OXIDATION RESISTANCE

Vitamin E is widely present in the human body and it is the most effective antioxidant: it reacts with free radicals in cell membranes and protects macro-constituents from degradation due to oxidation.^[2]

Vitamin E reacts with free radicals of highly crosslinked UHMWPE and prevents their reaction with oxygen, resulting in E-CROSS oxidation resistance.^{[2, 7, 10]}

By stabilizing free radicals, the material is more resistant to ageing and ageing-related complications, such as delamination and wear.^[6,10]

HIGH MECHANICAL STRENGTH

In the context of improving the wear performance, maintenance of the mechanical strength is important, in order to avoid the fracture and delamination of TKA inserts.^[1,11,12]

A relevant parameter for the definition of the mechanical strength is the tensile yield stress, i.e., the maximum tensile stress that the material can withstand without undergoing plastic deformation.

The crosslinking process improves the wear resistance of E-CROSS compared to conventional UHMWPE. As confirmed by laboratory tests, the presence of Vitamin E avoids the need for additional thermal treatments that may compromise the mechanical strength.^{[3, 7]}
 

ULTRA-LOW WEAR RATE

The GMK Sphere design optimizes the load distribution to reduce stress levels and to minimize polyethylene wear.^[7]

GMK Sphere has a lower risk of polyethylene delamination and has less than half the average wear rate observed in other fixed bearing knee implants.^{[7, 13]}

The GMK Sphere tibial insert in E-CROSS further improves the already excellent performance in terms of wear and delamination resistance of the GMK Sphere inserts.^[7]

E-CROSS tibial inserts have been tested in a knee simulator and have shown a 21% polyethylene wear rate reduction when compared to UHMWPE inserts.^[7]

E-CROSS'S MANUFACTURING PROCESS

• UHMWPE resin is blended with Vitamin E and subjected to compression molding.
• Irradiation is applied to initiate the highly crosslinking process.
• The material is machined into its final shape.

The blending process prior to compression molding allows for a more uniform distribution of Vitamin E inside E-CROSS, and therefore a better control of the material‘s properties and oxidation resistance.^{[1, 6]}

E-CROSS is not subjected to radiation during sterilization that could cause the formation of free radicals.^{[7, 8, 9]}