JP5311457B2 - Method of molding sliding member for artificial joint and sliding member for artificial joint molded by this method - Google Patents
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Landscapes
- Treatments Of Macromolecular Shaped Articles (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Materials For Medical Uses (AREA)
- Prostheses (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
Description
本発明は、膝関節や股関節に置換される人工関節に用いられる超高分子量ポリエチレンからなる摺動部材の成形方法及びこの方法で成形される人工関節用摺動部材に関するものである。 The present invention relates to a method for forming a sliding member made of ultrahigh molecular weight polyethylene used for an artificial joint to be replaced with a knee joint or a hip joint, and a sliding member for an artificial joint formed by this method.
人工関節は、一対の可動部材が互いに摺動するものであるが、一方は金属やセラミックといった部材で構成され、もう一方は金属やセラミックと摺動相性のよい樹脂で構成されるのが一般的である。この樹脂は、靱性と粘性に優れる超高分子量ポリエチレン（以下、ＵＨＭＷＰＥ）が多く用いられる。この場合、ＵＨＭＷＰＥには、摺動による摩耗が生じる他に酸素と反応して酸化する。また、関節に置換されて使用されている間にも体液等と反応して酸化する。 An artificial joint is a structure in which a pair of movable members slide relative to each other. One is composed of a metal or ceramic member, and the other is generally composed of a resin having good sliding compatibility with metal or ceramic. It is. As this resin, an ultra high molecular weight polyethylene (hereinafter referred to as UHMWPE) having excellent toughness and viscosity is often used. In this case, UHMWPE oxidizes by reacting with oxygen in addition to wear due to sliding. It also oxidizes by reacting with body fluids and the like while being replaced by a joint.
酸化が起ると、ＵＨＭＷＰＥが劣化してＵＨＭＷＰＥ粒子相互或いは相手方部材との間で界面破壊を引き起こすことが知られている。この破壊は、荷重と相関性があり、荷重が大きいほど大きな破壊を起こすことから、股関節や膝関節において問題となる。このため、酸化抑制の手段が種々試みられて来たが、下記特許文献１では、ＵＨＭＷＰＥにビタミンＥ（以下、ＶＥ）を０．００１〜１０Ｗｔ％添加することが提案されている。これによると、ＶＥには顕著な酸化抑制効果があり、かつ、人体に無害であることから、好適な添加物質である旨が述べられている。 It is known that when oxidation occurs, UHMWPE deteriorates to cause interfacial breakage between UHMWPE particles or with a counterpart member. This destruction has a correlation with the load, and the larger the load, the greater the destruction, which causes a problem in the hip joint and knee joint. For this reason, various means for suppressing oxidation have been tried, but the following Patent Document 1 proposes adding 0.001 to 10 Wt% of vitamin E (hereinafter referred to as VE) to UHMWPE. According to this, it is stated that VE is a suitable additive substance because it has a remarkable oxidation suppressing effect and is harmless to the human body.
一方で、ＵＨＭＷＰＥは、高温下での流動性が低くて成形性がよくないことも知られている。ＵＨＭＷＰＥを特定の形状に成形するには、通常は、型によるプレス成形で成形するが、成形性が悪いと、成形する形状に制約を受けたりすることがある。そこで、本発明者等は成形性の向上に努めて来たが、ＶＥはＵＨＭＷＰＥ粒子同士及び成形型との流動を容易にすることを見出して成形性を向上させるとともに、この成形を減圧下で行えば、更に一層の成形性が向上できることがわかり、下記特許文献２として提案している。 On the other hand, UHMWPE is also known to have poor flowability at high temperatures and poor moldability. In order to form UHMWPE into a specific shape, it is usually formed by press molding using a mold, but if the moldability is poor, the shape to be molded may be restricted. Therefore, the present inventors have made efforts to improve the moldability, but VE has found that the flow between the UHMWPE particles and the mold is facilitated to improve the moldability, and this molding is performed under reduced pressure. If it carries out, it turns out that the further moldability can be improved, and it has proposed as the following patent document 2.
