Osteolysis, or bone loss, in the vicinity of an orthopedic implant induced by the wear debris from implant devices is a significant challenge for patients with orthopedic implants and for clinicians treating these patients.
Attempts have been made to reduce the production of wear debris from implanted devices by coating articulating portions and/or other wear-prone portions of these devices to reduce friction. For example, biocompatible phospholipid polymers, such as 2-methacryloyloxyethyl phosphorylcholine (MPC), have been coated onto implants in an attempt to decrease friction between contacting device portions and, thus, reduce the production of wear debris. Moro, et. al., “Surface Grafting of Artificial Joints with a Biocompatible Polymer for Preventing Periprosthetic Osteolysis,” Nature Materials, 3, 829 (2004).
Hydrogels have shown promise for use in a variety of implantable devices and materials due, in part, to the biocompatibility and durability of materials formed from hydrogels. Additionally, hydrogel materials may exhibit rubbery and pliable behaviors, and/or have highly lubricious surfaces. An overview of considerations for biological and medical applications of hydrogels can be found in Peppas, et al., Ann. Rev. Biomed. Eng. 2, 9 (2000), which is incorporated by reference in its entirety.
Because of these properties, hydrogels are considered excellent lubricants for coating onto implantable medical devices. Unfortunately, hydrogels do not adhere well to certain metal, polymer and/or ceramic materials commonly used to manufacture implantable devices, and therefore, hydrogels may be difficult to coat onto the surfaces of such materials.