embodiment of the present invention, the joint spacer includes a foam, which includes a first outer surface formed by a raised portion and a planar portion, wherein the raised portion is located inside the first outer surface and the planar portion is located outside the first outer surface, wherein the porosity of the foam is greater in the raised portion than in the planar portion.

[0013] According to a further embodiment of the present invention, the joint spacer includes a foam, which includes a first outer surface formed by a raised portion and a planar portion, wherein the raised portion is located inside the first outer surface and the planar portion is located outside the first outer surface, wherein the porosity of the foam is greater in the raised portion than in the planar portion.

[0014] In a further embodiment, the joint spacer includes a second surface opposite to the first surface. In one embodiment, the second surface is substantially planar. The second surface may be made of a material different from the foam, or include a surface coating contained within the foam pores. In one embodiment, the first surface or the second surface is the surface of a polyurethane sheet. In one embodiment, the polyurethane sheet is fixed to the foam by physical entanglement with the foam. In one embodiment, the polyurethane sheet or foam surface is coated with a thin layer of collagen to form a boundary layer on the surface. In one embodiment, the second surface faces the bone and the convex protrusion faces the joint. In one embodiment, the second surface faces the joint and the convex protrusion faces the bone. In one embodiment, the joint spacer is positioned so that the surface facing the bone is located near the bone surface, such as the humeral head of the shoulder, and the first surface faces the inside of the joint. In one embodiment, the joint spacer is positioned so that the second surface is located near the bone surface, such as the humeral head of the shoulder, and the first surface faces the inside of the joint.

[0015] In a further embodiment, the joint spacer can be manufactured with reinforcing elements to assist fixation and / or increase mechanical strength, such as at the spacer interface within the anatomical structure. The reinforcing element can be made of a material different from the foam. The reinforcing element can be composed of sutures, straps, ribbons, textiles, or solid configurations such as bone screws or molded anchors. In one embodiment, the reinforcing element is made of a UHMWPE fiber band commonly used in orthopedic repair. In one embodiment, the position of the reinforcing element enables the joint spacer to be fixed to a bone surface, such as the humeral head of the shoulder, to fix the spacer at a specific position inside the joint.

[0016] The joint spacers disclosed herein may exhibit improvements in tissue ingrowth or repair, reduced inflammation, extended duration of treatment, improved dimensional stability, ease of management, more economical manufacture or management, reduced complications, improved placement stability, improved suture retention, reduced tearing, or increased patient comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A is a side cross-sectional view of a joint spacer according to one embodiment of the present invention.

[0018] Figure 1B is a side cross-sectional view of a joint spacer according to one embodiment of the present invention.

[0019] Figure 2 is a top view of a first side of a joint facing a joint of a joint spacer according to one embodiment of the present invention.

[0020] Figure 3 is a side cross-sectional view of the molding process before the foam is compressed.

[0021] Figure 4 is a side cross-sectional view of the molding process after the foam has been compressed.

[0022] Figure 5 is a side cross-sectional view of a joint spacer comprising two reinforcement elements in the form of sutures.

[0023] Figure 6 yes Figure 5 Top view of the illustrated embodiment.

[0024] Figure 7 is a side cross-sectional view of a joint spacer comprising two reinforcement elements in the form of sutures.

[0025] Figure 8 is a side cross-sectional view of a joint spacer comprising a textile embedded in foam. DETAILED DESCRIPTION

[0026] Figure 1AA side cross-sectional view of a joint spacer according to one embodiment of the present invention is shown. Figure 1A As shown, the joint spacer comprises foam 1 and a sheet 2 adhered to the surface of the foam. The joint spacer comprises a joint-facing side 3 and a bone-facing side 4.

[0027] Figure 1B A similar embodiment is shown in FIG. 5 , which is a side cross-sectional view of a joint spacer according to an embodiment of the present invention. Figure 1B As shown, the joint spacer comprises foam 1 and a sheet 2 adhered to the surface of the foam. The joint spacer comprises a joint-facing side 3 and a bone-facing side 4.

[0028] Figure 1A and Figure 1B The joint spacers of the embodiment of the present invention all include a convex protrusion 5 formed of foam. Each includes a peripheral portion 6A, 6B. The foam shown has a porosity that decreases radially from the thickest part of the convex protrusion to the peripheral portion and remains constant throughout the peripheral portion. Figure 1A and Figure 1B As shown, the peripheral portion is planar. In one embodiment, the change in porosity is achieved by compressing the shape of the foam raw material, as described below.

[0029] The joint spacer comprises foam. In one embodiment, the foam is an open cell foam. The foam is biocompatible. In one embodiment, the foam is biostable. In one embodiment, the foam is biodegradable. In one embodiment, the foam is elastic. In one embodiment, the foam comprises polyurethane. In one embodiment, the foam comprises thermosetting polyurethane.

[0030] In one embodiment, the foam has a continuous and interconnected void phase. The continuous and interconnected void phase is a continuous network structure that defines void spaces therein, and the void spaces include a plurality of interconnected pores that form a continuous network of interconnected channels. In one embodiment, the continuous and interconnected void phase extends from the surface of the foam. In one embodiment, the continuous and interconnected void phase runs through the foam, making the foam fluid permeable from one surface to another. In one embodiment, the foam includes an internal continuous and interconnected void phase and an external skin layer. In one embodiment, the continuous and interconnected void phase is formed by a network structure as described below.

[0031] In one embodiment, the foam is coated with a material to encourage cell growth or proliferation. In one embodiment, the coating material comprises collagen, fibronectin, elastin, hyaluronic acid, or a mixture thereof. In one embodiment, the surface of the joint spacer is coated with a thin layer of collagen to form a boundary layer on the surface. In one embodiment, the surface facing the bone comprises a layer of collagen. In one embodiment, the surface facing the joint comprises a layer of collagen. In one embodiment, the surface of the joint spacer is coated with a bioactive agent or a coating comprising a bioactive agent. In one embodiment, the foam is coated with a bioactive agent or a coating comprising a bioactive agent.

[0032] In one embodiment, the foam is as described in US7803395 or US9050176, both of which are hereby incorporated by reference in their entirety.

[0033] In one embodiment, the plurality of interconnected pores have an average diameter or other largest transverse dimension of at least about 50 micrometers. In one embodiment, the void space comprises about 70 wt % to about 99 wt % of the volume of the foam in its uncompressed state.

[0034] The foam is compressed at multiple locations from its neutral state. In one embodiment, the foam includes uncompressed locations. In one embodiment, the foam is compressed at all locations. In one embodiment, the foam has a density ratio of 15:1, 12:1, 10:1, or 9:1 to 2:1, 3:1, 4:1, 5:1, or 6:1 from its most compressed location to its least compressed location. In one embodiment, the foam has a density ratio of about 8:1 from its most compressed location to its least compressed location.

[0035] In one embodiment, the bulk density of the foam before any compression may be between about 0.008 g / cc and about 0.96 g / cc. In another embodiment, the bulk density is between 0.25 and 0.75 g / cc. In another embodiment, the bulk density may be between about 0.016 g / cc and about 0.56 g / cc. In another embodiment, the bulk density may be between about 0.008 g / cc and about 0.15 g / cc. In another embodiment, the bulk density may be between about 0.008 g / cc and about 0.127 g / cc. In another embodiment, the bulk density may be between about 0.008 g / cc and about 0.288 g / cc. In another embodiment, the bulk density may be between about 0.016 g / cc and about 0.115 g / cc. In another embodiment, the bulk density may be between about 0.024 g / cc and about 0.104 g / cc. The bulk density is measured according to the test method described in ASTM Standard D3574.

[0036] In one embodiment, the bone facing side comprises a sheet. In one embodiment, the sheet is adhered to a second side of the foam opposite the side comprising the convex protrusions. In one embodiment, the second side is planar. In one embodiment, the sheet is adhered to the side of the foam comprising the convex protrusions. In one embodiment, the sheet is adhered to the foam by physical entanglement of polymer chains.

[0037] In one embodiment, the sheet provides a smooth outer surface on the joint spacer, limiting friction on tissue surfaces (such as bone). Therefore, in one embodiment, the sheet is located on the side of the joint spacer facing the bone. In one embodiment, the hardness of the sheet is between Shore 50A, 60A, 70A or 75A to 80D, 75D, 70D, 60D or 50D. The sheet may also have advantages in further improving the suture retention of the joint spacer, such as in its peripheral portion. In one embodiment, the sheet covers the entire surface of the foam. In one embodiment, the sheet at least partially covers the surface of the foam.

