JP2011173980A - Molded article of ultrahigh molecular weight polyethylene - Google Patents
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- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 title claims abstract description 126
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 title claims abstract description 126
- GVJHHUAWPYXKBD-UHFFFAOYSA-N (±)-α-Tocopherol Chemical compound OC1=C(C)C(C)=C2OC(CCCC(C)CCCC(C)CCCC(C)C)(C)CCC2=C1C GVJHHUAWPYXKBD-UHFFFAOYSA-N 0.000 claims abstract description 28
- 238000004132 cross linking Methods 0.000 claims abstract description 24
- 230000005855 radiation Effects 0.000 claims abstract description 15
- WIGCFUFOHFEKBI-UHFFFAOYSA-N gamma-tocopherol Natural products CC(C)CCCC(C)CCCC(C)CCCC1CCC2C(C)C(O)C(C)C(C)C2O1 WIGCFUFOHFEKBI-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229930003427 Vitamin E Natural products 0.000 claims abstract description 13
- 239000011709 vitamin E Substances 0.000 claims abstract description 13
- 235000019165 vitamin E Nutrition 0.000 claims abstract description 13
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- WGVKWNUPNGFDFJ-DQCZWYHMSA-N β-tocopherol Chemical compound OC1=CC(C)=C2O[C@@](CCC[C@H](C)CCC[C@H](C)CCCC(C)C)(C)CCC2=C1C WGVKWNUPNGFDFJ-DQCZWYHMSA-N 0.000 description 2
- GZIFEOYASATJEH-VHFRWLAGSA-N δ-tocopherol Chemical compound OC1=CC(C)=C2O[C@@](CCC[C@H](C)CCC[C@H](C)CCCC(C)C)(C)CCC2=C1 GZIFEOYASATJEH-VHFRWLAGSA-N 0.000 description 2
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- GZIFEOYASATJEH-UHFFFAOYSA-N D-delta tocopherol Natural products OC1=CC(C)=C2OC(CCCC(C)CCCC(C)CCCC(C)C)(C)CCC2=C1 GZIFEOYASATJEH-UHFFFAOYSA-N 0.000 description 1
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- 235000010384 tocopherol Nutrition 0.000 description 1
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- 235000004835 α-tocopherol Nutrition 0.000 description 1
- 239000002076 α-tocopherol Substances 0.000 description 1
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- QUEDXNHFTDJVIY-DQCZWYHMSA-N γ-tocopherol Chemical compound OC1=C(C)C(C)=C2O[C@@](CCC[C@H](C)CCC[C@H](C)CCCC(C)C)(C)CCC2=C1 QUEDXNHFTDJVIY-DQCZWYHMSA-N 0.000 description 1
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Abstract
Description
本発明は、医療用インプラントに適用されて好適な架橋処理を施した超高分子量ポリエチレンの成形品に関するものである。 The present invention relates to a molded article of ultra-high molecular weight polyethylene which is applied to a medical implant and subjected to a suitable crosslinking treatment.
分子量が２００万を超える超高分子量ポリエチレン（以下、ＵＨＭＷＰＥ）は、通常のポリエチレンよりも耐摩耗性、耐衝撃性、耐薬品性、自己潤滑性に優れており、しかも、人体に安全であるので、多くの医療用インプラント（以下、インプラント）の主として摺動部分に使用されている。しかしながら、ＵＨＭＷＰＥは体内環境下では酸化が起こり易いことが知られている。この酸化が起こると、ＵＨＭＷＰＥの分子鎖が体液等の環境の下で切断され、分子量が低下してＵＨＭＷＰＥ特有の硬度や潤滑性が失われ、耐摩耗性が低下する。 Ultra high molecular weight polyethylene (hereinafter referred to as UHMWPE) having a molecular weight exceeding 2 million is superior to ordinary polyethylene in abrasion resistance, impact resistance, chemical resistance, and self-lubricating property, and is also safe for the human body. In many medical implants (hereinafter referred to as implants), they are mainly used for sliding parts. However, it is known that UHMWPE is likely to be oxidized in the body environment. When this oxidation occurs, the molecular chain of UHMWPE is cleaved in an environment such as a body fluid, the molecular weight decreases, the hardness and lubricity peculiar to UHMWPE are lost, and the wear resistance decreases.
