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WO2001008713A1 - Materiau façonne en polyethylene reticule, resistant a la fracture, possedant un poids moleculaire extremement eleve et articles fabriques avec ce materiau - Google Patents

Materiau façonne en polyethylene reticule, resistant a la fracture, possedant un poids moleculaire extremement eleve et articles fabriques avec ce materiau Download PDF

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Publication number
WO2001008713A1
WO2001008713A1 PCT/US2000/040494 US0040494W WO0108713A1 WO 2001008713 A1 WO2001008713 A1 WO 2001008713A1 US 0040494 W US0040494 W US 0040494W WO 0108713 A1 WO0108713 A1 WO 0108713A1
Authority
WO
WIPO (PCT)
Prior art keywords
polyethylene
mrads
molecular weight
irradiated
irradiation
Prior art date
Application number
PCT/US2000/040494
Other languages
English (en)
Other versions
WO2001008713A9 (fr
Inventor
Stephen Li
Original Assignee
New York Society For The Relief Of The Ruptured And Crippled Maintaining The Hospital For Special S Urgery
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by New York Society For The Relief Of The Ruptured And Crippled Maintaining The Hospital For Special S Urgery filed Critical New York Society For The Relief Of The Ruptured And Crippled Maintaining The Hospital For Special S Urgery
Priority to CA002403357A priority Critical patent/CA2403357A1/fr
Priority to AU76270/00A priority patent/AU7627000A/en
Priority to EP00965571A priority patent/EP1404387A1/fr
Publication of WO2001008713A1 publication Critical patent/WO2001008713A1/fr
Publication of WO2001008713A9 publication Critical patent/WO2001008713A9/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/14—Macromolecular materials
    • A61L27/16—Macromolecular materials obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/04—Macromolecular materials
    • A61L31/048—Macromolecular materials obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/3094—Designing or manufacturing processes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
    • A61F2002/30667—Features concerning an interaction with the environment or a particular use of the prosthesis
    • A61F2002/30682—Means for preventing migration of particles released by the joint, e.g. wear debris or cement particles
    • A61F2002/30685—Means for reducing or preventing the generation of wear particulates
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/3094—Designing or manufacturing processes
    • A61F2/30942—Designing or manufacturing processes for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
    • A61F2002/30957—Designing or manufacturing processes for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques using a positive or a negative model, e.g. moulds