[0038] In one embodiment, the sheet material comprises polyurethane. In one embodiment, the sheet material comprises thermoplastic polyurethane. In one embodiment, the sheet material is formed by casting a film comprising polyurethane dissolved in a solvent and then evaporating the solvent. In one embodiment, the sheet material is formed by molding or extrusion. In one embodiment, the thickness of the sheet material is between 10 microns and 1 millimeter. In one embodiment, the thickness of the sheet material is between 50 and 500 microns.

[0039] The joint spacer may exhibit elasticity, that is, the ability to recover or spring back to its original shape after being bent, stretched or compressed. This property may allow the joint spacer to be targeted and released at the surgical site using minimally invasive means, such as a catheter, endoscope, arthroscopy, laparoscope, cystoscope, or syringe. After being delivered at the targeted site, the joint spacer may substantially recover its shape.

[0040] At peripheral locations such as the joint spacer, the density of the foam is increased, allowing for increased resistance to suture tearing compared to the foam in an uncompressed state. Figure 2 A top view of a first side of a joint spacer facing the joint according to an embodiment of the invention is shown. The convex protrusion 5 has the shape of an oval portion, surrounded by a peripheral portion 6. The peripheral portion 6 comprises a plurality of holes 7, 8, 9, 10 which can be used to fix the joint spacer to the patient's anatomy.

[0041] The foam is formed from a matrix. In one embodiment, the matrix is ​​a polymer. In one embodiment, the matrix is ​​formed by reacting a mixture comprising: (i) a polyol, and (ii) an isocyanate component. In one embodiment, the mixture further comprises a chain extender. In one embodiment, the matrix is ​​thermosetting. In one embodiment, the matrix is ​​thermoplastic. In one embodiment, the elastic matrix does not contain isocyanurate and biuret linkages.

[0042] One embodiment relates to a method for preparing an elastic matrix comprising a continuous network of interconnected channels, the method comprising: (a) synthesizing a polycarbonate polyurethane foam by reacting a mixture comprising: (i) a polycarbonate polyol, (ii) an isocyanate component, and (iii) a blowing agent for forming the plurality of pores, the foam being composed of a plurality of cell walls defining a plurality of pores therein; and (b) igniting a combustible gas to remove at least about 40 wt % of the plurality of cell walls to form the continuous network of interconnected channels.

[0043] In one embodiment, the foam comprises polyurethane. In one embodiment, the sheet comprises polyurethane. Polyurethane comprises the reaction product of an isocyanate and a polyol. In one embodiment, the polyurethane comprises the reaction product of a diisocyanate, a polymerized aliphatic diol, and an optional chain extender. In one embodiment, the polyurethane consists of the reaction product of a diisocyanate, a polymerized aliphatic diol, and a chain extender diol. In one embodiment, the polyurethane is linear.

[0044] By reaction product is meant the isocyanate and the polyol participating in a simultaneous or sequential chemical reaction. For example, the reaction product of a diisocyanate, a polymeric aliphatic diol and a chain extender diol is formed when (i) the diisocyanate, the polymeric aliphatic diol and the chain extender diol are all reacted in a single solution, or (ii) a prepolymer is first formed by reacting the diisocyanate and the polymeric aliphatic diol, and this prepolymer is subsequently reacted with the chain extender diol.

[0045] The components of an exemplary polyurethane comprising a diisocyanate, a polymeric aliphatic diol, and a chain extender will now be described. These components may be present in the foam, the sheet, or both.

[0046] Diisocyanates

[0047] The polyurethane includes residues of diisocyanates. In one embodiment, the diisocyanate is aliphatic. In one embodiment, the diisocyanate is aromatic. In one embodiment, the diisocyanate includes 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,4-phenylene diisocyanate, hexamethylene diisocyanate (HDI), tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate (HMDI), isophorone diisocyanate (IPDI), or a mixture thereof. In one embodiment, the diisocyanate includes hexamethylene diisocyanate, dicyclohexylmethane 4,4′-diisocyanate, isophorone diisocyanate, or a mixture thereof. In one embodiment, the diisocyanate is composed of hexamethylene diisocyanate, dicyclohexylmethane 4,4'-diisocyanate, isophorone diisocyanate, or a mixture thereof. In one embodiment, the diisocyanate includes 4,4'-diphenylmethane diisocyanate (MDI), 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, or 1,4-phenylene diisocyanate. In one embodiment, the diisocyanate is composed of 4,4'-diphenylmethane diisocyanate (MDI), 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,4-phenylene diisocyanate, or a mixture thereof. In one embodiment, the diisocyanate includes 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, or a mixture thereof.

[0048] In one embodiment, the molecular weight of the diisocyanate is from 100 to 500 g / mol. In one embodiment, the molecular weight of the diisocyanate is from 150 to 260 g / mol.

[0049] In one embodiment, the diisocyanate in the polyurethane-forming formulation is at least 10 wt%, at least 20 wt%, at least 25 wt%, at least 30 wt%, at least 35 wt%, or at least 40 wt%, based on the total weight of the formulation. In another embodiment, the weight percentage of diisocyanate in the polyurethane-forming formulation is at most 50 wt%, at most 40 wt%, at most 35 wt%, at most 30 wt%, at most 25 wt%, or at most 20 wt%, based on the total weight of the formulation. In one embodiment, the weight percentage of diisocyanate residues in the polyurethane is at least 10 wt%, at least 20 wt%, at least 25 wt%, at least 30 wt%, at least 35 wt%, or at least 40 wt%, based on the total weight of the polyurethane. In another embodiment, the diisocyanate residues in the polyurethane are at most 50 wt%, at most 40 wt%, at most 35 wt%, at most 30 wt%, at most 25 wt%, or at most 20 wt%, based on the total weight of the polyurethane.

[0050] Polymer polyols

[0051] The polyurethane comprises the residue of a polymer polyol. In one embodiment, the polyurethane comprises the residue of a polymer diol. The polymer polyol comprises at least two OH groups and a main chain. The OH groups can be directly connected to the main chain or separated by a linker. For example, a hydroxyalkyl-terminated polydimethylsiloxane (with methanol as the end group) is a polymer diol.

[0052] In one embodiment, the polymer polyol comprises an aliphatic polymer polyol. In one embodiment, the polymer polyol comprises an aromatic polymer polyol.

[0053] In one embodiment, the polymer polyol comprises a poly(alkylene oxide) polyol, a polycarbonate, a polysiloxane, a random or block copolymer thereof, or a mixture thereof. In one embodiment, the polymer polyol comprises a poly(alkylene oxide) polyol, a polycarbonate, a random or block copolymer thereof, or a mixture thereof. In one embodiment, the polymer polyol comprises a C2-C 16 Fluoroalkyl or C2-C 16 Fluoroalkyl ether.

[0054] In one embodiment, the difunctional polymer polyol itself does not provide sufficient crosslinking for the polyurethane foam. Therefore, a higher functionality polyol, such as a triol or tetraol, is used.

[0055] In one embodiment, the polymer polyol comprises poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(isobutylene) glycol, polyester glycols, such as polyester glycols formed from adipic acid or isophthalic acid and a monomeric glycol, alkyl glycols such as hydrogenated polybutadiene glycol or polyethylene glycol, poly(hexamethylene carbonate) glycol, poly(polytetramethylene carbonate) glycol, polysiloxane glycol, random or block copolymer glycols of poly(ethylene oxide) and poly(propylene oxide), random or block copolymer glycols of poly(ethylene oxide) and poly(tetramethylene oxide), random or block copolymer glycols of poly(ethylene oxide) and polysiloxane, or mixtures thereof.

[0056] In one embodiment, the polymer polyol comprises a polycarbonate diol. In one embodiment, the polymer aliphatic diol comprises a polycarbonate diol of poly(hexamethylene carbonate) diol or poly(tetramethylene carbonate) diol. In one embodiment, the polymer diol comprises a polycarbonate diol having a number average molecular weight (Mn) of at least 500 g / mol, at least 750 g / mol, at least 1000 g / mol, or at least 1500 g / mol. In one embodiment, the polymer aliphatic diol comprises a polycarbonate diol having a number average molecular weight (Mn) of at most 10,000 g / mol, at most 7500 g / mol, at most 5000 g / mol, at most 4000 g / mol, at most 3000 g / mol, or at most 2500 g / mol.

[0057] In one embodiment, the polymer polyol comprises polysiloxane diol, polycarbonate diol or poly (tetramethylene oxide) glycol. In one embodiment, the polymer aliphatic diol is composed of polysiloxane diol, polycarbonate diol, poly (tetramethylene oxide) glycol or its mixture. In one embodiment, the polymer diol comprises a mixture of two or more of polysiloxane diol, polycarbonate diol or poly (tetramethylene oxide) glycol. In one embodiment, the polymer diol is composed of a mixture of two or more of polysiloxane diol, polycarbonate diol or poly (tetramethylene oxide) glycol.