一方で、ビタミンＥ（以下、ＶＥ）は抗酸化能を有することは知られており、下記特許文献１では、ＵＨＭＷＰＥのインプラントにＶＥを添加（以下、ＶＥ−ＵＨＭＷＰＥ）している。ＶＥ−ＵＨＭＷＰＥからなるインプラントでは、抗酸化能が向上するのはもちろんのこと、流動性が増して成形し易くなり、耐摩耗性も向上することが知られている。なお、ＵＨＭＷＰＥを摺動部分に使用すると摩耗粉が生ずるのは避けられないが、この摩耗粉はマクロファージの好餌となり、マクロファージは骨を溶解するＴＮＦ等のサイトカインなるタンパク質を産生して破骨細胞を活性化させてインプラントのルーズニングを生じさせることが知られている（これを生体為害性という）。しかし、ＶＥを含んだ摩耗粉は、ＶＥの添加量や成形条件によっては生体為害性も抑制することがわかっている（下記特許文献２）。 On the other hand, vitamin E (hereinafter referred to as VE) is known to have an antioxidant ability, and in Patent Document 1 below, VE is added to a UHMWPE implant (hereinafter referred to as VE-UHMWPE). It is known that an implant made of VE-UHMWPE not only has an improved antioxidant capacity, but also has an increased fluidity and becomes easy to mold, and wear resistance is also improved. In addition, when UHMWPE is used for the sliding part, it is inevitable that abrasion powder is generated. However, this abrasion powder serves as a prey for macrophages, and macrophages produce proteins such as TNF and other cytokines that dissolve bone to produce osteoclasts. It is known to activate implants to cause loosening of the implant (this is called biological harm). However, it has been found that wear powder containing VE also suppresses biological harm depending on the amount of VE added and molding conditions (Patent Document 2 below).
ところが、上記した特許文献１を含む従来のインプラントの素材であるＶＥ−ＵＨＭＷＰＥは、ＵＨＭＷＰＥの中にＶＥを分散させただけのものであるから、両方の特性を併有するものになる。つまり、ＶＥを添加したものは、ＵＨＭＷＰＥの分子間または粒子間に異質のＶＥが入り込むものであるから、抗酸化能はあるものの、硬度、伸び、クリープ量といった力学的特性を変化させることになり、これがそのままＶＥ−ＵＨＭＷＰＥの特性に反映していた。しかし、インプラントでは、部位によってはＵＨＭＷＰＥが適する場合もあれば、ＶＥ−ＵＨＭＷＰＥが適する場合もあるので、一律的にＶＥ−ＵＨＭＷＰＥを使えばよいというものではない。 However, VE-UHMWPE, which is a conventional implant material including Patent Document 1 described above, has only both characteristics because it is obtained by simply dispersing VE in UHMWPE. In other words, since VE is added, foreign VE enters between the molecules or particles of UHMWPE, so it has antioxidant ability, but changes the mechanical properties such as hardness, elongation, and creep amount. This was directly reflected in the characteristics of VE-UHMWPE. However, for implants, UHMWPE may be appropriate depending on the site, and VE-UHMWPE may be appropriate. Therefore, VE-UHMWPE may not be used uniformly.
さらに、下記特許文献３に見られるように、インプラントの成形過程の特定の工程で放射線エネルギーを投与してＵＨＭＷＰＥの分子鎖の結合を強化する架橋処理を行うものがある。インプラントに架橋処理を施すと、分子間の結合が強化されることによって硬度を増して耐摩耗性を高め、クリープ量を減少させるといった力学的性質を向上させることができるが、一方では、柔軟さが失われて脆性が増し、割れ易くなるという性質も有している。 Furthermore, as seen in Patent Document 3 below, there is a technique in which radiation energy is administered in a specific step of the implant molding process to perform a crosslinking treatment to strengthen the binding of the molecular chains of UHMWPE. Cross-linking the implant can improve mechanical properties such as increased intermolecular bonds, increased hardness, increased wear resistance, and reduced creep, but on the other hand, flexibility Is lost, the brittleness increases, and it is easy to break.
