Biodegradable Orthopedic Implants

current treatments using nondegradable fi xation materials have proven effi cacious, tissueengineering approaches with biodegradable implants are being considered as promising future alternatives [8, 49]. One possible advantage of these systems is that biodegradable implants can be engineered to provide temporary support for bone fractures, and because they can degrade at a rate matching new tissue formation, their use can eliminate the need for a second surgery [49]. In addition to providing support for the tissue surrounding a defect, the scaffold can serve as a substrate for seeded cells, facilitating new tissue formation at the site of injury [35, 100]. The incorporation of drugs or bioactive molecules may also accelerate new tissue formation, or can be used to treat specifi c conditions, such as osteomyelitis [4, 10]. In designing biodegradable orthopedic implants, several important factors should be considered. First, the material should degrade over an appropriate time, so that the scaffold functions as a temporary support, but allows space for newly generated tissue to replace the defect [49, 91]. Second, neither the initially implanted biomaterials nor the degraded materials and related products, such as monomers, initiators, and residual solvents, should elicit a serious infl ammatory or immunogenic response in the body [28]. Finally, the material should possess suffi cient mechanical strength to sustain loads applied to defects during the healing process. Additionally, the material should show a decrease in mechanical strength as defects are replaced with new tissue to List of Abbreviations