[0058] In one embodiment, the polymer polyol has a number average molecular weight (Mn) of at least 200 g / mol, at least 250 g / mol, at least 300 g / mol, at least 400 g / mol, or at least 500 g / mol, at least 600 g / mol, at least 700 g / mol, at least 800 g / mol, at least 900 g / mol, or at least 1000 g / mol. In one embodiment, the polymer aliphatic diol has a number average molecular weight (Mn) of at most 10,000 g / mol, at most 8500 g / mol, at most 6000 g / mol, at most 5000 g / mol, at most 4000 g / mol, at most 3000 g / mol, at most 2000 g / mol, or at most 1500 g / mol.

[0059] In one embodiment, polyurethane is formed by a formulation (based on the total weight of the formulation) comprising at least 20wt%, at least 30wt%, at least 40wt%, at least 50wt% or at least 60wt% of a polymer aliphatic polyol. In one embodiment, polyurethane is formed by a formulation (based on the total weight of the formulation) comprising at most 80wt%, at most 70wt%, at most 60wt% or at most 50wt% of a polymer polyol. In one embodiment, based on the total weight of the polyurethane, polyurethane comprises at least 20wt%, at least 30wt%, at least 40wt%, at least 50wt% or at least 60wt% of a polymer aliphatic polyol residues. In one embodiment, based on the total weight of the polyurethane, polyurethane comprises at most 80wt%, at most 70wt%, at most 60wt% or at most 50wt% of a polymer polyol residue.

[0060] Chain Extenders

[0061] In one embodiment, the polyurethane comprises residues of a chain extender. The chain extender is a low molecular weight polyol, typically a diol. If crosslinking is desired, a triol or higher functionality chain extender may be used. In one embodiment, the chain extender is a diol and the polyurethane is thermoplastic. In one embodiment, the chain extender is a diol and the polyurethane is thermosetting. In one embodiment, the chain extender is a diol and the polyurethane is thermoplastic.

[0062] In one embodiment, the polyurethane comprises residues of a chain extender diol. The chain extender diol is a non-polymeric diol having a molecular weight of 500 g / mol or less. In one embodiment, the chain extender diol is an alkyl diol containing 2 to 20 carbon atoms, one or more of which may be substituted with oxygen, silicon, phosphorus or sulfur. In one embodiment, the chain extender diol is an alkyl diol containing 2 to 20 carbon atoms, one or more of which may be substituted with oxygen or silicon. In one embodiment, the chain extender diol is an alkyl diol containing 2 to 20 carbon atoms, one or more of which may be substituted with oxygen. In one embodiment, the chain extender diol is an unsubstituted alkyl diol containing 2 to 20 carbon atoms.

[0063] An unsubstituted alkyl glycol is a glycol consisting of single bonded carbon and hydrogen atoms and two OH groups. A substituted alkyl glycol would be an alkyl glycol but one or more carbon atoms are replaced by other atoms, such as oxygen or silicon, while still retaining at least two carbon atoms. Examples of unsubstituted alkyl glycols include ethylene glycol, propylene glycol, butylene glycol, pentanediol, 1,4-cyclohexanedimethanol, and the like. Examples of substituted alkyl glycols include diethylene glycol, dipropylene glycol, 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane (BHTD), 1,3-bis(hydroxypropyl)tetramethyldisiloxane, 1,3-bis(3-hydroxyisobutyl)tetramethyldisiloxane, 3-ethoxy-1,2-propanediol, or 2,2'-thiodiethanol.

[0064] In one embodiment, the chain extender glycol includes ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,4-hex ... 5-hexanediol, 1,2-octanediol, 1,3-octanediol, 1,4-octanediol, 1,5-octanediol, 1,6-octanediol, 1,7-octanediol, 1,8-octanediol, 2,7-octanediol, neopentyl glycol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol or 1,1-cyclohexanedimethanol. In one embodiment, the chain extender diol comprises ethylene glycol, propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,4-hexanediol, 2,5-hexanediol, 1,2-octanediol, 1,3-octanediol, 1,4-octanediol, 1,5-octanediol, 1,6-octanediol, 1,7-octanediol, 1,8-octanediol, or 2,7-octanediol.

[0065] In one embodiment, the molecular weight of the chain extender is at least 60 g / mol, at least 70 g / mol, at least 80 g / mol, at least 90 g / mol, or at least 100 g / mol. In one embodiment, the molecular weight of the chain extender is at most 500 g / mol, at most 400 g / mol, at most 300 g / mol, at most 200 g / mol, or at most 150 g / mol.

[0066] In one embodiment, the chain extender comprises a polyol having a functionality of at least 3. In one embodiment, the chain extender comprises a monomeric triol or tetraol, or a propoxylate thereof. In one embodiment, the chain extender comprises glycerol, glycerol propoxylate, glycerol ethoxylate, 1,2,4-benzenetriol, 3-methyl-1,3,5-pentanetriol, pentaerythritol, pentaerythritol propoxylate, or pentaerythritol ethoxylate. In one embodiment, the molecular weight of the chain extender is between 90 and 500 g / mol. In one embodiment, the molecular weight of the chain extender is between 90 and 280 g / mol.

[0067] In one embodiment, the polyurethane is formed from a formulation comprising at least 1 wt%, at least 2 wt%, at least 5 wt%, at least 8 wt%, or at least 10 wt% of a chain extender diol (based on the total weight of the formulation). In one embodiment, the polyurethane is formed from a formulation comprising up to 20 wt%, up to 15 wt%, up to 12 wt%, up to 10 wt%, up to 8 wt%, or up to 5 wt% of a chain extender diol (based on the total weight of the formulation). In one embodiment, the polyurethane comprises at least 1 wt%, at least 2 wt%, at least 5 wt%, at least 8 wt%, or at least 10 wt% of chain extender diol residues based on the total weight of the polyurethane. In one embodiment, the polyurethane comprises up to 20 wt%, up to 15 wt%, up to 12 wt%, up to 10 wt%, up to 8 wt%, or up to 5 wt% of chain extender diol residues based on the total weight of the polyurethane.

[0068] End Group

[0069] In one embodiment, the polyurethane comprises one or more end groups. An end group is a functional group present at the end of a molecule. In one embodiment, the polyurethane is linear and comprises an end group at each end of the main chain. In one embodiment, the end group is linear. In one embodiment, the end group is branched. In one embodiment, the polyurethane comprises an average of at least 0.1 end groups, at least 0.25 end groups, at least 0.5 end groups, at least 1 end group, at least 1.5 end groups, at least 1.8 end groups, about 2 end groups, or at least 2 end groups. In one embodiment, the polyurethane comprises an average of up to 4 end groups, up to 2 end groups, or up to 2 end groups.

[0070] End groups can be formed by reacting terminal isocyanate groups present after the polymer backbone is formed with reactive groups on monofunctional compounds. For example, terminal isocyanate groups can react with 1-octanol or octylamine to form C8 alkyl end groups. End groups can also be formed by including a chain terminator, such as a monofunctional alcohol, in a formulation for forming a polyurethane. For example, a formulation for forming a polyurethane can include a diisocyanate, a polymeric aliphatic diol, a chain extender, and a monofunctional alcohol.

[0071] In one embodiment, the end groups comprise a hydrophobic poly(alkylene oxide), a hydrophilic poly(alkylene oxide), a copolymer comprising a hydrophilic poly(alkylene oxide) and a hydrophobic poly(alkylene oxide), a polysiloxane, a C2-C 20 Alkyl, C2-C 16 Fluoroalkyl, C2-C 16In one embodiment, the polysiloxane is poly(dimethylsiloxane). In one embodiment, the hydrophilic poly(alkylene oxide) is poly(ethylene oxide). In one embodiment, the hydrophobic poly(alkylene oxide) is poly(propylene oxide) or poly(tetramethylene oxide). In one embodiment, the end groups comprise a hydrophobic poly(alkylene oxide), a hydrophilic poly(alkylene oxide), a copolymer comprising a hydrophilic poly(alkylene oxide) and a hydrophobic poly(alkylene oxide), a C2-C 20 Alkyl, C2-C 16 Fluoroalkyl, C2-C 16 Fluoroalkyl ethers, or copolymers thereof. These end groups may be formed by monofunctional alcohols, including carbinols, or the above-mentioned amines.

[0072] In one embodiment, the terminal groups comprise C2-C 16 Fluoroalkyl or C2-C 16 Fluoroalkyl ethers. These end groups can be 16 Fluoroalkyl or C2-C 16 The monofunctional alcohol or amine of the fluoroalkyl ether is formed.

