It is widely recognized that early loosening of prosthetic components attributable to polyethylene wear debris is one of the main causes of failure in the medium-to-long term.
In the prosthetic components, due to UHMWPE deformability, wear debris are of micrometric dimensions elongated in shape (fibrils) and of nanometric dimensions, more spheroid in shape (nanoparticles).
Recently, crosslinking technologies have been developed, recognising four different steps:

• Radiation with gamma or beta rays at dose levels between 50 and 100 kGy, in order to achieve crosslinking.
• Heating at temperatures between 80°C and 160°C, to eliminate the residual free radicals generated during radiation.
• Machining of the component, which results in the removal of the superficial oxidised layer.
• Final sterilisation without radiation to avoid further alteration to the structure.

All UHMWPE types processed as above, have the following features (though with some differences related to treatment conditions):

• extremely low wear rates,
• absence of aging related phenomena and are indeed of great interest for clinical use.

Clinical trials are ongoing and the first positive preliminary results are now available¹.

After 10 million wear cycles on a hip joint simulator, the crosslinked UHMWPE wear rate is nearly zero and there is a significant difference between the 25 kGy sterilised and the crosslinked material wear rate. Therefore, after artificial aging, there is no difference in the wear rate for crosslinked UHMWPE².