しかし、ＶＥを添加したＵＨＭＷＰＥは酸化が抑制されて界面破壊を引き起し難いとはいっても、相手方金属やセラミックとたえず摺動するから、それに伴って摩耗し、摩耗粉を発生させる。そこで、下記非特許文献１では、ＶＥが無添加のものと０．３Ｗｔ％添加したものとの比較の下で摩擦回数と摩耗粉の発生の関係を調べたものが報告されている。これによると、ＶＥが添加されたものの方が無添加のものに比べて摩耗粉の発生が少ないことが示されており、その差は摩擦回数が多いほど大きくなっている。 However, although UHMWPE added with VE is suppressed from oxidation and hardly causes interface destruction, it slides constantly with the counterpart metal or ceramic, and thus wears and generates wear powder. Therefore, Non-Patent Document 1 below reports a study of the relationship between the number of frictions and the generation of wear powder under a comparison between the case where VE is not added and the case where 0.3 Wt% is added. According to this, it is shown that the generation of wear powder is less in the case where VE is added than in the case where VE is not added, and the difference increases as the number of frictions increases.
ところで、発生した摩耗粉は摺動面に留まらず周囲に拡散し、金属又はセラミックと骨との境界面にも浸透して行く。生体内に摩耗粉が存在していると、これを捕食するマクロファージが寄集して来ることが知られており、マクロファージはサイトカイン（ＴＮＦα等）を産出し、サイトカインは骨の吸収に関与しているといわれている。 By the way, the generated abrasion powder does not stay on the sliding surface but diffuses to the surroundings and penetrates to the interface between the metal or ceramic and the bone. It is known that macrophages that prey on wear powder gather in the living body, and macrophages produce cytokines (such as TNFα), which are involved in bone resorption. It is said that there is.
この結果、金属やセラミックと接する骨が溶解し、人工関節が強度を保てずにグラグラする、所謂、ルーズニングという現象を呈すことがある。ルーズニングが生ずると、場合によっては、再手術が必要なことがある。再手術ということになれば、患者、特に、高齢者にとっては多大な負担となる。
本発明は、以上の課題を解決したものであり、要するに、ＶＥを均一に分散させたＵＨＭＷＰＥを素材として人工関節用摺動部材を製作すれば、摩耗粉にもＶＥは均一に含まれることになり、この均一化が高いほどＶＥの作用による蛋白等の隣在物質への表面吸着が制御されることがわかったのである．蛋白等の表面吸着が制御されると、当然ながらマクロファージによる捕食も少なくなり、ルーズニングが抑制される。さらに、ＶＥには炎症抑制作用があり、この作用に基づいて摩耗紛の生物活性が抑制されることも判明し、この効果からもルーズニングの抑制が期待できる。 The present invention solves the above problems. In short, if a sliding member for an artificial joint is manufactured using UHMWPE in which VE is uniformly dispersed, the VE is uniformly included in the wear powder. Thus, it was found that the higher the homogenization, the more the surface adsorption to neighboring substances such as proteins by the action of VE is controlled. If the surface adsorption of proteins or the like is controlled, naturally, predation by macrophages is reduced and loosening is suppressed. Furthermore, VE has an anti-inflammatory action, and based on this action, it has also been found that the biological activity of the wear powder is suppressed.
以上の課題の下、本発明は、請求項１に記載した、所定の形状に成形されて相手方金属又はセラミックと摺動する超高分子量ポリエチレンからなる人工関節用摺動用部材の成形方法において、粒子状の超高分子量ポリエチレンにビタミンＥを０．０１〜０．３Ｗｔ％添加するとともに、成形中に８０〜１４０℃の温度で少なくとも３０分保持してビタミンＥを超高分子量ポリエチレン中に均一に分散させる均一分散化処理を行うことを特徴とする人工関節用摺動用部材の成形方法を提供するとともに、これにおいて、請求項２に記載した、成形及び均一分散化処理を一定の減圧下又は不活性ガス雰囲気内で行う手段を提供する。また、請求項３に記したように、請求項１及び２の成形方法で成形された人工関節用摺動用部材をを提供する。 Under the above object, the present invention is set forth in claim 1, in the molding method of a predetermined molded into shape mating metal or ceramic and the sliding is made of ultra high molecular weight polyethylene prosthesis for sliding member, particles Vitamin E is added to the ultra-high molecular weight polyethylene in an amount of 0.01 to 0.3 Wt%, and the vitamin E is uniformly dispersed in the ultra-high molecular weight polyethylene by holding at a temperature of 80 to 140 ° C. for at least 30 minutes during molding. A method for forming a sliding member for an artificial joint, characterized in that the uniform dispersion treatment is performed, wherein the molding and the uniform dispersion treatment according to claim 2 are performed under a certain reduced pressure or inactive. Means for performing in a gas atmosphere are provided. According to a third aspect of the present invention, there is provided a sliding member for artificial joints molded by the molding method of the first and second aspects.