[0073] In one embodiment, the terminal groups are composed of C2-C 16 Fluoroalkyl or C2-C 16 The monofunctional alcohol or amine of the fluoroalkyl ether is formed. In one embodiment, the end groups are formed from 1H,1H-perfluoro-3,6-dioxaheptan-1-ol, 1H,1H-nonafluoro-1-pentanol, 1H,1H-perfluoro-1-hexanol, 1H,1H-perfluoro-3,6,9-trioxadecan-1-ol, 1H,1H-perfluoro-1-heptanol, 1H,1H-perfluoro-3,6-dioxadecan-1-ol, 1H,1H-perfluoro-1-octanol, 1H,1H-perfluoro-1-nonanol, 1H,1H-perfluoro-3,6,9-trioxadecan-1-ol, 1H,1H-perfluoro-1-decanol, 1H,1H-perfluoro-1-undecanol, 1H,1H-perfluoro-1-lauryl alcohol, 1H,1H-perfluoro-1-myristyl alcohol, or 1H,1H-perfluoro-1-palmitol.

[0074] In one embodiment, the end group is monomeric, and the molecular weight is 200g / mol or more, 300g / mol or more, or 500g / mol or more. In one embodiment, the end group is monomeric, and the molecular weight is 1,000g / mol or less or 800g / mol or less. In one embodiment, the end group is polymeric, and the number average molecular weight (Mn) is 10,000g / mol or less, 8,000g / mol or less, 6,000g / mol or less, or 4,000g / mol or less. In one embodiment, the end group is polymeric, and the number average molecular weight (Mn) is 500g / mol or more, 1,000g / mol or more, or 2,000g / mol or more.

[0075] In one embodiment, the content of the end groups is at least 0.1 wt%, at least 0.2 wt%, at least 0.3 wt%, or at least 0.5 wt%, based on the total weight of the formulation forming the polyurethane. In one embodiment, the content of the end groups is up to 3 wt%, up to 2 wt%, or up to 1 wt%, based on the total weight of the formulation forming the polyurethane. In one embodiment, the content of the end groups is at least 0.1 wt%, at least 0.2 wt%, at least 0.3 wt%, or at least 0.5 wt%, based on the total weight of the polyurethane. In one embodiment, the content of the end groups is up to 3 wt%, up to 2 wt%, or up to 1 wt%, based on the total weight of the polyurethane.

[0076] Formation of polyurethane

[0077] Methods for forming polyurethanes are generally known in the industry. A catalyst may be used. In one embodiment, the catalyst is stannous octoate or dibutyltin dilaurate. Amine catalysts may also be used.

[0078] In one embodiment, the polyurethane is crosslinked. In one embodiment, the foam comprises a crosslinked polyurethane. Some polyurethanes may need to be crosslinked to achieve a stable foam so that the foam does not collapse. In one embodiment, the foam comprises a crosslinked polyurethane, and the sheet comprises a non-crosslinked polyurethane. In order to crosslink the polyurethane, a 3+ functionality compound, such as a triisocyanate, and / or a small amount of optional ingredients, such as a 3+ functionality hydroxy compound or other crosslinking agent having a functionality greater than 2, such as glycerol, is required to allow crosslinking.

[0079] Foam formation

[0080] The foam can be made using various procedures known in the industry. The following paragraphs describe an example procedure for forming the foam.

[0081] In one embodiment, a prepolymer is first prepared by conventional methods from at least one isocyanate component (e.g., MDI) and at least one multifunctional soft segment material having a functionality greater than 2 (e.g., a polyether-based soft segment having a functionality of 3). The prepolymer is then mixed with an optional catalyst and at least one difunctional chain extender (e.g., 1,4-butanediol) in a mixing vessel to cure or crosslink the mixture. In another embodiment, crosslinking and foaming (i.e., pore formation) occur simultaneously. In another embodiment, crosslinking and foaming occur simultaneously in a mold.

[0082] In one embodiment, a polyol component is mixed with an isocyanate component and a cell opener to form a first liquid. Other optional additives, such as viscosity modifiers, surfactants, chain extenders, and crosslinking agents are mixed to form a catalyst batch mixture. The first liquid and the catalyst batch mixture are then mixed in a mixing vessel to foam and crosslink. In another embodiment, foaming and crosslinking occur simultaneously. In another embodiment, this foaming mixture is poured into a mold through a nozzle and allowed to rise.

[0083] Alternatively, a so-called "one-shot" process may be used. One-shot embodiments do not require a separate prepolymer manufacturing step. In one embodiment, the materials are mixed in a mixing vessel and then foamed and cross-linked.

[0084] In another embodiment, all ingredients except the isocyanate component are mixed in a mixing vessel. The isocyanate component is then added, such as by high speed stirring, followed by crosslinking and foaming. In another embodiment, this foaming mixture is poured into a mold and allowed to rise.

[0085] Another embodiment involves mixing a polyol component with an isocyanate component and other optional additives (such as a viscosity modifier, a surfactant and / or a cell opener) to form a first liquid. Next, a second liquid is formed by mixing a blowing agent and optional additives (such as a gelling catalyst and / or a blowing catalyst). The first liquid and the second liquid are then mixed in a mixing vessel and then foamed and cross-linked. The foamed mixture can be poured into a mold through a nozzle and allowed to rise.

[0086] In another embodiment of the one-time method, the isocyanate component forms a first liquid. In one embodiment, the isocyanate component is maintained at a pressure of 5 psi to 30 psi higher than the ambient pressure, and in another embodiment, the temperature of the isocyanate component can be optionally controlled between 20°C and 30°C. The polyol component is mixed with other optional additives (such as viscosity modifiers and / or cell openers) to form a second liquid. In one embodiment, the polyol component is mixed or premixed with a cell opener and a viscosity reducer. In another embodiment, the polyol component can be optionally mixed or premixed with a cell opener and a viscosity reducer. Next, a third liquid is formed by mixing a blowing agent and a crosslinking agent, as well as an optional chain extender and optional additives (such as a gel catalyst and / or a blowing catalyst and a surfactant). The blowing agent is preferably water, and in one embodiment it is distilled water. The crosslinking agent is glycerol. In one embodiment, the blowing agent (water) and the crosslinking agent (glycerol) are always mixed before the foaming and crosslinking reactions. Then, the first liquid, the second liquid, and the third liquid are mixed in a mixing container and then foamed and crosslinked.

[0087] Consideration should be given to ensuring that the foaming liquid or reaction mixture is deposited at the bottom of the mold in a linear manner, or does not effectively retrace the flow path, so as to avoid introducing any flow disturbance or mixing of foaming liquids or reaction mixtures of different ages. In one embodiment, the foaming liquid or reaction mixture is deposited at the bottom of the mold in a linear manner, or does not effectively retrace the flow path, so that the foaming liquid or reaction mixture that flows out later from the mixing container does not introduce any flow disturbance or mix with the foaming liquid or reaction mixture that flows out earlier.

[0088] At the end of the foam rise, the foaming and cross-linking reactions are considered to be complete or substantially complete, thereby forming a matrix of a foam block or shape. In one embodiment, the matrix can then optionally be subjected to an additional high temperature curing treatment. Curing ensures the utilization and / or removal of any free isocyanates and amines and / or other unreacted components that were not reacted during the foam formation process. The curing temperature can be from 70°C to 120°C, and in other embodiments from 75°C to 110°C. The curing time can be from 30 minutes to 400 minutes, and in other embodiments from 60 minutes to 300 minutes. In one embodiment, the foam matrix is ​​not subjected to an additional high temperature curing treatment.

[0089] In one embodiment, the continuous and interconnected void phase is formed by a network structure. Network structure generally refers to the process of at least partially removing the cell walls, not just breaking or tearing them by a crushing process, which may produce fragments that must be removed by further processing. In another embodiment, the network structure process substantially completely removes at least a portion of the cell walls. The network structure can be achieved, for example, by at least partially dissolving the cell walls, which is called "solvent network structure" or "chemical network structure"; or by at least partially melting, burning and / or exploding the cell walls, which is called "combustion network structure", "thermal network structure" or "impact network structure". In one embodiment, two network structure steps are used, such as a first combustion network structure followed by a second combustion network structure. In another embodiment, the combustion network structure is followed by a chemical network structure. In another embodiment, the chemical network structure is followed by a combustion network structure.

[0090] One embodiment uses chemical reticulation, wherein the substrate is reticulated in an acid bath comprising an inorganic acid. Another embodiment uses chemical reticulation, wherein the substrate is reticulated in an alkaline bath comprising an inorganic base. Another embodiment uses solvent reticulation, wherein a volatile solvent that leaves no residue is used in the process. Another embodiment performs solvent reticulation at a temperature above 25°C. In one embodiment, a substrate comprising a polycarbonate polyurethane is solvent reticulated using a solvent selected from tetrahydrofuran ("THF"), dimethylacetamide ("DMAC"), dimethyl sulfoxide ("DMSO"), dimethylformamide ("DMF"), N-methyl-2-pyrrolidone, or a mixture thereof. The chemical reticulation may be optionally washed or dried.