ところで、放射線エネルギーの投与は酸化耐性を有するＶＥ−ＵＨＭＷＰＥではその影響が減殺されて（耐性が高い）、架橋され難いということも知られているが、上記した特許文献３では、投与対象はすべて一様な添加量を有するＶＥ−ＵＨＭＷＰＥである。したがって、架橋の効果も全部の部位に亘って一律的である。これがもし、ＵＨＭＷＰＥとＶＥ−ＵＨＭＷＰＥとを別々に配置できるとすれば、架橋の効果を所望の部位で変えることができる。 By the way, it is also known that the radiation energy administration is reduced in VE-UHMWPE having oxidation resistance (high tolerance) and difficult to be cross-linked. VE-UHMWPE with uniform loading. Therefore, the effect of cross-linking is uniform over the entire site. If this makes it possible to arrange UHMWPE and VE-UHMWPE separately, the effect of crosslinking can be changed at the desired site.
本発明は、このような課題を解決したものであり、ＵＨＭＷＰＥの中で抗酸化能を有するＶＥ−ＵＨＭＷＰＥを所望の部位に任意の形態で配置することで、特定の部位に架橋処理による長所のみを取り入れることができるようにしたものである。言い換えると、成形品の部位ごとに架橋度の異なるＵＨＭＷＰＥを配置できるようにしたものである。 The present invention solves such problems, and by arranging VE-UHMWPE having antioxidative ability in UHMWPE in an arbitrary form at a desired site, only the advantage of crosslinking treatment at a specific site is obtained. Can be incorporated. In other words, UHMWPE having a different degree of crosslinking can be arranged for each part of the molded product.
以上の課題の下、本発明は、請求項１に記載した、超高分子量ポリエチレンを用いて所定の形状に成形した成形品に放射線エネルギーを投与する架橋処理を施した超高分子量ポリエチレンの成形品において、ビタミンＥを添加した超高分子量ポリエチレンを超高分子量ポリエチレンの任意の部位に配置したことを特徴とする超高分子量ポリエチレンの成形品を提供するとともに、この任意配置の形態として、請求項２に記載した成層している形態、また、成層の形態として、請求項３に記載した、成層が階層的である形態、請求項４に記載した、成層が同層的である形態を提供する。 Under the above-mentioned problems, the present invention provides an ultra-high molecular weight polyethylene molded product obtained by subjecting a molded product molded into a predetermined shape using ultra-high molecular weight polyethylene according to claim 1 to a crosslinking treatment for administering radiation energy. In addition, the present invention provides an ultra-high-molecular-weight polyethylene molded article characterized in that an ultra-high-molecular-weight polyethylene to which vitamin E is added is disposed at an arbitrary part of the ultra-high-molecular-weight polyethylene, The stratified form described in (1) and the form of stratification described in claim 3 are the forms in which the stratification is hierarchical and the forms in which the stratification is described in claim 4 are the same.
さらに、任意配置の形態として、請求項５に記載した、ビタミンＥを添加した超高分子量ポリエチレンがビタミンＥを添加しない超高分子量ポリエチレンの中に部分的に存在している形態を提供するとともに、この形態において、請求項６に記載した、ビタミンＥを添加した超高分子量ポリエチレンが添加量の異なるビタミンＥを添加した超高分子量ポリエチレンの中に部分的に存在する形態を提供する。そして、これらの成形品の好適な例として、請求項７に記載した、成形品が医療用インプラントである手段を提供する。 Furthermore, as an arbitrarily arranged form, the ultra high molecular weight polyethylene added with vitamin E according to claim 5 is partially present in the ultra high molecular weight polyethylene not added with vitamin E, In this form, the ultra high molecular weight polyethylene to which vitamin E is added according to claim 6 is partially present in the ultra high molecular weight polyethylene to which vitamin E having a different addition amount is added. And as a suitable example of these molded products, the means as described in claim 7 is provided where the molded product is a medical implant.
請求項１の発明によると、成形品に求められる特性に応じてＶＥ−ＵＨＭＷＰＥをＵＨＭＷＰＥの中の任意の部位に配置できる。したがって、この成形品をインプラントに適用すれば、それぞれの部位ごとに要求される特性に応じてＵＨＭＷＰＥとＶＥ−ＵＨＭＷＰＥとを使い分けることができ、全体としてより性能の高いインプラントが得られる。具体的には、摺動部分であって摩耗粉が多く発生する個所には生体為害性の少ないＶＥ−ＵＨＭＷＰＥを、その他の部分では力学的特性が高いＵＨＭＷＰＥを配置するといったことが可能になる。 According to invention of Claim 1, VE-UHMWPE can be arrange | positioned in the arbitrary site | parts in UHMWPE according to the characteristic calculated | required by a molded article. Therefore, when this molded product is applied to an implant, UHMWPE and VE-UHMWPE can be used properly according to the characteristics required for each part, and an implant with higher performance as a whole can be obtained. Specifically, it is possible to arrange VE-UHMWPE having a low biological harm at a sliding portion where a lot of abrasion powder is generated, and UHMWPE having high mechanical properties at other portions.