請求項１の発明、すなわち、ＶＥを添加したＵＨＭＷＰＥを素材として人工関節用摺動部材を成形すると、ビタミンＥの炎症抑制作用や表面吸着制御作用により、結果的にルーズニングを抑制するのである。これにおいて、ＶＥの添加量はＵＨＭＷＰＥに対して０．０１〜０．３Ｗｔ％が適切であり、加えて、均一分散化処理を行うと、この効果をより完全にすることが解明できたのである。この均一分散化処理がルーズニングの抑制に関与する仕組みについてであるが、一般に、樹脂等の熱可塑性物質は高温であるほど、粒子の流動性、整列性、配向性は向上する。これらが向上すると、これにＶＥを添加する場合も、高温ほど分散は均一化するのである。 When the sliding member for an artificial joint is molded using the invention of claim 1, that is, UHMWPE added with VE as a raw material, the loosening is suppressed as a result by the inflammation suppressing action and the surface adsorption controlling action of vitamin E. In this, the addition amount of VE is appropriate to be 0.01 to 0.3 Wt% with respect to UHMWPE, and in addition, it was clarified that this effect could be made more complete by performing uniform dispersion treatment. . Regarding the mechanism in which this uniform dispersion treatment is involved in the suppression of loosening, in general, the higher the temperature of a thermoplastic material such as a resin, the better the fluidity, alignment and orientation of the particles. When these are improved, even if this is added to VE, the dispersion at higher temperatures is to homogenization.
しかし、あまり高温であれば、ＶＥが失活して添加の役割を果さなくなる。そこで、本発明の手法であるＶＥを添加したＵＨＭＷＰＥを８０〜１４０℃で３０分以上保持するという均一分散化処理がこれを代替するのである。実際、この処理を行うと、蛋白等の表面吸着が制限されることが確認されている。さらに、この処理を減圧下や不活性ガス雰囲気中で行うと、分散を促進して均一化をより高めるし、酸化も抑制することが確認されている。なお、この処理は、ＵＨＭＷＰＥの物理的特性を高め、成形性を向上させるという一面もある。 However, if the temperature is too high, VE is deactivated and does not play the role of addition. Therefore, the uniform dispersion treatment of holding UHMWPE to which VE, which is the method of the present invention, is added at 80 to 140 ° C. for 30 minutes or more replaces this. In fact, it has been confirmed that this treatment limits the surface adsorption of proteins and the like. Furthermore, it has been confirmed that when this treatment is carried out under reduced pressure or in an inert gas atmosphere, the dispersion is promoted to increase the homogenization and the oxidation is also suppressed. In addition, this process also has one side | surface of improving the physical characteristic of UHMWPE and improving a moldability.
以下、本発明の実施の形態を説明するが、まず、ＵＨＭＷＰＥの特性やＶＥを添加することの意義について説明しておく。ここでいうＵＨＭＷＰＥとは、分子量が３００〜６５０万ｇ／ｍｏｌの範囲のものをいう。このようなＵＨＭＷＰＥを使用するのは、これらが稠密性に富んで耐摩耗性、機械的強度に優れているからであるが、難成形性の材料であることが問題である。 Hereinafter, embodiments of the present invention will be described. First, the characteristics of UHMWPE and the significance of adding VE will be described. As used herein, UHMWPE refers to those having a molecular weight in the range of 300 to 6.5 million g / mol. The reason why such UHMWPE is used is that they are dense and excellent in wear resistance and mechanical strength, but are problematic in that they are difficult to mold.
人工関節用摺動部材に使用するＵＨＭＷＰＥは、医療用に適応されたものである必要があり、これには、Ｔｉｃｏｎａ社製のＧＵＲ１０２０、１０５０があり、これらはいずれもパウダーの形態で市販されているが、ペレット、タブレットの形態のものもある。そのいずれを使用してもよいが、成形時の熱による溶解性、気泡の生成性、添加物との均一な混合性の観点から、パウダー状のものがもっとも優れている。 UHMWPE used for the sliding member for artificial joints must be adapted for medical use, and there are GUR1020 and 1050 manufactured by Ticona, both of which are commercially available in powder form. There are also pellets and tablets. Any of them may be used, but powders are the most excellent from the viewpoints of heat solubility during molding, bubble formation, and uniform mixing with additives.