[0091] In one embodiment, a combustion grid may be employed in which a combustible atmosphere (e.g., a mixture of hydrogen and oxygen or a mixture of methane and oxygen) is ignited (e.g., by a spark). In another embodiment, the combustion grid uses a mixture of hydrogen, oxygen, and / or nitrogen.

[0092] The burning of the mesh is performed in a pressure chamber. In one exemplary procedure, the pressure of the pressure chamber is substantially reduced from atmospheric conditions, e.g., by evacuation for at least about 2 minutes, to below about 50-150 mTorr, and then hydrogen, oxygen, or a mixture thereof, is introduced. In another embodiment, the pressure of the pressure chamber is substantially reduced over one or more cycles, e.g., the pressure is substantially reduced, a non-reactive gas such as argon or nitrogen is introduced, and then the pressure is substantially reduced again, and then hydrogen, oxygen, or a mixture thereof is introduced. The temperature at which the burning of the mesh occurs can be affected, for example, by the temperature of the chamber being maintained and / or the hydrogen / oxygen ratio in the chamber. In another embodiment, the burning of the mesh is followed by an annealing period.

[0093] Forming a joint spacer

[0094] In one embodiment, the joint spacer is formed of a foam material. In one embodiment, the foam material has a rectangular parallelepiped, an elliptical cylinder, or an oval shape. In one embodiment, the thickness of the foam material, such as the depth of the rectangular parallelepiped or the height of the elliptical cylinder, is selected to be equal to the total thickness of the foam in the joint spacer. In such an embodiment, the foam is not compressed at least in one location.

[0095] To form the convex protrusions, the foam material is compressed into the mold in the direction of the convex protrusions. Figure 3 A side view of the molding process before compression is shown. The foam material 11 is compressed into the mold 12 along the direction 13. A back plate 14 can be used to form a flat surface opposite the convex protrusion. The mold 12 can include stops 15, 16 to achieve the desired compression of the foam both at the convex protrusion and the peripheral portion. As shown, the peripheral portion is flat. This step can be performed above room temperature to promote softening of the foam, and the optimal temperature is above 120°C to promote crosslinking and hydrogen bond formation in the polyurethane.

[0096] Figure 4 The process after the foam is compressed is depicted. The back plate 14 is in contact with the stoppers 15, 16. The foam 11 has been compressed to form the convex protrusion 17 and the peripheral portions 18A, 18B. At plane 19, the foam is not compressed because the distance between the back plate 14 and the deepest part of the mold 12 is equal to the thickness of the foam raw material. The peripheral portions 18A, 18B are compressed to an extent of about 8 times that of the convex protrusion at plane 19. As shown in the figure, the thickness of the peripheral portions is 1 / 8 of the thickness of the foam raw material. Therefore, the porosity at plane 19 is 8 times the porosity of the peripheral foam, and the density is 1 / 8 of the density of the peripheral foam.

[0097] In one embodiment, the porosity decreases with radial distance from the center of the joint spacer. In other words, the porosity decreases radially. This is because the thickness of the convex protrusion decreases and the compression of the foam increases as the radial distance from the thickest point of the convex protrusion increases.

[0098] Depending on how the foam is compressed, a variety of dimensions and properties can be achieved. For example, the mold surface may have varying curvatures, resulting in different levels of compression of the foam corresponding to the depth of the mold.

[0099] After compression, the foam is locked in its compressed state. In the case of thermosetting foams, the temperature may be raised to above 120°C to lock the compression. By separating the compressed foam from the mold, the joint spacer is obtained.

[0100] The porosity of the peripheral portion is less than the porosity of the thickest point of the convex protrusion. In one embodiment, the thickest point of the convex protrusion is the center of the convex protrusion, which can also be the center of the joint spacer. The compression in the foam of the peripheral portion, and therefore the reduction in porosity, may result in an increase in the strength of the peripheral portion. Most importantly, the tear resistance is increased (for example, by suturing). This increased tear resistance allows the joint spacer to be more permanently fixed by suturing or other common orthopedic methods, such as anchoring. In one embodiment, the joint spacer includes a plurality of holes in the peripheral portion. These holes are used to fix the joint spacer to the patient's anatomical structure by suturing.

[0101] In one embodiment, the sheet is attached to the flat surface of the foam. In one embodiment, the flat surface of the sheet and the foam are treated with a solvent. After treatment, the sheet and the foam are contacted, such as by reinserting the foam into a mold, stacking the sheet on the foam, and placing a backing plate on the sheet. After the solvent evaporates, the sheet adheres to the flat surface of the foam. Other methods of bonding the sheet and the foam are possible, such as by thermal bonding or using an adhesive.

[0102] In one embodiment, the sheet can be attached to the convex surface of the foam in the same manner as described for attaching the sheet to the flat surface of the foam. In one embodiment, the sheet can be first placed in the mold and the formed foam returned to the mold so that contact is created between the sheet and the foam during the attachment of the sheet to the foam.

[0103] In one embodiment, the joint spacer further comprises a reinforcing element. In one embodiment, the reinforcing element comprises an orthopedic suture, a textile, or an anchor. In one embodiment, the textile comprises a mesh. In one embodiment, the textile comprises a knitted or woven fabric.

[0104] The reinforcing element can be incorporated into the joint spacer in a variety of ways. In one embodiment, the reinforcing element is incorporated by injection molding or bonding a layer of material around the reinforcing element. In one embodiment, the position of the reinforcing element relative to the foam is fixed. In one embodiment, the reinforcing element is incorporated by passing the reinforcing element through the foam, such as by drilling a suitable hole and inserting the reinforcing element. In this case, the reinforcing element is typically fixed in the hole by compression and shaping of the foam. In one embodiment, the position of the reinforcing element is movable relative to the foam.

[0105] In one embodiment, the reinforcing element is secured in the joint spacer at the interface of the sheet and the foam. For example, the reinforcing element is secured in the joint spacer using solvent bonding by bonding the sheet and the foam together around the reinforcing element. Similarly, the reinforcing element can also be secured between multiple layers of sheets. For example, a first reinforcing element is secured by bonding a first sheet to a second sheet around the first reinforcing element, and a second reinforcing element is secured by bonding a second sheet and the foam around the second reinforcing element.

[0106] In one embodiment, the reinforcing element is inserted into the foam before heat compression. For example, a hole can be drilled in the foam stock and the reinforcing element is inserted through the hole. Subsequently, the assembly can be compressed into a convex protrusion as described above.

[0107] In one embodiment, the joint spacer includes a reinforcing element that is secured in a male protrusion by bonding multiple foam pieces together. For example, a first foam material can be bonded to a second foam material around the reinforcing element. The assembly can then be compressed into the male protrusion, as previously described, and optionally subsequently bonded to a sheet material.

[0108] In one embodiment, the reinforcing element comprises a polymer cable. A polymer cable is a cable composed of one or more polymers. In one embodiment, the polymer cable comprises a high yield strength material suitable for implantation in a human or animal body. In one embodiment, the polymer cable comprises polyethylene. In one embodiment, the polymer cable comprises thermoplastic polyethylene. In one embodiment, the polymer cable comprises or consists of ultra high molecular weight polyethylene. In one embodiment, the polymer cable comprises Dyneema Radiopaque fibers.

[0109] In one embodiment, the polymer cable comprises polymer fibers. A fiber is a long continuous filament. In one embodiment, the polymer cable is composed of polymer fibers. In one embodiment, the polymer cable comprises a braid composed of a plurality of individual polymer cables or fibers. In one embodiment, the polymer cable comprises a braid, including a hollow tubular braid, a solid circular braid, a spiral braid, a flat braid, a core-sheath (sometimes referred to as a kern-mantle or core-shell) braid, or a braid-on-braid. Braid-on-braid is a core-shell structure in which a braided core is covered by another braided structure. In one embodiment, the polymer cable comprises a yarn. A yarn is a continuous multi-strand, usually twisted fiber. In one embodiment, the polymer cable comprises a braided, knitted or woven cable, wherein the polymer cable comprises polymer fibers. In one embodiment, the polymer cable comprises a monofilament or multifilament yarn. The yarn may also include other components or additives to provide some additional functional effects, such as antibacterial or anti-inflammatory effects, knotting properties or visual contrast. In one embodiment, the polymeric cable comprises a radioactive agent. In one embodiment, the polymeric cable is a suture.

[0110] In one embodiment, the polymer cable comprises a flat shape, for example, a rectangular cross-section. For example, the polymer cable may be a flat ribbon, wherein in a cross-sectional view, the ratio between the height and width of the ribbon is less than 1, less than 0.5, less than 0.2, or less than 0.1.

