Methods of making a layered consolidated UHMWPE for use as a medical implant, and products made by the methods
The present invention relates to methods for making wear and oxidation resistant polymeric materials by high temperature melting. The invention also provides methods of making medical implants containing cross-linked antioxidant-containing tough and ductile polymers and materials used therewith also are provided.
1. A method of making a layered consolidated UHMWPE for use as a medical implant, wherein the method comprises the steps of:
blending a first ultrahigh molecular weight polyethylene (UHMWPE) powder, flakes or particles with at least one pharmaceutical agent excluding vitamin-E in a solvent that comprises water and ethanol to provide a first UHMWPE blend;
drying the first UHMWPE blend;
consolidating as layers the UHMWPE blend from drying step with a second UHMWPE without blending to a pharmaceutical agent to yield layered consolidated UHMWPE comprising at least one pharmaceutical agent excluding vitamin-E in one layer; and
machining the layered consolidated UHMWPE.
2. The method according to claim 1 , wherein the second UHMWPE is a consolidated UHMWPE.
3. The method according to claim 1 , wherein the consolidating step is by direct compression molding.
4. The method of claim 1 , wherein the second UHMWPE comprises a peroxide and an antioxidant.
5. The method according to claim 2 , wherein the first UHMWPE is cross-linked and oxidation resistant.
6. The method according to claim 3 , wherein the second UHMWPE was consolidated and heated to a temperature of at least 200° C.
7. The method according to claim 1 , wherein the drying is carried out under vacuum and a temperature below the melting point of the UHMWPE.
8. The method according to claim 1 , wherein the medical implant is selected from the group consisting of tibial insert, an acetabular liner, a glenoid liner, a patella, an interpositional device for any joint and a unicompartmental insert.