成形は加圧成形によるが、樹脂を加圧成形するには、加熱下におけるプレスとインジェクションとがあり、そのいずれであってもよいが、種々の形状のものを少量生産するにはプレスによるものの方が適する。加えて、本例では、この加圧成形を減圧下又は不活性ガス雰囲気内で行うようにしている。ＵＨＭＷＰＥを減圧下で成形すると、減圧に基づいてＵＨＭＷＰＥの粒子の流動性が高まり、成形が容易になって成形時間が短縮できるということがわかってきている。また、粒子や粒子間に存在する気泡が抜け、残存する酸素量を減らして酸化による弊害を少なくするという効果もあり、残存酸素量を減らす効果からいえば、不活性ガス雰囲気内で成形するのも適する。 Molding is performed by pressure molding. To press mold the resin, there are press and injection under heating, either of which can be used. Is better. In addition, in this example, this pressure molding is performed under reduced pressure or in an inert gas atmosphere. It has been found that when UHMWPE is molded under reduced pressure, the fluidity of UHMWPE particles is increased based on the reduced pressure, facilitating molding and reducing molding time. It also has the effect of eliminating particles and bubbles existing between particles, reducing the amount of remaining oxygen and reducing the harmful effects of oxidation, and in terms of the effect of reducing the amount of remaining oxygen, molding is performed in an inert gas atmosphere. Also suitable.
さらに、減圧下又は不活性ガス雰囲気内で成形や均一分散化処理をすることは、上記したＶＥの効果を減殺しないことにも寄与する。加えて、残存酸素量を減少させることは、製品にして使用中の酸化も抑制できるものとなる。この他、気泡の抜けによって稠密性が増し、衝撃強度も向上する。この意味から、減圧の程度は大きいほどよいが、０．１気圧以下であっても相当な効果があり、０．０１気圧以下であればほぼ十分である。 Furthermore, performing molding or uniform dispersion treatment under reduced pressure or in an inert gas atmosphere also contributes to not reducing the effects of the VE described above. In addition, reducing the amount of residual oxygen can suppress oxidation during use as a product. In addition, the denseness is increased by the removal of bubbles, and the impact strength is also improved. In this sense, the greater the degree of decompression, the better. However, even if it is 0.1 atm or less, there is a considerable effect, and 0.01 atm or less is almost sufficient.
また、ＶＥを添加すると、成形性が更に優れたものとなる。このＶＥは、和光純薬工業株式会社から日本薬局方トコフェロール（ｄｌ−α−ＴｏｃｏｐｈｅｒｏｌＪ．Ｐ）として液状又はパウダー状で市販されており、ここでのＶＥには、αートコフェロール、βートコフェロール、γートコフェロール、δートコフェロールとこれらの異性体、誘導体、混合物を含む。これらＶＥを添加するのは、ビタミンＥの炎症抑制作用や表面吸着制御作用、抗酸化作用を期してのことは勿論のこと、成形時のＵＨＭＷＰＥからなる素材の流動性を高める目的も有する。この点で、本発明におけるＶＥの添加は重要な意義を有し、単なる酸化防止に限らず、摩耗粉の減少及び生物活性の抑制、ひいてはこれを捕食するマクロファージが産出するＴＮＦαを減少せしめ、人工関節のルーズニングを抑制するためでもある。 Further, when VE is added, the moldability is further improved. This VE is commercially available in liquid or powder form as Japanese Pharmacopoeia Tocopherol (dl-α-Tocopherol J.P) from Wako Pure Chemical Industries, Ltd. The VE here includes α-tocopherol, β-tocopherol, Including γ-tocopherol, δ-tocopherol and isomers, derivatives, and mixtures thereof. The addition of these VEs has the purpose of enhancing the fluidity of the material composed of UHMWPE during molding, as well as the anti-inflammatory action, surface adsorption control action and antioxidant action of vitamin E. In this respect, the addition of VE in the present invention has an important significance, and is not limited to mere oxidation prevention, but also reduces abrasion powder and biological activity, and thus reduces TNFα produced by macrophages that prey on this, and artificial It is also for suppressing joint loosening.