Definitions

  • the invention relates to total joint replacement devices having improved fracture toughness, and to a method of making them.
  • the devices can be used in total joint replacements such as hip, knee, elbow and shoulder.
  • hip and knee devices The success rate of implantation of hip and knee devices is generally quite high but the life of these devices is often limited by the wear and damage of the polyethylene components.
  • UHMWPE is commercially produced as a powder and is available in several grades from several companies.
  • the grades generally differ in molecular weight and molecular weight distribution.
  • the powder is fabricated into devices by one of three methods: (1) extrusion into bars followed by machining of the device and (2) compression molding into sheets followed by machining and (3) direct compression molding.
  • Each method has advantages and disadvantages. Extrusion involves introducing a fixed amount polyethylene powder into a chamber; pushing this powder into a heated cylindrical barrel with a ram which then retracts, leaving the chamber empty and waits for the next fixed amount of powder. The process is continuous and each push of the ram advances the polyethylene through the heated barrel. In this manner, the powder is consolidated into a continuous bar with typically a round cross-section. The resulting bar stock is generally from one to six inches in diameter. Implants are then machined from this cylindrical bar stock.
  • Compression Sheet Molding involves introducing powder into a container that can be as large as 8 inches deep, 4 feet wide and 8 feet long. A platen large enough to cover the entire container is then used to apply heat and pressure to the polyethylene in the container. Implants are then machined from this sheet.
  • Direct Molding is different from sheet molding in that powder is placed into a mold that compresses it into the final shape of the device without need for machining (rather than a bar or a sheet which needs to be machined into the device shape). (Some machining may be used as part of finishing operations.)
  • the mold containing the powder is heated under pressure to consolidate the polyethylene and form the device. Devices formed in this fashion often exhibit a highly glossy surface finish.
  • the process conditions of direct molding are often quite different from compression molding sheet and different properties are often obtained.
  • polyethylene wear and damage takes one or more of the following forms (modes): burnishing (polishing); abrasion (generation of small particles); pitting (formation of pits); delamination (loss of 'sheets' of material); and fracture.
  • modes burnishing (polishing); abrasion (generation of small particles); pitting (formation of pits); delamination (loss of 'sheets' of material); and fracture.
  • burnishing polishing
  • abrasion generation of small particles
  • pitting formation of pits
  • delamination loss of 'sheets' of material
  • fracture The presence, location and extent of each of these damage or failure modes is dependent on material properties, as well as on design, kinematics, and individual patient factors.
  • Total Hip Replacements In total hip replacements, the main mode of polyethylene failure is abrasion and burnishing which generate small ( ⁇ 1 ⁇ diameter) polyethylene debris particles. These small particles caused by wear elicit a complex biological response which eventually leads to bone resorption which, in turn, causes implant loosening. On loosening of the implant, pain ensues and revision surgery becomes necessary. The process of bone loss due to particulate debris is termed osteolysis and is a major cause of hip replacement failure. Fractures of the polyethylene acetabular component in hip replacement devices are less common but do occur. Fracture of acetabular components has been shown to be design dependent.
  • Total Knee Replacements In total knee replacements, in addition to the generation of small debris particles, the damage to the polyethylene is often macroscopic in nature. Pitting, delamination and fracture are prevalent in total knee replacements. There have also been several reports which strongly associate pitting, delamination and fracture with decreases in polyethylene mechanical properties, specifically fracture and fatigue properties. Previous Methods to Reduce Wear. In the mid 1970's, Oonishi in Japan reported improvements on the wear properties of polyethylene by using high dosages of gamma irradiation. He used 100 Mrads of gamma irradiation to treat acetabular cups made from high density polyethylene for implantation. This is far above the 2.5-4 Mrads generally used to sterilize these components.
  • This high dose irradiation causes a high degree of cross linking in the polyethylene.
  • This cross linking has been shown to alter many of the properties of the polyethylene, including improving the wear properties. Oonishi demonstrated a factor reduction is wear. In the last few years, increasing cross linking levels have been revisited for the purpose of improving wear properties. There have been several reports on crosslinking achieved by either gamma irradiation or electron beam irradiation. While crosslinking has produced improvements in the wear resistance of polyethylene, it has also been shown to reduce other mechanical properties, most notably, the fracture toughness of the polyethylene. Fracture toughness of a polymer is a measure of the tendency of the material to resist fracture.
  • the invention is directed to a tough, wear resistant Ultra High
  • Molecular Weight Polyethylene shaped material prepared by the irradiation cross linking (using an irradiation dose higher than 4 Mrads, preferably 5 Mrads, and most preferably less than 10 Mrads of a UHMWPE article which has been shaped by direct compression molding.
  • the product can used in total joint replacement devices such as hip, knee, elbow and shoulder.
  • the invention is directed to a total joint replacement device or component thereof comprising a shaped crosslinked article made from UHMWPE subjected to a process comprising direct compression molding followed with irradiation at a dose higher than 4 Mrads, preferably 5 Mrads, and most preferably less than 10 Mrads.
  • Figure 1 is a graph of fracture toughness (J Integral curve in kJ/m 2 ) against average crack growth ( ⁇ a in mm) for unirradiated and 2.5 Mrad gamma-irradiated samples of extruded 4150HP polyethylene rods (Group 1).
  • the irradiated sample has lower fracture toughness because a lower energy per unit surface is required to grow a crack than in the case of the unirradiated sample.
  • Figure 2 is the same type of graph as Fig. 1 but depicting J integral curves for samples from Group 1 (extruded 4150HP rods) gamma irradiated at different doses from 0 to 50 Mrads. It is clear from these curves that increasing irradiation dose results in a reduction in toughness.
