e-plus

e+™
e+ Tibial
e+ Patellar
e+™
e+ Tibial
e+ Patellar
e+™

e+ Polyethylene

The knee-specific formula of the tibial inserts and patella components are blended with vitamin E and moderately cross-linked toreduce oxidation and reduce long-term wear.1

Re-Melting Not Required

In the case of most highly cross-linked polyethylenes, an anneal or re-melt step occurs following cross-linking to link free radicals (created by the irradiation). Annealing or re-melting polyethylene can reduce mechanical strength properties.2

Because vitamin E neutralizes the negative effects of free radicals,2 an anneal or re-melt step is rendered unnecessary. In a material yield strength test, compression molded samples and e+ samples performed statistically the same, while a highly cross-linked re- melted sample exhibited a 12% drop in yield strength.1

Maximum Mechanical Strength

The impact of oxygen exposure to e+ samples was evaluated in accelerated aging tests. Un-aged and aged e+ samples yielded the same results during yield strength testing.

Impact testing for the aged e+ sample actually revealed slightly better results than the un-aged sample1, indicating that oxygen has no negative impact on e+.

Blended In

Vitamin E is blended right into the resin, assuring complete homogeneous distribution. Scatter Electron Microscope (SEM) and polarized light microscopy from freeze fracture specimen show that e+ has equivalent consolidation as conventional compression molded UHMWPE.1

Accelerated Aging Performance

Infrared spectroscopy (FTIR) analysis showed no detectable oxidation in un-aged and intensely aged e+ samples.1 This explains why intense aging appears to have no effect on test samples.

Naturally Occurring Anti-Oxidant

Vitamin E (α-tocopherol) is the most effective naturally occurring anti-oxidant in the human body.2

  1. e+ testing data on file. Bench test results not necessarily indicative of clinical performance.
  2. S.M. Kurtz. “The UHMWPE Handbook: Ultra-high Molecular Weight Polyethylene in Total Joint Replacement”. Elsevier Academic Press, 2009.Jennings et al. The influence of femoral condylar lift-off on the wear of artificial knee joints. Proc Inst Mech Eng [H]. 2007 Apr;221(3):305-14.