[0111] In one embodiment, the reinforcement element itself can be secured to the patient's anatomy to secure the joint spacer in the joint. In one embodiment, the reinforcement element includes a ring or similar structure that allows another fixation element, such as a separate suture, to be secured to the reinforcement element. In one embodiment, the reinforcement element is positioned so that it can be connected to the joint spacer to a bone surface, such as the humeral head in the shoulder, to secure the spacer in a specific position within the joint.

[0112] Various configurations of reinforcing elements may be used. In one embodiment, the joint spacer includes two reinforcing elements that cross near the center of the joint spacer, each extending beyond the periphery of the joint spacer. In one embodiment, there is a single reinforcing element. In one embodiment, the reinforcing element is contained within the interior of the joint spacer.

[0113] Figure 5A cross section of one embodiment of a joint spacer comprising a reinforcing element is shown. As previously described, the joint spacer comprises a foam 21 forming a convex protrusion and a peripheral portion. The foam is fixed to a sheet 22. Sutures 23 and 24 are sandwiched between the foam and the sheet, and are arranged perpendicular to each other.

[0114] Figure 6 Shown with Figure 5 The joint spacer comprises a convex protrusion 25 and a peripheral portion 26. Sutures 23 and 24 extend from the joint spacer beyond the peripheral portion 26.

[0115] Figure 7 A cross section of one embodiment of a joint spacer comprising two reinforcement elements is shown. Figure 7 The embodiment shown in Figure 5 The embodiment shown in differs in that a second sheet is present. Thus, seam line 23 is sandwiched between the foam and the first sheet, while seam line 24 is sandwiched between the first sheet and the second sheet.

[0116] Figure 8 A cross section of an embodiment of a joint spacer is shown in which a textile is sandwiched between two layers of foam. Figure 8 The joint spacer in the can be assembled by providing a first foam material and a second foam material to sandwich the textile. The assembly is then compressed in a mold to create the convex protrusion and the peripheral portion as previously described. The sheet can then be attached. Figure 8 As shown, textile 31 is bonded within foam 32 .

[0117] According to one embodiment, the foam is compressed at one or more locations, thereby reducing its porosity and increasing its density at those locations. This increase in density may result in a favorable increase in suture retention strength, tensile strength, or other desirable mechanical properties, such as in the peripheral portion of the joint spacer. Depending on the compression ratio used during the molding process, the porosity and resulting physical properties of the compressed portions can be designed so that a moderately compressed foam is still open to cellular ingrowth, while a more compressed foam will have a lower porosity to achieve higher mechanical properties where desired.

[0118] application

[0119] Joint spacers as described above can be inserted into the patient's joint using known methods, such as through a cannula arthroscopy or through an open surgical procedure. In the arthroscopic delivery method, the joint spacer is compressed, such as by rolling it into a tubular shape and advancing it into the patient's joint cavity along a cannula. After deployment, the joint spacer is appropriately positioned on the joint-facing side and the bone-facing side and fixed to the patient's anatomical structure. This can be accomplished by anchoring sutures positioned at the periphery of the joint spacer (e.g., through holes in the peripheral portion) to the patient's tissue. The joint spacer can be used for any suitable joint of the patient, such as the knee or shoulder. Joint spacers as described above may have special uses in the shoulder joint cavity of patients suffering from rotator cuff tears, such as large rotator cuff tears that cannot be repaired.

[0120] The use of "a," "an," "the," and similar references in describing the present invention (especially in the context of the following claims) should be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Terms such as "including," "having," "comprising," and "containing" should be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise indicated. References to ranges of values ​​described herein are intended merely as a shorthand method of referring individually to each individual value within the range, unless otherwise indicated herein, and each individual value is incorporated into the specification as if it were individually referred to herein. The use of any and all examples or exemplary language (e.g., "such as") provided herein is intended solely to better illuminate the present invention and does not constitute a limitation on the scope of the present invention unless otherwise claimed. No language in the specification should be construed to indicate that any non-claimed element is essential to the practice of the present invention.

[0121] Preferred embodiments of the present invention are described herein, including the best mode of implementing the present invention known to the inventor. After reading the foregoing description, a person of ordinary skill in the art may find variations of these preferred embodiments. The inventor expects that skilled technicians will use these variations appropriately, and the inventor intends for the present invention to be practiced outside the manner specifically described herein. Therefore, the present invention includes all modifications and equivalents of the subject matter described in the claims attached hereto as permitted by applicable law. Although certain optional features are described as embodiments of the present invention, unless otherwise specifically stated or physically impossible to implement, this specification is intended to include and specifically disclose all combinations of these embodiments.

[0122] Description of Certain Exemplary Embodiments

[0123] The following description of exemplary embodiments of the present invention is intended to provide assistance to the reader, and is not intended to limit the invention disclosed herein to the following exemplary embodiments.

[0124] 1. A joint spacer comprising a first side and a second side opposite the first side, wherein the first side comprises a convex protrusion, the convex protrusion comprises foam, the foam having a porosity that decreases radially from the center of the first side to the edge of the convex protrusion, wherein the convex protrusion is at least partially surrounded by a peripheral portion, the peripheral portion comprises foam and the porosity of the foam is less than the porosity at the thickest point of the convex protrusion.

[0125] 2. The joint spacer according to the aforementioned exemplary embodiment, wherein the first side faces the joint and the second side faces the bone.

[0126] 3. The joint spacer according to any preceding exemplary embodiment, wherein the first side faces the bone and the second side faces the joint.

[0127] 4. The joint spacer according to any of the preceding exemplary embodiments, wherein the thickest point of the raised portion is the center of the raised portion.

[0128] 5. The joint spacer according to any of the preceding exemplary embodiments, wherein the thickest point of the raised portion is the center of the joint spacer.

[0129] 6. The joint spacer according to any preceding exemplary embodiment, wherein the peripheral portion is planar.

[0130] 7. The joint spacer according to any of the preceding exemplary embodiments, wherein the peripheral portion has a porosity that is approximately the porosity in the convex protrusion where the convex protrusion and the peripheral portion intersect.

[0131] 8. The joint spacer according to any of the preceding exemplary embodiments, wherein the thickness of the joint spacer is constant throughout the peripheral portion.

[0132] 9. A joint spacer, comprising a foam, wherein the foam comprises a first outer surface formed by a convex portion and a flat portion, wherein the convex portion exists inside the first outer surface and the flat portion exists on the periphery of the first outer surface.

[0133] 10. A joint spacer, comprising foam, wherein the foam includes a first outer surface formed by a raised portion and a planar portion, wherein the raised portion exists inside the first outer surface and the planar portion exists outside the first outer surface, wherein the porosity of the foam is greater in the raised portion than in the planar portion.

[0134] 11. A joint spacer, comprising foam, the foam comprising a first outer surface formed by a raised portion and a peripheral portion, the raised portion existing inside the first outer surface, the peripheral portion existing outside the first outer surface, wherein the porosity of the foam is greater in the raised portion than in the peripheral portion.

[0135] 12. A joint spacer comprising a foam, the foam comprising a first surface formed by a convex portion and a flat portion, the convex portion existing inside the first surface and the flat portion existing on the periphery of the first surface.

[0136] 13. A joint spacer, comprising foam, wherein the foam includes a first surface formed by a raised portion and a planar portion, wherein the raised portion exists inside the first surface and the planar portion exists on the periphery of the first surface, wherein the porosity of the foam is greater in the raised portion than in the planar portion.

[0137] 14. The joint spacer according to the preceding exemplary embodiment, wherein the first surface faces the joint and the second surface faces the bone.

[0138] 15. The joint spacer according to the preceding exemplary embodiment, wherein the first surface faces the bone and the second surface faces the joint.

[0139] 16. The joint spacer according to the preceding exemplary embodiment, wherein the first outer surface faces the joint and the second outer surface faces the bone.

[0140] 17. The joint spacer according to the preceding exemplary embodiment, wherein the first outer surface faces the bone and the second outer surface faces the joint.

[0141] 18. The joint spacer according to the preceding exemplary embodiment, wherein the raised portion comprises a convex protrusion.

[0142] 19. The joint spacer according to any of the preceding exemplary embodiments, wherein the thickness of the joint spacer decreases radially at the raised portion comprising the convex protrusions.

[0143] 20. A joint spacer comprising a first part and a second part, each of the first part and the second part comprising foam, the joint spacer comprising a first outer surface, the first outer surface comprising a raised portion and a planar portion, the raised portion existing inside the first outer surface, the planar portion existing on the periphery of the first outer surface, wherein the first part forms the raised portion, the second part forms the planar portion, and wherein the raised portion of the foam has a porosity that decreases with increasing radial distance from the center of the first outer surface.