ＵＨＭＷＰＥに配合するＶＥの割合は、０．０１〜０．３Ｗｔ％が適する。図２は種々の添加量で添加したＵＨＭＷＰＥの板を作製し、その酸化度（カルボニル基、ケトン基の検出）と酸化の浸透深さの関係を示すものであるが、０．０１〜０．３Ｗｔ％では深部までほぼ一様な酸化抑制効果が見られる。しかし、０．００５Ｗｔ％以下であるとあまり効果がないことが示されている。なお、０．３Ｗｔ％を超える添加量のものについては示されていないが、０．０１〜０．３Ｗｔ％の範囲ではほとんど差がないことから、これ以上添加したとしても、それほどの有位性は見られないと思われる。一方で、酸化抑制と蛋白の吸着及び摩耗粉の発生とは相関していることは明らかであるので、蛋白吸着の抑制に基づくルーズニングの抑制を目的とするＶＥの添加の割合も上記した範囲のものが適する。 The proportion of VE blended with UHMWPE is suitably 0.01 to 0.3 Wt%. FIG. 2 shows UHMWPE plates added with various addition amounts, and shows the relationship between the oxidation degree (detection of carbonyl group and ketone group) and the penetration depth of oxidation. At 3 Wt%, an almost uniform oxidation suppressing effect is seen up to the deep part. However, it is shown that there is not much effect when it is 0.005 Wt% or less. In addition, although it is not shown about the thing of the addition amount exceeding 0.3 Wt%, since there is almost no difference in the range of 0.01-0.3 Wt%, even if it adds more, it is so Seems not to be seen. On the other hand, since it is clear that the inhibition of oxidation is correlated with the adsorption of protein and the generation of wear powder, the ratio of VE addition for the purpose of inhibiting loosening based on the inhibition of protein adsorption is also in the above range. Is suitable.
ＵＨＭＷＲＥに対するＶＥの添加の方法は、成形前のＵＨＭＷＲＥにＶＥを添加して混合すればよい。この混合は、ＶＥの分布を均一にするために室温〜８０℃で行うが、ＶＥの浸透性を考えれば、高い温度で行うのが望ましい。しかし、混合時に発熱したりすることもあるので、あまり長時間かけて行うと、ＶＥを失活させる虞があるのは上述のとおりである。 As a method of adding VE to UHMWRE, VE may be added to UHMWRE before molding and mixed. This mixing is performed at room temperature to 80 ° C. in order to make the distribution of VE uniform, but it is desirable to perform the mixing at a high temperature in view of the permeability of VE. However, since heat may be generated during mixing, as described above, there is a possibility that VE may be deactivated if it is carried out for too long.
攪拌が終了すると、ＵＨＭＷＰＥを一旦溶解させる。この溶解は、ＵＨＭＷＰＥ粒子の表面を溶解させてその粒子同士を接着させるとともに、この溶解部分にＶＥを浸透させるものであり、ＵＨＭＷＰＥを成形素材とする場合には欠かせない操作である。溶解温度は、ＵＨＭＷＰＥが溶解する１６０〜１８０℃以上は必要であるが、２００℃以上の温度で長時間置いておくと、ＶＥを失活させるから、２２０℃程度で２０分弱加熱するのが適する。 When stirring is completed, UHMWPE is once dissolved. This dissolution dissolves the surfaces of the UHMWPE particles so that the particles adhere to each other, and allows VE to penetrate into the dissolved portion. This operation is indispensable when UHMWPE is used as a molding material. The melting temperature is required to be 160 to 180 ° C or higher at which UHMWPE dissolves, but if left at a temperature of 200 ° C or higher for a long time, VE is deactivated. Suitable.
溶解が完了すると、成形操作に入るのであるが、この成形前、成形中、成形後いずれかで次の処理を行う。それは、ＶＥをＵＨＭＷＰＥの粒子内に均一に分散させる上記した均一分散化処理を行うことであり、摩耗紛の減少及び生物活性を下げるためには不可欠な処理である。ＶＥは溶解時にＵＨＭＷＰＥの粒子間に取り込まれて分散するが、粒子内への分散を均一にするためにこの処理が必要になるのである。均一分散化はＶＥが添加されたＵＨＭＷＰＥを所定の温度で所定の時間置くことで可能になる。 When the dissolution is completed, the molding operation is started. The next treatment is performed before, during or after the molding. That is, the above-described uniform dispersion treatment for uniformly dispersing VE in the particles of UHMWPE is performed, which is an indispensable treatment for reducing wear powder and reducing biological activity. VE is taken up and dispersed between the particles of UHMWPE at the time of dissolution, but this treatment is necessary to make the dispersion in the particles uniform. Uniform dispersion can be achieved by placing UHMWPE with VE added at a predetermined temperature for a predetermined time.
