Radiation Degradation

Polyethylene cross-linked by irradiation has been used in a variety of consumer and industrial products over the last 40 years. The primary advantages of irradiation induced cross-linking include: greater tensile strength, improved thermal properties and increased abrasion resistance.
 
However, because irradiation causes molecular bond scission, residual free radical sites are inevitably left behind. This is particularly problematic for the polyethylene used in orthopedic implants. The subsequent oxidation caused by residual free radicals diminishes structural integrity, and thus makes the implant subject to premature failure in the patient.
 
Here we show how EPR is used as a quality control method for the release of polyethylene used in the manufacture of orthopedic implants.