[0144] 21. The joint spacer according to any preceding exemplary embodiment, wherein the foam is a single piece of foam.

[0145] 22. The joint spacer according to any preceding exemplary embodiment, further comprising a second outer surface opposite to the first outer surface.

[0146] 23. The joint spacer according to any preceding exemplary embodiment, further comprising a second outer surface opposite to the first outer surface, wherein the second outer surface is substantially planar.

[0147] 24. The joint spacer according to any preceding exemplary embodiment, wherein the porosity is substantially constant throughout the peripheral portion.

[0148] 25. The joint spacer according to any preceding exemplary embodiment, wherein the porosity of the foam in the peripheral portion is less than or equal to the minimum porosity in the raised portion.

[0149] 26. The joint spacer according to any preceding exemplary embodiment, wherein the porosity of the foam in the planar portion is less than or equal to the minimum porosity in the convex portion.

[0150] 27. The joint spacer according to any preceding exemplary embodiment, wherein the porosity of the foam decreases radially from its center in the longitudinal direction.

[0151] 28. The joint spacer according to any of the preceding exemplary embodiments, wherein the porosity of the foam decreases radially in the longitudinal direction from the thickest part of the foam in the transverse direction.

[0152] 29. The joint spacer according to any of the preceding exemplary embodiments, wherein the porosity of the foam decreases radially from its longitudinal center until the planar portion.

[0153] 30. The joint spacer according to any of the preceding exemplary embodiments, wherein the porosity of the foam in the raised portion decreases radially in the longitudinal direction from the thickest portion of the foam in the transverse direction.

[0154] 31. A joint spacer according to any preceding exemplary embodiment, wherein the porosity of the foam is greater at its centre than at its periphery.

[0155] 32. The joint spacer according to any preceding exemplary embodiment, wherein the foam has a substantially uniform porosity through its thickness at any given radial position of the raised portion.

[0156] 33. The joint spacer according to any preceding exemplary embodiment, wherein the raised portion and the peripheral portion are formed from a single piece of foam.

[0157] 34. A joint spacer according to any preceding exemplary embodiment, wherein the raised portion and the peripheral portion are formed from a single piece of foam that is compressed, and wherein the amount of compression varies with the thickness of the joint spacer.

[0158] 35. The joint spacer according to any preceding exemplary embodiment, wherein the foam comprises polyurethane foam.

[0159] 36. The joint spacer according to any preceding exemplary embodiment, wherein the polyurethane foam is an open cell polyurethane foam.

[0160] 37. The joint spacer according to any of the preceding exemplary embodiments, wherein the peripheral edge of said first surface consists of said planar portion.

[0161] 38. The joint spacer according to any preceding exemplary embodiment, wherein said raised portion is present at the center of said first surface.

[0162] 39. The joint spacer according to any preceding exemplary embodiment, wherein the peripheral portion surrounds the raised portion.

[0163] 40. The joint spacer according to any preceding exemplary embodiment, wherein the planar portion surrounds the convex portion.

[0164] 41. The joint spacer according to any preceding exemplary embodiment, wherein the peripheral portion comprises a plurality of holes extending through the joint spacer.

[0165] 42. The joint spacer according to any preceding exemplary embodiment, wherein the planar portion comprises a plurality of holes extending from the planar portion through the joint spacer.

[0166] 43. The joint spacer according to any preceding exemplary embodiment, wherein the raised portion comprises a sheet adhered to the foam.

[0167] 44. The joint spacer according to any preceding exemplary embodiment, wherein said planar portion comprises a sheet adhered to said foam.

[0168] 45. The joint spacer according to any preceding exemplary embodiment, wherein said first outer surface comprises a sheet adhered to said foam.

[0169] 46. ​​The joint spacer according to any preceding exemplary embodiment, wherein said second outer surface comprises a sheet adhered to said foam.

[0170] 47. The joint spacer according to any preceding exemplary embodiment, wherein the sheet material does not comprise foam.

[0171] 48. The joint spacer according to any preceding exemplary embodiment, wherein said foam and said sheet are physically entangled with each other.

[0172] 49. The joint spacer according to any preceding exemplary embodiment, wherein at least 90% of the surface area of ​​the sheet is entangled with the foam.

[0173] 50. The joint spacer according to any preceding exemplary embodiment, wherein the sheet material is polyurethane and the foam is polyurethane.

[0174] 51. The joint spacer according to any preceding exemplary embodiment, wherein the foam is biostable.

[0175] 52. The joint spacer according to any preceding exemplary embodiment, wherein the foam is biodegradable.

[0176] 53. The joint spacer according to any preceding exemplary embodiment, wherein the foam comprises thermoset polyurethane.

[0177] 54. The joint spacer according to any preceding exemplary embodiment, wherein the sheet material comprises thermoplastic polyurethane.

[0178] 55. The joint spacer according to any preceding exemplary embodiment, wherein the foam comprises polycarbonate polyurethane.

[0179] 56. The joint gasket according to any preceding exemplary embodiment, wherein the sheet material comprises polycarbonate polyurethane.

[0180] 57. The joint spacer according to any preceding exemplary embodiment, wherein said sheet and said foam both comprise polycarbonate polyurethane.

[0181] 58. The joint spacer according to any of the preceding exemplary embodiments, wherein the sheet and the foam each comprise a reaction product of an aromatic diisocyanate, a polycarbonate diol and a chain extender.

[0182] 59. The joint spacer according to any of the preceding exemplary embodiments, wherein the thickness of the sheet is from 10 microns to 1000 microns.

[0183] 60. The joint spacer according to any preceding exemplary embodiment, further comprising a plurality of holes proximate a periphery of the joint spacer, wherein the holes extend through the first (outer) surface and the second (outer) face.

[0184] 61. The joint spacer according to any preceding exemplary embodiment, wherein the peripheral portion comprises a plurality of holes.

[0185] 62. The joint spacer according to any of the preceding exemplary embodiments, wherein the first outer surface further comprises a layer of collagen.

[0186] 63. The joint spacer according to any of the preceding exemplary embodiments, wherein the second outer surface further comprises a layer of collagen.

[0187] 64. The joint spacer according to any preceding exemplary embodiment, wherein the bone-facing surface further comprises a layer of collagen.

[0188] 65. The joint spacer according to any of the preceding exemplary embodiments, wherein the joint-facing surface further comprises a layer of collagen.

[0189] 66. The joint spacer according to any of the preceding exemplary embodiments, further comprising a reinforcement element.

[0190] 67. The joint spacer according to any of the preceding exemplary embodiments, wherein the reinforcement element is embedded in the joint spacer.

[0191] 68. The joint spacer according to any of the preceding exemplary embodiments, wherein the reinforcement element is fully embedded in the body of the joint spacer.

[0192] 69. The joint spacer according to any of the preceding exemplary embodiments, wherein said reinforcement element passes through the body of said joint spacer and extends beyond said periphery.

[0193] 70. The joint spacer according to any preceding exemplary embodiment, wherein the reinforcing member is secured at the interface of the foam and the sheet by bonding the foam and the sheet around the reinforcing element.

[0194] 71. The joint spacer according to any preceding exemplary embodiment, wherein said reinforcing element is located at the interface of said foam and said sheet.

[0195] 72. The joint spacer according to any preceding exemplary embodiment, wherein said reinforcement element is sandwiched within said foam.

[0196] 73. The joint spacer according to any preceding exemplary embodiment, wherein the reinforcing element is secured within the foam by compressing the foam around the reinforcing element.

[0197] 74. The joint spacer according to any of the preceding exemplary embodiments, wherein the reinforcement element is sandwiched between two sheets.

[0198] 75. The joint spacer according to any preceding exemplary embodiment, wherein said reinforcing element is sandwiched between said foam and said sheet material.

[0199] 76. The joint spacer according to any preceding exemplary embodiment, wherein the reinforcement element comprises sutures.

[0200] 77. The joint spacer according to any of the preceding exemplary embodiments, wherein the reinforcement element is radiopaque.

[0201] 78. The joint spacer according to any preceding exemplary embodiment, wherein the reinforcement element comprises a polymer cable.

[0202] 79. The joint spacer according to any of the preceding exemplary embodiments, wherein the reinforcement element comprises a textile.

[0203] 80. The joint spacer according to any preceding exemplary embodiment, wherein the reinforcing element comprises a textile comprising a mesh.

[0204] 81. The joint spacer according to any preceding exemplary embodiment, wherein the reinforcing element comprises a textile comprising a knitted fabric or a braided fabric.

[0205] 82. The joint spacer according to any preceding exemplary embodiment, wherein the reinforcement element comprises a flat braid.

[0206] 83. The joint spacer according to any preceding exemplary embodiment, wherein the polymer cable has a rectangular or oval cross-section.

