Soft materials that aim to reproduce the tribological function of the natural joint are gaining popularity as an alternative concept to conventional hard bearing materials in the hip and knee. Polyurethane (PU) elastomers, in particularly polycarbonate urethane, are among the highest performing medical-grade polymers. They have mechanical and biological properties that make them suitable for use in orthopedic implants, as they demonstrate a unique combination of toughness, durability, flexibility, biocompatibility, and biostability. As presented in this paper, newly developed implants based on polycarbonate urethane perform more similarly to the natural joint in their mechanical response to load, and in their ability to utilize a thinner structure similar to that of cartilage, without jeopardizing the integrity or stability of the implant. Several wear studies of implants based on PU demonstrate a very low damage level to the implants’ articulating surfaces following repeated loading, and provide good assurance that this material can generate a low and stable wear rate in the long term. Animal studies further provide understanding of the biological response to PU implants in the hip and knee. Short-term clinical results are now becoming available from several commercial products. These generally show good functioning of these implants in the body and no material-related complications.
*Active Implants LLC, Memphis, TN
†New England Baptist Hospital, Boston, MA
B.M. conducts clinical research for Active Implats. Brian McKeon, MD has no financial interest in Active Implants. J.E. is an Active Implants employee.
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