ＵＨＭＷＰＥの溶解は圧力の小さい状況の下で行うのが適するのは当然であるから、これらの操作・処理は成形前に行うのがもっとも好ましい。ただし、あまり圧力をかけない状況であれば、成形中に行ってもよいことが確認されており、この加熱を成形型で行ってもよく、この場合は、成形時間を短縮できる利点がある。また、成形後に行っても効果は得られる。さらに、上述したように、この成形を減圧下又は不活性ガス雰囲気中で行えば、一層の好結果が得られる。 Since it is natural that UHMWPE is dissolved under a low pressure condition, it is most preferable to perform these operations and treatments before molding. However, it has been confirmed that it may be performed during molding if the pressure is not so much applied, and this heating may be performed with a molding die. In this case, there is an advantage that the molding time can be shortened. Further, the effect can be obtained even after the molding. Furthermore, as described above, if this molding is performed under reduced pressure or in an inert gas atmosphere, a better result can be obtained.
図３は以上の処理をしたＵＨＭＷＰＥの板を作製してこれを金属と摩擦してどれくらい摩耗粉が発生したかをＶＥの添加量との関係で調べたものであるが（摩耗粉は電子顕微鏡で観察）、０．３Ｗｔ％のものは無添加のものに比べて摩耗粉の発生量が少なくなっている。一方で、３Ｗｔ％のものは添加量が多すぎてかえって摩耗粉の発生が増えている。このことから、ＶＥの添加量にも適量があることがわかり、多すぎると、不純物的な働きをしてかえって耐摩耗性、耐強度を低下させるのではないかと思われる。ただ、０．３Ｗｔ％は適切であるのは確かである。 FIG. 3 shows a UHMWPE plate that has been processed as described above, and the amount of wear powder generated by rubbing the UHMWPE plate with a metal was examined in relation to the amount of VE added. In the case of 0.3 Wt%, the amount of wear powder generated is smaller than that of the additive-free one. On the other hand, the amount of 3 Wt% is too much to add and the generation of wear powder is increasing. From this, it can be seen that there is an appropriate amount of VE to be added, and if it is too much, it may act as an impurity and reduce the wear resistance and strength. However, it is certain that 0.3 Wt% is appropriate.
図４はＵＨＭＷＰＥ表面に吸着した蛋白質の分布状態を評価したものである。実験は血漿蛋白成分の中で最も存在割合の多いアルブミンを用い、実験器具へのアルブミン吸着を抑制するために、ＭＰＣポリマーで表面処理された製品を使用し、蛍光色素であるＦＩＴＣをアルブミンに標識して蛍光顕微鏡で観察した（蛍光観察像の撮影条件は統一してある）。ｄｌ−α−Ｔｏｃｏｐｈｅｒｏｌの含有量が増加すると背景のアルブミンの吸着量がほぼ均一に減少している（一部に表面粗さによると思われる不整像が見られる）。 FIG. 4 is an evaluation of the distribution state of proteins adsorbed on the UHMWPE surface. The experiment uses albumin, which has the highest abundance of plasma protein components, uses a product surface-treated with MPC polymer in order to suppress albumin adsorption to the laboratory equipment, and labels FITC, a fluorescent dye, on albumin And observed with a fluorescence microscope (the imaging conditions for the fluorescence observation image are unified). As the content of dl-α-Tocopherol increases, the amount of background albumin adsorbed almost uniformly decreases (an irregular image that is thought to be partially due to surface roughness is observed).
図５はＵＨＭＷＰＥ表面上へのアルブミン吸着量を相対蛍光輝度で定量評価したグラフである。蛍光観察像の全ピクセルを輝度分類（分解能：８ビット）して平均輝度と標準偏差を算出し、ＶＥを添加しない試料の平均輝度を１として、ＶＥ添加試料の輝度と相対比較した。ここに示されるように、ＶＥを添加して分散させた試料では，ＵＨＭＷＰＥ原材料粒子の大きさである１００ミクロン以下のオーダーにおいてもＵＨＭＷＰＥ表面への蛋白質の吸着がほぼ均一に抑制されている。 FIG. 5 is a graph in which the amount of albumin adsorbed on the surface of UHMWPE is quantitatively evaluated by relative fluorescence luminance. All pixels of the fluorescence observation image were classified into luminance (resolution: 8 bits), the average luminance and the standard deviation were calculated, and the average luminance of the sample to which VE was not added was set as 1, and compared with the luminance of the sample added with VE. As shown here, in the sample dispersed by adding VE, protein adsorption on the surface of UHMWPE is substantially uniformly suppressed even in the order of 100 microns or less, which is the size of the UHMWPE raw material particles.