加えて、請求項１の発明では、成形品に放射線の照射によって架橋処理を施すのであるから、硬度が増して耐磨耗性が向上する。しかし、放射線エネルギーの投与による効果は被照射体（成形品）の耐酸化性が高いほど耐性があることから、摩擦を起こす部位にＶＥ−ＵＨＭＷＰＥを配置しておけば、架橋効果は多少低下するものの、長所である柔軟さを維持しつつ、短所である脆性の増大、割れといったことが防がれる。 In addition, in the invention of claim 1, since the molded article is subjected to a crosslinking treatment by irradiation with radiation, the hardness is increased and the wear resistance is improved. However, since the effect of administration of radiation energy is higher as the oxidation resistance of the irradiated object (molded article) is higher, if VE-UHMWPE is arranged at a site causing friction, the crosslinking effect is somewhat reduced. However, while maintaining the flexibility, which is an advantage, it is possible to prevent the disadvantages such as increased brittleness and cracking.
すなわち、架橋処理を施したとしても、摩擦個所における磨耗粉による生体為害性の少なさといったＶＥ−ＵＨＭＷＰＥによる効果を依然として享受できるのであり、この場合の架橋効果の低下による磨耗粉の減少の抑制は上記特許文献２の手法が大いに貢献するのである。さらに、放射線は素材であるパウダーや成形前のブランクに照射するものと違って最終工程で得られた成形品に照射するのであるから、工程を簡略化でき、放射線による滅菌処理がより効率的になる。 That is, even if the cross-linking treatment is performed, the effects of VE-UHMWPE such as the low biological damage caused by the wear powder at the friction part can still be enjoyed. In this case, the reduction of the wear powder due to the reduction of the cross-linking effect is suppressed. The technique of the above-mentioned Patent Document 2 greatly contributes. In addition, radiation is irradiated to the molded product obtained in the final process, unlike the powder or blank before molding, which simplifies the process and makes sterilization by radiation more efficient. Become.
以下、本発明の実施の形態をインプラントを例をとって説明するが、これに限られるものではなく、ＵＨＭＷＰＥやＶＥ−ＵＨＭＷＰＥを架橋して硬度等の力学的特性を高めるすべての産生品に適用できる。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が、ここでいうＵＨＭＷＰＥとは、分子量が２００〜７００万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、耐衝撃性等の力学的特性にも優れているからである。 Hereinafter, embodiments of the present invention will be described by taking implants as examples. However, the present invention is not limited to this, and is applicable to all products that increase the mechanical properties such as hardness by cross-linking UHMWPE and VE-UHMWPE. it can. First, the characteristics of UHMWPE and the significance of adding VE will be described. UHMWPE here refers to those having a molecular weight in the range of 2 to 7 million. The reason why such UHMWPE is used is that they are dense and excellent in mechanical properties such as wear resistance and impact resistance.
インプラントの素材として使用する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社製の商品名ＨｏｓｔａｌｅｎＧＵＲ１０２０、１１２０、１０５０、１１５０やＭｏｎｔｅｌ社製の商品名Ｈｉｆａｘ１９００があり、これらはいずれもパウダーで市販されているが、ペレット、タブレットのものもある。そのいずれを使用してもよいが、成形時の熱による融解性、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適している。 UHMWPE used as an implant material must be adapted for medical use, including the product names Hostalen GUR1020, 1120, 1050 and 1150 manufactured by Ticona, and the product name Hifax1900 manufactured by Montel, These are all commercially available in powder form, but there are also pellets and tablets. Any of them may be used, but powders are most suitable from the viewpoints of meltability by heat during molding, bubble formation, and uniform mixing with additives.