  • Figure 3 is the same type of graph but depicting J integral curves for samples from Group 1A (extruded 4150HP, electron beam irradiated from 2.5 to 50 Mrads). Toughness decreases as the irradiation dose increases, similar to
  • Figures 4 to 9 are graphs that compare the J curves for the ram-extruded samples from Group 1 with the directly molded samples of Group 2 at 2.5, 5, 10, 20 and 50 Mrads respectively. In all cases, the directly molded samples have higher J values than the ram extruded samples.
  • Figure 10 is a graph that compares the J curves for (i) ram-extruded 4150HP, (ii) directly molded 4150HP and (iii) directly molded polyethylene 1900 samples after 5 Mrads of gamma irradiation. Both the molded samples, regardless of resin grade, have higher crack growth resistance than the ram- extruded sample.
  • Figure 11 is a graph that compares the J integral values for directly molded 4150HP irradiated with a higher dose (5 Mrad) with the ram extruded sample irradiated with only 2.5 Mrad. Contrary to expectation, the 5 Mrad irradiated molded sample has higher toughness than the 2.5 Mrad gamma irradiated extruded sample.
  • Figure 12 is a graph that compares the J integral values for directly molded 4150HP irradiated with 10 Mrad with the 5 Mrad irradiated ram extruded sample. Contrary to expectation, the 10 Mrad irradiated molded sample has higher toughness than the 5 Mrad irradiated extruded sample.
  • Figure 13 is a graph that compares the J integral values for 20 Mrad directly molded 4150HP with the 10 Mrad irradiated ram extruded sample.
  • the 20 Mrad irradiated molded sample has higher toughness than the 10 Mrad irradiated extruded sample.
  • the direct molded irradiated material and articles according to the invention can withstand considerably more radiation, (thereby improving wear resistance more than the prior art) while maintaining the same fracture toughness (or even better fracture toughness) than extruded or sheet-molded materials or articles of the prior art that received considerably less radiation.
  • the materials/articles of the invention have better toughness than their extruded or compression sheet-molded counterparts of the prior art receiving a lower radiation dose.
  • the Molded Cross Linked, Low-Modulus Polyethylene materials according to the invention will preferably have oxidation resistance and low modulus (which provides for low stresses). They have a significantly improved wear resistance afforded by higher than 4, preferably at least 5, and most preferably at least 10 Mrad irradiation without significant loss of fracture toughness vs. non-directly molded counterparts.
  • a directly molded, cross linked polyethylene with modulus ⁇ 800 MPa would be advantageous in total knee replacements where the stresses are high and a decreased modulus is desirable.
  • the upper limit of the radiation dose depends on many factors, inclu ⁇ ing the degree to which the wear properties need to be improved. There have been reports in the art of doses as high as 100 Mrads or 200 Mrads, but the optimum will depend on the properties that need to be achieved, and especially the trade off that can be made between fracture toughness and wear properties.
  • UHMWPE polyethylene resin commonly used to make total joint replacement devices can be used to make direct-molded, irradiation- crosslinked articles according to the invention.
  • Non limiting examples are:
  • Devices according to the invention can be made by methods known in the art, exemplified in U.S. Patent No. 5,702,458, Dec. 30, 1997, Joint Prosthesis, Burstein, Albert H., et al.; U.S. Patent No. 5,314,479, May 24, 1994, Modular Prosthesis, Rockwood Jr., Charles A., et al.; U.S. Patent No. 4,822,364, Apr. 18, 1989, Elbow Joint Prosthesis, Inglis, Allan E., et al.; U.S. Patent No. 4,778,475,
  • Fracture Toughness Testing The fracture toughness of different materials was evaluated using the J Integral method. This testing results in the generation of a curve that relates the energy required to grow a crack certain distance. The energy units are KJ/m 2 and the crack growth distance is in mm. The higher the J value, the tougher the material. These tests were conducted on 10 x 20 x 90 mm samples with a single edge notch, in accordance with ASTM D813-81.
  • Group 1 extruded and gamma irradiated
  • Group 1A extruded and electron beam irradiated
  • Group 2 directly molded and gamma irradiated
  • Group 3 directly molded and gamma irradiated but with a different polyethylene resin grade than the other 3 groups.
  • Group 1 Ram extruded 4150HP UHMWPE: gamma irradiated.
  • the original polyethylene resin was provided by Hoechst Celanese now called Ticona (Houston, Texas) and the ram extrusion conducted by PolyHi Solidur (Fort Wayne, In.). The material was then machined into J integral test specimens. At least 6 samples (10 x 20 x 90mm) were irradiated at each of the following gamma irradiation doses: 0, 2.5, 5, 10, 20, 50 Mrads. J integral testing was conducted and the amount of energy per unit surface (kJ/m 2 ) vs ⁇ a (change in crack length) was obtained at each dose.
  • Group 1A Same material as Group 1 but electron beam irradiated. The material was then machined into J integral test specimens. At least 6 samples
  • Group 2 Directly molded 4150HP resin.
  • the resin used was from the same lot and of the same grade used to make the ram extruded material in Group
  • Samples were prepared by direct molding 4150HP powder into 4 molds with the dimensions 10 x 20 x 90 mm. Sufficient polyethylene resin was used to ensure fully dense specimens. Stainless plates covered both surfaces of the mold. The platens of the press were heated to 165°C and the mold was placed between the platens. The pressure was raised to 8.1 Mpa using a Carver 2699 hydraulic press for a period of time long enough to completely melt all the polyethylene powder (typically longer than 5 minutes). The pressure was released and the mold was immediately quenched in room temperature water to produce a material with modulus ⁇ 800 MPa. This provided a cooling rate of approximately 175°C/minute.
  • At least 6 samples (10 x 20 x 90mm) were irradiated at each of the following gamma irradiation doses: 2.5, 5, 10, 20, 50 Mrads. J integral testing was conducted and kJ/m 2 vs ⁇ a (change in crack length) was obtained at each dose.
  • Group 3 directly molded 1900 resin. The same molding conditions were used as for Group 2 except that 1900 UHMWPE resin (Montel, Wilmington, De.) was used instead of 4150HP.
  • 1900 UHMWPE resin Montel, Wilmington, De.
  • At least 6 samples (10 x 20 x 90mm) were obtained and irradiated at a gamma irradiation dose of 5 Mrads. J integral testing was conducted and kJ/m 2 vs ⁇ a (change in crack length) was obtained.
  • Table 1 presents KJ/m 2 required to grow a crack .5mm as a function of irradiation dose and type for Gamma and Electron Beam Irradiated
  • Crosslinking is determined by the final product having less than 50% extractables, as determined by ASTM D2765-90 test.