このことは、数十ミクロン以下の摩耗紛の大きさのレベルにおいてもＶＥが均一に分布していることが窺い知れ、これによって、ＶＥの炎症抑制作用や表面吸着制御作用が最大限に期待できるのである。ＶＥがＵＨＭＷＰＥ中に均一に分散されていないと、ＵＨＭＷＰＥの摩耗粉によっては、ＶＥの含有が過小のものもあれば、過大のものもあり、いずれの場合も、ＶＥ添加の効果が十分でないことが推察できる。大事なのは、摩耗粉にＶＥが均一に含有されていることであり、これが蛋白吸着の抑制、発生した摩耗粉の生物活性を下げることに寄与するのである。 It is well known that VE is evenly distributed even at the level of wear powder size of several tens of microns or less, and as a result, VE inflammation suppressing action and surface adsorption controlling action can be expected to the maximum. It is. If VE is not uniformly dispersed in UHMWPE, depending on the wear powder of UHMWPE, some VE content may be excessive or excessive, and in either case, the effect of adding VE is not sufficient. Can be guessed. What is important is that the VE is uniformly contained in the wear powder, which contributes to suppression of protein adsorption and lowering the biological activity of the generated wear powder.
次に、成形について図面を参照して説明するが、本例のものは成形型によってＵＨＭＷＰＥの溶解とＶＥの均一分散化（熱）処理をするものであるが、本発明はこれに限定されるものではない。図１は本発明に係る成形方法を具現するための成形装置の一例の説明図であるが、この装置は、所要の形状の成形空間（雌型）１と成形体（雄型）２とが対向して装設される上下一対の金型３、４とからなり、これら金型３、４を密閉した成形室５内に上下二つの加熱冷却盤６、７で挟んで配置できるように収容する。なお、この成形室５には、真空ポンプ（図示省略）に連結される吸気ダクト８が連通されているし、上加熱冷却盤６の上方には加圧器（図示省略）も装備されている。 Next, molding will be described with reference to the drawings. In this example, UHMWPE is dissolved and VE is uniformly dispersed (heated) by a mold, but the present invention is limited to this. It is not a thing. FIG. 1 is an explanatory view of an example of a molding apparatus for embodying the molding method according to the present invention. This apparatus has a molding space (female) 1 and a molded body (male) 2 having a required shape. It consists of a pair of upper and lower molds 3 and 4 that are installed opposite to each other, and accommodates these molds 3 and 4 so as to be sandwiched between two upper and lower heating and cooling panels 6 and 7 in a sealed molding chamber 5. To do. The molding chamber 5 is connected to an intake duct 8 connected to a vacuum pump (not shown), and a pressurizer (not shown) is also provided above the upper heating / cooling board 6.
成形に際しては、まず、成形室５を室温にしておき、上加熱冷却盤６と上金型３を上昇させて成形空間１を露出させ、この空間１にＶＥを添加して混合したＵＨＭＷＰＥを充填する。次いで、上金型３の成形体２が成形空間１に作用するように降ろしてその上に上加熱冷却盤６を載せ、この状態で真空ポンプを作動させて成形室５内の空気を吸引して減圧する。なお、成形室５内を減圧にしてから金型３、４や加熱冷却盤６、７を操作するものであってもよい。そして、加熱冷却盤６、７で金型３、４の温度を上げてＵＨＭＷＰＥを溶解させるが、この温度があまり高いとＶＥを失活させるから、約２２０℃で２０分弱の状況に置いておけばよい。この雰囲気であれば、ＶＥを失活させないことが確認されている。 At the time of molding, first, the molding chamber 5 is kept at room temperature, the upper heating / cooling board 6 and the upper mold 3 are raised to expose the molding space 1, and VE is added to the space 1 and mixed with UHMWPE mixed. To do. Next, the molded body 2 of the upper mold 3 is lowered so as to act on the molding space 1, and the upper heating / cooling board 6 is mounted thereon, and in this state, the vacuum pump is operated to suck the air in the molding chamber 5. And depressurize. Alternatively, the molds 3 and 4 and the heating and cooling boards 6 and 7 may be operated after reducing the pressure in the molding chamber 5. Then, the temperature of the molds 3 and 4 is raised by the heating / cooling boards 6 and 7 to dissolve the UHMWPE, but if this temperature is too high, the VE is deactivated. Just keep it. In this atmosphere, it has been confirmed that VE is not deactivated.