一方、ＶＥとは、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、混合物を含むものでありエーザイ株式会社から日本薬局方トコフエロール（ｄｌ−α−Ｔｏｃｏｐｈｅｒｏｌ ＪＰ）として液状又はパウダーで市販されているが、液状の方が取扱いや混合が容易で適している。ＵＨＭＷＰＥにＶＥを添加する割合は、０．０１〜３重量％、中でも０．１〜１．０重量％程度が適しており、これよりも少ないとその効果が十分ではなく、また、多すぎても添加の割合に比べて効果が増えないし、場合によっては低下する。 On the other hand, VE includes α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol and isomers, derivatives, and mixtures thereof, and is obtained from Eisai Co., Ltd. in Japan Pharmacopoeia Tocopherol (dl-α-Tocopherol JP). ) As a liquid or powder, but the liquid is easier to handle and mix. The proportion of VE added to UHMWPE is suitably about 0.01 to 3% by weight, especially about 0.1 to 1.0% by weight. If it is less than this, the effect is not sufficient, and too much. Also, the effect does not increase compared to the ratio of addition, and in some cases it decreases.
ＵＨＭＷＰＥに対するＶＥの添加の方法は、ＵＨＭＷＰＥのパウダーに液状のＶＥを添加して混合すればよい。この添加した液状のＶＥはＵＨＭＷＰＥのパウダーの中に均一に分散される必要がある。ＶＥの分散が均一でないと、インプラントの抗酸化能や成形性、また、生体為害性にむらが生じ、結果的に性能低下を招くからである。この均一分散化処理は、添加した液状のＶＥとＵＨＭＷＰＥのパウダーをある程度の温度で十分に攪拌することで行う（攪拌の方法は問わない）。この温度は高い方が適するが、あまり高いと、ＶＥを失活させる可能性があるから、室温〜８０℃程度の温度が適する。 As a method for adding VE to UHMWPE, liquid VE may be added to UHMWPE powder and mixed. The added liquid VE needs to be uniformly dispersed in the UHMWPE powder. This is because if the dispersion of VE is not uniform, the antioxidant ability and moldability of the implant and the biological harm are uneven, resulting in a decrease in performance. This uniform dispersion treatment is performed by sufficiently stirring the added liquid VE and UHMWPE powder at a certain temperature (the stirring method is not limited). A higher temperature is suitable, but if it is too high, VE may be deactivated, so a temperature of about room temperature to about 80 ° C. is suitable.
次に、以上のＵＨＭＷＰＥとＶＥ−ＵＨＭＷＰＥのパウダーを用いて特定形状のインプラントに成形する場合について説明する。まず、この両者をインプラント内で配置させようとする部位・位置に所望の形状と量をもって配置する。この配置の設定は、金型によるが、ジグを用いる人手によるものであっもよいし、機械的な制御によってもよい。 Next, the case where it shape | molds to the implant of a specific shape using the powder of the above UHMWPE and VE-UHMWPE is demonstrated. First, the two are arranged with a desired shape and amount at a site / position to be arranged in the implant. Although the setting of this arrangement depends on the mold, it may be manually performed using a jig, or may be controlled mechanically.
成形の際には、金型の中に以上のＵＨＭＷＰＥとＶＥ−ＵＨＭＷＰＥのパウダーを積層状に投入したなら（上下に成層させる例）、上からプレスで押圧して成形する。このときの熱的条件はＵＨＭＷＰＥの粒子を融解させる必要があり、この融解によって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、この融解部分にＶＥを浸透させるものであり、ＵＨＭＷＰＥやＶＥ−ＵＨＭＷＰＥをインプラントに成形する場合には重要な操作・処理である。 At the time of molding, if the above UHMWPE and VE-UHMWPE powders are put into a mold (in the case of stratification in the upper and lower directions), they are molded by pressing with a press from above. The thermal conditions at this time are required to melt the UHMWPE particles, which melts the surfaces of the UHMWPE particles to bond the particles to each other and to infiltrate VE into the melted portion. This is an important operation and processing when VE-UHMWPE is formed into an implant.
