Screws made of bone are little studied in literature. Structural, mechanical and osseointegration/ osteoinduction-related aspects are important research topics to be addressed prior to the use of in vivo bone grafts. However, the first issue that should be addressed is the machineability of bone tissues. Another relevant issue is regarding the feasibility of building bone screws in pre-determined dimensions. In those researches, screws were made of cortical bone samples removed from the medial-diaphyseal portion of bovine tibiae in a standardized fashion. Bone machining was performed in a horizontal lathe by using two pieces of tool: steel bits and aluminum-oxide tip-mounted grindstone, producing 22 screws. The evaluation of bone screws' dimensions was performed in a profile projector, taking 10 metal screws as reference. In general, the metrological analysis showed no significant changes within bone and metal screws groups. Major dimensional problems found in both screw groups were: very high alpha angles in bone grafts and similar metal grafts presenting a body diameter in a much lower value than expected. We concluded that bone tissue is machineable and the production of screws with pre-defined dimensions was shown to be possible in the bone.
Bone screws; Biomedical Engineering; Biomechanics
