e+™
e+™
e+ Polyethylene
2 Formulas, 1 Solution
DJO Surgical is proud to offer its e+ vitamin E blended polyethylene across all product lines. Two highly specialized formulas have been developed: a moderately-cross linked formula for sliding and gliding kinematics and a highly-cross linked formula for ball and socket type kinematics. Both formulations have been demonstrated to significantly reduce oxidation and long-term wear.1
Moderately cross-linked products:
- EMPOWR Knee System™
- 3DKnee™ System
- EXPRT™ Revision Knee
- Movation™ Knee
- AltiVate™ Anatomic Shoulder System
- Turon® Shoulder System
Highly cross-linked products:
- FMP® Acetabular Hip System
- AltiVate Reverse® Shoulder System
- RSP® Shoulder System
- Overview
- References
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
- e+ testing data on file. Bench test results not necessarily indicative of clinical performance.
- 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.