このときの融解温度は、ＵＨＭＷＰＥが溶解する２００℃以上は必要であるが、あまり高い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。また、圧力も必要であるが、圧力は成形に必要な範囲でよく、８０〜１５０Ｋｇｆ／ｃｍ2 程度でよい。この融解操作によって、ＶＥは更にＵＨＭＷＰＥの中に均一に分散され、ＵＨＭＷＰＥの成形性も改善されるものとなる。なお、この融解操作によってＵＨＭＷＰＥとＶＥ−ＵＨＭＷＰＥの界面も接着される。 The melting temperature at this time is required to be 200 ° C. or higher at which UHMWPE dissolves, but if left at a very high temperature for a long time, VE is deactivated, so it is suitable to heat at about 220 ° C. for a little less than 20 minutes. . Moreover, although a pressure is also required, a pressure may be a range required for shaping | molding and may be about 80-150Kgf / cm < 2 >. By this melting operation, VE is further uniformly dispersed in UHMWPE, and the moldability of UHMWPE is improved. Note that the interface between UHMWPE and VE-UHMWPE is also bonded by this melting operation.
ところで、以上の加圧成形を減圧下や不活性ガス雰囲気下で行うと、成形がより易しく、インプラントの品質も向上する。成形を減圧下で行えば、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時間も短縮できる。さらに、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る。この場合の減圧の程度は大きいほど好ましいが、０．１気圧以下であれば十分な効果がある。なお、残存酸素量を減らすという観点からいえば、窒素ガス等の不活性ガス雰囲気下での成形も適している。 By the way, when the above pressure molding is performed under reduced pressure or in an inert gas atmosphere, molding is easier and the quality of the implant is improved. If the molding is performed under reduced pressure, the fluidity of the UHMWPE particles is increased based on the reduced pressure, facilitating the molding and shortening the time. Further, there is an effect that particles and bubbles existing between the particles are removed and the amount of remaining oxygen is reduced to reduce the harmful effects of oxidation. In this case, the degree of decompression is preferably as large as possible, but if it is 0.1 atm or less, a sufficient effect is obtained. From the viewpoint of reducing the amount of residual oxygen, molding under an inert gas atmosphere such as nitrogen gas is also suitable.
図１は簡単のために成形品をキュービックとした場合の斜視図であるが、（ａ）は下がＵＨＭＷＰＥ（Ａ）で上がＶＥ−ＵＨＭＷＰＥ（Ｂ）の二層構造のものであり、（ｂ）は真ん中をＶＥ−ＵＨＭＷＰＥ（Ｂ）にしてその上下をＵＨＭＷＰＥ（Ａ）にした三層構造のものであり、その成形方法、条件は上記と同じである。なお、これらの例は上下（階層的）に成層したものであるが、並列（同層的）に成層してもよい。また、それぞれのＵＨＭＷＰＥやＶＥ−ＵＨＭＷＰＥは一様な厚みになっているが、厚みを部分的に変えてもよい。 FIG. 1 is a perspective view in the case where a molded product is cubic for simplicity, but (a) is a two-layer structure with UHMWPE (A) on the bottom and VE-UHMWPE (B) on the top, b) has a three-layer structure in which the middle is VE-UHMWPE (B) and the upper and lower sides are UHMWPE (A), and the molding method and conditions are the same as above. In addition, although these examples are stratified up and down (hierarchical), you may stratify in parallel (same layer). Moreover, although each UHMWPE and VE-UHMWPE have a uniform thickness, the thickness may be partially changed.
（ｃ）はＵＨＭＷＰＥ（Ａ）の中にＶＥ−ＵＨＭＷＰＥ（Ｂ）を部分的に存在させたものであるが、この場合は、ＵＨＭＷＰＥのパウダーの所定の個所に特定の形状、大きさ、数の筒型を挿入し、この筒型の中にＶＥ−ＵＨＭＷＰＥのパウダーを投入した後、筒型を抜き取って上記と同様な処理をすればよい。なお、図示のものは、ＶＥ−ＵＨＭＷＰＥ（Ｂ）を上面に覗かせて縦に挿設しているが、横或いは斜めであってもよいし、中途に隠れるように埋入することも可能である。 (C) is the one in which VE-UHMWPE (B) is partially present in UHMWPE (A). In this case, a specific shape, size and number of UHMWPE powder are specified at predetermined locations. A cylindrical mold is inserted, VE-UHMWPE powder is put into the cylindrical mold, the cylindrical mold is extracted, and the same processing as described above may be performed. In addition, although the thing of illustration shows VE-UHMWPE (B) on the upper surface, it is installed vertically, it may be horizontal or diagonal, and it can also be embedded so that it may be hidden in the middle. is there.
