Surfaces to control tissue adhesion for osteosynthesis with metal implants: in vitro and in vivo studies to bring solutions to the patient.

For internal fracture-fixation, metal currently remains the material of choice, since it provides strength for bone fragment support, good ductility for presurgical contouring and has been shown extensively to be biopassive. For decades, the application of metal internal fixators has proven undoubtedly successful and is deemed by many as the greatest advance in orthopedic medicine to date. However, based on this unrivalled success, newer and more challenging applications for metal internal fixators have emerged. For instance, given the large increase in the occurrence of these procedures in children and the different mechanical and biological requirements based on anatomical site of implantation, the functional requirements of metal implants have become increasingly more demanding. Given this changing demand for metal internal fixators, a more pragmatic application approach is necessary. Therefore, current metal internal fixator-related orthopedic research is based on defining specific cell and tissue responses to materials both in vitro and in vivo, as well as methods to empirically facilitate implantation site-specific tissue responses. This review discusses current knowledge from both the author's as well as others' laboratories pertaining to cell- and tissue-specific responses to metal internal-fixation materials, with specific emphasis on a surface microtopographical approach to alleviating removal-related morbidity. The review also describes the 'effective roughness spectrum' hypothesis for control of cell surface integration.