以上の溶解処理が終了すると、加熱冷却盤６、７を冷却させて金型３、４の温度を１００℃程度に下げ、この状態で少なくとも３０分保持する。これによって、ＶＥは溶解したＵＨＭＷＰＥの粒子間に均一に分散される。このときの条件は１００℃で３０分以上が適当であるが、８０〜１４０℃の温度或いは３０分以下の時間でも許容される。また、これら温度や時間の条件は、成形時の減圧条件又は不活性ガスの充密度によって調整が可能である。 When the above melting process is completed, the heating and cooling boards 6 and 7 are cooled, the temperature of the molds 3 and 4 is lowered to about 100 ° C., and this state is maintained for at least 30 minutes. Thereby, VE is uniformly dispersed among the dissolved UHMWPE particles. The condition at this time is suitably 30 minutes or more at 100 ° C., but a temperature of 80 to 140 ° C. or a time of 30 minutes or less is acceptable. These temperature and time conditions can be adjusted by reducing the pressure during molding or the charge density of the inert gas.
１ 成形空間（雌型）
２ 成形体（雄型）
３ 金型
４ 金型
５ 成形室５
６ 加熱冷却盤
７ 〃
８ 吸気ダクト
1 Molding space (female mold)
2 Molded body (male)
3 Mold 4 Mold 5 Molding chamber 5
6 Heating / cooling panel 7 〃
8 Air intake duct
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| DE4306593A1 (en) * | 1993-03-03 | 1994-09-08 | Hoechst Ag | Stabilized molding compound made of polyethylene, a process for its production and use |
| EP1795212A3 (en) * | 1996-07-09 | 2007-09-05 | Orthopaedic Hospital | Crosslinking of polyethylene for low wear using radiation and thermal treatments |
| JP4315261B2 (en) * | 1998-02-25 | 2009-08-19 | ナカシマメディカル株式会社 | Sliding member for artificial joint and manufacturing method |
| EP0995449A1 (en) * | 1998-10-21 | 2000-04-26 | Sulzer Orthopädie AG | UHMW-polyethylene for implants |
| SE9900519D0 (en) * | 1999-02-17 | 1999-02-17 | Lars Lidgren | A method for the preparation of UHMWPE doped with an antioxidant and an implant made thereof |
| AU742611B2 (en) * | 1999-07-29 | 2002-01-10 | Depuy Orthopaedics, Inc. | Gamma irradiated heat treated implant for mechanical strength |
| JP3717360B2 (en) * | 2000-02-04 | 2005-11-16 | ナカシマプロペラ株式会社 | Method for forming sliding member for artificial joint |
| DK1276436T3 (en) * | 2000-04-27 | 2009-04-06 | Orthopaedic Hospital | Oxidation-resistant and abrasion-resistant polyethylenes for human conductor replacements and processes for making them |
| WO2004064618A2 (en) * | 2003-01-16 | 2004-08-05 | Massachusetts General Hospital | Methods for making oxidation resistant polymeric material |
| AT412969B (en) * | 2003-05-19 | 2005-09-26 | Klaus Dr Lederer | NETWORKED, ULTRA-HIGH-MOLECULAR POLYETHYLENE (UHMW-PE) |
| CA2554777C (en) * | 2004-02-03 | 2012-10-09 | Orhun K. Muratoglu | Highly crystalline cross-linked oxidation-resistant polyethylene |
| WO2005110276A1 (en) * | 2004-05-11 | 2005-11-24 | The General Hospital Corporation Dba Massachusetts General Hospital | Methods for making oxidation resistant polymeric material |
| CA2674955C (en) * | 2007-01-25 | 2015-05-26 | The General Hospital Corporation | Methods for making oxidation-resistant cross-linked polymeric materials |
| AU2008222967B2 (en) * | 2007-03-02 | 2012-12-13 | Cambridge Polymer Group, Inc. | Cross-linking of antioxidant-containing polymers |
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