図２に示すものは、インプラントとして人工膝関節の脛骨側部材の関節面（インサート）に成形したものであるが、このような特定の形態に成形するには、金型を成形品に即したものにしておけばよい。このうち、（ａ）のものは、人工膝関節の大腿骨側部材（金属製）が載って摺動面となる上面全体をＶＥ−ＵＨＭＷＰＥ（Ｂ）にしたものである。また、（ｂ）のものは、上面のうち、大腿骨側部材の二つの顆が載る部分のみをＶＥ−ＵＨＭＷＰＥ（Ｂ）にしたものである。 The one shown in FIG. 2 is formed on the joint surface (insert) of the tibial side member of an artificial knee joint as an implant. In order to form such a specific form, the mold is adapted to the molded product. Just make it a thing. Among these, (a) is a VE-UHMWPE (B) in which the entire upper surface serving as a sliding surface on which the femoral side member (made of metal) of the artificial knee joint is placed. In the case of (b), only the portion of the upper surface where the two condyles of the femoral side member are placed is made VE-UHMWPE (B).
この顆が載る部分は圧力と摩擦が大きく、ＶＥ−ＵＨＭＷＰＥの抗酸化能や生体為害性の少なさといった長所が望まれる個所でもある。このように、所望の部位のみをＶＥ−ＵＨＭＷＰＥとするのは、ＶＥ−ＵＨＭＷＰＥはＵＨＭＷＰＥに比べて価格も高く、また、ＶＥとＵＨＭＷＰＥとを混合するには攪拌操作も必要とするから、この攪拌操作が簡略化され、全体の製造コストを安くできるからである。さらに、後述する架橋処理の影響をその部位に応じて架橋度を変えて受けるためでもある。図３に示すものは、人工股関節の骨頭が納まるライナーを示したものであるが、この場合は骨頭と圧接して摺動面となる下部をＶＥ−ＵＨＭＷＰＥ（Ｂ）にしている。 The part where the condyles are placed has a large pressure and friction, and is a place where VE-UHMWPE is desired to have the advantages such as the anti-oxidation ability and the low biological harm. In this way, VE-UHMWPE is used only for the desired site because VE-UHMWPE is more expensive than UHMWPE, and mixing is required to mix VE and UHMWPE. This is because the operation is simplified and the entire manufacturing cost can be reduced. Furthermore, it is also for receiving the influence of the crosslinking process mentioned later, changing a crosslinking degree according to the site | part. FIG. 3 shows a liner in which the head of an artificial hip joint is housed. In this case, the lower part serving as a sliding surface in pressure contact with the head is VE-UHMWPE (B).
ところで、以上は、ＶＥを添加しないＵＨＭＷＰＥにＶＥを添加したＶＥ−ＵＨＭＷＰＥを配置した例であるが、ＶＥ−ＵＨＭＷＰＥの中にＶＥの添加量（率）が違うＶＥ−ＵＨＭＷＰＥを配置することもできる。つまり、ＵＨＭＷＰＥと各々添加量が違うＶＥ−ＵＨＭＷＰＥをインプラントの任意の部位にそれぞれ集積して配置することができるのである。上記した特許文献２でも触れてあるが、ＶＥの添加量が異なると、磨耗粉の発生や生体為害性が異なることから、それに応じてもっとも好ましい形態がとれるのである。 By the way, the above is an example in which VE-UHMWPE with VE added is added to UHMWPE without VE added, but VE-UHMWPE with a different VE addition amount (rate) can also be placed in VE-UHMWPE. . That is, VE-UHMWPE having a different addition amount from UHMWPE can be accumulated and arranged at any site of the implant. As mentioned in the above-mentioned Patent Document 2, if the amount of VE added is different, the generation of wear powder and the harmfulness to living organisms are different, so that the most preferable form can be taken accordingly.
本発明では、インプラントを成形した後に放射線エネルギーを投与する架橋処理を行うのである。この架橋処理は成形後のインプラントに直接施してもよいが、流通に備えて適宜な包装材で包装されたインプラントに施してもよい。ＵＨＭＷＰＥ（ＶＥ−ＵＨＭＷＰＥも同じ）はある程度は分子鎖で互いに絡み合って架橋しているが、これにガンマ線やＸ線或いは電子線等の放射線を照射すると、そのエネルギーでこの分子鎖を一旦切断して再結合させることになり、このときに絡み合いや繋がりの相手が変わったり、結合が連続したりして架橋が強化されるのである。 In the present invention, a cross-linking treatment is performed in which radiation energy is administered after the implant is formed. This cross-linking treatment may be performed directly on the molded implant, or may be performed on an implant packaged with an appropriate packaging material in preparation for distribution. UHMWPE (VE-UHMWPE is the same) is entangled with each other by molecular chains to some extent, and when this is irradiated with radiation such as gamma rays, X-rays or electron beams, this molecular chain is once cut by the energy. At this time, the entanglement or connection partner is changed, or the bond is continued and the cross-linking is strengthened.
