Radiation melt treated ultra high molecular weight polyethylene prosthetic devices
AssigneesThe General Hospital Corporation, Massachusetts Institute of Technology
InventorsEdward W. Merrill, William H. Harris, Murali Jasty, Orhun Muratoglu, Charles R. Bragdon, Daniel O. O'Connor, Premnath Venugopalan
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Abstract
A medical prosthesis for use within the body which is formed of radiation treated ultra high molecular weight polyethylene having substantially no detectable free radicals, is described. Preferred prostheses exhibit reduced production of particles from the prosthesis during wear of the prosthesis, and are substantially oxidation resistant. Methods of manufacture of such devices and material used therein are also provided.
Claims25
A preformed material for subsequent production of a wear resistant medical implant comprising a cross-linked consolidated Ultra High Molecular Weight Polyethylene (UHMWPE) produced by a method comprising the steps of:
- (a) irradiating consolidated UHMWPE to cross-link polyethylene molecules and to achieve an absorbed radiation dose and generate radiation-induced heat, wherein the UHMWPE is pre-heated to a temperature below the melting temperature of the UHMWPE;
- (b) following step (a), subsequently irradiating the consolidated cross-linked UHMWPE to achieve a subsequent absorbed radiation dose and generate further radiation-induced heat, wherein the temperature of the consolidated cross-linked UHMWPE is above room temperature and below the melting temperature of the consolidated cross-linked UHMWPE;
- (c) repeating step (b) until a total absorbed radiation dose of 7.5 to about 100 MRad is obtained;
- and
- (d) allowing the cross-linked consolidated UHMWPE to cool.
A method for increasing the wear resistance of a preformed Ultra High Molecular Weight Polyethylene (UHMWPE) comprising the steps of:
- (a) irradiating the preformed UHMWPE in the solid state to cross-link UHMWPE molecules and to achieve an absorbed radiation dose and generate radiation-induced heat, wherein the UHMWPE is pre-heated to a temperature below the melting temperature of the UHMWPE;
- (b) following step (a), subsequently irradiating the preformed cross-linked UHMWPE to achieve a subsequent absorbed radiation dose and generate further radiation-induced heat, wherein the temperature of the preformed cross-linked UHMWPE is above room temperature and below the melting temperature of the preformed cross-linked UHMWPE;
- (c) repeating step (b) until a total absorbed radiation dose of 7.5 to about 100 MRad is obtained;
- and
- (d) allowing the preformed cross-linked UHMWPE to cool.
A medical device comprising a Ultra High Molecular Weight Polyethylene (UHMWPE) material produced by a method comprising the steps of:
- (a) irradiating consolidated UHMWPE to cross-link UHMWPE molecules and to achieve an absorbed radiation dose and generate radiation-induced heat, wherein the UHMWPE is pre-heated to a temperature below the melting temperature of the UHMWPE;
- (b) following step (a), subsequently irradiating the consolidated cross-linked UHMWPE to achieve a subsequent absorbed radiation dose and generate further radiation-induced heat, wherein the temperature of the consolidated cross-linked UHMWPE is above room temperature and below the melting temperature of the consolidated cross-linked UHMWPE;
- (c) repeating step (b) until a total absorbed radiation dose of 7.5 to about 100 MRad is obtained;
- and
- (d) allowing the cross-linked consolidated UHMWPE to cool.
Dependencies are inferred from the claim text.