[0207] 84. The joint spacer according to any of the preceding exemplary embodiments, wherein the polymer cable has a flat shape, wherein a ratio of a height to a width of the polymer cable is less than 1, less than 0.5, less than 0.2, or less than 0.1.

[0208] 85. The joint spacer according to any of the preceding exemplary embodiments, further comprising a second reinforcement element, wherein the reinforcement element and the second reinforcement element cross inside the joint spacer.

[0209] 86. The joint spacer according to any preceding exemplary embodiment, further comprising a second reinforcement element, wherein the reinforcement element and the second reinforcement element are positioned perpendicular to each other.

[0210] 87. A method of forming a joint spacer, comprising the steps of:

[0211] a. compressing the foam into a mold having a concave shape, wherein the perimeter of the foam is wider than the perimeter of the concave shape, thereby producing a first outer surface including a convex portion and a planar portion and a second outer surface including a planar portion in the foam; and

[0212] b. Lock the foam in its compressed state.

[0213] 88. The method according to the preceding exemplary embodiment, wherein the raised portion has a porosity that decreases in a radial direction.

[0214] 89. A method of forming a joint spacer, comprising the steps of:

[0215] a. compressing the foam into a mold having a concave shape, wherein the compression results in the formation of a convex portion of the foam, and the porosity of the foam in the convex portion decreases radially from the center thereof; and

[0216] b. Lock the foam in its compressed state.

[0217] 90. The method according to any preceding exemplary embodiment, wherein the foam comprises reinforcing elements.

[0218] 91. The method according to any preceding exemplary embodiment, wherein the foam comprises reinforcing elements prior to the step of compressing the foam.

[0219] 92. The method according to any preceding exemplary embodiment, further comprising the step of physically entangling the sheet material to the exposed surface of the foam.

[0220] 93. The method according to any preceding exemplary embodiment, further comprising the step of solvent bonding the sheet to the exposed surface of the foam.

[0221] 94. The method according to any of the preceding exemplary embodiments, further comprising the step of separating the foam from the mold, thereby obtaining a joint spacer.

[0222] 95. The method according to any preceding exemplary embodiment, wherein the step of locking the foam in its compressed state is performed by heating the foam.

[0223] 96. The method according to any preceding exemplary embodiment, wherein the step of physically entangling the sheet to the exposed surface of the foam is preceded by a step of locking the foam in its compressed state.

[0224] 97. A joint spacer formed by the method of any preceding exemplary embodiment.

[0225] 98. A method of forming a joint spacer according to any of the preceding exemplary embodiments, wherein the obtained joint spacer is a joint spacer according to any of the preceding exemplary embodiments.

[0226] 99. A method of treating a patient, comprising the steps of:

[0227] a. Inserting a joint spacer according to any of the aforementioned exemplary embodiments into a joint cavity of a patient.

[0228] 100. A method of treating a patient, comprising the steps of:

[0229] a. Insert the joint spacer of any of the aforementioned exemplary embodiments into the joint cavity of a patient so that the flat portion faces the bone and the convex portion faces the interior of the joint cavity.

[0230] 101. A method of treating a patient, comprising the steps of:

[0231] a. Insert the joint spacer of any of the aforementioned exemplary embodiments into the joint cavity of a patient so that the convex portion faces the bone and the flat portion faces the interior of the joint cavity.

[0232] 102. The method according to the aforementioned exemplary embodiment further comprises the following steps:

[0233] b. Anchoring the sutures located in the holes in or around the joint spacer to the patient's tissue.

[0234] 103. The method according to any of the preceding exemplary embodiments, further comprising the steps of positioning a suture into the joint spacer and attaching the suture to the patient's tissue.

[0235] 104. The method according to the preceding exemplary embodiment, wherein the sutures in the joint spacer pass through the foam and the sheet and are retained by a reinforcing element.

[0236] 105. The method according to the preceding exemplary embodiment, wherein the reinforcement element is a textile.

Claims

1. A joint spacer, comprising foam, the foam comprising a first outer surface formed by a raised portion and a peripheral portion, the raised portion existing inside the first outer surface, the peripheral portion existing outside the first outer surface, wherein the porosity of the foam is greater in the raised portion than in the peripheral portion.

2. A joint spacer comprising a first side and a second side opposite to the first side, wherein the first side comprises a convex protrusion, the convex protrusion comprising foam having a porosity that decreases radially from the center of the first side to the edge of the convex protrusion, wherein the convex protrusion is at least partially surrounded by a peripheral portion, the peripheral portion comprising foam and the porosity of the foam is less than the porosity at the thickest point of the convex protrusion.

3. A joint spacer according to any preceding claim, wherein the thickest point of the raised portion is the centre of the raised portion.

4. A joint spacer according to any preceding claim, wherein the thickness of the joint spacer decreases radially in a raised portion comprising the convex protrusions.

5. A joint spacer according to any preceding claim, further comprising a second outer surface opposite the first outer surface, wherein the second outer surface is substantially planar.

6. A joint spacer according to any preceding claim, wherein the porosity is substantially constant throughout the peripheral portion.

7. A joint spacer according to any preceding claim, wherein the porosity of the foam in the peripheral portion is less than or equal to the minimum porosity in the raised portion.

8. A joint spacer according to any preceding claim, wherein the porosity of the foam in the raised portion decreases radially in the longitudinal direction from the thickest part of the foam in the transverse direction.

9. A joint spacer according to any preceding claim, wherein the porosity of the foam is greater at its centre than at its periphery.

10. A joint spacer according to any preceding claim, wherein the foam has a substantially uniform porosity through its thickness at any given radial position of the raised portion.

11. A joint spacer according to any preceding claim, wherein the raised portion and the peripheral portion are formed from a single piece of foam which is compressed, and wherein the amount of compression varies with the thickness of the joint spacer.

12. A joint spacer according to any preceding claim, wherein the polyurethane foam is an open cell polyurethane foam.

13. A joint spacer according to any preceding claim, wherein the peripheral portion surrounds the raised portion.

14. A joint spacer according to any preceding claim, wherein the peripheral portion comprises a plurality of holes extending through the joint spacer.

15. A joint spacer according to any preceding claim, wherein the raised portion comprises a sheet of material adhered to the foam.

16. A joint spacer according to any preceding claim, wherein the joint spacer comprises a planar surface opposite the first surface, and wherein the planar surface comprises a sheet adhered to the foam.

17. A joint spacer comprising a first part and a second part, each of the first part and the second part comprising foam, the joint spacer comprising a first outer surface, the first outer surface comprising a raised portion and a planar portion, the raised portion existing inside the first outer surface, the planar portion existing on the periphery of the first outer surface, wherein the first part forms the raised portion, the second part forms the planar portion, and wherein the convex protrusion has a porosity that decreases with increasing radial distance from the center of the first outer surface.

18. A joint spacer according to any preceding claim, wherein the first outer surface comprises a sheet adhered to the foam.

19. A joint spacer according to any preceding claim, wherein the second outer surface comprises a sheet adhered to the foam.

20. A joint spacer according to any preceding claim, wherein the foam and sheet material are physically entangled with each other.

21. A joint spacer according to any preceding claim, wherein the sheet material is polyurethane and the foam is also polyurethane.

22. A joint spacer according to any preceding claim, wherein both the foam and the sheet are biostable.

23. A joint spacer according to any preceding claim, wherein the foam comprises polycarbonate polyurethane and the sheet comprises polycarbonate polyurethane.

24. A joint spacer according to any preceding claim, wherein the thickness of the sheet is between 10 microns and 1000 microns.

25. A joint spacer according to any preceding claim, further comprising a reinforcement element embedded in the joint spacer.

26. A joint spacer according to any preceding claim, wherein the reinforcing element is fixed to the interface of the foam and the sheet by bonding the sheet and the foam around the reinforcing element.

27. A joint spacer according to any preceding claim, wherein the reinforcing element is fixed within the foam by compression of the foam surrounding the reinforcing element.

28. A joint spacer according to any one of claims 25 to 27, wherein the reinforcing element comprises sutures, polymer cables or textiles.

29. A method of forming a joint spacer, comprising the steps of: a. compressing the foam into a mold having a concave shape, wherein the perimeter of the foam is wider than the perimeter of the concave shape, thereby producing a first outer surface including a convex portion and a planar portion and a second outer surface including a planar portion in the foam; as well as b. Lock the foam in its compressed state.

30. A method according to the preceding claim, wherein the raised portions have a porosity which decreases in radial direction.

31. A method according to any preceding claim, wherein the step of locking the foam in its compressed state is performed by heating the foam.

32. A method according to any preceding claim, further comprising the step of physically entangling the sheet material to the exposed surface of the foam.

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