すなわち、分子鎖が互いにクロスリンクされた状態に態になるのであり、この状態のＵＨＭＷＰＥ又はＶＥ−ＵＨＭＷＰＥを以下ではＸＬ−ＵＨＭＷＰＥという。分子鎖がクロスリンクされた結果、硬さや耐磨耗性（磨耗粉の減少）といった力学的特性を向上させることができるのである。ただし、抗酸化能を有するＶＥ−ＵＨＭＷＰＥではその効果が減殺されることは上記したとおりである。 That is, the molecular chains are cross-linked to each other, and the UHMWPE or VE-UHMWPE in this state is hereinafter referred to as XL-UHMWPE. As a result of the cross-linking of molecular chains, mechanical properties such as hardness and wear resistance (reduction of wear powder) can be improved. However, as described above, the effect of VE-UHMWPE having antioxidant ability is reduced.
以上が本発明に係るＵＨＭＷＰＥのインプラントを成形する過程であるが、これを整理すると、以下の工程をとることになる。素材（ＵＨＭＷＰＥのパウダー）→ＶＥの添加→ＵＨＭＷＰＥにおけるＶＥの均一分散化処理（ＶＥ−ＵＨＭＷＰＥの調製）→ＵＨＭＷＰＥとＶＥ−ＵＨＭＷＰＥそれぞれの型込め→成形→放射線照射（ＸＬ−（ＶＥ）ＵＨＭＷＰＥの出現）ということになる。 The above is the process of molding the UHMWPE implant according to the present invention. When this is arranged, the following steps are taken. Material (UHMWPE powder) → Addition of VE → Uniform dispersion treatment of VE in UHMWPE (preparation of VE-UHMWPE) → Molding of UHMWPE and VE-UHMWPE → Molding → Radiation (XL- (VE) UHMWPE appearance )It turns out that.
架橋処理を施す放射線の照射は、酸素のない状態で照射することが必要である。酸素が存在すると、切断された分子鎖が酸素と結合して酸化するからである。このため、照射室を脱気して真空に近い状態にするか窒素ガス等の不活性ガス中で成形品（インプラント）に放射線を照射する。この条件は、３０〜３００ｋＧｙの電子線を照射した後、同じ雰囲気下で８０〜１５０℃で１２〜７２時間の間アニーリングすればよい。なお、上記した溶解操作に加えてこの架橋処理は、インプラントの表面に付着したり、内部に混入した細菌やウイルスを死滅させる滅菌処理も兼ねることになる。 The irradiation of the radiation for performing the crosslinking treatment needs to be performed without oxygen. This is because when oxygen is present, the broken molecular chain is combined with oxygen and oxidized. For this reason, the irradiation chamber is evacuated to a state close to vacuum, or the molded product (implant) is irradiated with radiation in an inert gas such as nitrogen gas. As for this condition, after irradiation with an electron beam of 30 to 300 kGy, annealing may be performed at 80 to 150 ° C. for 12 to 72 hours in the same atmosphere. In addition to the above-described dissolution operation, this crosslinking treatment also serves as a sterilization treatment that adheres to the surface of the implant or kills bacteria and viruses mixed inside.
Ａ ＵＨＭＷＰＥ
Ｂ ＶＥ−ＵＨＭＷＰＥ
A UHMWPE
B VE-UHMWPE
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| JP2014004352A (en) * | 2012-05-31 | 2014-01-16 | Kyocera Medical Corp | Sliding material and method of manufacturing the same |
| JP2014124502A (en) * | 2012-12-27 | 2014-07-07 | Kyocera Medical Corp | Method for manufacturing sliding member of artificial joint and sliding member of artificial joint |
| JP2014166229A (en) * | 2013-02-28 | 2014-09-11 | Kyocera Medical Corp | Sliding material and method of manufacturing the same |
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