E-MAX is vitamin E-blended (E), mechanically-annealed (MA), crosslinked (X) polyethylene.
Developed in Conjunction with Renowned Polymer Experts
The E-MAX technology was developed by polymer scientists at Massachusetts General Hospital (MGH) and Cambridge Polymer Group (CPG). Engineers collaborated with MGH and CPG to tailor the material’s mechanical properties to meet hip and knee design requirements.
Each step of the E-MAX manufacturing process was designed to capitalize on lessons learned from the experience with first-generation XLPE.
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1 Raw Material 1020 UHMWPE resin is blended with 0.1% (by weight) vitamin E powder. |
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2 Form Bars Raw material is compression-molded into sheets and machined into bars. |
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3 Radiation Crosslinking Gamma radiation is applied, creating crosslinks and some residual free radicals. The vitamin E scavenges some of the free radicals that would otherwise form crosslinks, consequently reducing the crosslinking efficiency of any particular radiation dose.[1] Thus, engineers optimized the radiation dose for E-MAX, ensuring that the crosslink density for hip liners is comparable to 10 Mrad XLPE. For tibial inserts, where more fatigue strength is required, the radiation dose was optimized to achieve a crosslinking density comparable to 7 Mrad XLPE. [2] |
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4 Mechanically Anneal The bars are warmed and then compressed, allowing the residual free radicals to become mobile and combine into additional crosslinks—eliminating free radicals to near the detection threshold.[2,3] |
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5 Machine, Package, and Sterilize Components are machined, packaged and EtO-sterilized, thus avoiding the change in material properties or the reintroduction of free radicals associated with gamma sterilization. |
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- Kurtz S, Bracco P, Costa L. Chapter 16 Vitamin-E-blended UHMWPE biomaterials. In UHMWPE Biomaterials Handbook Second Edition (ed. Kurtz SM). Elsevier: Amsterdam, 2009.
- Materials Characterization testing. Test report TP0322. On file with KYOCERA Medical Technologies, Inc.
- Bhattacharyya S, Matrisciano L, Spiegelberg S, Harris W, Muratoglu O. Mechanical elimination of residual free radicals in an irradiated UHMWPE rod: advantages over melting. 50th annual meeting of the orthopaedic research society. 2004:1474.