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  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Veterinary Medicine (AREA)
  • Public Health (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • Surgery (AREA)
  • Vascular Medicine (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Dermatology (AREA)
  • Medicinal Chemistry (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Transplantation (AREA)
  • Materials For Medical Uses (AREA)
  • Prostheses (AREA)

Abstract

L'invention concerne un polyéthylène robuste, résistant à l'usure, possédant un poids moléculaire extrêmement élevé (UHMWPE) et préparé par réticulation d'un articule façonné en UHMWPE au moyen de doses d'irradiation supérieures à 4 Mrads, de préférence supérieures à 5 Mrads et, dans un mode de réalisation préféré, inférieures à 10 Mrads. Elle concerne, en particulier, des dispositifs de remplacement total d'articulations, ainsi que des procédés servant à les fabriquer pour la hanche, le genou, le coude et l'épaule.
PCT/US2000/040494 1999-07-30 2000-07-26 Materiau façonne en polyethylene reticule, resistant a la fracture, possedant un poids moleculaire extremement eleve et articles fabriques avec ce materiau WO2001008713A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CA002403357A CA2403357A1 (fr) 1999-07-30 2000-07-26 Materiau faconne en polyethylene reticule, resistant a la fracture, possedant un poids moleculaire extremement eleve et articles fabriques avec ce materiau
AU76270/00A AU7627000A (en) 1999-07-30 2000-07-26 Fracture-resistant, cross-linked ultra high molecular weight polyethylene shaped material and articles made therefrom
EP00965571A EP1404387A1 (fr) 1999-07-30 2000-07-26 Materiau faconne en polyethylene reticule, resistant a la fracture, possedant un poids moleculaire extremement eleve et articles fabriques avec ce materiau

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US14647499P 1999-07-30 1999-07-30
US60/146,474 1999-07-30

Publications (2)

Publication Number Publication Date
WO2001008713A1 true WO2001008713A1 (fr) 2001-02-08
WO2001008713A9 WO2001008713A9 (fr) 2002-08-15

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PCT/US2000/040494 WO2001008713A1 (fr) 1999-07-30 2000-07-26 Materiau façonne en polyethylene reticule, resistant a la fracture, possedant un poids moleculaire extremement eleve et articles fabriques avec ce materiau

Country Status (4)

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EP (1) EP1404387A1 (fr)
AU (1) AU7627000A (fr)
CA (1) CA2403357A1 (fr)
WO (1) WO2001008713A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997029793A1 (fr) * 1996-02-13 1997-08-21 Massachusetts Institute Of Technology Dispositifs de prothese a base de polyethylene a poids moleculaire tres eleve, traites par fusion et rayonnement
WO1998014223A1 (fr) * 1996-10-02 1998-04-09 E.I. Du Pont De Nemours And Company Procede de fabrication de prothese medicale en polyethylene reticule a poids moleculaire tres eleve a equilibre ameliore des proprietes a l'usage et de resistance a l'oxydation
WO1998016258A1 (fr) * 1996-10-15 1998-04-23 The Orthopaedic Hospital Polyethylene reticule a gradient de surface, resistant a l'usure

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997029793A1 (fr) * 1996-02-13 1997-08-21 Massachusetts Institute Of Technology Dispositifs de prothese a base de polyethylene a poids moleculaire tres eleve, traites par fusion et rayonnement
WO1998014223A1 (fr) * 1996-10-02 1998-04-09 E.I. Du Pont De Nemours And Company Procede de fabrication de prothese medicale en polyethylene reticule a poids moleculaire tres eleve a equilibre ameliore des proprietes a l'usage et de resistance a l'oxydation
WO1998016258A1 (fr) * 1996-10-15 1998-04-23 The Orthopaedic Hospital Polyethylene reticule a gradient de surface, resistant a l'usure
WO1999052474A1 (fr) * 1996-10-15 1999-10-21 The Orthopaedic Hospital Polyethylene resistant a l'usure a gradient de surface de reticulation

Also Published As

Publication number Publication date
EP1404387A1 (fr) 2004-04-07
WO2001008713A9 (fr) 2002-08-15
CA2403357A1 (fr) 2001-02-08
AU7627000A (en) 2001-02-19

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