Wear-resistant antibacterial UHMWPE-based implant materials obtained by radiation crosslinking

The crosslinking of ultrahigh molecular weight polyethylenes (UHMWPEs) by irradiation has been employed for decades to enhance the wear resistance of these materials when used as a load-bearing implant component for joint arthroplasty. This surgical procedure can restore the mobility of patients affected by severe arthritis by the implantation of an artificial joint made of an articulating pair and a bearing component. While the surgery is usually successful, one of the most severe complications is peri-prosthetic joint infection (PJI), which can be extremely difficult to treat and eradicate. The use of UHMWPEs as a platform for the local delivery of antibiotics in addition to their structural function could be extremely beneficial for the improvement in the outcome of PJIs. In this study, we investigated whether irradiation can be used to sterilize and crosslink antibiotic-loaded UHMWPEs, and its effect on the drug eluting and antibacterial properties of these materials. We found that the antibiotics gentamicin sulfate and vancomycin hydrochloride were stable in irradiated UHMWPEs and did not hinder crosslinking of the UHMWPE matrix. Effective crosslinking led to optimal wear resistance, which was comparable to that of clinically available UHMWPEs. Sustained drug release was observed for an extended duration (up to six months) and both the drug eluents and eluted material surfaces showed antibacterial activity against Staphylococcus aureus, the most common causative bacterium for PJIs.